Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 311514
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1114 AM EDT FRI OCT 31 2014

.SYNOPSIS...
A STRONG UPPER LEVEL LOW WILL MOVE TOWARDS THE REGION THIS
EVENING...HELPING TO PUSH A COLD FRONT THROUGH THE FORECAST AREA
TONIGHT. BEHIND THIS FRONT...MUCH COLDER AIR WILL FOLLOW ALONG
WITH BREEZY CONDITIONS. THE FIRST WIDESPREAD FROST ALONG WITH THE
FIRST FREEZE OF THE SEASON FOR SOME AREAS WILL LIKELY OCCUR SUNDAY
NIGHT/MONDAY MORNING.

&&

.NEAR TERM /THROUGH TONIGHT/...
THIS AFTERNOON...WV LOOP ALREADY INDICATING THE SEVERAL SHORT
WAVES THAT WILL DEEPEN THE TROUGH ACROSS THE EAST COAST AS THE
RIDGE CONTINUES TO BUILD ACROSS THE WEST/ROCKIES. THE FORECAST
WILL REMAIN BASICALLY DRY THROUGH THE DAY. HOWEVER...MODELS HAVE
INDICATED THAT LIGHT RAIN/SHOWERS WILL DEVELOP ACROSS THE
MIDLANDS...ESPECIALLY THE WESTERN MIDLANDS...A FEW HOURS EARLIER
THAN PREVIOUSLY EXPECTED. COULD SEE SOME SCATTERED SHOWERS MOVING
INTO THE WESTERN/NORTHERN MIDLANDS BY THE EARLY EVENING HOURS.
GUIDANCE AND LOCAL NUMBERS IN GOOD AGREEMENT WITH AFTERNOON HIGH
TEMPERATURES. HAVE STAYED CLOSE TO CONSENSUS AND FORECASTED
MID/UPPER 60S NORTHWEST/NORTH TO LOWER 70S CSRA/SRN MIDLANDS.

TONIGHT...MODELS REMAIN IN GOOD AGREEMENT THE EVOLUTION OF THE
COMPLEX WEATHER PATTERN ACROSS THE EASTERN U.S. THE DEEP UPPER
LEVEL TROUGH WILL CONTINUE ACROSS THE REGION...WITH A STRONG
SHORTWAVE MOVING AROUND THE BASE HELPING TO CUTOFF THE LOW
OVERNIGHT AS IT MOVES THROUGH TN AND NRN GA. GIVEN THE STRONG
DYNAMICS OF THIS SYSTEM...WITH A STRONG COLD POOL ALOFT MOVING
TOWARDS THE REGION...THE MODELS CONTINUE THE TREND OF BRINGING
SHOWERS INTO THE WESTERN AND NORTHERN MIDLANDS TONIGHT...WITH THE
HIGHEST RAIN CHANCES NORTH. THE LEADING EDGE OF THE FRONT
ASSOCIATED WITH THIS SYSTEM SHOULD PUSH THROUGH TONIGHT...WITH
WINDS INCREASING LATE TONIGHT AND TOWARDS MORNING. ALTHOUGH THERE
WILL BE A NOTICEABLE COOLDOWN BEHIND THE LEADING EDGE...THE MAIN
COLD SURGE WILL NOT MOVE IN UNTIL TOMORROW. OVERNIGHT LOWS RIGHT
NOW FORECAST GENERALLY AROUND 40.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
THE LOW WILL CONTINUE TO MOVE EAST-SOUTHEAST INTO THE UPSTATE/UPPER
SAVANNAH RIVER VALLEY BY SATURDAY MORNING THEN CONTINUING EASTWARD
ACROSS SC TO THE CAROLINA COAST BY SATURDAY AFTERNOON/EARLY
EVENING.

HAVE CONTINUED WITH LIKELY POPS INCREASING TO CATEGORICAL POPS ON
SATURDAY ACROSS THE NORTHERN MIDLANDS WITH A GRADUAL TAPER IN POPS
SOUTHWARD THROUGH THE PERIOD. SIGNIFICANT COLD POOL...WITH H5
TEMPERATURES FALLING TO -26 TO -28 DEGREES C BY SATURDAY
AFTERNOON. WITH SUCH COLD TEMPERATURES ALOFT...WOULD NOT BE
SURPRISED TO SEE A FEW REPORTS OF FROZEN PRECIPITATION
EARLY/MIDDAY SATURDAY. THIS WOULD MAINLY BE IN THE FORM OF
GRAUPEL. BEST CHANCE WILL BE ACROSS THE NORTHERN HALF OF THE CWA.
ALTHOUGH SURFACE TEMPERATURES WILL BE IN THE 40S...SOME OF THIS
MAY MAKE IT DOWN TO THE SURFACE. THIS HAS OCCURRED IN SIMILAR PAST
EVENTS. HOWEVER...EXPECT RAIN TO BE THE MAIN PRECIPITATION TYPE
THROUGH THE EVENT.

