lakeville weather journal

System advanced more cold and drier air in from the NW last night than expected in the model runs, thanks to a short-lived H70 circ that developed near KGFK overnight and raced off towards CYQT skittering away from increasing low and mid-level jet from northwest...as of this writing, (1830Z-ish) wind shift has just occured here at Lakeville. Temp and wind field changeover is bisecting the Metro east/west attm. -SN now in report from KFCM, and 5°F cooler, bringing them right to freezing at SFC. As I write, temp is dropping here at Lakeville from a high of 43 this morning, and as soon as we get 32 and the back side of the rain shield, snow should follow...

Low pressure center is over KALO attm, progged well by both NAM and GFS, but the 00Z and 12Z NAM runs continued to trend a little more slowly on progress...GFS has moderated its quick pace enough to bring back in some confidence on my part. RUC is tracking well, and places low center near KCWA at 2200CST, with max wind field out of the NW just entering metro. GFS concurs, and places a nice precip max over metro between sundown and 1900CDT. Only prob with this prognosis is the drying effect of the rapidly expanding ridge that is now centered over KBIS. MPX WSR-99D depicts the drying effect nicely as the edge of the rain/snow shield seems to be eroding from west to east, now along a KBRD-KILL-KMML line. Precip max right now is painted over KMKT and along the MN river valley until near Jordan, MN where the metro heat island is diminishing the rates. Another blob of precip (all in RA) is moving N along the boundary from KRST vcty towards SE metro. With temps falling the way they are, this might be first shot of mixed to -SN fall here in LVN, due to arrive within next 45 to 90 minutes (19Z to 2030Z)...thence the MN river swath will hook in from the west and SW side to give us a fleeting shot of SN.

All of this...barring any redevelopment...should give us anywhere from 1-3" of slushy wet snow. I expect the tapering and clearing to begin just after sunset, as opposed to the 12Z model runs...mainly due to that ridge pressing in from the west. So...here is your New Years forecast for Lakeville...see ya in 2007!!

New Years Eve...snow develops between 1-2pm, 1-3" of slushy accumulation. Tapering off by 6pm. Temps drop to low of 25 overnight. Partial clearing by midnight. NW winds 10-18 mph.
New Years Day...Mostly sunny. High 30. NW wind 10-15, diminishing after dark. Increasing clouds overnight, low 27.
Tuesday...Partly Cloudy. High 32. West winds 5-7 mph. Low 28.

Posted by pierre at 12:27 PM | Permalink

Now we are starting to see the snow picture a little more clearly...current regime for our area just became a bit more interesting. Sfc low has developed over Spirit Lake, IA (attm) at about 1017mb, with a very well defined trough/stationary front extending northward along the MN/Dakota borders. Southward from this low extends the ever-present cold front that extends through the main-system stacked H70 and H30 low that is positioned over KMCI attm,

Very large rain shield has moved northward from the IA low, and has dropped between 1/3" and 1/2" over most areas of southern and central MN. NAM guidance from 12Z run has been right on the money for the progress of this system...and I have no probs going with it for the outlook. Main concern still remains the freezing point...and it is so very very very close in so many snapshots in the models, everything is going to have to be categorical...will update in the AM:

Tonight...Rain. 100% chc. Low 35. ESE wind 5-7 mph.
Sunday...Rain. 100% chc. High 42. S-SW wind 5-10 mph.
New Years Eve...Rain, changing to freezing rain, changing to snow. Freezing rain possible after 9pm. Snow Possible after midnight. Low 32. Snow accumulation of 1-3" possible. Wind SW 5-10 switching to NW 10-15 mph after midnight.
New Years Day...Periods of snow. High 32. Wind NW 10-13 mph. Low 28.

Posted by pierre at 7:50 PM | Permalink

50/50...my prediction of chances for snow before 2006 comes to a close. The current weather regime really leaves a lot to be desired...in the way of certainty, and in the way it is affecting us. We are now locked under mostly cloudy skies for the rest of the year, as the main system has now pushed into NC TX with a quasi-stationary front arcing north from the sfc low through KS, northeastward from MCI to DSM, and then slicing back se-ward towards PIA and CMI. The front is subtle, with only about a 30 deg wind shift and a 1-3°C temp diff.

