lakeville weather journal

I really am not convinced of many "Global Warming" theories out there...but I thought in light of the current hot weather conditions and the debate that is out there I would title my post as such. I also did it for a shameless plug of the site (web search engines will point to us more often with a popular topic in the title), and a friend of mine keeps talking about it.

SInce I have precious little time to do analysis, and actually write something original, I am going to paste in the write-up done by NWS-MPX in the day shift forecast discussion...it has some good background on the current weather trend. Stay cool everyone!!

THE DOMINANCE OF FAIR...BUT HOT WEATHER OVER THE UNITED STATES
CONTINUES TO BE THE MAIN FOCUS OF RECENT METEOROLOGICAL DISCUSSION.
WHILE STRONG WESTERLIES MEANDER AROUND A PRONOUNCED OMEGA BLOCK OVER
CANADA...THE ATMOSPHERE ABOVE THE CONTINENTAL UNITED STATES REMAINS
HIGHLY BAROTROPIC. AS SUCH...HOT WEATHER HAS BEEN OBSERVED AROUND
THE ENTIRE COUNTRY...FROM CALIFORNIA TO THE CAROLINAS. STEMMING
FROM PROLONGED PERIODS OF LOWER THAN NORMAL PRESSURE AT THE NORTH
POLE AND HIGHER THAN NORMAL PRESSURE IN THE TROPICS...ALSO KNOWN AS
THE POSITIVE PHASE OF THE ARCTIC OSCILLATION...THIS CURRENT WEATHER
REGIME IS LIKELY TO CONTINUE INTO MID AUGUST OVER MUCH OF THE UNITED
STATES. FORTUNATE FOR THE NORTHERN THIRD OF THE COUNTRY...SLIGHT
MERIDIONAL DEVIATIONS IN THE UPPER LEVEL FLOW ARE FORECAST TO
CONTINUE TO FLOW SOUTH ACROSS THE UPPER MISSOURI AND MISSISSIPPI
RIVER VALLEYS THROUGH THE END OF THE WEEK.

Posted by pierre at 5:50 PM | Permalink

It has been a slight respite for Pierre and the weather journal...but last week's trends were right on the mark...and our summer of normality, albeit a bit dry, continues. This week's big story is a total deja vu of the story about two weeks past, which I wrote up in "Total Hottness"...as a matter of fact, I could copy it verbatim. Let's take a look...

I am sure many of you have already seen in local media forecasts that the temps will be pushing the century mark (and possibly over that mark) into the weekend. All models are pointing at an impressive ridge of Continental Tropical - cT - (desert-borne) air surging into our region. Preceeding the hot push is a slight chance of convection Thursday night into Friday morning. A surface trough is hinted at by the ETA model specifically, whereas the GFS gets more bullish in the cT ridge buidling in under a zonal flow that wipes out any troughing in the lower levels. I am not conviced that the GFS has the best view of the sitch, however, and I want to remain optimistic on any chance of precip. Helping my optimism is humidity values and a strong Gulf-borne low-level flow preceeding the trough. Precipitable water values soar as well, pushing 2" plus. CAPE value predictions are boosted as well, and the vorticity max ridges over the same areas. This suggests a line of development somewhere in east-central Sodak Thursday after 21Z. Any MCS should carry into the TC Metro by early AM.

WEEKEND OUTLOOK... Sunny, HOT, highs 97 to 100. Lows mid-low 70's.

I think that about does it!!

Posted by pierre at 4:15 PM | Permalink

As written in the last post, the morning MCS debris hung out all day, exasperbated by scattered popups of convective activity...mainly of the showery variety. Overriding cap to the south also kept things at bay as surface front drifted to central MN before a late-afternoon stallout. The frontal movement allowed outflow boundaries to set up a good support system and enough of a dryline near sunset to break the cap south of the MN river valley. Explosive supercells lined up from MKT to RST through the 04Z hour, and started dropping heavy rain and some hail. Wind fields from WSR-88D showed 60kt returns, and some mesocylonic signatures.

