lakeville weather journal

One day left in May...and not too bad a day at that. We have only had 1.08" of rain here in Lakeville this month...paltry in comparison to an extremely wet April (which rang in 3.85"). We will have a slight chance of seing some more in the May bucket before the end of the day as a short wave trough ripples through the Dakotas. Although relative humidities are not as high as they were over the holiday weekend, precipitable water is still present in moderate numbers for model runs tomorrow. The main question is the position of the jet streak, which is directly overhead. Should the jet shift a little to our north, we may get a better chance of precip, but for now models point to the opposite. So I will also have low chcs for precip tomorrow, but don't be surprised when a downpour shows up!

After tomorrow night, the trough will slide east and the jet will filter in some drier Canadian air. Between late Thurs and Saturday, the ridge will build in significantly behind a pronounced N-S jetstreak over the Mississippi Valley. Trends suggest that the models will shy from warmer temps despite the dryout. NWS-MPX already has considered raising temps in their forecast, and I will do the same. Longer term is very unconfirmed, however, as 1/2 the models move in a stronger wave/frontal system akin to last weekends, with high precip potential...and the other 1/2 keeps the strong ridge in place with nothing more than fair 80 degree days through early next week.

WEDNESDAY... Partly Cloudy, High 85. 40% chc of showers and thunderstorms after sundown. Low 65. Winds ENE 5-10 mph, shifting to SE overnight

THURSDAY ... Mostly Sunny, High 82. Low 63. Wind NW 5-10

FRIDAY ... Mostly Sunny, High 87. Low 65, N-NE winds 0-5 mph

Posted by pierre at 12:09 AM | Permalink

...1805 local...

Well, t-storm development did occur like expected, with one exception...nothing for Lakeville!! The front has propogated east enough to set up some very strong storms that developed just south and north of the metro, but then moved east of us as they entered mature stage.

Accoring to the latest look at the NOAA-Mesonet, the front is knocking on our doorstep, with definititve wind shifts noted in Meeker and Kandiohi counties already...and slight shifts in Carver and Scott. We will be next for the westerlies.

...SHORT TERM FORECAST (UPDATED)...

Steady to slowly falling temps through the PM expected, mainly after sundown.
40% chance of showers and thunderstorms until 10pm. Heavy rain and strong winds are possible with these storms. Low tonight 70. Chances for precip continue to decrease as night wears on.

Posted by pierre at 6:06 PM | Permalink

...at 1500 CDT/2000Z...

Line of strong storms formed from BJI south to about LXL (Little Falls) around 1330-1400 and is intensifying and pushing east...this line (per satellite) should continue to form along frontal bdy through STC and southward over the next few hours.

Secondary line, pre-fronrtal in nature, and most likely due to localized breaking of CAP in S MN, forming from Northfield to FBL, and over the IA border to MCW.

Both lines moving ENE at around 20 MPH. With the southern line having a 50/50 chc of clipping Lakeville on its way past, this should break the local cap more...evidence of this already with multiple TCU's (towering cumulus clouds) in the vicinity. As front out west of us advances, and the northern line builds southward, chance of storms and rain potential increases through the prime time hours this holiday evening...

...SHORT TERM LAKEVILLE FORECAST...

High of 93 achieved...steady to slowly falling temps through the PM expected, mainly after sundown.
90% chance of showers and thunderstorms, arriving around or after 6pm, and continuing until 10pm. Heavy rain and strong winds are possible with these storms. Low tonight 70

Posted by pierre at 2:53 PM | Permalink

As expected, things are coming together for a possible severe weather event today in MN. The Storm Prediction Center has written a mesoscale discussion this morning for the potential hail and damaging winds that storms could produce if they develop mid-afternoon.

1650Z NOAA-Mesonet obs show the surface front just west of a KRRT-KAXN-KOTG position, and moving slowly east. Should things "fire" in the realm of thunderstorms, this line will be a focal point. Assuming around a 20-30 mph movement of the front, this line should be at or near the Lakeville area between 4-6pm. Here is the only anomoly for southern or even east-central sections of the state - atmospheric capping. When the heating of the atmosphere is relatively even and saturated as you go higher, there is less tendancy for convective "buoyancy" of the air. The latest raobs are not up yet, but the 7AM launches both at MPX and INL had 10C up at 700MB (around the 10000 ft level), which is pretty warm for just after sunrise! Assuming the CAP is still in place, especially in southern MN, convection will be prevented.