The 12Z runs on NAM and GFS are very divergent again, and herin lies the uncertainty factor. GFS seemed to have missed out on init and in the first 6-12hrs, as a quick surface analysis from mesonets defines the surface low well north of the model track. NAM nailed it, and gets the wind fields right as well, so I am going to lean towards it for this entry, just as I did in the last. Hardest thing to discern on these model runs is the LLJ, which seemingly has now taken on more of a mid-level prominence somwhere between 50H and 70H, rather than lower. Nonetheless, moisture transport has not been hindered...in fact the humidity analysis remains consistent with the model(s) development of the system over the last few runs.

NAM tracks the low much more slowly than GFS, and much akin to the track of the previous Devner storm (from last week). What is more defined on this modeling is the coupling of the upper low and the upper jet on this system...until we get past 48 hrs, where certainty hits a low again. Positioning of the jet and the surface low in the 12Z NAM makes the changeover from rain to snow for our area difficult to pinpoint...with precip chances harder to make out. It would seem from this vantage point that we could get cut-off before we see white (much like the previous storm)...but we just can't nail it down with this much ambigutiy on a model that has not fared the best in the 60-84hr timeframe as of late.

Looking at MOS does not give me the best reference point as well...nor have recent WFO forecast discussions been giving any hints. Right now, best "hints" I have going now are the NAM's positioning and deepening of the low as it traverses the MN/IA border New Years Eve, and a factor not realized yet by the models: new snowpack in Northern and Central MN! Right now a nice band of snow and mixed precip is falling in nrn MN, and adding to a 1-3" snowband that fell earlier from Lake Mille Lacs north and northeastward. Some mixed, slushy precip may also be falling in parts of the north metro. This could play a more definative affect on dynamic cooling of the system as it approaches from the SW on Sunday. Watchful waiting will remain the rule of the day...

Posted by pierre at 2:22 PM | Permalink

Here we are the week in-between Christmas and New Years, and once again the model maps are pointing to a pre-holiday mess. Much akin to the system that affected us late last week, the storm system now affecting the windward side of the Rockies should pose some unique forecast challanges as we move into the latter part of the week. First, however, a quick review of the holiday weekend...

Saturday night (Christmas Eve) the s/w actually did not slow up as the models had suggested, and instead raced through and mainly fizzled. Clear skies overnight led to sunny skies Sunday. As mid level moisture did move in as progged, however, the clouds did increase, and between late Monday and today (Wednesday) these cloud fields have thickened. We experienced no precipitation, and temps have remained seasonable, but yet on the mild side...highs holding in the 30's, and lows in the upper 20's.

Now looking ahead...currently a surface low has developed in central SD and its associated s/w is going to move southeasterly, with the cyclonic feature passing over SW MN, and keeping clouds prevalent across srn MN. This feature will weaken as it moves off, however, and rather than an increased north-northwest flow in passing, a very strong southerly flow at the low level develops tonight through the late Friday period. This will usher in moisture from the Gulf, as well as some isentropic uplglide from the flow over the dome of the sub-freezing temp air that hugs the surface of the MN/WI region.

The main feature of the upcoming system will be a 700MB low that develops over the four corners tomorrow afternoon. This low will move off the srn Rockies and over the TX panhandle as the jet stream dives deeper around it...also developing the split-jet regime that we saw last week, with the true polar jet remaining in mid-Canada and the southern branch racing around the low. This will block the arctic air up to the north, and models show no hint of release until maybe 1/2/07.

True aspect of the storm track is hard to discern at this point, as NAM and GFS diverge at about 24-30h, and to point, NWS-MPX threw out the NAM after 24h. The GFS does track the system slower and has been more accurate lately, and since we can't look past 84h with NAM, maybe GFS is the way to go. I think, however, there is one important feature that GFS does not capture like NAM does yet, and that is the strong LLJ that evolves ahead of the system...NAM is very definitive on this feature, and temp diferences aside the LLJ and theta-E advection developed by NAM looks very much like a "spring storm" setup. For this reason...and the NAM's initialization and prog of current SD sfc system...I like the NAM.

