000
FXUS64 KBMX 201112
AFDBMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
515 AM CST THU NOV 20 2008
.UPDATE...FOR AVIATION DISCUSSION.
&&
.SHORT TERM...TODAY AND TONIGHT.
EXPECTING A MUCH WARMER DAY TODAY AS WE TRANSITION AHEAD OF THE
NEXT COLD FRONT. PREFRONTAL SUBSIDENCE IS LIKELY THE ODER OF THE
DAY...SO HAVE KEPT TEMPS SLIGHTLY ABOVE GUIDANCE NUMBERS. THINGS
WILL BEGIN WITH AN ABRUPT CHANGE COME OVERNIGHT...HOWEVER...AS
ANOTHER DRY FRONT WILL COME SCREAMING THROUGH THE STATE AROUND
MIDNIGHT OR SO. MOST WILL NOT NOTICE TEMP-WISE AT FIRST...BUT THE
WINDS WILL SHARPLY TURN NORTH AND BE GUSTY THROUGH THE OVERNIGHT.
THIS WILL SEND THE COOLER AND DRIER AIR QUICKLY THIS WAY. I HAVE
GONE OUT ON A LIMB WITH THE OVERNIGHT LOWS...KEEPING THEM
RELATIVELY WARM DUE TO THE WELL- MIXED BOUNDARY LAYER THROUGH THE
OVERNIGHT...SO EXPECTING MID TO UPPER 30S. THIS IS A LOT WARMER
THAN MODEL GUIDANCE NUMBERS...BUT THEY TRADITIONALLY DO NOT HANDLE
WELL MIXED BOUNDARY LAYERS...MAINLY DUE TO SOMEWHAT COARSE
VERTICAL RESOLUTIONS.
17/KLAWS
.LONG TERM...FRIDAY THRU WEDNESDAY.
A FAST MOVING DRY COLD FRONT WILL BRING ANOTHER SHOT OF CANADIAN
AIR INTO THE AREA FRIDAY. DESPITE ABUNDANT SUNSHINE...HIGHS ON
FRIDAY WILL BE ABOUT 15 DEGREES BELOW AVERAGE. NORTH WINDS BEHIND
FRONT WILL NOT BE AS STRONG AS PREVIOUS SYSTEMS AND WINDS MAY STAY
JUST BELOW LAKE WIND ADVISORY. THIS SYSTEM WILL PUSH THRU QUICKLY
WITH NORTHERLY FLOW BECOMING SOUTHEAST BY SATURDAY AFTERNOON.
LOWS FRIDAY NIGHT WILL BE TRICKY AS WINDS DIMINISH QUICKLY AFTER
SUNSET. AIR MASS WILL BE VERY DRY...BUT 1000-850MB FLOW WILL
BECOME EASTERLY NEAR 15 KNOTS AFTER 06Z. SURFACE WINDS WILL LIKELY
DECOUPLE AND FORECAST LOWS ARE NEAR LOW MEMBER OF GFS MOS ENSEMBLE
MOS GUIDANCE.
A WEAK SHORT WAVE TROF WILL PASS NORTH OF AREA SATURDAY NIGHT.
THIS SYSTEM DOES NOT EXTEND DOWN TO THE SURFACE SO IT WILL HAVE NO
DISCERNIBLE EFFECTS ON WEATHER. MODERATING TEMPERATURES OVER THE
WEEKEND DUE TO SOUTHEASTERLY LOW LEVEL FLOW WITH READINGS BACK UP
TO NEAR AVERAGE BY SUNDAY. A MUCH STRONGER SHORT WAVE TROF WILL
APPROACH THE LOWER MISSISSIPPI RIVER VALLEY REGION SUNDAY NIGHT.
THIS SYSTEM WILL BE ABLE TO TAP ENOUGH GULF MOISTURE FOR A CHANCE
OF SHOWERS ON MONDAY AND MONDAY EVENING. THIS UPPER TROF WILL PUSH
A FAST MOVING COLD FRONT THRU LATE MONDAY...WITH RAIN PUSHING OUT
OF THE AREA BY MIDNIGHT MONDAY NIGHT. MOSTLY CLEAR SKIES TUESDAY
AND WEDNESDAY WITH TEMPERATURES SLIGHTLY BELOW AVERAGE. AT THIS
TIME...THANKSGIVING DAY LOOKS RAIN FREE.
58/ROSE
&&
.AVIATION...12Z TAF DISCUSSION
VFR CONDITIONS EXPECTED OVER THE NEXT 24 HOURS. WINDS WILL
PROGRESSIVELY GET STRONGER AND TURN MORE NORTHERLY TODAY AS A COLD
FRONT PASSES THROUGH THE AREA. THE STRONGEST WINDS 10 TO 15 MPH
WITH GUSTS AS HIGH AS 25 MPH ARE EXPECTED SOMETIME AFTER 00Z AND
CONTINUE UNTIL THE END OF THE PERIOD.
17/KLAWS
&&
.FIRE WEATHER...A VERY DRY AIR MASS WILL OVERSPREAD THE AREA ON
FRIDAY WITH SURFACE DEWPOINTS FALLING INTO THE TEENS FRIDAY
AFTERNOON AND CONTINUING INTO SATURDAY. RELATIVE HUMIDITIES WILL
FALL BELOW 25 PERCENT FOR SEVERAL HOURS BOTH FRIDAY AND SATURDAY
AFTERNOONS CREATING HIGH FIRE DANGER.
58/ROSE
&&
.BMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