Assuming the CAP is eroded or weakened, Lakeville's chances are not as great as folks up north. Near-term model solutions (namely the RUC) show best instability and potential north of STC through BRD, and then up towards INL. Although the ETA puts more instability behind (or in the wake of) the front, development of any line or complex of storms will most likely be north-to-south. In any case, I do think we will get wet...not certain about windy or drenched, but we will get wet!

REST OF MEM DAY... Mostly Sunny thru mid-afternoon, turning partly to mostly cloudy in evening, 60% chc of thunderstorms, some could be severe. High 95, wind S-SW 8-10, turning to the W-NW after sundown. Low 70.

Posted by pierre at 11:46 AM | Permalink

...Update as of 2220 CDT Fri...

Forecast is still right on par for winds and temps...other local forecasters also seeing similar guidance on this. Models now bumping temps even more for the next three days, so therefore will look at slight temp mods myself. Monday night rain scenario looks good now. ETA and GFS are slightly disagreeing on frontal passage timing, however. GFS has run very well so far on system movement, so will go with it for now. All severe indicies and rain potential have progged upwards with most recent model runs. Using NIU's Storm Machine outputs on forecast soundings per the GFS, I picked up moderate Showalter and Lifting Indecies, as well as high rel hum proggs in west-cnt MN around the 21Z-00Z timeframe Monday evening. I would expect lots of rain, if not a little wind and hail.
---updated forecast---
SAT - Sunny, humid. High 92, SSE wind 10-15 mph, low 72

SUN - Hot and Humid, Partly Cloudy by afternoon, High 95, South wind 5-10, low 72

MEMORIAL DAY - Partly Cloudy and Warm, High 92, 60% chc Thunderstorms in evening

Posted by pierre at 10:21 PM | Permalink

ETA Model predicted temps 7pm Sunday

My last entry examined the convective potential of the storm system slowly moving out of MN today. The MCS I was looking for evolved into a textbook squall line along the I-29 corridoor on Tues night. These storms hit mature stage quickly, topping out around 45000 ft within 2 hrs of initial development. This occuring after sundown, and with no low level flow "pushing" behind the storms for a faster eastward pace, only remnants grazed Lakeville in the early AM hrs yesterday. The front passed through much later than expected as well, allowing temps to rise up on a southerly flow quite quickly yesterday. We hit 83 here, and then temps fell off sharply as a secondary shortwave trough cycled through and brought a round of showers after about 6pm.

Looking forward to the holiday weekend presents us with the potential of 90 degree weather almost to a point of certainty. Our current weather maker is yet another cutoff low, now located in the Wasau-Stevens Pt., WI vicinity, and sliding southeast. There is an impressive surface ridge over the Four Corners that is expanding eastward quickly, and it will push out the low without much more adeiu.

The ridge has some maritime tropical origin and has warmed significantly over the desert SW. As it broadens its coverage east of the Rockies, it will park the upper jet on the Canadian Shield tomorrow, allowing the warmth to build back in...a surface low will form near Devils Tower, WY, and a trough will form up along the Front Range. As this low deepens at the surface, the jet will trough in earnest in the Pacific NW, swinging around the low and then streaking back up northward to Canada. This will be the catalyst for a strong southerly flow for MN.

Models are showing a 60+ kt low level jet streak, ushering hot and humid conditions into MN for the weekend. We can count on 85 pushing 90 for Saturday with a warm, humid southerly breeze for the bass opener - and no precip in the cards that I can see. As we approach Sunday and Monday, my concerns turn to covective potential. The models hold extremely high dewpoints through the weekend, and moderate precipitable water values - so saturation is present. CAPE values on the 12Z ETA run soared in Central MN Sunday evening to 3500-4000 J/kg, and lifted indicies are moderately high as well...the problem is that the ridge will still be in control, and vorticity models do not concur for development -- and the Devils Tower low will still be omega blocked by the ridge.

So...Memorial Day is our first potential day for precip of the weekend...but timing is a problem. This far out the models are not presenting much certainty for timing of frontal passage. As the weekend moves on, I will try to post some updates on precip chances for the holiday.