So for now, I am going to give some credit to the SD system nipping the TC metro with some precip tonight, and then stick with NAM MOS temps/clds/wind through the forecast. Precip type and chances for the last weekend of 2006 will remain an elusive part of the forecast for now, but initial look gives the impression of a rain-changing-to-snow system, with changeover happening New Years Eve...

Wednesday...Mostly Cloudy, High 41. 40% chc of rain after sundown. Low 30. SE winds 5-7pmh.

Friday...Mostly Cloudy, High 36. 40% chc of rain developing after noon. Then rain likely after sundown, low 32.

Posted by pierre at 10:10 AM | Permalink

Merry Christmas from Lakevilleweather.com!!

After being robbed by the previous system of any white Christmas chances, I was apethetic to update the postings regarding that storm. The event left the TC Metro half-white, and half-grey/brown, with the combo of ice and dormant vegetation in the south. While out and about on Friday, the MN River valley was definitively the factor in the snow making process...with cold air advection slipping southbound under the moderate southerly flow that was driving the RA/FZRA band northward, it must have pooled and abutted against the geographic feature of the southern bluffline (the Buck Hill/Cliff Fen/Johnny Cake/Pilot Knob "rim" of bluffs)...as anyone driving northbound on I-35W or MN-77 or even US-169 could see the immediate shift from bare ground to snow cover as they descended into the river valley. Now, with highs in the mid-upper 30's yesterday, that snow is mainly gone, and the rest of the snowfall that had blanketed the northern 1/2 of the Metro will be gone by sundown today with highs progged in the 40's.

ETA MOS is progging 44+ in fact, and if cloudiness continues to hold off from the approaching shortwave, we will hit it. Some considerations the models are not hitting on are the interaction of the upper low developing over the TX panhandle, being propped a bit by the 120kt jet max encircling it, and promoting some more moisture transport from the Gulf. The models do, however, denote a slight moisture transport over the next 18 hrs from the south...but more prominently the AB Clipper and its associated low will usher in low-level humidities of +90% overnight.

Depending on shortwave timing, this could be enough for some pretty snow showers and flurries to develop across MN tonight and into Christmas morning. Right now the s/w is marching across western NoDak, just getting ready to pass KBIS, with prevalent wind shift already occuring. Models seem to suggest a bit of slowing today, with arrival somwhere between sundown and midnight tonight. With moisture and cloud layer not exiting until noon-ish Christmas day, we can expect that small snow chance to exist from the time surface air temps approach freezing again, and Christmas afternoon. That temp point is progged by GFS to come around 9pm, and NAM around midnight. GFS has better handle on the system tracks recently, so I am going to (along with many of the NWS WFO's) going to lean towards it in producing my Noel forecast for Lakeville...peace and joy to you and yours!!!

Christmas Eve Day...Increasing cloudiness, high 44. South wind 5-10mph.
Christmas Eve...Mostly cloudy, overnight low of 28. 30% chance of snow showers or flurries after 9pm. West wind 5-7mph.
Christmas Day...Cloudy, 40% chc snow flurries or passing showers, high of 32. Northwest winds 10-15mph. Decreasing clouds in the evening, overnight low of 20.
Tuesday...Mostly sunny skies, high 31. North wind 5-7 mph. Low 22.

Posted by pierre at 11:07 AM | Permalink

Well, I got done with the previous post and looked outside and saw that icicles had formed on the trees...FZRA had arrived. Then I looked at the weather station console and noticed that the wind readout was zero, but out the window I could see the trees swaying a bit. A quick step outside revealed that the anemometer and vane had been encased in ice, frozen! Here is a closeup (click to enlarge):

Well, the 12Z GFS came out this afternoon publicly while I was out and about...here in Lakeville, the precip has been pretty much FZRA all day, just over a 1/2" in the bucket (and that may be inaccurate due to the ice content in the tipper). There has been some sleet and IP/SP mixing in at time. Around 20Z the strongest band of precip moved up over the belt-line of the Twin Cities, where it collided with a good amount of colder air that has been sub-freezing from the mid-layer to surface for quite some time now (better than 24hrs?). A nice band of moderate snow developed and moved northward dumping between .5" and 1.5" in the last hour in some places.

