DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0219 PM CDT FRI MAY 22 2009
VALID 222000Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
HAVE GREATLY EXPANDED THUNDER POTENTIAL ACROSS MUCH OF TX BASED ON
WWD MOISTURE SURGE AND DEEPENING CONVECTION OVER PORTIONS OF THE
HILL COUNTRY. ADDITIONALLY...ISOLATED THUNDERSTORMS HAVE EVOLVED
ACROSS PARTS OF OK AND THIS AREA WILL BE ADDED TO THUNDER AS WELL.
FARTHER NORTH ACROSS THE UPPER MS VALLEY...WELL DEFINED UPPER
VORT/SHORTWAVE TROUGH IS SHEARING EAST ACROSS MANITOBA INTO NWRN
ONTARIO. THUNDERSTORMS ARE DEVELOPING SWWD ALONG TRAILING COLD
FRONT INTO NWRN MN/NERN ND AND THIS ACTIVITY SHOULD SPREAD ACROSS
NRN MN INTO THE EVENING HOURS. MOST CONCENTRATED ACTIVITY IS
EXPECTED TO REMAIN NORTH OF THE BORDER WHERE LARGE SCALE FORCING IS
GREATER.
OTHERWISE...STRONG THUNDERSTORMS SHOULD DEVELOP OVER PARTS OF ERN WY
LATER THIS AFTERNOON AS LOW LEVEL LAPSE RATES CONTINUE TO STEEPEN
ALONG FAVORED ZONE OF CONVERGENCE.
..DARROW.. 05/22/2009
.PREV DISCUSSION... /ISSUED 1114 AM CDT FRI MAY 22 2009/
ANOTHER QUIET CONVECTIVE DAY IS EXPECTED TODAY ACROSS MUCH OF THE
UNITED STATES AS STRONG WESTERLIES ARE CONFINED TO THE NORTHERN TIER
OF STATES...AND RICH LOW LEVEL MOISTURE ONLY RESIDES OVER THE
SOUTHEAST REGION. SCATTERED AFTERNOON THUNDERSTORMS ARE EXPECTED
OVER THE GULF COAST STATES IN ASSOCIATION WITH BROAD UPPER LOW OFF
IN THE CENTRAL GULF. HOWEVER...EXTENSIVE CLOUDS AND WEAK LAPSE
RATES WILL COMBINE WITH MARGINAL VERTICAL SHEAR TO SUPPRESS
ORGANIZED SEVERE STORMS.
...NEB/SD/WY...
WEAK EASTERLY/UPSLOPE LOW LEVEL FLOW IS FORECAST TO DEVELOP OVER
WESTERN NEB AND EASTERN WY THIS AFTERNOON. THIS WILL HELP TO
TRANSPORT SLIGHTLY MORE MOIST AND UNSTABLE AIRMASS INTO HIGHER
TERRAIN OF EASTERN WY...WHERE CONCENSUS OF MESOSCALE AND OPERATIONAL
MODELS DEVELOP SCATTERED STORMS. THESE STORMS MAY DEVELOP EASTWARD
INTO WESTERN NEB DURING THE EVENING. WEAK FLOW ALOFT WILL RESULT IN
SLOW MOVING MULTICELL CLUSTERS CAPABLE OF SOME HAIL.
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