Mesonet not showing much of a definative analysis for the frontal positioning, but before dirunal winds died off the 02Z analysis showed the front at about a DLH-STC-RWF line. Tops from the southern MN MCS have spread out over the entire SE 1/4 of MN, including the TC metro, which will serve to usher the frontal movement along with associated cooling. Tomorrow AM we should wake to clear skies and drier air. Seasonal July weather continues in the zonal flow for the next couple days, and there is a hint that enough theta-E advection will give rise to another rain event Friday. Lack of southerly flow to couple with said advection will limit chances however, so next couple model runs may run this solution drier if this doesn't change.

Outlook in models has polar jet going even further north to almost a Yukon position by early next week. Dome of high pressure forms over the great basin and moves over much of the CONUS by late Monday. As the ridge moves off to the east tues-wed, we could see a repeat set up of today with the return of the upper jet to a north-south or "merdianal" flow. Only time will tell...for now we have yet another nice weekend in the forecast, and our gilded summer continues.

THURSDAY...Sunny Skies, High 83. North wind 5-10 mph, low 63.

FRIDAY...Partly Cloudy, High 86. 30% chance of thunderstorms after noon. Low 65

SATURDAY and SUNDAY...Mostly Sunny, Highs in the mid-upper 80's, Lows in the upper 60's.

Posted by pierre at 11:47 PM | Permalink

MCS strengthened a touch and broadened out with AM sunrise...moved through MSP area with heavy rain...almost 1" here in Lakeville.

Now (12:00pm) mesonet obs are pinpointing cold front/assoc trough already crossing the Couteau into western MN. Should it slow, chances for redevelopment west of the metro this evening increase, however this already seems unlikely. MCS debris not showing much haste in clearing, so daytime heating is somewhat abated. Temp and dewpt now both around 65F around metro...some new cells popping around Redwood County at this time, may be the "new line"...looking out windows to the west, outflow boundry is visable with scud rollup over west metro. New development may be just overhead with ingredients timing around 4pm-ish?? Again, all depends on heating, western/southcentral storms around the MN river valley will keep cap from forming...so heat will determine explosivity. SPC has moved moderate threat off to the SE of metro. We are still in the slight risk for remainder of Day 1 Outlook.

Posted by pierre at 12:11 PM | Permalink

Today might be the day Twin Cities stormchasers get their wish...a local setup for severe weather to work. SPC even has us in the moderate risk for severe storms for the first time this season. Looking at the latest RUC model run (the 09Z run), the ingredients are coming together nicely indeed. Currently, an MCS did develop nocturnally over Nodak, and present WSR-88D radar loops on this activity show storms have reached mature stage and are dumping out through west central MN during dissipation. Models are guessing at some outflow boundary to set up near the EC/SE MN region this afternoon. Warm and moist air will surge up from the Gulf of Mexico ahead of the cold front/shortwave moving in from Nodak overnight tonight. The outflow boundary prev mentioned will act as a virtual warm front in a classic triple-point setup by around 21Z it looks like. SPC forecasters are also looking at shear development...evident from RUC's modeling of 1000-700mb winds ramping up from the south, turning southwesterly in a velocity max northeast of the triple point, and then turning westerly in the upper levels. Daytime heating is a concern as well...highs will push up and over 90 in southeast/southcentral MN, with dewpoints mid-60's plus...the instability will be unfettered as any capping will surely be quelled by the outflow boundary, and/or the shortwave. If I can do updates through the day, I will, but for now, forecast looks preferable for a rockin evening for weather!

WEDNESDAY...Line of dissipating showers will affect TC Metro mid-morning, followed by a warm, humid afternoon...Showers and Thunderstorms, some severe, redevelop after 4pm. High 87, chance of rain 80%. Rain ends by midnight, low 65.

THURSDAY...Clear. High 85. Wind north 5-10mph. Low 65.

FRIDAY...Partly Cloudy. High 87, wind light and variable.

Posted by pierre at 7:16 AM | Permalink

Our hot weekend has ushered in a stretch of climatological status quo. Many forecasters were worried about the lack of precipitation coupled with the heat, and it has been problematic with wildfires now ravaging the BWCA in northeastern MN. Dewpoints in the area over the weekend were also high, pushing the humidex over 100, and keeping heat indicies in the upper 90's with the correlating temps. Some "heat bursts" were able to break the capped atmosphere and produce some splash and dash showers yesterday, and the weak surface front wandered mid-state throughout the day Sunday keeping clouds in tact.

