Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 061102
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
602 AM EST SAT FEB 6 2016

.SYNOPSIS...
LOW PRESSURE WILL DEVELOP OFF THE SOUTHEAST COAST TONIGHT AS AN
UPPER TROUGH MOVES OVER THE REGION...THEN LIFT AWAY FROM THE
REGION SUNDAY. MUCH COLDER WEATHER IS EXPECTED NEXT WEEK AS AN
UPPER TROUGH BECOMES ESTABLISHED ALONG THE EASTERN PART OF THE
COUNTRY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SURFACE HIGH PRESSURE WILL REMAIN ENTRENCHED OVER THE FORECAST
AREA TODAY WITH AN INCREASE IN GENERALLY HIGH CLOUDS AS AN UPPER
TROUGH APPROACHES FROM THE WEST. TEMPERATURES WILL BE STARTING
OFF QUITE COOL AS MANY LOCATIONS ARE IN THE UPPER 20S TO NEAR 30
ALREADY...AND MAX TEMPERATURES TODAY WILL BE IN THE LOWER 50S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
INTERESTING SCENARIO SHAPING UP TONIGHT INTO SUNDAY AS UPPER
TROUGH TO THE WEST WILL BECOME A CLOSED LOW OVER THE SOUTHEASTERN
STATES AND RESULT IN THE DEVELOPMENT OF COASTAL LOW WHICH WILL
DEEPEN RAPIDLY THROUGH THE PREDAWN HOURS SUNDAY AND THROUGH THE
DAY AS IT THEN LIFTS NORTHEASTWARD AWAY FROM THE REGION. MODELS
HAVE TRENDED A BIT FURTHER WEST COMPARED TO LAST NIGHT REGARDING
THE EXTENT OF MEASURABLE RAINFALL SO HAVE MADE SOME POP
ADJUSTMENTS TO ACCOUNT FOR THIS WITH CHANCE POPS INTO THE CENTRAL
MIDLANDS/CSRA AND KEEPING LIKELY POPS ACROSS THE EASTERN MIDLANDS.
THERE IS THE POTENTIAL FOR SOME PTYPE ISSUES AS THE UPPER LOW
MOVES OVERHEAD BRINGING STRONG DYNAMICS TO THE REGION WHILE THE
LOWER LEVELS COOL DUE TO COLD ADVECTION AS THE COASTAL LOW DEEPENS
AND THE PRESSURE GRADIENT INCREASES. MOST OF THE MODEL GUIDANCE
KEEPS THE SIGNIFICANT QPF TO THE EAST OF THE FORECAST AREA WITH
THE EASTERN MIDLANDS BEING MOST AFFECTED. THE INCREASED PRESSURE
GRADIENT WILL RESULT IN BREEZY CONDITIONS AND A LAKE WIND ADVISORY
WILL BE POSTED FOR LAKE MARION...ALLOWING LATER SHIFTS TO EXPAND
IF NECESSARY TO OTHER LAKES.

EXAMINATION OF THE THERMAL PROFILES THROUGH MODEL SOUNDINGS AND
TIME HEIGHTS REVEAL THE POTENTIAL FOR A BRIEF PERIOD OF SNOW
MIXING WITH RAIN OR EVEN TURNING TO ALL SNOW IF PRECIPITATION IS
HEAVY ENOUGH ACCOUNTING FOR DIABATIC COOLING EFFECTS. THE MOST
LIKELY TIME FRAME FOR THIS TO OCCUR LOOKS TO BE AROUND 09Z-15Z.
THERE IS SUFFICIENT MOISTURE IN THE SNOW GROWTH AREA TO SUPPORT
WINTER PRECIP AND THE NAM IS BY FAR THE MOST AGGRESSIVE WITH COLD
AIR AND BRINGING MUCH MORE MOISTURE AND QPF OVER THE REGION
COMPARED TO THE REST OF THE OPERATIONAL MODEL GUIDANCE AND WAS
CONSIDERED THE OUTLIER...THOUGH IF THAT SOLUTION VERIFIES WE COULD
SEE A WINTER EVENT. HOWEVER...LOOKING AT ENSEMBLE DATA AND ANALOG
GUIDANCE THERE IS LOW CONFIDENCE AT THIS TIME IN A WINTER EVENT
WITH IMPACTS OCCURRING. WPC ALSO NOT CARRYING ACCUMULATING SNOW
OVER OUR AREA WITH THIS EVENT. WILL CARRY A PERIOD OF RAIN/SNOW
ACROSS THE EASTERN MIDLANDS BUT NOT ANTICIPATING MUCH ACCUMULATION
AS SURFACE TEMPS REMAIN JUST ABOVE FREEZING AND SOIL/ROAD TEMPS
WILL BE QUITE WARM AS WELL MINIMIZING IMPACTS...UNLESS
PRECIPITATION IS FALLING AT A VERY HIGH RATE. SO OVERALL...LOW
CONFIDENCE IN THE EVENTUAL PRECIP TYPE LATE TONIGHT INTO SUNDAY AS
IT WILL LIKELY BE HIGHLY DEPENDENT ON WHERE THE SURFACE LOW ENDS
UP TRACKING BUT FOR NOW WILL CONTINUE WITH A CONSERVATIVE LOW
IMPACT FORECAST. TEMPERATURES WILL WARM THROUGH THE DAY SUNDAY BUT
REMAIN BELOW NORMAL...ESPECIALLY IN THE EASTERN MIDLANDS WHERE
PRECIPITATION WILL OCCUR.