THURS AFT/EVE - Mostly Cloudy, 30% chc showers, high 72, NW wind 10-15, low 56

FRI - Sunny. Warmer, with a high of 84, winds N, shifting to W by midday 5-10

FRI PM - Clear, light SE wind 5-7, low 64

SAT - Sunny, humid. High 87, SSE wind 10-15 mph, low 72

SUN - Hot and Humid, Partly Cloudy by afternoon, High 92, South wind 5-10, low 72

MEMORIAL DAY - Partly Cloudy and Warm, High 86, 40% chc Thunderstorms in evening

Posted by pierre at 12:47 PM | Permalink

My Tuesday forecast has been right on track with one exception - temps have now well surpassed by guess of 76. We hit 84 in the 1400 hour, and that temp seems to have stabilized. Dewpoint has now hit 50 as well, so we are experiencing a summer (not spring) day in Lakeville. Looking at the NOAA-MADIS network of surface observations, temps have hit 88-90 and dewpts are 60-65 along the SD-MN border. Forcing is farther west yet, but once it moves into this area of maximum potential (in terms of heating and moisture) some decent storms should fire up in SW MN.

I would expect a MCS (mesoconvective system) forming and moving out of the Sioux Empire ENE towards us late tonight - let's say 9-10pm. Depending on the extent of the MCS and the following debris layers of cloudiness tomorrow, we may have a secondary event firing overhead around the lunch hour Wednesday. Precipitable water values in the models continue to run relatively high for the period, so in any case higher chances of precip are better than lower. As the associated low centers over western Lk Superior tomorrow afternoon, and then moves ESE thru the day, we should at least see some wrap-around showers as the low deepens.

Lucky for us, warm advection will continue through the week, and although tonight and tomorrow's passing system will slightly lower the temps, we will not see highs drop out of the 70's. In fact, we could see a rebound to 80's pushing 90 by weekend. The GFS outputs also tag on some hefty dewpts, so I can see a good shot of mid-80's plus as long as we maintain a southerly-or-westlery flow over the weekend.

TUES NIGHT - T-storms arrive 9-10pm, south winds 5-10, some storms with heavy rain, freq ltning. Low 67

WED AM - Partial Clearing, south wind, turning westerly 5-10, increasing clouds after lunch

WED PM - 50% showers and thunder after 1pm, high 75. Wind turning WNW 10-15

THURS - Mostly Cloudy, 30% chc of passing showers/thunder, high 77, WNW wind 10-15

FRI - Mostly Sunny, Dry, high 84

SAT (MN Bass Opener...how is this for biased optimism?!) - Partly Cloudy, Humid, high 88!!

Posted by pierre at 3:33 PM | Permalink

I am glad I took (most of) the weekend off from forecasting. The MPX forecasters and the local news guys all missed the vorticity-induced strand of showers that scattered down from ND into MN throughout the day. This was behind an unforecast shift in the jet that caused the instability to increase. Most of the Twin Cites metro saw a beautiful morning today with loads of sun and quickly increasing temps level off into mediocrity with temps only barely tagging the 60 degree mark by the beginning of sundown and mostly cloudy skies.

That impulse has moved east now, and skies are clearing out. Winds have already dropped silent, and without any low-level advection to speak of under the increasing high pressure, frost concerns are in the cards tonight in rural areas. Mainly north and east of the Metro, temps will definitively hit close to freezing, and with dewpoints right about 30-33, that means frost. Here in suburban Lakeville, we will miss the mark...I am thinking about 38 for the low (still chilly tho!)

So this week will have a nice fresh start. A cool Monday AM with sunny skies will create a good environment for dirunal heating. We should see 70 for real tomorrow. Tuesday introduces a nice ripple in the mid and upper level jets, which accoring to early models will bring a rain/thunder feature for Tuesday PM. The SPC raised their eyebrows tonight over this feature, and put us under a slight risk for severe storms for that time period. The GFS wants to give it all to us; timing the precip in "prime time" around the 00Z mark, precip H2O and lifted indicies at sub-tropic levels, and the vorticity plots lining up in classic form for a MSP-area severe weather outbreak. The ETA wants to put these features in a concentrated MCS forming along the SD-NE-IA border intersections, and move NE into MN. This has been a common trend for the ETA this spring, without much merit. ETA has nice CAPE predictions as well, but they align more with a West-Central MN spawning ground for the event.

General agreement in the models about the "instigator": a short wave and associated surface cold front that will push over the Central Rockies by late Monday night. Future model runs should hopefully give some creedence to the placement of our rain and thunder by tomorrow night.

