Tuesday, July 14, 2009

Severe thunderstorm threat falling by the wayside as FCSTD yesterday

Forecast problems...The chance for severe thunderstorms is the main problem as what we talked about yesterday and last night...Winds will become gusty today through Wednesday night....Temps remain below normal through the rest of the work week..Slightly warmer for the upcoming weekend....No long term forecast this morning as we will need to hit up the possible severe weather threat,reasons why it may not happen, along with reasons why it may happen...

CURRENT CONDITIONS.......

Thanks to a Southerly wind flow last night temps were able to be warmer than yesterday...Temps in the middle 50s to lower 60s prevail....Dewpoint temps in the middle to upper 40s..Winds through out the FA range from calm to around 8 MPH from the South/Southeast....

SFC ANALYSIS......

High pressure is off to our East return flow as kicked in this early morning hrs...Low pressure over Far Northern MT/Southern Canada with a attended CLD FNT reaching South through the Western DAS.......What does this all mean for our FA...Lets get right to it.....

TODAY THROUGH TONIGHT.....

Models are in rather good agreement on features this morning,along with placements of the low pressure and CLD FNT...First off the bat lets talk about the SFC details...Low pressure is FCST to track along the USA/Canada border through 00Z Wednesday before heading Northeast by 06Z Wednesday...This will drag a CLD FNT through Central DAS into the Eastern DAS by 18Z Tuesday...Then into Western MN by 00Z Wednesday FNTL BNDRY should be on WI door step around 06Z Wednesday...The NAMSTER still would like to split the thunderstorm areas into two areas..First area would ride Northeast into Canada along the mid to upper level VORT MAX...The other area would ride South in Southern MN through Northern/Central IA ..Which is were we find a Low to Mid level low pressure/shortwave....GFS and ECWMF keeps the thunderstorms covering a larger area....Am going to blend all three I do like GFS/ECWMF the best but there are some good things with the NAMSTER that just can't be ignored...
Ok time to talk about severe thunderstorms..As many new medias and some blogs I have seen a screaming severe thunderstorms...However this I did say would happen yesterday.......Dry air still over the FA dewpoint temps confirms this...Looking at this mornings SKEW-T soundings also shows very dry air over the FA this morning...GFS does FCST 2M SFC dewpoints to increase to around 60 by 00Z Wednesday..The 08Z RUC model shows 2M SFC dewpoints increase to around 60 by 2100 UTC time frame... 3hr pressure tend by 1800 UTC do fall to around -5 MBs to around -1.5 MBs in my Southern FA Lifted Index range from -2c to around -4c by later this afternoon..Strong LLJ 35 to 45 KT is FCSTD to set across MO through IA,and MN into WI...Mid level Jet from 50 to around 60 KT also over Southern MN and IA back down into MO...This where the best severe thunderstorm threat along with tornado threat is focused....The tornado threat would be the time of storm imitation,then the storms should from into a long live squall line.....Further North in MN...Thunderstorms should reform along the CLD FNT...Storms should form into a line rather fast and push Eastwards across MN...Storms should become MCS in nature in Eastern MN and move through WI, Eastern IA into IL...This system is FCSTD to be a fast mover.....Here is where the problem still is...This mornings convection over MN/along with showers moving into my FA...How fast can this large area of broken showers/thunderstorms clear the area....Along with breaks in the CLD cover....If this can move out and give us a few hrs of SFC heating this will aid in destabilization and increase INSTBY...As of right now I'm not banking on the CLD field to break...Looking at the Satellite large area of CLDS blanket the upper Midwest.....Hence my thinking severe thunderstorm threat is little to non across the FA...So still going against the SPC thinking....However if we can break into a few hours of SFC heating this for sure would change things...Then we could be dealing with severe thunderstorms...So for the sake of argument let say we get breaks...The main threat would be damaging winds along with large hail..Tornado threat I would be over MN.......Ok time to put my head on the chopping block....AM not forecasting severe thunderstorms for the FA.....Will be watching this all morning into the afternoon hrs...So this FCST may be updated on the latest trends/model runs.....Highs today around the middle 70s...Winds can gust close to 30 MPH form the S/SE...Lows tonight fall back into the middle 60s.....Still rather windy tonight....

Rest of the work week..Temps may not make it out of the 60s come Thurs...So the below normal temps stay alive,as summer decided to take an extended vacation.....