Forecast concerns now will be on redevelopment of precip and what type it will be over next 24 hrs. As noted before, models now starting to concur a bit on tracking the center of the storm across IA and then NNE over CHI/MKE. This more easterly track, along with enough mid-level warm air wrapping around the low will make snow chances diminish for Lakeville. MPX WFO has placed the snow chances more heavilly north of the Twin Cities beltline (as a "catch up" like they describe in the mid-afternoon update) and keep south metro in the mixed/rain pops. After the 18Z and 00Z models get pub'd, will do another update.

Posted by pierre at 3:01 PM | Permalink

As stated previously, the forecast for Friday has become decidedly white. The question 36 hours ago was "how much"...and now with some notable congruencies in parts of the models, we have some better guesses. First, some overall observations of how this storm system is coming along in terms of Lakeville...

Yesterday, our Canadian shortwave took a little more time than the models had predicted, leaving mid- and low-level moisture well in place for some forcing from the main storm to push into SoMN yesterday afternoon. This gave us 0.04" of light rain. Once the s/w did make its way through, however, the "drying" was significant last night...not only did the rain activity get pushed about 100-120 miles south, but the dewpoint and wind shift was prevalent. Looking at data plots for the station, a significant drop in dewpoint and corresponding W to N to S shift in the winds occured between 22Z and 02Z yesterday. The rebound of moisture was expeditious, and we have expereinced traces of -RA all night long.

Models are having no problem with initialization, as the characteristics of this H7 cyclone are easy to pick out in soundings and obs. Denver received just over a foot of snow overnight, and the highest reading so far for this storm has been 52" in Glen Haven, CO. Sfc circulation is easy to pick out on the MADIS mesonet (over Hayes, KS), and the system is now right on path projected by the 21/00Z init of both GFS and NAM. Now that the 21/12Z models are coming out, storm paths projections for our region are begining to solidify.

12Z NAM has slowed the system just a touch, and kept sfc circ on a more southerly path. The previous runs of the NAM had a path that would bring the sfc low over MSN by 00Z Saturday (1800 CST Friday). Now the 12Z NAM has run that feature up to a MKE position. H7 circulation also shifts slightly east in the 12Z run...this all making 12Z NAM look like a compromise between the 21/00Z NAM and GFS runs (GFS had painted a much more easterly track). 21/12Z NAM also paints up a much warmer scenario in the lower levels...and with the more easterly track, the main snow event for our region would shift to NoWI and the UP Friday night into Saturday.

With any of the model shifts, however, this has yet to be recognized in comparison with the other models yet to come out today. Therefore, I am going to give a categorical outlook for now, without very much focus on snow amts just yet...much in line with the MPX and ARX WFOs as they had examined the 21/00Z model runs. What I can do with certainty is talk about the next 24 hours, as current obs will give good basis. Currently, out the window at 15Z is -RA mixed with some "unknown" precip...and KLVN ASOS recording is stating "unknown precip..remarks, snow on runway". This could mean either sleet or snow is adhering to the surface. Indeed, we are right about 0°C. WSR-88D depicts a well formed band of -RA to RA along a MML-RGK line and about 100 mi wide, movingb slowly northward. MnDOT RWIS sensors are not depiciting any ice on the roads (yet) along the I-35 corridoor, however road surface temps range currently between 1° and 3°C...with traffic and a chemical environment (unlike the runway at KLVN), main roads and freeways will most likely remain only wet through the day, with some bridges getting slippery as we move towards sunset. Will update further as able with new model outputs and info later today...

Today...Cloudy, cold rain showers, mixed with sleet at times. High 34. Low 27 overnight with 40% chc of rain mixing with snow. Wind easterly at 5 mph.

