DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0351 AM CDT WED APR 23 2014
VALID 261200Z - 011200Z
...DISCUSSION... ..SIGNIFICANT MULTI-DAY SEVERE EVENT EXPECTED ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS SATURDAY AND SUNDAY AND ACROSS THE MS VALLEY AND MID SOUTH ON MONDAY...STRONG TORNADOES ARE POSSIBLE...
MEDIUM RANGE FORECAST CONTINUES TO BE HEAVILY WEIGHTED TOWARD THE ECMWF DUE TO RUN-TO-RUN CONSISTENCY REGARDING THE 500MB EVOLUTION OF WRN U.S. TROUGH. CONCERNS REGARDING POLAR FRONT UNDERCUTTING STRONG SWLY FLOW ALOFT HAVE ABATED THIS MORNING. LATEST GUIDANCE DEEPENS LEE CYCLONE OVER SERN CO SATURDAY AFTERNOON WITH SUBSEQUENT MOVEMENT INTO WRN KS ON SUNDAY. INTENSE 500MB SPEED MAX APPROACHING 90KT SHOULD ROUND THE BASE OF THE TROUGH ALONG THE AZ/MEXICAN BORDER THEN EJECT INTO SWRN KS EARLY SUNDAY. AS A RESULT SFC LOW IS NOT EXPECTED TO ADVANCE APPRECIABLY EWD UNTIL LATER MONDAY AS SECONDARY MID-LEVEL SPEED MAX DEVELOPS FROM NORTH TX INTO THE LOWER OH RIVER VALLEY.
MODERATE TO EXTREME INSTABILITY SHOULD DEVELOP EAST OF THE DRYLINE SATURDAY AFTERNOON ALONG ERN PLUME OF STEEP LAPSE RATES. STRONGLY DIFLUENT FLOW ALOFT SHOULD ENCOURAGE VIGOROUS SUPERCELL DEVELOPMENT FROM PORTIONS OF WCNTRL TX...NWD INTO KS. VERY LARGE HAIL AND TORNADOES CAN BE EXPECTED WITH THIS ACTIVITY.
IT/S NOT ENTIRELY CLEAR HOW FAR EAST THE DRYLINE WILL MIX SUNDAY AS LOWEST PRESSURES WILL REMAIN FOCUSED ACROSS THE HIGH PLAINS OF WRN KS. MODELS MIX DRYLINE EAST OF I-35 CORRIDOR ACROSS OK BY 18Z SUNDAY BUT THE DAY5 FORECAST WILL ACCOUNT FOR DRYLINE NOT MIXING ACROSS THE PLAINS AS FAST AS MODELS CURRENTLY DEPICT. AS A RESULT...SUBSTANTIAL MID-LEVEL FLOW SHOULD OVERSPREAD THE MOIST/BUOYANT WARM SECTOR AND ANOTHER DIURNALLY-INITIATED ROUND OF POTENTIALLY TORNADIC SUPERCELLS COULD EVOLVE.
LATER MONDAY IT APPEARS THE SFC FRONT/DRYLINE SHOULD ADVANCE INTO THE MS VALLEY. SCATTERED-NUMEROUS SUPERCELLS SHOULD EVOLVE AHEAD OF THE FRONT FROM LA...NWD INTO MO AND POSSIBLY AS FAR EAST AS MIDDLE TN. TORNADOES AND LARGE HAIL REMAIN POSSIBLE WITH WARM-SECTOR CONVECTION.
As if the Euro couldn't get any more threatening after yesterday's 12z run...the 00z run is even more volatile. Winds at all the levels are stronger, CAPE is higher, and moisture return is no problem. I'm not too concerned for my area just yet, but it'll definitely be interesting come the weekend to see how everyone starts reacting. Seems like it doesn't take much to spin up tornadoes in Dixie Alley, so when I see numbers like this, my stomach drops.
Wow! Monday afternoon low level winds:
Monday afternoon 500 mb winds:
And with a tilt like such, I don't see a squall line with this system. This favors supercells.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NEW ORLEANS LA 836 AM CDT WED APR 23 2014
.SHORT TERM... REMINDER THAT WEDNESDAY IS WEEKLY RADIO TEST DAY AROUND 11 AM THIS MORNING.
.LONG TERM... THE NEXT HWO ISSUANCE WILL INTRODUCE A CHANCE OF STRONG TO POSSIBLY SEVERE THUNDERSTORMS FOR EARLY NEXT WEEK...BASED ON LATEST MODEL TRENDS AND SPC 4-7 DAY OUTLOOK. NO OTHER CHANGES AT THIS TIME.
.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY
SEVERE THUNDERSTORMS WITH WIND GUSTS UP TO 60 MPH AND HAIL UP TO 1 INCH WILL BE POSSIBLE ALONG AND NORTHWEST OF A WINNSBORO...TO YAZOO CITY...TO EUPORA LINE LATE THURSDAY AFTERNOON THROUGH THURSDAY EVENING MAINLY FOR THE ARKLAMISS DELTA REGION.
IN ADDITION...CONFIDENCE IS INCREASING FOR THE POSSIBILITY OF MULTIPLE ROUNDS OF SEVERE THUNDERSTORMS ACROSS THE REGION LATE SUNDAY THROUGH MONDAY NIGHT. THIS POTENTIAL WEATHER EVENT IS STILL SEVERAL DAYS AWAY...AND THE TIMING AND IMPACTS WILL LIKELY BE ADJUSTED IN LATER FORECASTS.
.SPOTTER CALL TO ACTION STATEMENT... THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER OPERATIONS MAY BE NEEDED FOR PORTIONS OF THE REGION THURSDAY THROUGH THURSDAY NIGHT AND SUNDAY THROUGH MONDAY.
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST LOUISIANA...SOUTH MISSISSIPPI AND THE ADJACENT COASTAL WATERS.
.DAY ONE...THIS AFTERNOON AND TONIGHT
AREAS OF FOG...POSSIBLY DENSE...WILL BE POSSIBLE OVERNIGHT. VISIBILITY MAY DROP TO ONE QUARTER MILE OR LESS AT TIMES.
RIVER FLOOD WARNINGS ARE IN EFFECT FOR THE LOWER PEARL RIVER AND THE MISSISSIPPI RIVER AT RED RIVER LANDING. REFER TO THE LATEST RIVER FLOOD STATEMENTS FOR MORE DETAILS.
.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY
RIVER FLOODING WILL BE ONGOING ON THE PEARL RIVER AND PORTIONS OF THE MISSISSIPPI RIVER DURING THE OUTLOOK PERIOD. REFER TO THE LATEST RIVER FLOOD STATEMENTS FOR MORE DETAILS.
CONFIDENCE IS INCREASING FOR THE POSSIBILITY OF STRONG TO SEVERE THUNDERSTORMS ACROSS THE AREA STARTING MONDAY INTO TUESDAY MORNING. THIS POTENTIAL WEATHER EVENT IS STILL SEVERAL DAYS AWAY...AND THE TIMING AND IMPACTS WILL LIKELY BE ADJUSTED IN LATER FORECASTS.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT ANTICIPATED. - wtf?
Last Edit: Apr 23, 2014 11:02:53 GMT -6 by CajunWX
GFS has CAPE values over 3,000 J/KG in parts of South Louisiana with widespread 2,000 J/KG across most of Louisiana, Mississippi, and Western Alabama. Best shear does appear over parts of Mississippi and Alabama. GFS isn't nearly as aggressive with the shear and instability like the Euro, which should be running in about a hour.
