Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 070542
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1242 AM EST SUN FEB 7 2016

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ACROSS THE FORECAST AREA THROUGH THE
WEEKEND...WHILE STRONG LOW PRESSURE FORMS OFF THE CAROLINA COAST. A
COLD FRONT WILL PUSH THROUGH THE REGION ON MONDAY...USHERING IN
BELOW NORMAL TEMPERATURES AND AN INCREASE OF MOISTURE INTO THE
MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 1240 AM...THE WEAK RADAR ECHOES HAVE DIMINISHED WITH FLURRY
REPORTS ENDING. STILL EXPECT THE BULK OF THE PRECIP TO REMAIN EAST
OF THE CWFA...WITH LIGHT SNOW SHOWERS OR FLURRIES POSSIBLE WELL EAST
OF I-77 OVERNIGHT.

OTHERWISE...THE FORECAST REMAINS ON TRACK WITH THE POTENT CLOSED
UPPER LOW MOVING EAST TOWARD THE AL/GA BORDER LATE THIS
EVENING...AND ASSOCIATED RAPID CYCLOGENESIS UNDERWAY OFF THE
SOUTHEAST COASTLINE. DESPITE THE EVENING EXCITEMENT OF BRIEF FROZEN
PRECIP FALLING FROM HIGH CLOUD BASES...THE MAIN AREA OF CONCERN FOR
OUR FORECAST AREA CONTINUES TO BE LOCATIONS SOUTHEAST OF A CHESTER
SC TO MONROE NC LINE. CONSIDERABLE UNCERTAINTY CONTINUES OVER WHERE
ANY HEAVIER BANDING STRUCTURES MIGHT SET UP WEST OF THE OFFSHORE
LOW...WITH EASTERN PIEDMONT AND COASTAL PLAIN SECTIONS OF THE
CAROLINAS THE MOST LIKELY CANDIDATES. HOWEVER...DEEP LAYER
FRONTOGENESIS COULD WELL WRAP SHOWERY ACTIVITY WESTWARD THROUGH THE
PIEDMONT TO OVERLAP WITH THE INCREASINGLY COLD PROFILES NEAR THE
INTERSTATE 77 CORRIDOR. THE LATEST RAP AND NAM WET BULB PROFILES
NEAR CLT DEPICT SUBFREEZING TEMPERATURES IN ALL BUT THE VERY LOWEST
FEW HUNDRED FEET OVERNIGHT...AND THIS WOULD SEEM TO SUPPORT SNOW
VERSUS RAIN AS THE PRIMARY PTYPE WITH ANY SHOWERS REACHING WESTWARD
INTO THE LOWER PIEDMONT. POPS HAVE BEEN PUSHED INTO THE LOW LIKELY
RANGE FOR FAR SE UNION COUNTY NC AND A DUSTING OF SNOW WILL BE
POSSIBLE ON GRASSY SURFACES THERE OVERNIGHT INTO SUNDAY MORNING.
TEMPS WERE COOLED SLIGHTLY BASED ON OBSERVATIONAL
TRENDS...DEVELOPING LOW LEVEL COLD ADVECTION...AND SOME
EVAPORATIONAL COOLING IN SPOTS.

