DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CDT SUN MAY 04 2014
VALID 071200Z - 121200Z
...DISCUSSION...
MEDIUM-RANGE MODELS HAVE CONTINUED OVER THE PAST SEVERAL RUNS TO
COME INTO BETTER AGREEMENT WITH DEPICTION OF THE UPPER TROUGH
ADVANCE INTO THE CENTRAL U.S. DAYS 4-5 /I.E. WED.-THU./...WITH THE
GFS AND ECMWF NOW SHOWING STRONG SIMILARITY THROUGH DAY 5 BUT
DIVERGING GRADUALLY THEREAFTER.
BOTH MODELS ADVANCE A LONGITUDINALLY EXTENSIVE WRN TROUGH TO ROUGHLY
THE FRONT RANGE OF THE ROCKIES BY THE END OF DAY 4. WITH THE
EVOLVING PLAINS WARM SECTOR LIKELY TO REMAIN GENERALLY CAPPED
THROUGH THE AFTERNOON/EVENING OF DAY 4...MOST DEEP CONVECTIVE
ACTIVITY SHOULD REMAIN TO THE COOL SIDE OF THE WARM FRONT...AND THUS
SEVERE RISK SHOULD REMAIN LIMITED.
DAY 5....BOTH MODELS DEPICT A SHUNTING OF THE MOST ENERGETIC PORTION
OF THE UPPER TROUGH QUICKLY NEWD ACROSS THE CENTRAL PLAINS AND
EVENTUALLY THE UPPER MS VALLEY...AS IT IMPINGES ON A FAIRLY STOUT
ERN U.S. RIDGE. AS SUCH...A SIMILAR NEWD ACCELERATION OF A
DEEPENING SURFACE LOW...FROM ITS INITIAL POSITION OVER THE CENTRAL
PLAINS TO THE LK SUPERIOR VICINITY LATE IN THE PERIOD...IS EXPECTED.
AS THIS OCCURS...EWD ADVANCE OF A COLD FRONT ACROSS A
THERMODYNAMICALLY UNSTABLE WARM SECTOR WILL YIELD WIDESPREAD
WARM-SECTOR THUNDERSTORM DEVELOPMENT.
A COMPLICATING FACTOR WITH RESPECT TO EVOLUTION OF SEVERE RISK DAY 5
IS THAT BOTH MODELS ACTIVATE CONVECTION ACROSS TX LATE DAY 4 AND
INTO THE DAY 5 PERIOD. WHILE SOME SEVERE RISK WOULD EXIST WITH THIS
CONVECTION LATE DAY 4 ACROSS PARTS OF WRN AND CENTRAL TX...GREATER
RISK IS EVIDENT DAY 5 ACROSS PARTS OF N CENTRAL TX AND INTO THE ERN
HALF OF OK AND THE ARKLATEX REGION...AS THE MOISTENING BOUNDARY
LAYER DIURNALLY DESTABILIZES. HERE...SEVERE RISK -- INCLUDING SOME
TORNADO POTENTIAL -- IS EXPECTED.
THIS SRN BATCH OF CONVECTION MAY HAVE EFFECTS ON AREAS FARTHER N --
I.E. INTO PARTS OF NERN OK/SERN KS AND THE OZARKS...BUT A SECOND
AREA OF LIKELY SEVERE RISK IS EXPECTED ACROSS PARTS OF ERN KS/NRN MO
AND INTO IA/SRN MN -- NEARER THE SURFACE LOW WHERE THE STRONGEST
FLOW ALOFT/MOST FAVORABLE SHEAR IS EXPECTED. RISK FOR HAIL/DAMAGING
WINDS ALONG WITH ISOLATED TORNADOES IS EXPECTED IN THIS REGION
THROUGH THE AFTERNOON AND EVENING.
WHILE TWO DISTINCT AREAS OF SEVERE RISK MAY RESULT -- A NRN AND SRN
AREA -- ON LARGER RISK AREA WILL BE INCLUDED ATTM PENDING LATER
FORECAST DETAILS.
WITH THE UPPER TROUGH PROGGED TO CONTINUE QUICKLY NEWD INTO CANADA
DAY 6...LESSER SEVERE RISK IS PROGGED AND THUS NO RISK AREAS WILL BE
INCLUDED ATTM.
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