SWODY1
SPC AC 171546
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1046 AM CDT THU MAY 17 2007
VALID 171630Z - 181200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
1030 SURFACE HIGH CENTERED NEAR SERN MN THIS MORNING...IN WAKE OF
DEEP MID/UPPER LEVEL TROUGH ACROSS THE ERN HALF OF THE CONUS...WILL
MAINTAIN SURFACE RIDGING OVER MOST THE CENTRAL STATES. RESULTANT
LIMITED MOISTURE/INSTABILITY WITH OFFSHORE FLOW OVER THE GULF COAST
WILL SUPPORT UNSEASONABLY LOW SEVERE THREAT ACROSS MUCH OF THE U.S.
TODAY. EXCEPTIONS WILL BE NEAR WEAK LOW CENTER AND ASSOCIATED MID
LEVEL COLD POCKET MOVING INTO THE SRN APPALACHIANS... AS WELL AS FAR
SERN AZ/SWRN NM/SWRN TX AND PORTIONS OF THE NRN ROCKIES/WRN MT.
BRIEF LIVED SEVERE THREAT MAY ALSO SHIFT SLOWLY ENEWD AWAY FROM THE
CENTRAL ROCKIES LATER TODAY.
..SERN AZ/SWRN NM/SWRN TX...
SRN STREAM SYSTEM EVIDENT ON WV IMAGERY OVER NM THIS MORNING WILL
KEEP SHIFTING SLOWLY EWD TODAY. IN WAKE OF THIS SYSTEM...LOW LEVELS
WILL REMAIN RELATIVELY MOIST WITH SURFACE DEW POINTS AT 15Z HOLDING
IN THE 50-55F RANGE FOR THE MOST PART. STRONG AFTERNOON HEATING AND
H5 TEMPS AROUND -10C SHOULD THEREFORE ALLOW AIR MASS TO BECOME
MARGINALLY TO MODERATELY UNSTABLE. EXPECT HIGHER TERRAIN
THUNDERSTORMS WILL INCREASE BY THE MID TO LATE AFTERNOON AND SPREAD
SLOWLY EWD THIS EVENING. MID-UPPER LEVEL WLY FLOW WILL REMAIN
FAIRLY WEAK. HOWEVER...WHEN COMBINED WITH ESELY SURFACE
WINDS...DEEP LAYER SHEAR MAY APPROACH 30-35 KT. THUS...AN ISOLATED
SEVERE HAIL/WIND EVENT...INCLUDING BRIEF SUPERCELL STRUCTURES...CAN
BE EXPECTED WITH THE STRONGER STORMS.
..SRN OH/ERN KY/WRN WV/NERN TN...
THOUGH LOW LEVEL AIR MASS IS RELATIVELY COOL/DRY...VERY COLD MID
LEVEL AIR AND FOCUSED ASCENT INVOF UPPER LOW AND ASSOCIATED WEAK
SURFACE LOW SHOULD SUPPORT WEAK INSTABILITY AND AID IN DEVELOPING A
FEW THUNDERSTORMS. WILL KEEP LOW SEVERE PROBABILITIES FOR
BRIEF-LIVED AND MARGINALLY SEVERE HAIL/WIND WITH THE STRONGER CORES
INTO THE EARLY EVENING OVER THIS REGION.
..NRN ROCKIES INTO WRN MT...
RIDGING ALOFT WILL BUILD OVER THE ROCKIES/NRN HIGH PLAINS THROUGH
THE DAY. THOUGH ALONG NWRN PERIPHERY AND ATOP THE RIDGE...MODEST
SWLY/WLY MID LEVEL WINDS WILL PREVAIL OVER THIS AREA. MID LEVEL
MOISTURE EVIDENT ON BOI/TFX 12Z SOUNDINGS SUGGEST DEEP MIXING WILL
BE SUFFICIENT FOR WEAK INSTABILITY AND A FEW THUNDERSTORMS OVER
HIGHER TERRAIN THIS AFTERNOON. HAIL AND OCCASIONALLY STRONG OUTFLOW
WINDS NEAR SEVERE LEVELS MAY ACCOMPANY ACTIVITY AS IT SPREADS ENEWD
THROUGH THE EVENING.
..CENTRAL AND NRN HIGH PLAINS...
RESIDUAL MID LEVEL MOISTURE WITHIN WEAK FLOW REGIME WILL REMAIN OVER
THE CENTRAL ROCKIES TODAY...AND SUPPORT SCATTERED AFTERNOON
THUNDERSTORMS OVER HIGHER TERRAIN. SLOW MOVING CLUSTERS MOVING
ACROSS LOWER ELEVATIONS THROUGH THE EVENING MAY PRODUCE HAIL/STRONG
OUTFLOW WINDS. HOWEVER...OVERALL ORGANIZATION/SEVERE THREAT WILL
REMAIN LOW WITH THIS ACTIVITY.
.EVANS/GRAMS.. 05/17/2007
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