A BRIEF DRY PERIOD IS EXPECTED LATE SUNDAY INTO MONDAY MORNING BUT
A DEEP AND EXPANSIVE CLOSED UPPER LOW WILL DESCEND UPON THE GREAT
LAKES AND OHIO VALLEY REGION ON MONDAY. STRONG HEIGHT FALLS AND
INCREASED LAPSE RATES WILL SUPPORT SCATTERED SHOWERS DURING THE
AFTERNOON AND WILL CONTINUE LOW CHANCE POPS.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE EXTENDED FORECAST PERIOD WILL BE CHARACTERIZED BY BELOW NORMAL
TEMPERATURES AND GENERALLY DRY WEATHER. UPPER LOW OVER THE OHIO
VALLEY WILL LIFT NORTHEASTWARD INTO SOUTHEAST CANADA BY WEDNESDAY
MORNING AS DRY NORTHWESTERLY FLOW CONTINUES ACROSS THE FORECAST
AREA. MUCH COOLER AIR WILL SETTLE OVER THE REGION THROUGH MID WEEK
WITH HIGHS NEARLY 15-20 DEGREES BELOW NORMAL IN THE 40S AND
OVERNIGHT LOWS IN THE 20S. UPPER FLOW BECOMES A BIT MORE ZONAL BY
THE END OF THE WEEK ALLOWING FOR A SLIGHT WARMING TREND TO NEAR
NORMAL TEMPERATURES.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS EXPECTED THROUGH THIS AFTERNOON.

SURFACE HIGH PRESSURE CURRENTLY OVER THE REGION...WITH DRY LOW
LEVEL AIR IN PLACE...PRECLUDING FOG CONCERNS EARLY THIS MORNING.
SATELLITE INDICATING SOME THIN HIGH LEVEL CLOUDINESS STREAMING
ACROSS. STRONG UPPER TROUGH CURRENTLY OVER THE CENTRAL CONUS WILL
DIVE INTO THE SE CONUS TONIGHT. STRONG UPPER LIFT AND DIVERGENCE
OVER TOP OF LOW LEVEL BAROCLINIC ZONES ASSOCIATED WITH OLD FRONTAL
BOUNDARY AND THE GULF STREAM ALLOWS A LOW PRESSURE AREA TO BEGIN
DEVELOPING OFFSHORE LATE TODAY AND THIS EVENING WHICH IS EXPECTED
TO INTENSIFY AND SHIFT NE. GENERAL MODEL CONSENSUS HAS MOISTURE
SHIFTING NORTH INTO MAINLY THE SOUTHERN AND EASTERN PORTIONS OF
OUR FORECAST AREA THIS EVENING AND TONIGHT. THIS WILL FAVOR BETTER
PRECIPITATION CHANCES AND ASSOCIATED RESTRICTIONS AT OGB AND
POINTS TO THE SOUTH AND EAST OF THERE. THERE IS A CHANCE FOR A
RAIN/SNOW MIX...MAINLY AT OGB. CURRENT INDICATIONS ARE THAT SURFACE
TEMPS WILL BE WARM ENOUGH THAT IF SNOW FELL IT WOULD MELT WITHOUT
SIGNIFICANT ACCUMULATION.

EXTENDED AVIATION OUTLOOK...RESTRICTIONS MAY LINGER SUNDAY...MAINLY
AT OGB. A COLD FRONT WILL MOVE THROUGH LATE MONDAY WITH A SLIGHT
CHANCE OF SHOWERS AND POSSIBLE RESTRICTIONS. BREEZY CONDITIONS
POSSIBLE AT TIMES MON THRU WED.

&&

.HYDROLOGY...
MINOR FLOODING CONTINUES ON THE CONGAREE RIVER AT CAROLINA
EASTMAN AND FOR THE NORTH FORK OF THE EDISTO RIVER AT ORANGEBURG.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...LAKE WIND ADVISORY FROM 4 AM TO 6 PM EST SUNDAY FOR SCZ031-
     036>038.

&&

$$


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