AY 1 SEVERE WEATHER OUTLOOK
STREAMWIZE STORM PREDICTION
2:00 AM EST SAT NOV 21 2009
VALID 21/07Z-22/12Z
GNRL TSTMS ARE FORECAST THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTHERN AND CENTRAL LOUISIANA... SOUTHERN MISSISSIPPI... SOUTHERN ALABAMA AND THE WESTERN FLORIDA PANHANDLE
GNRL TSTMS ARE FORECAST THIS AFTERNOON FOR PARTS OF WESTERN WASHINGTON... WESTERN OREGON AND FAR NORTHWEST CALIFORNIA.
LATEST VAPOR CHANNEL IMAGERY AND 21/0Z UPPER AIR ANALYSIS INDICATES SHRT-WV/VORT MAX CURRENTLY TRAVERSING CENTRAL TX... A POWERFUL TROUGH AXIS IS ALONG THE PACIFIC COAST FROM WESTERN CANADA SOUTHWARD INTO CENTRAL CALIFORNIA.
...GULF COAST...
AFOREMENTIONED SHRT-WV IS FORECAST TO EJECT INTO THE NORTHWESTERN GULF THROUGH EARLY MORNING... HIGH RESOLUTION WRF-NMM SUGGEST CYCLONEGENISIS AIDED BY 60-70KNT SPEED MAX ASSOCIATED WITH SHRT-WV.
MODEL PROGGES SUGGEST 35-45KNT H85 LLJ WILL DEVELOP
THROUGH EARLY AFTERNOON... THIS COMBINED WITH AFOREMENTIONED 60-70KNT H5 SPEED
MAX.. WILL AID 0-6KM SHEAR 45-55KNTS.
PRIMARY QUESTION WILL BE OVERALL LOWER ATMOSPHERIC INSTABILITY. SFC LOW IS
FORECAST TO LIFT NORTHEAST INTO SOUTHEAST LOUISIANA BY MID-AFTERNOON... THIS
WILL BRING WARM FRONT NORTH INTO SOUTHERN MS/SOUTHWEST AL... TD'S IN THE
MID/UPPER 60'S ARE POSSIBLE SOUTH OF WARM FRONT.. THIS COMBINED WITH STEEPENING
MID-LEVEL LAPSE RATES 6-7C/KM WILL LIKELY ALLOW FOR MORE SFC BASED INSTABILITY
THAN CURRENTLY FORECAST BY MODELS.. WITH SBCAPE /1000-2000J/KG/ POSSIBLE.
MODEL FORECAST SOUNDINGS INDICATE BACKED LOW LEVEL FLOW AND VEERING WITH HEIGHT... DERIVED HODOGRAPHS REVEAL STRONG CURVATURE IN THE LOWER 2KM.. THIS CORESPONDS TO FORECAST 0-1KM SHEAR 20-30KNTS.
GIVEN AFOREMENTIONED KINEMATIC FIELDS AND INDICATIONS OF STRONGER INSTABILITY THAN CURRENTLY FORECAST BY MODELS... STRONG DEEP LAYER SHEAR IN PLACE AND WARM FRONT FORECAST TO MOVE NORTH INTO GULF COAST STATES.. GIVEN FORECAST STRONG DIRECTIONAL LOW LEVEL SHEAR... SUPERCELLS WOULD BE POSSIBLE... HOWEVER ONGOING RAIN ACROSS THE LOWER MS VALLEY.. MAY HELP TO STABILIZE BOUNDARY SUFFICIENTLY TO MITIGATE ALL BUT ISOLATED SEVERE CONVECTION.
REGION WILL NEED TO BE MONITORED FOR A POSSIBLE CATEGORICAL UPGRADE IN LATER OUTLOOKS.
...WARNER
21-11-09