| Categorical Graphic |
|---|
 |
| Probabilistic Tornado Graphic |
 |
| Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
| Probabilistic Damaging Wind Graphic |
 |
| Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
| Probabilistic Large Hail Graphic |
 |
| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
SPC AC 121628
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT THU JUL 12 2012
VALID 121630Z - 131200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN PLAINS...
...NRN PLAINS...
UPPER VORTICITY MAX NEAR THE SW MANITOBA/NORTH CENTRAL ND BORDER IS
EXPECTED TO CONTINUE MOVING SLOWLY EWD REACHING THE NWRN MN BORDER
LATE TONIGHT. A WEAK SURFACE COLD FRONT FROM ERN ND SWWD INTO
CENTRAL AND SWRN SD WILL MOVE SLOWLY EWD AND PROVIDE A FOCUS FOR
THUNDERSTORM DEVELOPMENT THIS AFTERNOON. 12Z REGIONAL SOUNDINGS
INDICATE THAT STEEP MID LEVEL LAPSE RATES HAVE SPREAD ACROSS THIS
AREA AND...WHEN COUPLED WITH STRONG DIABATIC HEATING AND SURFACE DEW
POINTS IN THE LOW/MID 60S...WILL ENHANCE INSTABILITY WITH CAPE
REACHING 1500-2000 J/KG LATER THIS AFTERNOON AND EVENING.
THUNDERSTORMS ARE EXPECTED TO DEVELOP BY MID-LATE AFTERNOON NEAR THE
FRONT OVER PARTS OF THE DAKOTAS. MID LEVEL WINDS OF 20-25 KT WILL
PROVIDE SUFFICIENT SHEAR FOR MULTICELL STORM STRUCTURES WITH
STRONGER CELLS CAPABLE OF PRODUCING LARGE HAIL AND LOCALIZED SEVERE
WIND GUSTS THROUGH THE EVENING HOURS. ADDITIONAL STORMS MAY ALSO
DEVELOP SWWD ALONG A SURFACE TROUGH ACROSS WRN NEB INTO NERN CO.
LOW LEVEL MOISTURE WILL BE LOWER NEAR THE TROUGH WITH THERMODYNAMIC
PROFILES FAVORING HIGH-BASED STORMS CAPABLE OF PRODUCING STRONG
DOWNBURST WINDS AND POSSIBLE HAIL.
...SWRN US...
AN UPPER LOW OVER THE EXTREME NRN GULF OF CA IS FORECAST TO MOVE
NWWD TOWARD SERN CA AND MAINTAIN A MOIST SELY FLOW OVER THE AREA.
CONSIDERABLE CLOUDS ARE EVIDENT FROM WRN AZ ACROSS THE LOWER CO
RIVER VALLEY WHICH WILL MODULATE DIABATIC HEATING OVER MUCH OF THE
AREA THIS AFTERNOON. HOWEVER...THERE WILL BE POCKETS OF
THINNING/CLEARING OF CLOUDS /ESPECIALLY FROM SERN AZ INTO NWRN AZ/
AND WHERE THIS OCCURS STRONGER DESTABILIZATION IS LIKELY TO OCCUR.
AN INCREASE IN CONVECTION IS EXPECTED TO OCCUR THIS AFTERNOON AND
EVENING AS THE LOW MOVES NWWD AND A SHORT WAVE TROUGH SEEN IN WATER
VAPOR IMAGERY LIFTS NWD INTO SRN/CENTRAL AZ. RELATIVELY STRONG
ESELY MID LEVEL WINDS /20-30 KT/ WILL ALLOW CONVECTION TO SPREAD
WWD/NWWD WITH TIME...WITH STRONGER STORMS CAPABLE OF PRODUCING
STRONG WINDS AND POSSIBLY MARGINAL HAIL. GIVEN THE BROAD ZONE OF
STRONGER WINDS ALOFT...AREA WILL BE MONITORED FOR SIGNS OF GREATER
DESTABILIZATION THAN CURRENTLY EXPECTED AND A SUBSEQUENT INCREASE IN
ORGANIZED SEVERE POTENTIAL.
...SERN STATES...
VERY MOIST ENVIRONMENT WITH PW AOA 2 INCHES WILL PERSIST FROM SE TX
INTO THE GULF CST STATES...THE TN VLY...AND THE CAROLINAS
TODAY...ALONG AND E OF POSITIVE TILT UPR TROUGH. WEAK MID LVL
CIRCULATION THAT DROPPED SSE ACROSS OK AND NE TX OVERNIGHT SHOULD
SERVE TO SOMEWHAT SHARPEN THE LARGER SCALE TROUGH AND NUDGE IT E
INTO THE LWR MS VLY THIS AFTERNOON. SLIGHTLY STRONGER FLOW ON E SIDE
OF THE TROUGH MAY FOSTER WEAK ORGANIZATION IN DIURNALLY-ENHANCED
STORM CLUSTERS OVER REGION...ESPECIALLY ALONG THE SRN EDGE OF THE
DEEP-LAYERED CLOUD AXIS WHERE STRONGER HEATING WILL OCCUR. WEAKLY
SHEARED...VERY MOIST ENVIRONMENT SUGGESTS THAT ANY SEVERE THREAT
WILL BE LIMITED TO ISOLATED WET MICROBURSTS.
..WEISS/GARNER.. 07/12/2012
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
CURRENT UTC TIME: 1634Z (11:34AM), RELOAD THIS PAGE TO UPDATE THE TIME
No comments:
Post a Comment