MONDAY/MON NIGHT - Clear, light winds, high 70, low 45

TUESDAY - Clear turning partly cloudy in late afternoon, High 76, S wind 5-8 mph

TUESDAY NIGHT - Partly Cloudy, 50% chance showers and thunderstorms, 6-8pm, low 55

WEDNESDAY - Clearing skies at daybreak, then clouds return in erly afternoon, 40% chc showers and thunder, high 72-75. Low wed night 48.

Posted by pierre at 9:58 PM | Permalink

It happens to be my favorite season...and today will prove my point well. Yesterday's prog is right on track. The cold front is moving south over MN, and at this time is between St. Cloud and Brainerd. Ahead of the front, some towering cu's are popping near the 'Cities, fueled by the sunrise. Once the front passes, we should have a mostly-sunny to partly-cloudy day, breezy behind the front, but warm, drier air has filtered in ahead of the front. Temps will move north of 70 with the lower humidities.

High pressure will continue to move in behind the front, but the jet will keep significantly warmer air bottled up over the great basin and desert SW. Will have to look forward to today's soundings to see if the pattern shows a break to get us into a more "late-spring" setup with warmer temps and increasing humidity over the weekend. Enjoy the end of the workweek!

TODAY - Partly cloudy, high 76. North winds 15, gusting to 25 mph in the afternoon

TONIGHT - low 47, northwest winds 15 to 20 mph decreasing to 5 mph after midnight.

THURSDAY - partly cloudy , high 72. northwest winds 5 to 10 mph.

THURSDAY NIGHT - low 45. north winds 5 to 15 mph.

FRIDAY - partly cloudy. high 73. north winds 5 to 15 mph.

Posted by pierre at 8:30 AM | Permalink

So, I had typed up a huge analysis of the weather picture for the preceeding post, and a forecast. Somehow it was deleted in the posting process (most likely user error!). So here is an abbreviated discussion, as I am too lazy to do all that over again...

Today, dirunal showers and some thunder are passing through the eastern Metro. We hit our high of 73 already.

Wednesday, cold front swings out of Canada, "Clipper Style" and gives us some AM rain. Then clearing to another nice day, albeit breezy.

Models having problems with longer term, some saying dry and warmer, some saying mild and wet. So, uncertain after this week what the heck we will have. For now I tend to believe at least dryness for friday.

WED - 40% chc of AM showers, clring by noon, High 72, Low 45, Winds NW 7-15 mph

THU - Partly Cloudy, High 70, Winds NW 5-10

FRI - Partly Cloudy, High 75, Winds light and variable?

Posted by pierre at 4:53 PM | Permalink

Sunny skies have re-invaded Minnesota. (yay!) The late afternoon model runs yesterday had a huge shift as the balloon soundings returned with data suggesting the high pressure ridge was sweeping in on the upper jet much sooner than expetced. So now we have to deal with diurnal precip chances. Eastern MN has best chances, with CAPE values progged on the ETA at 1000-1500 J/kg.

Posted by pierre at 4:49 PM | Permalink

Fishing opener was as expected...which was not desireable! My friends and I braved the early Saturday weather on Lake Waconia to find walleye...with no luck. We did catch fish...but officially we were "skunked" (you MN anglers will know what I mean ;).

My forecast was right on...we did have the rain and the temps worked out correctly. The sun did peek out after 3pm. The problem with the forecast was the wind...it was more like 20mph plus out on the lake (my 5-10mph prog was the only "ray of hope" according to one friend, and that ray was snuffed out). Sunday was on par as well, with the exception of dryness...we had some showers in the AM, and then Lakeville remained dry. High was 60, not 63...but I like that margin.

So what the heck for the rest of the week? One look at the model outputs and it is pretty clear - we are stuck in a rut! The low clouds hanging around spread back to the middle of the Dakotas...and the dang low that we have been dealing with for a week now is still having trouble moving east. The upper jet is like frozen in position, swooping down from north-south along the Dakota border, then making a 90 degree turn at the Gulf of Mexico and heading east along the Gulf seaboard. Both the ETA and GFS hint at the Jet cutting off the low even more mid-week, when the max jetstreak shifts to a southern branch...I call it the "Sunset Limited" as it follows this well known transcontinental southern rail route.

Up north, we will see continued mixed clouds and sun. Unsure yet on major precip chances, but if dirurnal heating interacts enough with moisture and some mixed instability, we could have some splah-and-dash type showers through the next couple days.

TODAY - Mostly Cloudy - 30% chc of showers after noon, thru 5pm, High 62, N wind 5-10

Tuesday - Duplicate of TODAY, except high closer to 70. Some partial clearing after sunset.