Saturday...Cloudy, 30% chc snow. High 28. NW wind 5-10mph.

PS... Hope to have lakevilleweather.com winter weather page and snow measurements live on website today.

Posted by pierre at 10:00 AM | Permalink

Just in time for the holiday travel season, and the official start of the winter season, a winter storm has taken strong shape to affect the majority of the CONUS from now through Sunday. Currently, the southwest-born storm has tapped a boatload of Pacific moisture, with the upper/mid level cyclone now pushing into southern CO and the surface low approaching the TX panhandle. Ahead of the the surface low, frontogenesis is occuring with a warm front extending across the Red River and the cold front now crossing the Rio Grande. Already the system shows some signs of tapping Gulf moisture, as the Pacific moisture laden upper/mid low is set to drop heavy snow on the front range overnight.

Models are now agreeing on system movement, but disagreeing on moisture content and precip potential...particularly at the end of the short term model (now on the 22nd) which is decidedly "white" now, due to the fact that a new push of cold cP air from Canada is being tagged by the models now to invade coincedentally with the arrival of the low. So as fasr as snow is concerned, the only question is how much accumulation we will have. Currently, winter storm watches are posted as close as SoDak for the intrusion of freezing precip starting late Wednesday. As the models prog the upper low to couple with the surface low, the main difference in the last runs is in the jet. Now the split-off southern branch is looking more like it will run with the system, with both GFS and NAM painting a 120kt max nosing over central MO Thursday evening. This will punch the warm air from the southern jet over IA and southerm MN while the cold cP slides underneath from the north and hugs the barren ground of the Gopher state. The result will mean mixed precip for sure, and a great possibility for freezing precip as temps plunge Thursday.

As the system tracks from CO to NE to IA to IL over the next 12, 24, 48, and 72 hours respectively, all eyes will be on travel conditions as they deteriorate. First hunches for the Lakeville area per the model output stats are in agreement between the GFS and NAM for freezing rain or sleet changing to snow overnight Wednesday, then a mix of sleet and rain Thursday, changing all over to snow sometime late Thursday, and then snow for at least the first half of Friday. The models break from each other on the snow potential and amounts on the Thursday - Friday period...with the NAM progging 1-3" and GFS 4-6".

No confidence has been given in either of these projections, as the amount of drier air that could stymie the system is still a question. Tonight the s/w trough that will usher in the cP is also showing strong subsidence and drying tendancies. Future model runs, as well as upper air data soundings, will give us much more certainty tomorrow. Your Lakeville forecast...slightly extended:

Wednesday...clear skies in AM turning mostly cloudy by sundown. High 43. Mixed precipitation moves in after 10pm, mainly sleet, temps drop to 26. 50% chance of precip. WNW winds 5-7.

Friday...Snow showers. 70% chance of precip, with 2" of accumulation possible. High 30. Low 23. NE wind 5-7.

Posted by pierre at 5:49 PM | Permalink

As recognized in the "Autumnal Review" of the last post, it has not been a "normal" fall and early winter season for Lakeville. That may change with model solutions now starting to settle on a somewhat major shift in the zonal jet stream pattern for late week. Currently, the polar jet is running at around 170kts in the upper levels, racing from the Mexican Pacific coastline, over the Four Corners, across the Great Plains, the Great Lakes and exiting the CONUS over Maine. This places Lakeville directly under the jet max, and all current condition indicators concur...with mostly sunny skies (just high scattered ci in conjunction with the jet core), calm winds at the surface, and a steady temp...after a high yesterday of 36°F and cooling overnight to 17°F, temps have only rebounded to 30°F so far approaching 1900Z and may not get much above yesterday's 36°F.

Change to this pattern has already evolved east of the Sierra Nevadas as the jet had been digging southward along that range over the weekend, and with a kick from the current Aleutian low that has a trough extending south off the CA coast, will spawn an upper level low circulation over the CA desert. Negative tilt resulting from the cyclogenisis will give rise to a corresponding surface low over the Baja.