TEMPERATURES ON SATURDAY WILL BE SIGNIFICANTLY COLDER...NEARLY
15-20 DEGREES COLDER THAN RECENT DAYS...WITH HIGHS STRUGGLING TO
REACH 50 DEGREES IN THE MIDLANDS. MAX TEMPERATURES WILL RANGE FROM
THE MID TO UPPER 40S NORTHERN MIDLANDS TO MID 50S IN THE CSRA. THE
OTHER FACTOR DURING THIS PERIOD WILL BE THE INCREASING SURFACE
GRADIENT AND THE 50 KNOT LOW LEVEL JET...AT 3K TO 4K FT...MOVING
ACROSS THE REGION SATURDAY AFTERNOON AND EVENING. THE STRONGEST
WINDS WILL DEVELOP ACROSS THE CWA ON SATURDAY AND CONTINUE
SATURDAY EVENING WITH A GRADUAL DECREASE TOWARD SUNDAY MORNING.
WITH THE LAKE WATER TEMPERATURES IN THE UPPER 60S TO AROUND 70
DEGREES AND STRONG COLD AIR ADVECTION...EXPECT WINDS TO REMAIN
RATHER BREEZY ACROSS THE LAKES FROM SATURDAY MORNING TO SUNDAY
MORNING. WILL CONTINUE WITH THE CURRENT LAKE WIND ADVISORY WHICH
RUNS FROM 10 AM EDT SATURDAY UNTIL 10 AM EST SUNDAY. SUSTAINED
WINDS 15 TO 25 MPH WITH GUSTS AS HIGH AS 30 TO 40 MPH EXPECTED ON
SATURDAY/SATURDAY EVENING.

AS THE UPPER LOW MOVES OFFSHORE LATE SATURDAY WITH COLD DRY
CANADIAN HIGH PRESSURE BUILDING OVER THE AREA FOR THE REMAINDER OF
THE WEEKEND. A STRONG PRESSURE GRADIENT WILL PERSIST THROUGH THE
OVERNIGHT HOURS SATURDAY NIGHT WHICH WILL PREVENT STRONG
RADIATIONAL COOLING BY KEEPING BOUNDARY LAYER WELL MIXED AND LOW
TEMPS WILL BE DETERMINED BY THE COLD ADVECTION TAKING PLACE WITH
LOWS GENERALLY IN THE MID 30S WHICH IS VERY CLOSE TO GUIDANCE AND
LOCAL NUMBERS.

SUNDAY WILL FEATURE MOSTLY SUNNY SKIES WITH SLIGHTLY WARMER BUT
STILL WELL BELOW NORMAL TEMPERATURES WITH HIGHS IN THE 50S. SUNDAY
NIGHT CONTINUES TO BE THE BEST NIGHT FOR WIDESPREAD FROST AND THE
POTENTIAL FOR FREEZING TEMPERATURES. IDEAL RADIATIONAL COOLING
CONDITIONS ARE EXPECTED WITH A VERY DRY AIRMASS IN PLACE WITH PWAT
VALUES AROUND 0.20...CLEAR SKIES AND NEAR CALM WINDS...AS SURFACE
HIGH PRESSURE SETTLES OVERHEAD. THE GUIDANCE HAS CONTINUED TO
TREND DOWNWARD FOR MINIMUM TEMPERATURES LATE SUNDAY NIGHT/EARLY
MONDAY MORNING. DUE TO THIS AND THE ABOVE CONDITIONS HAVE LOWERED
TEMPERATURES A COUPLE OF DEGREES ACROSS THE CWA. EXPECT MUCH OF
THE AREA TO HAVE TEMPERATURES IN THE LOWER 30S WITH SOME MIDDLE
30S ACROSS THE SOUTHERN MIDLANDS. OVERNIGHT LOWS WILL FALL INTO
THE LOWER TO MID 30S...ALTHOUGH SOME OF THE TYPICAL COLD SPOTS
LIKE CEDAR CREEK...PELION...SALUDA...JOHNSTON AND MCCORMICK COULD
FALL BELOW FREEZING. SOME OF THE NUMBERS FOR BUSH FIELD TAKE THE
TEMPERATURE DOWN INTO THE MID/UPPER 20S...QUITE IMPRESSIVE AND
SEASONABLY COLD FOR EARLY NOVEMBER.