Wednesday - Partly Cloudy, High 72, 30% chance showers or thunder after 3pm. Wind WNW 5-10

Posted by pierre at 11:29 AM | Permalink

MN Anglers (myself included) are looking forward to a special day tomorrow...the opening of fishing season. It's a pretty big deal in the "Land of 10,000 Lakes". Even the Governor makes a special trip to some MN locale to drop a line. One thing has been pretty much all-too-common for openers...the weather sucks! We Minnesotans don't really know why or how we have come to deserve such a curse...but there you have it.

So what happened? My forecasts have been pretty much on par, but yesterday I had a reprive from sitting down and scouring the models. This weather system has gone from a series of short waves into a monster of a long wave. The same "Gitchigummi Low" that plagued us early this week has now become a "Wolverine Low", and has parked yet again over lake Michigan, just to the northwest of Muskegeon. If you have seen the national radar or satellite loops, you have witnessed the intense wrap-up the low has done - the cyclonic flow is evident, and it looks much like a giant land-based hurricane. Of course (and thankfully) it is not anything else like a hurricane, though...no thunderstorms or tornados to speak of. Winds have been clocked over 70 mph on the immediate backside of the low in parts of WI yesterday, but these too are not hurricane like.

This is (as described many times) just a really deep pool of cold air that has concentrated in the atmosphere. The axis of the low is now "tilting" or "retrograding" now as forward (eastward progress) remains blocked. Instead of a neat sphereical mass, the pool becomes egg shaped, and is tilting back towards MN. The models all pinpoint this in agreement. So the next question becomes precipitation chances. The ETA wants it to rain pretty nicely through Saturday evening, giving us about a 50/50 chance of precip throughout. Other models (AVN and GFS included) have smaller chances, but they do not guarantee dryness.

I really hesitated to write this forecast entry this AM. It is really too depressing, but hopefully the models are proven wrong and the low breaks free and pushes off. Once can always hope, right?

TODAY... Rain Rain Rain. High 47. Low tonight 40. Wind NNW 10-20 mph
SAT ... Cloudy. 40% chance of rain in AM, then some breaks in clds by 3pm, high 52. Low 45. Wind N 5-10 mph.
SUN ... Partly Cloudy, dry. High 63. Good day to go for a walk with your mom! Wind N 5-10 mph.

Will update if needed. By the way...tomorrow is full moon. Solunar tables will point to around noon for best fishing.

Posted by pierre at 8:52 AM | Permalink

Above is Vorticity prog from the ETA model for 1300 CDT Wednesday

We hit 76!! Just think of all those forecasts a couple weeks back where I was thinking we would push 75, and it barely ever came true...now today when I thought 70 was reasonable, we break up to 76!! As moisture in the form of diurnal showers moved in, temps moderated back closer to 70-72. But what a day!! Sun mixed with the ol' splash and dash variety of showers. It was gorgeous...

Now on to pressing matters... Models are all in agreement about the unsettled pattern blocked in over MN. Yet another shortwave is going to swing down from Canada tomorrow around the axis of a surface low parked over northwest WI. Behind tomorrows wave will arrive the dreaded upper low the models have been forewarning of since last weekend. The kicker to all this is the mid-level vorticity...as both ETA and GFS models have the maximum vorticity values predicted to run from the MN Arrowhead, all the way down to Sioux Falls, and this "vort max" is predicted to stick around in the 700-500MB levels through late Friday. Precipitable water values in the models remain 1-1.5...couple that with the low(s), and the shower threat remains throughout.

Currently, we have mostly clear skies for the next few early AM hours. Then patchy showers will spread over metro thru sunrise. I like the MOS guideance from all models for tomorrow in relationship to sky conditions. Temps should remain supressed, and I think we will see 65 for sure, but would be surprised to go much higher...this is all dependent on amount of sun/cloud mix before deck of mid-level clouds overtakes us through the PM as the shortwave moves in and through. If conditions start out like Tuesday with lots of sun before noon, we will bust 70 again.

Wednesday... Partly Cloudy in AM, turning mostly cloudy after noon. 50/50 chc of showers. Cannot rule out a clap of thunder mixed in. High 67. NW winds 5-10

Wed Night... Mostly cloudy. Showers tapering off after sundown. Low 47. NW winds 5-10

Thurs/Thurs Night... Mostly cloudy, cooler. 40% chc scatterd showers. High 55. N wind 10-15 Low 42

Friday... Shower chance remains...temps 55-60, N-NW winds 5-15

Saturday... Partly cloudy, clearing, high 63. N winds turning NE 5-15.

