SPC AC 180722
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0222 AM CDT THU JUN 18 2009
VALID 201200Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...ERN U.S...
SEVERE THUNDERSTORMS WILL BECOME INCREASINGLY DIFFICULT TO PREDICT
DURING THE DAY3 PERIOD AS UPPER TROUGH SETTLES INTO THE NERN U.S.
LATEST THINKING IS THERE WILL BE CONSIDERABLE THUNDERSTORM ACTIVITY
ACROSS THE OH VALLEY DAY2...POSSIBLY EXTENDING INTO THE MIDDLE
ATLANTIC REGION BY EARLY DAY3. FRIDAY NIGHT ACTIVITY MAY NOT BE
HANDLED THAT WELL BY SHORT RANGE GUIDANCE...ESPECIALLY IF MULTIPLE
MCS/S EVOLVE AND FORCE OUTFLOW ACROSS WHAT MODELS PERCEIVE TO BE A
PRISTINE BOUNDARY LAYER NEAR/EAST OF THE APPALACHIANS. IF
INSTABILITY CAN REBOUND ACROSS VA/MD/PA THEN A THREAT FOR SEVERE
THUNDERSTORMS WILL EXIST ALONG/NORTH OF DIGGING SPEED MAX BENEATH
UPPER TROUGH. AT THIS TIME BUOYANCY/CONVERGENCE ISSUES ARE JUST TOO
UNKNOWN FOR AN ORGANIZED SEVERE RISK.
...CNTRL PLAINS...
WARM ADVECTION WILL INCREASE ALONG TRAILING FRONTAL ZONE ACROSS NRN
OK/KS SATURDAY. ALTHOUGH MID LEVEL TEMPERATURES ARE FORECAST TO BE
RATHER WARM...H5 VALUES BETWEEN MINUS 4-6...FORECAST SOUNDINGS
DEPICT VERY MOIST PROFILES CHARACTERIZED BY PWAT VALUES AROUND 2
INCHES...ESPECIALLY ALONG AN AXIS FROM WRN OK INTO ERN KS/WRN MO.
THUNDERSTORMS SHOULD EVOLVE ALONG NWRN PERIPHERY OF UPPER RIDGE
WHERE MID LEVEL FLOW WOULD SUPPORT AT LEAST MULTICELL UPDRAFTS.
GIVEN THE WARM MID LEVEL TEMPERATURES/THICKNESS VALUES WILL OPT FOR
LOW SEVERE PROBABILITIES AT THIS TIME. HOWEVER...ISOLATED
DOWNBURSTS AND EVEN SOME HAIL COULD ACCOMPANY THE STRONGER ACTIVITY.
THIS AREA MAY NEED A SLIGHT RISK AS SCENARIO BECOMES A BIT MORE
CLEAR.
..DARROW.. 06/18/2009
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
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