SPC AC 221627
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CDT THU APR 22 2010
VALID 221630Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT FOR
PARTS OF THE SRN/CENTRAL PLAINS...
...CENTRAL/SRN PLAINS THROUGH TONIGHT...
A STRONG MIDLEVEL LOW CENTERED NEAR LAS VEGAS WILL MOVE SLOWLY EWD
THROUGH EARLY FRIDAY...AS AN EMBEDDED SPEED MAX ROTATES AROUND THE
LOW /FROM THE NRN GULF OF CA/ AND EJECTS NEWD TOWARD THE SRN HIGH
PLAINS. THE APPROACH OF THIS EMBEDDED SHORTWAVE TROUGH TONIGHT WILL
CONTRIBUTE TO DEEPENING OF THE LEE CYCLONE NOW IN SE CO. S/SE OF
THE LEE CYCLONE...THE DRYLINE WILL BECOME BETTER DEFINED THIS
AFTERNOON/EVENING FROM EXTREME SE CO/SW KS SWD ACROSS THE CENTRAL TX
PANHANDLE TO W CENTRAL TX. OVERNIGHT...A PACIFIC COLD FRONT /NOW IN
CENTRAL NM/ WILL SURGE EWD WITH THE EJECTING SHORTWAVE TROUGH AND
OVERTAKE THE DRYLINE ACROSS THE TX PANHANDLE AND W TX.
A MARGINAL HAIL THREAT WILL CONTINUE THROUGH THE DAY WITH ELEVATED
CONVECTION N OF THE WARM FRONT INTO E CENTRAL/SE KS. FARTHER
W/SW...THE WEAK ELEVATED CONVECTION NOW OVER SW KS AND SW OK/NW TX
WILL MOVE AWAY FROM THE DRYLINE IN CONJUNCTION WITH A WEAK LEAD
SHORTWAVE TROUGH. SURFACE HEATING WILL INCREASE IN THE WAKE OF THIS
CONVECTION AS STRATUS CLOUDS BEGIN TO ERODE FROM W TO E...WHILE
BOUNDARY LAYER DEWPOINTS OF 60-65 F SPREAD NWD FROM CENTRAL/NW TX
TOWARD THE TX PANHANDLE AND WRN OK /56-60 F DEWPOINTS ARE EXPECTED
FARTHER NW INTO KS/. 12Z OBSERVATIONS AND MODEL FORECAST SOUNDINGS
SUGGEST THAT SURFACE TEMPERATURES OF 75-80 F ALONG THE DRYLINE WILL
REMOVE CONVECTIVE INHIBITION AND CONTRIBUTE TO MLCAPE RANGING FROM
1500 J/KG IN WRN KS TO 2500 J/KG NEAR THE TX/OK BORDER. AT LEAST
ISOLATED THUNDERSTORM DEVELOPMENT IS EXPECTED ALONG THE CENTRAL TX
PANHANDLE/SW KS DRYLINE BY ABOUT 21-22Z. GIVEN THE PRESENCE OF
MODERATE INSTABILITY AND INCREASING DEEP-LAYER VERTICAL
SHEAR...SUPERCELLS ARE LIKELY.
THE PRIMARY INITIAL SEVERE THREAT WILL BE ISOLATED VERY LARGE HAIL
WITH SUPERCELLS ACROSS THE TX PANHANDLE...AND A COUPLE OF TORNADOES
FARTHER N ALONG THE KS/CO BORDER AS STORMS MOVE OFF THE DRYLINE AND
CROSS THE WARM FRONT. THE TORNADO THREAT IS EXPECTED TO INCREASE
TOWARD EVENING ACROSS THE ERN TX PANHANDLE AND WRN OK AS LOW-LEVEL
MOISTURE SLOWLY INCREASES AND THE LLJ STRENGTHENS. ANY SURVIVING
DISCRETE STORMS FROM LATE AFTERNOON WILL HAVE THE POTENTIAL TO
PRODUCE AN ISOLATED STRONG TORNADO NEAR SUNSET /OR JUST AFTER/ AS
SRH INCREASES AND INSTABILITY REMAINS BASED AT THE SURFACE WITH
RELATIVELY SMALL CONVECTIVE INHIBITION.
OVERNIGHT...A LINE OF THUNDERSTORMS IS EXPECTED TO DEVELOP ACROSS W
TX AS THE COLD FRONT OVERTAKES THE DRYLINE. THESE STORMS WILL MOVE
QUICKLY EWD/NEWD TOWARD CENTRAL/NW TX AND WRN/CENTRAL OK LATE
TONIGHT. THE STRONGEST STORMS WILL BE CAPABLE OF PRODUCING LARGE
HAIL/DAMAGING WINDS...WHILE A TORNADO OR TWO WILL BE POSSIBLE WITH
EMBEDDED SUPERCELL STRUCTURES.
...SE NEW ENGLAND THIS AFTERNOON...
SCATTERED THUNDERSTORMS WILL LIKELY FORM ALONG A WEAK SURFACE COLD
FRONT...AND IN ADVANCE OF A WEAK MIDLEVEL WAVE MOVING EWD FROM NY.
STEEP LOW-MIDLEVEL LAPSE RATES AND COLD TEMPERATURES ALOFT MAY
PROMOTE THE FORMATION OF SMALL HAIL...BUT SEVERE STORMS ARE NOT
EXPECTED GIVEN WEAK VERTICAL SHEAR AND POOR LOW-LEVEL MOISTURE.
..THOMPSON/ROGERS.. 04/22/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
|