Posted by pierre at 12:10 AM | Permalink

Waking up this AM to pure sunshine made me wander down to the computer to re-check models for the week...Now some alignment is happening with regard to the low - or the central pressure point - of our current weather maker. Checking MESONET data of both governmental and private weather stations this hour, good plot of surface winds correlated to the low center, wrapping around a point near Hinckley, MN. Central pressure of 1002 mb correlates as well, and stationary nature of the associated front or trough is characterized by matched pressure readings and fair wind/skies across MN this AM.

The problem with this setup, is that we may not see much movement from the low...models this AM show high pressure anchored over Appalachia blocking any eastward progress. The next short wave will usher in the upper level low, and we will get stuck with the cool, cloudy, spotty showers that are becoming too common. So for now, here is my update on the weekly planner (not getting better...)

Today: Partly, turning Mostly Cloudy, High 73, humid
Tonight: Mostly Cloudy, 50% chance of showers after 5pm, low 47
Wed: Partly Cloudy, 40% chc of showers, High 60, W winds 5-10
Wed Night: Cloudy, low 45, showers possible, W-NW winds 5-10
Thurs: Cloudy, cool, High 52 (ugh!), NW winds 10-15
Fri: Partly Cloudy, remaining cool, high 55, North winds 5-10
Sat: Partly Cloudy, high 65, eastlery winds, 10-20

Posted by pierre at 7:35 AM | Permalink

The main plan is to look forward to the weekend in this post, as friends have been asking for a good outlook for fishing opener this Saturday. I have some thoughts...but first a quick look at Tues thru Fri:

Tonights weather seems to be the first indicator of a system that will stubbornly hang on for a bit more. Models point to a couple more short waves (areas of low pressure) to rotate in from Manitoba as the relative humidities stay between 50 and 60 percent. A surface low should set up shop over western Lake Superior tomorrow night, and we should have a fair shot at some precip through the evening, as we will be still on the "warm and moist" side of things. This system will spin NE to allow an upper level low to drop in here Wed night into Thurs. This will be one of those "cold pool" lows we have seen already this early spring: cool temps, dreary skies, and damp. The warmth will be trapped well south by the jet which will be diving down along the front range of the Rockies into TX, AR, and LA. The accompanying cold pool of air, while seemingly "parked" over MN will be clashing with warm, moist Gulf air in these southern locales, and a nice mesoconvective event should setup for anyone living south of the Ozarks on Wed night.

Post Thursday has a lot to do with that surface low over Lake Superior and the somewhat-correlated upper low. If the Gitchigummi low deepens much, which it may, progress of any clearing before Friday late will be tough. In wake of the whole system, the flow will remain NWerly as high pressure builds back in. The GFS model run at 18Z hints at another shortwave or frontal system getting us wet by suppertime on opener (Sat PM). I have little confidence in this, especially as other models are favoring a sluggish exit of the early week system, followed by a strong ridge of high pressure by Fri. That being said, I think the GFS has had a good handle of these early spring systems thus far, especially with the jet parking warmer temps and Gulf moisture south of Interstate 80.

So, my prognosis (or weekly planner) is this:

Tonight: 40% chc showers and thunder, low 53
Tuesday: Mostly Cloudy, High 73, humid, 30% chc of showers
Tues Night: Mostly Cloudy, low 45, 50% chance of showers after 5pm
Wed: Partly Cloudy, High 60, N winds 5-10
Wed Night: Cloudy, low 45, showers possible, W-NW winds 5-10
Thurs: Cloudy, cool, High 52 (ugh!), NW winds 10-15
Fri: Sunny, warmer, high 65, west winds 5-10
Sat: Partly Cloudy, high 70, southerly winds, 10-20

This is the longest stab at a forecast I have ever attempted. I really hope the GFS is wrongo on the wave progged for opener...but this is Minnesota!!

Posted by pierre at 11:22 PM | Permalink

Interesting setup and resolution to tonights convective events across MN. Original line of storms (as depiected and commented on in the preceding post) fell apart after crossing the Couteau des Praries into west central MN. Then the front stalled out...in its place right now is a low pressure trough running currently Devils Lake, ND, to Morris, MN to Fairmont, MN, with a pressure of around 963 mb. This stallout occured just about the time the dryline set up along this same area, and with the cap eroded just after sundown significant potential remained for thundercell development. The bulk of activity has churned up along a line from Anoka to Victoria to Mankato to Fairmont (all in MN). Cells have clipped east-north-east at 30-40 mph.