We set a new record high of 97 on Saturday, with a heat index of 105 (another record). Dewpoints are now falling off as the front has pushed southeast...and despite the temps around 90, it feels much more bareable with dewponts back around 50. This reprive will hold through tuesday before the next shortwave and associated surface front approaches from the west. The ETA model has an impressive prog on the system, with all elements for strong convection and/or a soaking rain event coming together on Wednesday. Timing is still a struggle, however, and the GFS is dragging the system out a little. Given enormous precipatble water values, dewpoints surging north of 70 again, and theta-E advection pushing a strong ridge over the Sioux Empire region, I think we will have widespread precip and storms...at some time, or times.

Anomolies in between models include timing of/development of jetstream max nosing a left exit into west central MN, and the development of CAPE values pooling ahead of the front, around 3500-4500 J/kg. Future model runs should sew up the differences, however most weather pros are looking at MCS development ahead of a possible isontropic upglide overnight tues-wed AM. This may carry through during rush hour for the TC metro on Wednesday, with possible redevelopment pre-frontal passage Wednesday at supper time. Again, future models will test this theory. For now, I will stick to conservative MOS forecasts along with a hunch that the setup will drag per the GFS solution currently in hand.

MONDAY...Mostly Sunny and dry. High 90, Low 74. Northwest wind 5 mph.

TUESDAY...Partly Cloudy, High 92, Low 75...Westerly turning southerly winds 5-10 mph

WEDNESDAY...Partly Cloudy, High 93. 50% chance of showers and thunder after 6pm. Low 72.

Posted by pierre at 2:35 PM | Permalink

I am sure many of you have already seen in local media forecasts that the temps will be pushing the century mark (and possibly over that mark) into the weekend. All models are pointing at an impressive ridge of Continental Tropical - cT - (desert-borne) air surging into our region. Preceeding the hot push is a slight chance of convection Thursday night into Friday morning. A surface trough is hinted at by the ETA model specifically, whereas the GFS gets more bullish in the cT ridge buidling in under a zonal flow that wipes out any troughing in the lower levels. I am not conviced that the GFS has the best view of the sitch, however, and I want to remain optimistic on any chance of precip. Helping my optimism is humidity values and a strong Gulf-borne low-level flow preceeding the trough. Precipitable water values soar as well, pushing 2" plus. CAPE value predictions are boosted as well, and the vorticity max ridges over the same areas. This suggests a line of development somewhere in east-central Sodak Thursday after 21Z. Any MCS should carry into the TC Metro by early AM.

After the short wave event Thursday, temps will continue to build in earnest. MOS pitching 97 tops, but with the cooler tendancy of especially MEX output, I think the bumps to 100 are very justified. More hints being dropped as of late about another s/w trough passing through late Sunday, but too early to really give it creedence.

WEDNESDAY...Warmer, hazy, and humid, mostly sunny. High 87. Light and variable winds, Low 67.

THURSDAY...Hot, humid, hazy. Partly Cloudy, High 94. South wind 10 mph. 30% chc thunder late night, low 72.

FRIDAY...Remnant thunder in AM, Partly Cloudy, High 96. Low 72.

WEEKEND OUTLOOK... Sunny, HOT, highs 97 to 100. Lows mid-low 70's.

Posted by pierre at 11:20 AM | Permalink

Everyone is thinking it...I went for a walk around the neighborhood this evening, and those who could (per local watering restrictions) were giving lawns and gardens a good long drink. We have been running quite the rain deficit this summer, about 2-3" behind since early June. The Climate Prediction Center has targeted the upper midwest as likely for drought development. Meanwhile everyone would like to see a good soaker!