SOME THOUGHTS FOR SUNDAY NIGHT/MONDAY MORNING...AT A MINIMUM WILL
LIKELY NEED A FROST ADVISORY. IF GUIDANCE CONTINUES THE DOWNWARD
TREND COMBINED WITH EXCELLENT RADIATIONAL CONDITIONS MAY NEED TO
CONSIDER A FREEZE WARNING FOR PORTIONS OF THE CWA.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
THE MEDIUM RANGE MODEL GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT
IN THE OVERALL UPPER PATTERN EARLY IN THE EXTENDED FORECAST
PERIOD...BUT DIFFERENCES INCREASE FOR THE WED/THU TIME FRAME.

A 1030MB SURFACE RIDGE WILL BE ANCHORED OVER THE CAROLINAS MONDAY
AND MONDAY NIGHT...WHILE AN UPPER RIDGE AXIS OVER THE
OHIO/MISSISSIPPI VALLEYS WILL SHIFT EASTWARD OVER THE FORECAST
AREA. MONDAY MORNING TEMPERATURES WILL START OFF WELL BELOW NORMAL
IN THE LOWER TO MID 30S...WITH WIDESPREAD FROST EXPECTED ALONG
WITH SOME AREAS OF FREEZING/BELOW FREEZING TEMPERATURES. FULL
SUNSHINE EXPECTED WITH A DRY AIRMASS IN PLACE WILL YIELD SLIGHTLY
WARMER TEMPERATURES COMPARED TO SUNDAY BUT STILL REMAINING WELL
BELOW NORMAL. THE SURFACE RIDGE WILL SHIFT OFFSHORE ON TUESDAY
WITH A RETURN SOUTHERLY FLOW EXPECTED AROUND THE SURFACE
HIGH...WHICH WILL PROVIDE WARMER TEMPERATURES AND INCREASED LOW
LEVEL MOISTURE. NEAR NORMAL TEMPERATURES EXPECTED TUESDAY WITH
HIGHS IN THE UPPER 60S TO LOWER 70S AND MUCH WARMER MIN
TEMPERATURES TUESDAY NIGHT IN THE UPPER 40S.

THE FORECAST BECOMES A BIT MORE CHALLENGING AND LESS CONFIDENT BY
MID WEEK. THE GFS SHOWS A FRONTAL BOUNDARY APPROACHING THE
REGION...DRIVEN BY NORTHERN STREAM SHORTWAVE ENERGY MOVING ACROSS
THE NORTHERN TIER STATES AND CROSSING THE FORECAST AREA LATE
THURSDAY AND THURSDAY NIGHT.  THE ECMWF IS SIMILAR WITH THE FRONTAL
POSITION MID WEEK AND PUSH IT ACROSS THE AREA SOMETIME
THURSDAY...BUT HAS LESS MOISTURE ASSOCIATED WITH THE FRONT AND
DEPICTS A CUTOFF UPPER LOW OVER THE DESERT SOUTHWEST...INFUSED WITH
ENERGY AND MOISTURE ASSOCIATED WITH THE REMNANTS OF TD 21.  WILL
CONTINUE TO CARRY SLIGHT CHANCE POPS WED/THU WITH APPROACHING
FRONT.  TEMPERATURES WILL WARM BACK TO NEAR OR SLIGHTLY ABOVE NORMAL
VALUES.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
SURFACE LOW PRESSURE AND ITS ASSOCIATED COLD FRONT WILL CROSS THE
AREA THIS EVENING. SHOULD SEE INCREASING CLOUDS AHEAD OF THE FRONT
THIS AFTERNOON. SHOWERS EXPECTED TO MOVE INTO THE AREA THIS
EVENING WITH HIGHEST POPS OVER THE NORTH. POPS ARE TOO LOW...
LESS THAN 50 PERCENT TO INCLUDE IN THE TAFS AS A PREVAILING OR
TEMPO GROUP BUT WILL PUT VCSH. NORTHWEST WINDS WILL INCREASE
BEHIND THE COLD FRONT EARLY SATURDAY MORNING. HAVE VFR THROUGH THE
TAF PERIOD EXCEPT IFR TO MVFR AT CAE...CUB...AND OGB AFTER 09Z AS
CIGS LOWER.

.EXTENDED AVIATION OUTLOOK...
SOME SHOWER ACTIVITY AND MVFR CIGS POSSIBLE SATURDAY AS VERY COLD
AIR ALOFT ROTATES THROUGH THE AREA. BREEZY TO POSSIBLY WINDY
CONDITIONS EXPECTED SATURDAY INTO SUNDAY MORNING.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...LAKE WIND ADVISORY FROM 10 AM EDT SATURDAY TO 10 AM EST SUNDAY
     FOR SCZ015-016-018-020>022-025>031-035>038-041.
GA...LAKE WIND ADVISORY FROM 10 AM EDT SATURDAY TO 10 AM EST SUNDAY
     FOR GAZ040-063>065-077.
&&

$$









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