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Apr 7, 2014 1630 UTC Day 1 Convective Outlook

April 7, 2014

Apr 7, 2014 1630 UTC Day 1 Convective Outlook

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DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1049 AM CDT MON APR 07 2014

VALID 071630Z – 081200Z

…THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE SERN U.S. TO TIDEWATER REGION…

…THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE UPPER OH VALLEY INTO CUMBERLAND PLATEAU…

…SYNOPSIS…

A FULL LATITUDE TROUGH EXTENDING FROM AN UPPER LOW OVER HUDSON BAY SWD INTO THE SRN PLAINS WILL UNDERGO INTENSIFICATION AS IT PROGRESSES EWD INTO THE GREAT LAKES AND MS VALLEY. WITHIN THIS BROADER-SCALE PATTERN…A LEAD SHORT-WAVE TROUGH AND ASSOCIATED 100 KT JET STREAK AT 500 MB WILL TRANSLATE FROM THE OZARK PLATEAU/MID SOUTH INTO THE UPPER OH VALLEY AND LOWER GREAT LAKES. THIS SYSTEM WILL BE FOLLOWED BY ANOTHER VORTICITY MAXIMUM AND MIDLEVEL JET STREAK WHICH WILL MOVE THROUGH THE BASE OF THE PARENT TROUGH ALONG THE GULF COAST BEFORE EMERGING ACROSS THE SRN ATLANTIC STATES LATE IN THE PERIOD. IN RESPONSE TO THIS UPPER-AIR PATTERN EVOLUTION…A BROAD 50+ KT SSWLY LLJ WILL DEVELOP NWD THROUGH THE NERN U.S…ENHANCING THE POLEWARD FLUX OF HEAT AND MOISTURE EAST OF THE APPALACHIANS.

AT THE SURFACE…LOW PRESSURE OVER WRN KY AS OF MID MORNING WILL CONTINUE TO DEEPEN WHILE DEVELOPING NNEWD INTO OH BY LATE AFTERNOON/EVENING BEFORE REACHING LAKE ONTARIO BY DAYBREAK TUESDAY. A TRAILING COLD FRONT EXTENDING FROM THIS LOW SSWWD TO OFF THE CNTRL GULF COAST WILL ADVANCE EWD TO NEAR THE ATLANTIC COAST BY 08/12Z. MEANWHILE…A WEDGE FRONT WILL MOVE NWD THROUGH THE CAROLINAS AND COASTAL PARTS OF THE MID ATLANTIC STATES TOWARDS NEW ENGLAND…THOUGH THE MOVEMENT OF THIS BOUNDARY WILL BE SLOWED BY THE REINFORCEMENT OF COLD AIR TO IT/S NORTH BY ONGOING PRECIPITATION.

…SERN STATES TO MID ATLANTIC COAST THIS AFTERNOON INTO TONIGHT…

AS MENTIONED IN THE SYNOPSIS…THE NWD DEVELOPMENT OF THE LLJ WILL HASTEN THE POLEWARD FLUX OF A HIGH-PW AIR MASS FROM OFF THE ERN GULF OF MEXICO AND WRN ATLANTIC NWD THROUGH THE PIEDMONT AND COASTAL PLAIN WITH MLCAPE APPROACHING 500-1000 J/KG BY AFTERNOON. LATEST CONVECTION-ALLOWING MODEL GUIDANCE IS IN REASONABLY GOOD AGREEMENT IN SUGGESTING A CONTINUED EWD PROGRESSION OF THE ONGOING QLCS TOWARD THE SRN ATLANTIC COAST WITH ADDITIONAL DOWNSTREAM STORM DEVELOPMENT POSSIBLE BY AFTERNOON ALONG THE WEDGE FRONT MOVING NWD THROUGH THE CAROLINAS.

REGIONAL VAD DATA WITHIN THE NWD-EXPANDING WARM SECTOR INDICATE VERTICALLY VEERING WIND PROFILES WITH RELATIVELY STRONG LOW-LEVEL AND DEEP-LAYER SHEAR. EXPECT A SIMILAR KINEMATIC ENVIRONMENT TO PERSIST TODAY WHICH SHOULD SERVE TO MAINTAIN ORGANIZED CONVECTIVE ELEMENTS EMBEDDED WITHIN THE LARGER-SCALE QLCS…INCLUDING SUPERCELLS AND BOWING STRUCTURES CAPABLE OF DAMAGING WINDS AND A FEW TORNADOES.

FOR ADDITIONAL NEAR-TERM GUIDANCE ON THIS REGION…SEE MCD 310 AND WW 67.

…UPPER OH VALLEY THIS AFTERNOON INTO EVENING…

VISIBLE SATELLITE DATA SUGGEST THAT CLOUDS WILL LIMIT ROBUST HEATING TODAY. SHOULD MORE SUBSTANTIAL CLOUD BREAKS DEVELOP…STEEPENING LOW TO MIDLEVEL LAPSE RATES AND DEWPOINTS RISING INTO THE LOWER 50S MAY YIELD POCKETS OF WEAK SURFACE-BASED INSTABILITY /I.E. MLCAPE OF 250-500 J PER KG/. GIVEN THE BACKED SURFACE WINDS OWING TO THE ISALLOBARIC RESPONSE TO THE MIGRATORY SURFACE LOW AND THE NEWD PROGRESSION OF THE 90-100+ KT MIDLEVEL JET STREAK INTO THE REGION…THE SETUP MAY SUPPORT A BROKEN BAND OF LOW-TOPPED SUPERCELLS AND/OR BOWING STRUCTURES WITH A RISK FOR A COUPLE TORNADOES…LOCALLY DAMAGING WINDS AND PERHAPS SOME HAIL. THIS THREAT SHOULD DIMINISH BY MID TO LATE EVENING AS THE BOUNDARY LAYER BEGINS TO COOL AND STABILIZE.

…CNTRL OK INTO CNTRL TX THIS AFTERNOON/EVENING…

SIMILAR TO YESTERDAY/S SETUP ACROSS WRN TX…COLD MIDLEVEL TEMPERATURES WILL COMBINE WITH DAYTIME HEATING TO PROMOTE THE DEVELOPMENT OF STEEP LOW TO MIDLEVEL LAPSE RATES AND WEAK SURFACE-BASED INSTABILITY /I.E. MLCAPE OF 250-500 J PER KG/ ALONG A WIND SHIFT/WEAK FRONT MOVING SEWD ACROSS THE REGION. ISOLATED TO WIDELY SCATTERED STORMS WILL BE POSSIBLE ALONG THIS FEATURE AS DEEP-LAYER ASCENT IS ENHANCED BY THE PRESENCE OF THE MIDLEVEL TROUGH. ISOLATED OCCURRENCES OF HAIL APPROACHING SEVERE LEVELS AND LOCALLY STRONG WIND GUSTS WILL BE POSSIBLE WITH THE BEST POTENTIAL FOR LONGER-LIVED/ROTATING UPDRAFTS RESIDING ACROSS THE CONCHO VALLEY AND EDWARDS PLATEAU OF TX WHERE DEEP-LAYER SHEAR WILL BE ENHANCED BY THE PRESENCE OF A MIDLEVEL JET STREAK MOVING THROUGH THE BASE OF THE TROUGH.

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