The weekend was yet another blue-ribbon set of days for boaters and beachgoers. Sunday cooled off in the wake of the suface cold front we watched develop and move in since Thursday. Now models are again trying to reset the scene for precip chances. The polar jet is now further north, and predicted to stay there. A sub polar branch is guessed to drop out of Saskatchewan by late Monday, giving enough spin above to then form a cut-off low in the mid levels amid the great plains. Should this 700MB low drop in at the right time, we could see a better chance of rain. Right now most guesses are around 50/50 through Wednesday. Tomorrows model runs and soundings will give us a better peak at what may transpire this week.

MONDAY... Dry and seasonal. Mostly sunny, High 82. Light easterly wind. Low 63

TUESDAY...30% chance of lingering AM showers, then partly cloudy, wamer with humidity increasing. 50% chc of thunderstorms re-developing after 4pm. High 85. Low 60 with rain ending by midnight. Southeast, turning southwest winds 5-10.

WEDNESDAY...Partly Cloudy. High 87. Slight chance of afternoon thunder. Low 64. Southwest wind turning northwest 10-15.

THURS-SUNDAY OUTLOOK...Hot and Dry again. Mostly sunny, Highs in low-mid 90's.

Posted by pierre at 9:30 PM | Permalink

Forecasting a dry spell is no fun...and we have entered a relatively dry run for the range. Only a slight anomoly to the ongoing zonal flow this week and next, and that is an increase in southerly moisture in the low-mid levels into the early weekend. The polar jet is stuck up along the Canadian shield again, keeping us out of the fray so to speak. Models show theta-E edvection building a ridge along the Couteau des Praries and stretching across central MN by Saturday afternoon. This is coupled with more creedence for precipitable water values on the increase for raising slight chances as early as Friday into Saturday for splash-and-dash shower activity. Diurnal heating will trigger them, but capping may be of concern as we remain far south of the jet. Should MOS temps hold, plus a healthy buffer, the cap could be almost a foregone conclusion...ETA CAPE forecasts teast at 1000+ J/kg for Sat PM but again any capping will keep instability at bay.

GFS definitively paints an upper-level trough to cross northern MN and WI Saturday night...also prominent upper jet max exiting in this region...right now left front exit is progged over Kenora...but ETA depicts jetlet exiting over eastern Lk Superior. Should jet sag even 100 nm south, DLH and western Lk Superior region may see good svr weather event as result. Long wave trough currently developing in lee of Rockies should genesis to cold front due to pass through our area by Sunday. Precipitable water, advection, and timing around potential cap will determine any precip chances thru weekend. For now I will stick close to MOS guidance for much of forecast...

THURSDAY...Mostly Sunny, High 85. Light winds from W-N. Low 62

FRIDAY...Mostly Sunny in AM, Turning Partly Cloudy after lunchtime, High 87. Winds turning SW 5-10 mph. 30% chc showers after 3pm. Low 65

SATURDAY...Partly Cloudy, Humid, and Warm, High 92. 30% chc thunderstorms after dark. Low 62

SUNDAY...Clear and Dry. High 85. Low 60.

OUTLOOK WEEK OF 7/10/06... Hot and Dry....highs at or abv 90. Slight Precip chances again Wed night into Thurs.

Posted by pierre at 9:01 AM | Permalink

I hope everyone had a great 4th of July Holiday! The weather was excellent. We have definately tamed down into the "dog days of summer" which WCCO-TV meteorologist Paul Douglas reminded me last night refers to Sirius, the "Dog Star", which rises in the southern summer sky and since it was the brightest star, ancient Greeks thought it contributed to heating the Earth.

The warmer, drier spell we have over us is raising fire dangers across Minnesota. Today the Minnesota DNR just placed the 7-county Twin Cities metro under MODERATE fire danger risk level, joining all but the southern 1/3 of MN in that risk category. Lakeville technically is included in that moderate range being located in Dakota County. We have a Fire Weather Page on lakevilleweather.com that depicts our calculation of fire danger risk as well as includes a bunch of data from the MN-DNR on fire weather (the page updates hourly and was just redesigned yesterday). Our calculation of fire danger uses the Canadian/European model of calculation (because that is what is built into our software)...and although right now we show "LOW" at a Fire Weather Index of barely 1, this could change dramatically as heating builds through the days and weeks to come with little to no precip.

See part 2 for weather discussion.

Posted by pierre at 8:47 AM | Permalink