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Apr 2, 2014 1300 UTC Day 1 Convective Outlook

April 2, 2014

Apr 2, 2014 1300 UTC Day 1 Convective Outlook

day1otlk

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 AM CDT WED APR 02 2014

VALID 021300Z – 031200Z

…THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL/SRN PLAINS TO MID-SOUTH REGION…

…SYNOPSIS…
PRINCIPAL UPPER-AIR INFLUENCE ON CONVECTION WILL BE COMPLEX SYNOPTIC-SCALE CYCLONE WITH MULTIPLE CENTERS…EVIDENT IN MOISTURE-CHANNEL IMAGERY FROM NRN ROCKIES SWWD ACROSS CA. LEADING/EMBEDDED VORTICITY MAX NOW OVER ID SHOULD WEAKEN AS IT DRIFTS EWD…WHILE SEVERAL BASAL SHORTWAVES PIVOT CYCLONICALLY BETWEEN SRN CA AND BLACK HILLS. BY 00Z…POSITIVELY TILTED TROUGH SHOULD TAKE SHAPE AND EXTEND FROM ERN MT ACROSS UT TO SRN CA. BY 12Z…500-MB TROUGH STILL WILL BE POSITIVELY TILTED BUT NOT AS MUCH…WHILE LOCATED FROM ND SSWWD OVER ERN CO TO SERN AZ. BY THAT TIME MAIN VORTICITY MAX SHOULD BE LOCATED OVER CENTRAL/NERN NM.

AT SFC…11Z ANALYSIS SHOWED MAIN CYCLONE STILL OVER SERN CO…WITH SEGMENTED WARM FRONT SEWD OVER WRN/CENTRAL OK TO WRN AR. DRYLINE WAS DRAWN FROM CDS AREA SWWD ACROSS WRN PERMIAN BASIN THEN SEWD INTO NRN COAHUILA. DRYLINE IS EXPECTED TO BECOME MORE MERIDIONAL THROUGH AFTN FROM WRN OK TO W-CENTRAL TX…BY MIXING EWD OVER TX AND BACKING NWWD ACROSS OK. DRYLINE SHOULD SHIFT NWWD ENOUGH TO INTERSECT NWD-MOVING WARM FRONT BY 00Z-03Z TIME FRAME INVOF KS/OK BORDER…BETWEEN DDC…GAG AND AVK. OVERNIGHT…SFC LOW WILL TRAVEL ALONG CYCLONICALLY CURVED BAROCLINIC ZONE TO S-CENTRAL/SERN KS…WITH TRAILING COLD FRONT MOVING SEWD INTO NWRN OK. WARM FRONT WILL MOVE NWD OVER SERN KS AND SRN MO.

…CENTRAL/SRN PLAINS…
ISOLATED TO WIDELY SCATTERED TSTMS MAY DEVELOP THIS AFTN AND/OR EVENING…WITH VERY LARGE/DAMAGING HAIL…SVR GUSTS AND TORNADOES POSSIBLE FROM ANY SUSTAINED CONVECTION.

MAIN CONCERNS INVOLVE TIMING/COVERAGE OF TSTMS. EXPECT WEAK LOW-LEVEL FORCING…ASIDE FROM LOCALIZED/SUB-MESOSCALE EFFECTS…IN PRESENCE OF STG EML-RELATED CAPPING AS OBSERVED ON 12Z MAF/OUN/FWD RAOBS. THIS MAKES TSTM DEVELOPMENT VERY UNCERTAIN…IN WARM-SECTOR ENVIRONMENT THAT OTHERWISE STRONGLY FAVORS MULTI-HAZARD SUPERCELLS. ONLY WEAK CONVERGENCE IS EXPECTED ALONG DRYLINE WITH SLY WINDS PROGGED TO ITS IMMEDIATE W…WHILE POTENTIAL EXISTS FOR MUCH OR ALL OF SFC FRONT TO REMAIN CAPPED AS WELL. DIURNAL TSTM INITIATION INVOF DRYLINE AND WARM FRONT MAY BE VERY SPARSE…AND SOME POSSIBILITY EXISTS FOR NONE ALONG THOSE BOUNDARIES UNTIL AFTER DARK. FARTHER E…NON-DRYLINE/NON-FRONTAL DEVELOPMENT HAS BEEN INDICATED IN FREE WARM SECTOR BY SOME OPERATIONAL MODELS AND SREF MEMBERS. HOWEVER…THIS SCENARIO APPEARS RATHER IMPROBABLE GIVEN STRENGTH OF EML AND LACK OF APPARENT BOUNDARY FOCI OUTSIDE FRONT/DRYLINE.

