FXUS64 KBMX 011010
AFDBMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
410 AM CST TUE DEC 1 2009
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT.
BASED ON CURRENT WEATHER CONDITIONS OF MOSTLY CLEAR SKIES AND TEMPERATURES
IN THE 30S...HARD TO BELIEVE THAT WE WILL BE DEALING WITH HEAVY RAINFALL
AND SEVERE THUNDERSTORMS WITHIN THE NEXT 24 TO 36 HOURS. HIGH
CLOUDS ARE STREAMING NORTHEASTWARD TOWARDS ALABAMA AS STORM SYSTEM
BEGINS TO TAKE SHAPE OFF THE TEXAS COAST. RAIN SHIELD ALREADY
MOVING INTO THE LOUISIANA COAST. CLOUDS WILL GRADUALLY THICKEN
TODAY AS MOISTURE INCREASES FROM TOP TO BOTTOM. DUE TO COLD START
THIS MORNING AND EXPECTED CLOUD COVER TODAY...LOWERED HIGH
TEMPERATURES A FEW DEGREES MOST AREAS. LIGHT RAIN SHOULD REACH
SOUTHWEST COUNTIES BY SUNSET.
FOR TONIGHT...RAIN WILL OVERSPREAD CENTRAL ALABAMA DURING THE
EVENING HOURS AND SOUTHEAST WINDS WILL INCREASE TO 10 TO 20 MPH.
GFS MODEL STILL SHOWING A SURFACE LOW TRACK FARTHER EAST THAN
NAM/CANADIAN/ECMWF. FORECAST WILL BE BASED ON A TRACK CLOSER TO
THE NAM MODEL BASE ON CONSENSUS OF OTHER MODELS AND THE RUN TO RUN
CONSISTENCY OF THE NAM MODEL. THERE WILL LIKELY BE A LOW LEVEL
BAROCLONIC ZONE THAT WILL SET-UP ACROSS NORTHWEST FLORIDA AND
SOUTHEAST ALABAMA LATER TONIGHT AND WEDNESDAY MORNING. THIS BOUNDARY
WILL MOST LIKELY BE JUST NORTH OF SURFACE WARM FRONT...AND IT
WILL BE FOCUS FOR THE HEAVIEST RAINFALL. A FLASH FLOOD WATCH WILL
BE ISSUED FOR TONIGHT AND WEDNESDAY FOR AREAS ALONG AND SOUTH OF A
WHITE HALL...TO ALEXANDER CITY...TO ROANOKE LINE. RAINFALL TOTALS WILL
LIKELY BE IN THE ONE TO TWO INCH RANGE IN WATCH AREA...WITH UP TO
ONE INCH ELSEWHERE. A LAKE WIND ADVISORY WILL LIKELY BE NEEDED FOR
MUCH OF THE SOUTHERN HALF OF THE COUNTY WARNING AREA... BUT WILL
LET DAY SHIFT HANDLE ISSUANCE.
FOR WEDNESDAY...THE HEIGHT OF THE STORM WILL BE DURING THIS TIME
PERIOD. HEAVY RAINFALL WILL SPREAD OVER ALL OF CENTRAL ALABAMA BY
SUNRISE WEDNESDAY AND SURFACE WINDS WILL BE IN THE 15-25 MPH RANGE.
PREVIOUS NAM MODEL RUNS WERE SHOWING MID 60S DEWPOINTS ADVECTING
WELL NORTHWARD INTO CENTRAL ALABAMA. LATEST MODEL RUN SEEMS MORE
PRACTICAL WITH 60 DEGREE DEWPOINTS GETTING AS FAR NORTH AS MONTGOMERY.
THIS LINES UP PRETTY WELL WITH STORM PREDICTION OUTLOOK FOR DAY2.
SEVERE THREAT WILL PRIMARILY BE IN THE 9 AM TO 3 PM TIME FRAME AS
CONVECTIVE LINE SHOULD BE ENTERING WESTERN GEORGIA BY MID AFTERNOON.
