April 20-21 MW/OV/GL/PLAINS Severe Weather, SPC Risk Level: Day 4-8 Possible - Forecasts & OBS Options

[Southern Indiana]

I know theres a major event playing out this weekend but I just wanted to put this up here because discussion has apparently begun in my area for this weather system. The big reason is Louisville has a huge fireworks show and boat races, airplanes, things of that nature this coming weekend.

The louisville meteo seems to think this will be a strong system and provided these two maps for starting points

Note: I could not use his map which shows a little stronger instability due to image compatibility issues, here is twister data's, which does not show as strong of an instability level that far out. Also it showed higher temps than the twisterdata GFS model I am posting now.






So with the combination of instability, actual front coming through our area, and Temps in the 80's, its going to be a good mix for some Severe weather potential.

[The Snowman]

Looks like some precipitation could be ongoing up in my neck of the woods.

Attached thumbnail(s)

 

[The Snowman]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0359 AM CDT SAT APR 14 2012

VALID 171200Z - 221200Z

...DISCUSSION...
THE MEDIUM RANGE MODELS BEGIN THE DAY 4 TO 8 PERIOD WITH AN
UPPER-LEVEL TROUGH OVER THE SCNTRL U.S. AND MOVE THIS FEATURE ACROSS
THE GULF COAST STATES TUESDAY/DAY 4 INTO TUESDAY NIGHT. A THREAT FOR
STRONG THUNDERSTORMS COULD EXIST ACROSS THE LOWER MS VALLEY AND EWD
ALONG THE GULF COAST TUESDAY AFTERNOON. ON WEDNESDAY/DAY 5...THE
MODELS DEVELOP WNWLY FLOW ACROSS THE CNTRL STATES AND RETURN SOME
LOW-LEVEL MOISTURE INTO THE SRN PLAINS. ON THURSDAY/DAY 6...THE
MODELS CONTINUE MOISTURE ADVECTION ACROSS THE GREAT PLAINS MOVING AN
UPPER-LEVEL TROUGH INTO THE REGION FROM THE WEST. THIS ALONG WITH
THE DEVELOPMENT OF MODERATE INSTABILITY COULD SUPPORT A SEVERE
THREAT WITH STORMS THAT INITIATE ACROSS THE SRN AND CNTRL PLAINS.
THE POTENTIAL FOR STRONG THUNDERSTORMS WOULD SHIFT EWD INTO THE
ARKLATEX AND MID MS VALLEY ON FRIDAY/DAY 7 WITH A CHANCE FOR AN
ENHANCED SEVERE THREAT THERE AS WELL. AT THIS POINT...THE SYNOPTIC
SETUP AND CONVECTIVE ENVIRONMENT ON THURSDAY AFTERNOON AND EVENING
IN THE SRN AND CNTRL PLAINS APPEARS FAVORABLE FOR SEVERE STORMS.
HOWEVER...CONFIDENCE IS NOT GREAT ENOUGH TO INTRODUCE A SEVERE
THREAT AREA ON DAY 6 OR DAY 7.

This post has been edited by The Snowman: Apr 14 2012, 07:47 AM

[WeatherMonger]

New Day 4-8 outlook shifts it towards areas hit yesterday

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0336 AM CDT SUN APR 15 2012

VALID 181200Z - 231200Z

...DISCUSSION...
BOTH THE GFS AND ECMWF ARE IN GENERAL AGREEMENT THROUGH MID WEEK
REGARDING THE OVERALL PATTERN ACROSS THE CONUS. BEYOND THURSDAY THE
GFS IS CONSIDERABLY MORE AGGRESSIVE IN THE EVOLUTION OF ERN U.S.
TROUGH AS IT DIGS INTO THE MID SOUTH.

PRIOR TO THE AFOREMENTIONED MODEL DIVERGENCE...FLOW WILL INCREASE A
BIT ACROSS THE SRN/CNTRL PLAINS WITHIN THE BASE OF THE PROGRESSIVE
TROUGH. IT APPEARS A FRONTAL SURGE WILL OCCUR ACROSS THE PLAINS
WHICH WILL FORCE A BOUNDARY ACROSS KS INTO OK ON THURSDAY. IF
SUFFICIENT MOISTURE/INSTABILITY CAN ESTABLISH ITSELF ACROSS THIS
REGION BY DAY5 THEN THERE IS SOME CONCERN THAT ROBUST STORMS MAY
DEVELOP ACROSS THIS REGION. HOWEVER...PREDICTABILITY IS A BIT TOO
LOW REGARDING THIS SCENARIO TO WARRANT A SIGNIFICANT SEVERE RISK AT
THIS TIME. BEYOND DAY5 TOO MUCH UNCERTAINTY EXISTS WITHIN THE MODEL
GUIDANCE ACROSS THE GULF STATES TO SUPPORT A SEVERE RISK.

..DARROW.. 04/15/2012

CLICK TO GET WUUS48 PTSD48 PRODUCT

[jdrenken]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0330 AM CDT TUE APR 17 2012

VALID 201200Z - 251200Z

...DISCUSSION...
MEDIUM RANGE MODEL GUIDANCE IS AGAIN SLOWER AND A BIT FARTHER WEST
AND SOUTH WITH ITS EVOLUTION OF AN UPPER LOW THIS WEEKEND ALONG THE
GULF COAST. AS THE UPPER TROUGH DEEPENS AND DIGS SOUTH INTO TX
DURING THE DAY4 PERIOD IT WOULD SEEM LIKELY THAT THUNDERSTORMS WILL
DEVELOP ACROSS MUCH OF CNTRL/ERN TX WITHIN GREATEST ZONE OF WARM
SECTOR INSTABILITY. IF CURRENT MODEL TRENDS HOLD THERE MAY BE
ENOUGH DEEP LAYER SHEAR/INSTABILITY TO WARRANT A RISK OF SEVERE
THUNDERSTORMS ACROSS TX FRIDAY WHICH COULD EVOLVE INTO A LARGER
COMPLEX OF CONVECTION THAT COULD DRIVE INTO THE NWRN GULF BASIN OVER
THE WEEKEND. GIVEN THAT THE MODELS HAVE YET TO SETTLE ON A
CONSISTENT SOLUTION WILL NOT INTRODUCE AN ORGANIZED RISK OF SEVERE
THUNDERSTORMS THIS PERIOD.

..DARROW.. 04/17/2012