Sunday, June 21, 2009

Ever changing forecast...The joys of this job....

Forecast problems..Today showers and thunderstorms..Strong to severe thunderstorms possible later this afternoon..Then a chance of strong to severe thunderstorms Monday,and Tuesday mainly during the over night hrs...So this FCST discussion will revolve around the strong/severe thunderstorms chances...No long term FCST this go around....

SFC ANALYSIS...

Low pressure/trof over SE SD along with a warm front reaching through IA down into TN...Another low pressure/trof over NE MT with a CDFNT reaching South through Eastern MT back into Central WY...What does this all mean for the FA ? you ask..Lets dive right into and find out....

TODAY THROUGH TUESDAY....

Low pressure /trof is FCSTD to move into Southern MN this will help kick a warm FNT Northwards through out the day...Low pressure/trof only makes into Central MN by 1200 UTC..Warm FNT pushes into my Southwestern and Western sectors of the FA...System should be moving North/Northeast of the FA by mid morning on Monday...Back to today...As this system moves Northeast showers and thunderstorms will become more likely this morning..Radar showing this rather well this early morning...Here is where problems show up with the chances of severe thunderstorms....Limiting factors would be as follows...1 how fast can the morning mess clear the area to allow good SFC heating to take place..2 how fast will the atmosphere be able to under go destabilization later this afternoon...3 Convention temps.....Lets see if we can make sense of all of this....
First off the track...Lets look at this morning trash moving into the area....Thinking is showers and thunderstorms will be in two waves one coming in this morning..This should clear my Southern zones by early afternoon then clear my central areas by mid afternoon...If we get enough breaks in the clouds SFC heating should be strong enough to DSTBLZ the atmosphere....Again if showers and thunderstorms hold longer than FCSTD,along with more clouds AM not going to worry about strong to severe thunderstorms in my FA...Convection temps are FCSTD to be right around 80 see no reason why that won't be meant...850 - 500MB LAPSE RATES are FCSTD to be around 5.0 C/KM LIFTED INDEX FCSTD to be around 0 to -2 C PWS increase to around 1.67 inches later this afternoon....Most of the severe weather dynamics are there later this afternoon into the evening hrs...Big concern right now is will the atmosphere have the time to under go the destabilization procedure..Guess it's time to put my head out on the chopping block and say no to severe thunderstorms..Am thinking showers/non severe thunderstorms and clouds will hold strong across my FA...Highs today will be on either side of 80 with clouds and showers and thunderstorms moving into the area through the morning...If severe thunderstorms do form later today into the evening,main threat would be large hail and damaging straight line winds....
Ok now lets address tomorrow's severe thunderstorm threat...This is easy one....Atmosphere should remain capped through out the afternoon hrs...Thinking is this possible event will take place during the over night hrs...MCS are FCSTD to form over the Eastern Dakotas and march Eastwards into the FA..If this does happen we could be looking at a shot of severe thunderstorms Monday night...Main threat here would be damaging winds along with some hailers...Still cap may be to strong for things to fire...Monday looks to be a hot humid day across the FA highs well into the 80s close to 90......
Now lets look at Tuesday's severe thunderstorm threat....Am thinking the FA will be capped once again...SFC temps push back into the upper 80s to lower 90s,so another hot humid day on tap....Tuesday night does look like we will have a better shot at MCS forming...This will lead to a line of thunderstorms moving into the FA some of these storms could become severe during the over night hrs...Main threat would be damaging winds,along with large hail....
So this FCST cycle has the potential to become an active one...Will update FCST as needed through out the day,unless I decide to head out chasing,which attm looks highly unlikely....Though IA is looking good for severe thunderstorms......