MAIN LIMITING FACTOR WILL BE WIDESPREAD RAIN AND CLOUD COVER.
GIVEN HIGH SHEAR VALUES...AN ISOLATED TORNADO CANNOT BE RULED OUT.
ANOTHER ONE TO THREE INCHES OF RAINFALL POSSIBLE ACROSS FLASH
FLOOD WATCH AREA...WITH STORM TOTALS OF TWO TO FOUR INCHES.
ISOLATED TOTALS NEAR SIX INCHES POSSIBLE.
FOR WEDNESDAY NIGHT...THE HEAVY RAINFALL AND STRONG CONVECTION
SHOULD BE OUT OF AREA BY SUNSET WEDNESDAY AS SURFACE LOW MOVES
RAPIDLY NORTHEAST AND PUSHES COLD FRONT THROUGH AREA. DUE TO
INTENSITY OF LOW LEVEL CYCLONE...THERE WILL BE PLENTY OF WRAP
AROUND CLOUDS ON BACK SIDE OF FRONT..AND CHANCES FOR LIGHT RAIN
WILL CONTINUE THROUGH THE OVERNIGHT HOURS WEDNESDAY AS UPPER LEVEL
TROF MOVES ACROSS AREA.
58/ROSE
.LONG TERM...THURSDAY THROUGH MONDAY.
IT APPEARS THAT AN ACTIVE SOUTHERN STREAM FLOW PATTERN WILL CONTINUE
DURING THIS PERIOD...WHICH MEANS CONFIDENCE IS LOW ON TIMING AND
INTENSITY OF EACH SYSTEM. MUCH COLDER AIR WILL MOVE INTO AREA
THURSDAY AND FRIDAY. MODELS ARE STRONGLY HINTING AT ANOTHER GULF
LOW FORMING ON FRIDAY AND MOVING RAPIDLY EAST NORTHEAST. THIS
SYSTEM COULD BRING SOME LIGHT PRECIPITATION TO SOUTH ALABAMA
FRIDAY NIGHT...BUT CONFIDENCE TO LOW AT THIS TIME TO INTRODUCE
PRECIPITATION..ESPECIALLY SINCE THICKNESS VALUES ARE COLD ENOUGH
TO SUPPORT FROZEN PRECIPITATION. ANOTHER WEAKER SYSTEM HAS BEEN
SHOWING UP EARLY NEXT WEEK..AND INCLUDED CHANCE OF RAIN ON MONDAY.
58/ROSE
&&
.AVIATION...06Z TAF DISCUSSION.
SOME PATCHY FOG POSSIBLE AT TCL..ANB LIMITING VSBYS TO 4
MILES. OTHERWISE NO PROBLEMS THROUGH 15Z. MID AND HIGH CLOUDS
OVERSPREAD THE AREA FROM THE SOUTHWEST THROUGH 00Z. FROM 00Z TO 06Z
AREA OF RAIN SHIFTS NORTHWARD ACROSS MGM AND TOI WITH CEILINGS
4000 TO 6000 FEET AND VSBYS 5 TO 6 MILES.
&&
.PRELIMINARY POINT TEMPS/POPS...
GADSDEN 55 45 58 37 49 / 0 90 100 50 10
ANNISTON 58 49 61 39 51 / 10 100 100 40 10
BIRMINGHAM 58 53 58 39 50 / 10 90 100 40 10
TUSCALOOSA 57 53 59 39 50 / 10 90 90 30 10
CALERA 59 53 60 41 51 / 10 100 90 30 10
AUBURN 59 49 61 43 55 / 10 100 100 20 10
MONTGOMERY 58 54 64 43 53 / 20 100 100 20 10
TROY 57 56 64 43 56 / 20 100 100 20 10
&&
.BMX WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH TONIGHT AND
WEDNESDAY FOR SOUTHEAST COUNTIES.
&&
$$
