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000
FXUS64 KHUN 162249 AAA
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
549 PM CDT SUN JUN 16 2013

.UPDATE...
FOR 00Z TAFS

&&

.DISCUSSION...
/ISSUED 239 PM CDT SUN JUN 16 2013/
WATER VAPOR IMAGERY AND H5 RAP ANALYSIS INDICATED UPPER LEVEL RIDGING
BREAKING DOWN OVER THE SOUTHERN CONUS, WITH A FEW STORM SYSTEMS
TRAVERSING THE SOUTHERN CANADIAN PROVINCES THIS AFTN. AN UPPER LEVEL
LOW WAS COMING ASHORE IN THE PACNW, WITH AN UPPER LOW BECOMING AN
OPEN WAVE OVER SOUTH/CENTRAL CANADA, WITH THE LAST OF THE 3 SYSTEMS
QUICKLY PUSHING EASTWARD TOWARD NEWFOUNDLAND. SEVERAL DISTURBANCES
WERE NOTED WEST TO EAST ACROSS THE CENTRAL PORTIONS OF THE COUNTRY,
WITH THE ONE CROSSING THE MS RIVER RESPONSIBLE FOR THE SCT CONVECTION
ACROSS OUR LOCAL AREA THIS AFTN. ON THE SFC, A WEAK COLD FRONT WAS
DRAPED WESTWARD ACROSS THE GREAT LAKES REGION, EXTENDING SOUTHWESTWARD
BACK INTO THE CENTRAL PLAINS. SCATTERED SHOWERS/STORMS WERE NOTED ON
REGIONAL RADAR MOSAICS THIS AFTN.

FOR TONIGHT, EXPECT THE CONVECTIVE TREND TO CONTINUE AND OVERSPREAD
THE AREA FROM WEST TO EAST AS THE DISTURBANCE ALOFT PASSES OVERHEAD.
GIVEN THE INCREASING MOISTURE ACROSS THE AREA (WITH DEWPOINTS IN THE
UPPER 60S/LOWER 70S) AND SOUTHERLY FLOW IN PLACE, FELT CONFIDENT TO
INCREASE POPS FOR OVERNIGHT TO 50%. SHORT-TERM MODELS SUPPORT THIS
DECISION, WITH MOS GUIDANCE FOLLOWING SUIT AS WELL. THE ONLY FLY IN
THE OINTMENT FOR TONIGHT REVOLVES AROUND AN INTERESTING FEATURE OF
NOTE CURRENTLY DEVELOPING OVER THE ARKLAMISS AS OF THIS WRITING. A
LARGE CLUSTER OF TSTORMS IS UNDERWAY, MOVING OFF TO THE SOUTH/EAST.
THIS MAY CUTOFF MOISTURE/SOUTHERLY FLOW OVERNIGHT, WHICH WOULD IMPACT
THE COVERAGE OF SHRA/TSRA THROUGH 12Z MON. WILL MONITOR THIS TREND
AND THE EVENING SHIFT MAY NEED TO UPDATE THIS TONIGHT.

OTHERWISE, MODELS ARE IN DECENT AGREEMENT THAT SHOWERS/STORMS WILL
CONTINUE DEVELOPING AROUND THE AREA THROUGH EARLY WEDNESDAY AS THE
WEAK COLD FRONT TO THE NW MEANDERS SOUTHWARD, WASHING OUT SOMEWHERE
BETWEEN HERE AND MONTGOMERY, AL. THE ECMWF AND GFS DIFFER IN THEIR
OPINION OF EXACTLY WHERE THIS FRONT WILL END UP, WITH THE GFS FAR
MORE BULLISH WITH ITS SOUTHWARD EXTENT (ALONG THE COAST), WHEREAS THE
ECMWF IS MORE BELIEVABLE FOR THIS TIME OF YEAR (CLOSER TO OUR CWA)
GIVEN THE STRENGTH OF THE RIDGE THAT WILL BUILD IN BEHIND THIS FRONT.
WITH THE FRONT IN THE VICINITY AT THE SFC, AND SEVERAL DISTURBANCES
PASSING OVERHEAD ALOFT IN NW FLOW DURING THIS TIMEFRAME, HAVE
INCREASED POPS TO THE DEFINITE CATEGORY TOMORROW NIGHT INTO TUESDAY,
AS AN MCS DEVELOPS TO OUR NW AND ROLLS THROUGH BY 12Z TUESDAY. TEMPS
WILL HEAVILY DEPEND ON THE CONVECTION FROM TOMORROW THROUGH EARLY
WEDNESDAY, BUT FOR NOW, HAVE TRENDED TOWARD THE LOWER END OF MOS
GUIDANCE FOR HIGHS AND THE UPPER END OF MOS GUIDANCE FOR LOWS WITH
THE EXPECTATION OF CLOUDIER CONDITIONS WITH THE SHOWER/STORM COVERAGE
IN PLACE.

BEYOND WEDNESDAY, SHOWERS/STORMS WILL BE CONFINED SOUTH OF THE CWA AS
UPPER RIDGING BUILDS EASTWARD FROM THE SOUTHERN PLAINS. AT THE SAME
TIME, THE BERMUDA HIGH WILL PUMP MOISTURE INTO THE REGION FROM THE
SOUTHEAST, SPARKING AFTN/EVENING SHOWERS/STORMS BY THE WEEKEND.
WHETHER OR NOT ANY OF THIS ACTIVITY WILL BE ENHANCED OROGRAPHICALLY
IN OUR LOCAL AREA IS YET TO BE DETERMINED. WHILE WE`LL BE ON THE
EASTERN PERIPHERY OF THE UPPER RIDGE, OROGRAPHIC EFFECTS MAY BE
ENOUGH TO OVERCOME THE WEAKER RIDGING IN PLACE IN OUR EASTERN
COUNTIES. EITHER WAY, THE WEATHER PATTERN IS DEFINITELY TRYING TO
TRANSITION TO MORE OF A SUMMERTIME ONE, WITH CONVECTION MORE LINKED
TO PEAK HEATING, AND DISSIPATING SHORTLY AFTER SUNSET EACH DAY. AS
THE MID-SHIFT THIS MORNING NOTED, ASTRONOMICAL SUMMER OFFICIALLY
BEGINS AT 1204AM FRIDAY MORNING.

12

&&

.AVIATION...
FOR 00Z TAFS... PULSE CONVECTION WILL CONTINUE THRU EARLY THIS
EVENING UNTIL HEATING CEASES WHEN A DECREASE IN COVERAGE SHOULD
OCCUR. MOST CIGS AND VSBYS WILL REMAIN VFR OUTSIDE OF THE CORE OF
THE HEAVIEST STORMS. HAVE MAINTAINED AN EARLY TEMPO GROUP OF -TSRA AT
KMSL AS THE CLUSTER OF STORMS IN MS PUSHES EAST. AN UPPER LEVEL
DISTURBANCE LATE TONIGHT MAY PRODUCED RENEWED DEVELOPMENT, BUT
CONFIDENCE TO LOW TO INCLUDE PREVAILING TS PERIODS THRU MONDAY. A
BETTER CHANCE OF REDEVELOPMENT MAY OCCUR AGAIN ON MONDAY DURING PEAK
AFTERNOON HEATING.

AK

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

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AT WEATHER.GOV/HUNTSVILLE.