As I write, MPX's 88D has picked up another line forming along the same points, now extending to Spencer, IA (at 2315CDT/0415Z). Some of these cells may work their way up to the southern metro and Lakeville. I would say at this point we have seen the bulk of activity for the night, although preciplitable water values have remained high in the models, most of this fuel is being stayed in Iowa, where they have had more severe activity tonight.

40% chance of showers and thunder through 2AM, then mostly cloudy thru the night, low temp of 53.

Posted by pierre at 11:10 PM | Permalink

Squall preceeding cold front is firing in area where the atmospheric cap has eroded according to balloon soundings from Aberdeen, SD this afternoon. Twin Cities timing looks to be 7-10pm for this convective activity. See previous post for discussion...

Posted by pierre at 4:43 PM | Permalink

The sun did come out again this weekend...Saturday was excellent, today was nice as well, although cloudiness rolled in around 10am. That was expected, as a thrust of moist and warm air in the mid to lower atmosphere moved up from around Omaha to Lakeville. Looking ahead now to the work week, rain will be coming, and soon.

Right now, a nice line of thunderstorms has formed up from Jamestown, ND, to Pierre, SD. This line is moving east at a leisurely pace...around 20 mph. Some cells have prompted severe t-storm warnings, but only for wind and dime-size hail...nothing tornadic. But as these storms move east through sundown, they will hold on to their shape some, as they overrun the moist airmass that has parked now over MN. The lighning will persist, but the hail certainly will not. The complex should resolve into a line of showers that I think may affect us here in Lakeville around rush hour tomorrow AM.

Some of the computer models are struggling with the aftereffects of this line of weather, because as it dissipates, it will leave a good stretch of clouds from central MN, stretching to about Eau Claire, WI. This may keep some temps moderated tomorrow here. However, I think western MN will be the focus of a good dryline by 3pm tomorrow. The 18Z runs of the NAM and GFS models are at odds of timing, and the NAM seems to "rush" the precip activity through the mid day to late afternoon. The GFS pays a little closer attention to the affects of a progged surface low shipping in from NE to west-central MN by around dinnertime tomorrow. It is this feature that has caught my interest.

Should conditions dry up significantly before the sfc low arrives, there could be enough spark for some good springtime thunderstorms. CAPE (Convective Available Potential Energy) predictions are looking to be around 2000 J/kg again from Sioux Falls to Granite Falls (as it was with the convection predicted last week). The "push" for all of this is the surface cold front that is right now drifting past Dickinson, ND...by 3 pm tomorrow it will be on a line about Fargo, ND-Watertown, SD-Scottsbluff, NE. Ahead of the front warm moist surface winds will stream in plenty of instability, augmented by the secondary rouge low pressure center.

Models show 30-50% chance for Lakeville to see rain after 5pm. So for now, I say expect some showers around dawn, giving way to partly cloudy skies, 70 degrees by 3pm with a line of thunderstorms developing in southwest-west central MN, arriving in Twin Cities between 6pm and 8pm.

I should have a busy afternoon and evening tomorrow outside of the weather world, so I may not to give updates after 5pm, but I will try to get some more certainty into this forecast before then!

Posted by pierre at 8:41 PM | Permalink

I am a little curious when we will get out from under the cold snap and mess of cloudiness we currently are having here in Lakeville. The early-week springtime weather has given way to the current pattern, and I would rather have the former. Speaking of which, the 8pm guess on thunder in Lakeville was dead on! A line of thunderstorms developed just west of here, almost on top of us. We received a lot of lightning and thunder, and a brief downpour - I think it worked out to about 0.06" in about 10 minutes.

Anyway, today should see brightening skies at some point...satellite images show that the clearing line just passed Bemidji in the northern part of the state at 1030. The trend will to be to clear from NW to SE over the day. Not tons of sun for us, but we will see the clouds break up towards suppertime. Then a warming trend will begin to occur...a cold and deep low pressure system anchored over Hudson Bay in Canada this week has been bending the polar jet around it, placing MN right under the river of cold air shipping in from the NW Territory. That flow will shift east, making room for a nice ridge of high pressure to center itself over Iowa. Temps will moderate north of 60 by Saturday noon. Expect 70+ for Sunday!!

