000
FXUS62 KCAE 201921
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
221 PM EST FRI NOV 20 2009

.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE LOWER OHIO VALLEY WILL DRIFT EAST
OVER THE NEXT 24 HOURS. SKIES WILL BE CLEAR OVERNIGHT WITH PATCHY
FOG DEVELOPING TOWARD SATURDAY MORNING. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE WESTERN GULF OF MEXICO WILL MOVE NORTHEAST
ACROSS THE FLORIDA PANHANDLE BY SUNDAY NIGHT. THIS SYSTEM WILL
SPREAD RAIN NORTHEAST ACROSS THE AREA LATE SATURDAY NIGHT INTO
MONDAY MORNING. RAINFALL AMOUNTS WILL RANGE FROM A HALF TO THREE
QUARTERS OF AN INCH BEFORE ENDING MONDAY.

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SKIES WILL REMAIN CLEAR THROUGH THE EARLY EVENING AS HIGH PRESSURE
DOMINATES. TEMPERATURES WILL BE IN THE LOWER 60S BY THAT TIME WITH
LIGHT NORTHEAST WINDS.

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
ECMWF/NAM MOVE LOW PRESSURE FROM THE GULF OF MEXICO TO WESTERN
FLORIDA PANHANDLE BY SUNDAY EVENING. THE GFS WAS FASTER IN MOVING
THE SYSTEM. LEANED TO THE SLOWER NAM/ECMWF SOLUTION...SO REMOVED
THE CHANCE OF RAIN SATURDAY...REDUCING POPS SATURDAY NIGHT TO HIGH
CHANCE AND INCREASING THE CHANCE TO 100 PERCENT SUNDAY. HIGH
PRESSURE TO THE NORTH WILL PREVENT ANY WARMER AIR FROM REACHING
THE SURFACE SO EXPECT HIGHS ONLY IN THE 50S SUNDAY.

MODEL GUIDANCE RANGES FROM AROUND A QUARTER OF AN INCH FROM BUFKIT
GRIDS FROM THE NAM TO OVER 1.75 INCHES FROM THE GFS. USED HPC
GUIDANCE FOR THE RAINFALL AMOUNT FORECAST WHICH KEPT AMOUNTS
GENERALLY LESS THAN AN INCH. THERE IS A POTENTIAL FOR HEAVY RAIN
ESPECIALLY IF THE GFS VERIFIES...BUT ALL MODELS GUIDANCE WEAKENS
THE SYSTEM AS IT MOVES NORTHEAST. THEREFORE DID NOT MENTION HEAVY
RAIN IN THE FORECAST AT THIS TIME.

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE 12Z GFS AND ECMWF RUN SHOW A DIVERGENCE WITH THE GFS FASTER IN
MOVING SYSTEMS THAN THE ECMWF. TEMPERATURES WILL RISE BACK INTO
THE UPPER 60S TO THE LOWER 70S TUESDAY AS A PACIFIC ORIGIN HIGH PRESSURE
MOVES ACROSS THE MID ATLANTIC STATES. A STRONG SYSTEM DEVELOPS
OVER THE MIDWEST TUESDAY AND SWINGS A COLD FRONT THROUGH THE
REGION WEDNESDAY. WITH FORCING WELL TO THE NORTH...IT LOOKS TO BE
A DRY FRONTAL PASSAGE AND THAT IS REFLECTED IN THE FORECAST. THE
FRONT WILL BE FOLLOWED BY A COLD AIR MASS FROM SOUTHERN CANADA.
THIS WILL DROP LOWS INTO THE  A COLD AIR MASS FROM CANADA THEN
CROSSES THE MOUNTAINS DROPPING LOW TEMPERATURES INTO THE UPPER 30S
TO LOWER 40S BY FRIDAY MORNING. LEANED TOWARD THE GFS IN THE
EXTENDED FORECAST.

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
REMAINING CLOUDS DISSIPATING OVER TAF LOCATIONS THIS AFTERNOON. VFR
CONDITIONS SHOULD CONTINUE THROUGH MOST OF THE REMAINDER OF THE
PERIOD. ANOTHER CHANCE OF FOG EARLY SATURDAY MORNING. EXPECT MVFR
CONDITIONS 10Z-14Z...SOME IFR IS POSSIBLE DURING THIS PERIOD AS WELL.

EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
LIKELY OCCUR LATE SATURDAY NIGHT AND SUNDAY ASSOCIATED WITH AN
AREA OF LOW PRESSURE EXPECTED TO MOVE NORTHEASTWARD FROM THE GULF
OF MEXICO.

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.

SYNOPSIS...12
NEAR TERM...12
SHORT TERM...12
LONG TERM...12
AVIATION...77