SWODY1
SPC AC 201240
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0740 AM CDT WED OCT 20 2010
VALID 201300Z - 211200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER SERN NM AND SWRN TX...
...SYNOPSIS...
HIGH AMPLITUDE FLOW PATTERN IS FORECAST TO PERSIST THROUGH THE
PERIOD WITH AN UPPER RIDGE REMAINING OVER THE PACIFIC NW/NRN
INTERMOUNTAIN REGION...WHILE DOWNSTREAM LONG WAVE TROUGH OVER THE
ERN STATES IS REINFORCED BY A SHORT WAVE TROUGH DROPPING SEWD ACROSS
SRN MAN/NWRN ONT. SATELLITE IMAGERY SHOWS THE LOWER LATITUDE
CUT-OFF UPPER LOW OVER EXTREME NRN BAJA CA NOW MOVING SLOWLY
EWD...AND THE SYSTEM IS EXPECTED TO REACH SWRN AZ LATER TONIGHT.
...SERN NM/SWRN TX...
SELY LOW LEVEL MOIST UPSLOPE FLOW IS EXPECTED TO BECOME BETTER
ESTABLISHED THIS AFTERNOON AND EVENING IN THE WAKE OF THE WEAK COLD
FRONT MOVING ACROSS SWRN TX...IN RESPONSE TO PRESSURE FALLS
DEVELOPING OVER THE SRN/CNTRL ROCKIES. SURFACE DEW POINTS ARE
CURRENTLY IN THE 50S F OVER MUCH OF SWRN TX AND LOW LEVEL MOISTURE
IS LIKELY TO INCREASE INTO SERN NM DURING THE AFTERNOON. STEEP LAPSE
RATES EVIDENT IN 12Z AREA SOUNDINGS ARE LIKELY TO CONTINUE OVER THE
REGION...AND WHEN COUPLED WITH DIURNAL HEATING...THE ENVIRONMENT
WILL DESTABILIZE WITH MLCAPE INCREASING TO 1000-1500 J/KG DURING THE
AFTERNOON.
LARGE SCALE ASCENT WILL GRADUALLY INCREASE IN ASSOCIATION WITH LOW
LEVEL UPSLOPE FLOW AND DIVERGENCE ALOFT IN ADVANCE OF THE UPPER LOW.
WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS
AFTERNOON AS DIABATIC HEATING ELIMINATES ANY REMAINING WEAK CAP.
WIND PROFILES ARE FORECAST TO EXHIBIT VEERING WITH HEIGHT PROVIDING
SUFFICIENT BULK SHEAR TO ENHANCE STORM ORGANIZATION AND INTENSITY.
THIS WILL PROMOTE A FEW SEVERE STORMS...INCLUDING ISOLATED
SUPERCELLS...DURING THE AFTERNOON AND EVENING WITH STRONGER CELLS
CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WIND GUSTS. ALTHOUGH
STORM INTENSITY MAY SLOWLY WEAKEN BY 03-06Z...A FEW STRONGER CELLS
MAY PERSIST INTO THE OVERNIGHT HOURS MAINLY OVER PARTS OF CNTRL/SERN
NM.
...FAR SRN NV/SERN CA INTO NM...
DIURNAL HEATING BENEATH COOL MID-LEVEL TEMPERATURES ASSOCIATED WITH
THE UPPER LOW WILL RESULT IN MODEST DESTABILIZATION ACROSS THIS
REGION. LARGE-SCALE ASCENT WILL SUPPORT AN INCREASE IN AFTERNOON
SHOWERS AND THUNDERSTORMS AS THE AIR MASS DESTABILIZES...ACROSS AZ
AND VICINITY INITIALLY AND THEN SPREADING EWD INTO NM LATER IN THE
AFTERNOON/EVENING.
WITH MODERATE MID-LEVEL SLYS/SELYS IN ADVANCE OF THE UPPER
LOW...SHEAR SUFFICIENT FOR SOME UPDRAFT ORGANIZATION MAY ALLOW A FEW
LONGER-LIVED STORMS TO EVOLVE DESPITE MODEST CAPE. WHILE
APPRECIABLE SEVERE WEATHER IS NOT ANTICIPATED...MARGINALLY-SEVERE
HAIL AND/OR GUSTY WINDS MAY OCCUR WITH THE STRONGEST CELLS.
..WEISS/ROGERS.. 10/20/2010
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