From this event today, the jet will split into a northern- and southern-branch, with the former acring over AB and SK towards northern MB and ON, then down over Lk Superior towards the confluence of the branches over the OH valley. The southern branch is progged by the GFS to run from the southern tip of Baja to a core max over the TX panhandle through mid-week, as the upper low slowly moves across the Great Basin towards the plains. Lower-level progs show the surface low moving up from NM to KS and NE by Thursday. The GFS progs a turn at the Sioux Empire to move the low directly east and even a little more southeast as it gets affected by the northern branch of the jet...the effect is much like a ping-pong ball moving between two currents.

Unclear at this stage of modeling for the system is moisture content. The upper midwest has seen its fair share of weather makers over the last month, however each has been moisture deficient. GFS paints a typical latent moisture picture enrichening the MS valley pre-arrival of the system to the upper midwest. However, since no frontogenisis is hinted by the models, and due to the "blocking" type setup the split jet presents, no moisture transport feature is evident from the progs. The only chance this weather maker has of contributing significant precip to the upper midwest is its ability to carry moisture from its Pacific-related genesis.

In the 72-hours preceding the manifestation of this pattern over our area, we can expect to remain in a high-pressure dominant situation...southern MN will be comfortably between the two branches of the jet, with light westerly winds, clear skies, and temps above normal in the low 40's. Come Wednesday night, the pattern will shift with the influx of clouds and a windshift to the SW and then SE as the system approaches. Long term outlook has Thursday into Friday looking like our weather days, but still too early to acsertain the extent of significant weather...your Lakeville forecast:

Monday...Fair and cool. High 35 with scattered high clouds, calm winds turning west at 7mph. Low 17 overnight.

Wednesday...Mostly sunny in AM, turning partly cloudy by sundown. High of 40. Low of 32 overnight, with 30% chance of mixed precip in the early am hours of Thursday.

Posted by pierre at 12:38 PM | Permalink

The Lakeville Weather Journal took a hiatus, as you might of noticed, over the last few months...but so did any notable weather for Lakeville over the same time period. Kinda. What has been extremely notable *has been* the weather...we are in an autumnal drought, and have experienced higher than normal daytime temps for the last 15 days. Here are some highlights from the last few months:

High Temp November 8th: 77°F
High Temp so far December: 50°F (Dec 14th)
Coldest Temp last 45 days: -2°F (Dec 7th)

The average temp so far in December is 26°F, however, showing that at least nighttime temps have been plunging below freezing. Most dominant in the abnormalities of the regional climate for the season has been the lack of precipitation. With the warm and dry autumn, trees and plants have suffered - abscission occured on a near-normal timeframe in our region, will the full extent of dormancy for the trees, plants, occurring no sooner than mid-November. With the leaves off, and the temps remaining mainly above freezing, the lack of precip caused horticulturists to admonish people to water trees and lawns in November.

November came and went with only a trace of precip. December has seen a .13" rainfall, but no accululating snow. In fact, no snow whatsoever. Some mixed flakes have been reported in the form of flash-flurries that moved through with some low stratus on a couple Alberta Clippers that rushed the area early in the month. December, in fact, did start out with temps below normal, with a major shift in the Polar jet - ushering a large mass of cP that had been densifying in coldness over the Northwest Territories in late November. The cP moved in and almost set up a rex-blocking scheme that would have placed MN in the big chill for more than two weeks. Instead, steady implulses over the jet in the form of Alberta clippers, and a large impluse that evolved from a dissipating Asian typhoon moved the cP east and north off the CONUS.

Now, mid-December, the region has remained in the doldrums of a zonal pattern for the last week or so, bringing mild daytime temps and cold nights. If the region had any snowpack, a typical feature for this time of the year, temps would be normalized during the daytime hours even with the zonal jet riding the MN/IA border. There is a major shift through a complex split of the polar jet - again 'rare' for the season, but it could spell a return to somewhat "normal" climate for the region from Christmas into the New Year. The next post will detail the first looks at this system, as the models have it set up...

Posted by pierre at 11:59 AM | Permalink