THAT STATED…UNCONDITIONAL SVR PROBABILITIES ARE BEING MAINTAINED DUE TO POTENTIAL FOR ANY TSTMS THAT DO FORM TO EVOLVE INTO SUBSTANTIALLY DAMAGING SUPERCELLS. BY LATE AFTN…SFC DIABATIC HEATING SHOULD ACT IN TANDEM WITH STEEP LOW-MIDLEVEL LAPSE RATES…ANTECEDENT BOUNDARY-LAYER MOIST ADVECTION…AND RESULTANT 60S F SFC DEW POINTS…TO YIELD 3000-4000 J/KG MLCAPE IN MOIST SECTOR. INCREASING HIGH-CLOUD COVER WITH SWD EXTENT…ALREADY NOTED IN IR IMAGERY…WILL RESTRICT HEATING AND RELATED LIFT INTO W-CENTRAL TX AND PERHAPS SRN OK…THOUGH AREA WHERE NRN EDGE OF HIGH-CLOUD CANOPY CROSSES DRYLINE OVER NW TX/SWRN OK MAY BE ONE POTENTIAL INITIATION ZONE…IN ADDITION TO TRIPLE-POINT AREA. LOW-LEVEL SHEAR…MRGL DURING EARLY-MID AFTN…WILL STRENGTHEN WITH TIME INTO EARLY EVENING. FCST SOUNDINGS SUGGEST WINDOW OF OPPORTUNITY WILL EXIST FROM ABOUT 00-03Z FOR LLJ-ENLARGED HODOGRAPHS TO YIELD 300-400 J/KG EFFECTIVE SRH…WHILE LIFTED PARCELS STILL ARE SFC-BASED AMIDST LARGE CAPE. THIS FITS WELL-KNOWN ENVIRONMENTAL SCENARIOS FOR EVENING/EARLY NOCTURNAL TORNADO PRODUCTION…IF STORMS CAN DEVELOP.

…AR/MID-SOUTH REGION…
ONE OR MORE CLUSTERS OF TSTMS MAY DEVELOP TODAY AND THIS EVENING IN WARM/MOIST CONVEYOR LOCATED OVER AR…PERHAPS MOVING INTO PORTIONS NWRN MS AND WRN TN. THIS ACTIVITY WOULD BE LOCATED ALONG ERN RIM OF EML…AND AS SUCH…NOT SUBJECT TO SUCH STG CAPPING FOR BOUNDARY-LAYER PARCELS THAT MAKES POTENTIAL SO CONDITIONAL FARTHER W. HOWEVER…GIVEN ITS INITIALLY ELEVATED/ISENTROPICALLY LIFTED NATURE…SPECIFIC TIMING/LOCATION FOR SUCH CONVECTION TO BECOME SVR ALSO IS UNCERTAIN.

AIR MASS OVER THIS REGION WILL BECOME FAVORABLY UNSTABLE FROM MIDDAY THROUGH AFTN…WHILE VERTICAL WIND PROFILES EXHIBIT PRONOUNCED VEERING AND STRENGTHENING WITH HEIGHT. AS SUCH…CONVECTION MAY EVOLVE INTO SUPERCELLS AND/OR BOWS…WITH FULL SPECTRUM OF SVR POSSIBLE…INCLUDING RISK OF TORNADOES. ANY ACTIVITY FROM FARTHER W THAT CAN PERSIST INTO OVERNIGHT HOURS…AND GROW UPSCALE AMIDST STG LOW-LEVEL WAA/MOISTURE TRANSPORT…ALSO MAY MOVE INTO THIS REGION LATE TONIGHT. BUOYANCY WILL DIMINISH WITH EWD EXTENT AS MORE LOW-LEVEL TRAJECTORIES EMANATE FROM LOWER-THETAE ANTICYCLONIC FLOW REGIME.

…LOWER MO VALLEY REGION…
ISOLATED/MRGL SVR HAIL CANNOT BE RULED OUT THIS MORNING WITH CLUSTERS OF ELEVATED TSTMS OVER THIS REGION…PER 12Z SGF RAOB YIELDING ELEVATED MUCAPE APCHG 2500 J/KG AND 50-55 KT EFFECTIVE SHEAR MAGNITUDE. TONIGHT…INTENSIFYING LLJ AND RELATED WAA/ISENTROPIC LIFT WILL YIELD POTENTIAL FOR MORE ELEVATED CONVECTION…AMIDST STRENGTHENING DEEP-SHEAR CONDITIONS FAVORABLE FOR SUPERCELLS AND ATTENDANT HAIL RISK.

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