Our next precip chance may come either late Sunday or sometime Monday. I am not sure which way to go on this one, as the models seem to be misaligned too much for my taste. NWS and others are leaning to Monday...I am going to wait a bit to take a stand on better timing. For now, lets say that we will see precip between 9pm Sunday and 9pm Monday. (That way we can still enjoy the weekend).

Posted by pierre at 10:44 AM | Permalink

Read the Tornado Watch text here.

Issued just as I hit "save" on the last post. I expect these storms to develop and move ENE over the evening hours. Looks like no major mods needed to my original predictions. DPs and RH in SW MN still high, despine dirunal showers. Plenty of southerly flow still too... Expect rumbles after 8pm in Lakeville.

Posted by pierre at 3:29 PM | Permalink

The Storm Prediction Center is on the verge of issuing a watch box for MN this afternoon, as indicated by Mesoscale Discussion 722:

A line of showers quickly developed in western MN, and is racing due east at around 35 mph, should clip the metro with some sprinkles. Behind that, however, the dryline has re-establihshed, per satellite imagrey, and the line of heavier cells we have been awaiting is firing from Sioux Falls to Yankton:

Posted by pierre at 3:05 PM | Permalink

All guidance from yesterday's entry regarding thunder tonight is on par. The picture is becoming more clear now on timing and strength as the models are settling for commonality in some elements. The NAM and GFS both have the mid-level convergence progged at 00Z-03Z, right between FSD and SUX. The cold front is taking shape in western NoDak right now, with definate wind shifts occuring last hour (1400Z) in DIK and RAP, and west of that line. Front should be about ABR-HON by mid-late afternoon, and I expect storms to start "firing" along the Dakota/MN borders shortly thereafter.

Severity will be determined by how much convergence actually occurs. CAPE values are modeled by the NAM to push 1500-2000 J/kg by 00Z in SW MN, so we know we have the instablility. Adding to these factors is an intense dirunal heatup...temps should break 80 in that part of the state today. SPC has wind and hail damage possible with their severity risk assesment. If upper jet (now predicted to sweep in quickly in late afternoon out of the west) intensifies at all, I think tornadic threat for SW MN will increase.

For us in Lakeville...today sunny and 76. Clouds increasing approaching mid-afternoon. Storms after 9PM, some with strong winds. Will update as needed.

Posted by pierre at 10:55 AM | Permalink

After hours of messing with the script (when it only should have taken 30 minutes) I have developed new weather stickers and banners for the website! Feel free to copy the code below each to add to your own webpages!

Posted by pierre at 12:33 PM | Permalink

We are finally seeing the back side of the weather system that generated the continuous rain activity over the weekend. We have seen about 1.6" here in Lakeville, and even as I write scatterd showers continue to wrap through the area.

The noon hour surface analysis showed the low now over Sauk Center, MN, and continuing to head north. Later today a pretty strong upper jet stream will finally swoop out of Manitoba and push out the system. This will allow for high pressure to quickly fill back in, along with a very warm low-level jet from the southwest. Temps should rebound quickly tomorrow with clearing skies and winds from the south-southwest (maybe 75...it is my favorite temp to shoot for lately?)

The interesting feature is the destabilization of the atmosphere in this transition phase. As the low-level winds bring in the warm air, upper winds will continue to intensify. The GFS model shows a H3 jet max speed of 110 knots nosing into western MN on Tuesday night, approaching midnight Wednesday...and the directional flow of that upper jet is troughing around the associated low progged to move out of Saskatchewan into Nodak as this new weather maker heads for MN. That low will serve energy to "pump" moisture into the system, and mid-level exhange winds between the low-level jet and the upper-level jet may give the right "twist" to the atmosphere to destabilize.

What does this all mean? Thunderstorms...and perhaps some "heartier" ones (as one NWS forecaster in Chanhassen characterized them) at that. The Storm Prediction Center has taken note as well, and has included MN in a slight risk for the severe weather. Typically, if they are putting us in that category 36 hours out...they have good reason to. So for now, we can count on some more precip, and some thunder for late Tuesday night into early Wed AM. Like always, we will have to wait and see...

For today, mixed sun, clouds, and spotty showers...very "splash and dash weather"...and highs around 60. Clearing after sundown, lows should dip to around 45-50. Tuesday, sun in AM and early afternoon, high 75. Increasing clouds for evening.

Posted by pierre at 11:59 AM | Permalink