ON SUNDAY...THE UPPER TROUGH REACHING THE COASTAL WATERS WILL
FURTHER DEEPEN THE OFFSHORE SURFACE LOW THROUGH THE DAY. OUR REGION
SHOULD REMAIN DRY BEHIND THE DEPARTING DEEPER MOISTURE...BUT GUSTY
NORTHERLY WINDS MAY DEVELOP BEHIND THE SYSTEM...ESPECIALLY ACROSS
THE EASTERN HALF OF THE FORECAST AREA. MAXIMUM TEMPERATURES SHOULD
MAKE IT BACK TO AROUND NORMAL.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
AS OF 230 PM SATURDAY...A COLD FRONT WILL APPROACH THE SOUTHERN
APPALACHIANS EARLY MONDAY MORNING. BY THE TIME THE FRONT
ARRIVES...LOW TEMPERATURES ACROSS THE CWA ARE FORECAST TO RANGE FROM
THE UPPER 20S ACROSS THE MTNS TO LOW TO MID 30S ACROSS THE UPPER
SAVANNAH RIVER VALLEY. 12Z GFS360 INDICATES THAT A LARGE FIELD OF
BROAD Q-VECTOR CONVERGENCE WILL SWEEP ACROSS THE WESTERN CAROLINAS
AND NE GA ON MONDAY. THE COMBINATION OF THE SFC COLD FRONT AND
PASSING MID LEVEL SYNOPTIC SCALE FORCING WILL SUPPORT PRECIP CHCS
SPREADING ACROSS THE FOOTHILLS AND PIEDMONT DURING MONDAY AFTERNOON.
BETWEEN 18Z MON TO 0Z TUES...H85 WINDS WILL SHIFT FROM THE NW AND
INCREASE TO 25-30 KTS...SUPPORTING UPSLOPE FLOW ALONG THE TN BORDER.
GIVEN THE SFC TEMPERATURES AND LOW LEVEL THERMAL PROFILES...PRECIP
SHOULD FALL AS EITHER SNOW OR A COLD RAIN. SNOW IS EXPECTED ACROSS
THE MTNS IN THE MORNING...THEN SHOULD MIX OVER TO RAIN WITHIN THE
VALLEY FLOOR BY MID DAY. TEMPS ACROSS THE RIDGES SHOULD YIELD HIGH
ELEVATION SNOWFALL THROUGH THE DAYLIGHT HOURS. AREAS EAST OF THE
MTNS SHOULD SEE ONLY RAINFALL AS HIGH TEMPS WARM TO THE 40S ACROSS
THE REGION.

MODERATE TO STRONG H85 CAA WILL SWEEP ACROSS THE FORECAST AREA
MONDAY NIGHT...WITH MTN LOCATIONS COOLING TO -12 TO -14 C BY 12Z
TUES. MIN TEMPS ARE FORECAST TO RANGE FROM THE TEENS ACROSS THE MTNS
TO LOW 20S WITHIN THE VALLEYS...UPPER 20S TO THE EAST. COLD H85
TEMPS WILL REMAIN ACROSS THE MTNS THROUGH THE DAY...SUPPORTED BY
THICK CLOUD COVER AND GUSTY NW WINDS. CATE TO LIKELY POPS WILL
REMAIN ACROSS THE TN BORDER COUNTIES THROUGH THE MORNING...REDUCING
TO CHC POPS DURING THE AFTERNOON. FOOTHILL TO PIEDMONT AREAS WILL
REMAIN GENERALLY DRY. HIGH TEMPS SHOULD REMAIN BELOW FREEZING ACROSS
THE MTNS TO AROUND 40 EAST. MON AND TUES...TOTAL SNOWFALL FORECAST
GIVES 2 TO 4 INCHES ALONG THE SPINE OF THE APPALACHIANS TO 1-2
INCHES ACROSS THE VALLEYS OF THE TN BORDER COUNTIES. LITTLE TO NO
ACCUMS EXPECTED ACROSS THE FOOTHILLS.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM SATURDAY...ONE MORE PIECE OF CHANNELED VORTICITY WILL
DIVE THRU THE EASTERN CONUS TROF TUESDAY NIGHT...ENHANCING QG
FORCING ACROSS THE SOUTHERN APPALACHIANS. FROM WEDNESDAY THRU
THURSDAY NIGHT...THE EASTERN TROF WILL LIFT OUT SOMEWHAT...RESULTING
IN MORE ZONAL FLOW ATOP THE CWFA. THEN ANOTHER CLIPPER SHORT WAVE
SYSTEM WILL DIVE INTO THE MIDWEST ON FRIDAY...AND CARVE OUT THE
EASTERN TROF AGAIN BY SATURDAY.

AT THE SFC...A LARGE LOW PRESSURE SYSTEM WILL BE GRADUALLY FILLING
OVER THE NORTHEAST...KEEPING OUR AREA UNDER PERSISTENT LLVL NWLY
FLOW. MOISTURE WILL CONTINUE TO BANK UP ALONG THE USUAL NW FLOW
UPSLOPE AREAS...BUT SHUD GRADUALLY TAPER OFF WEDNESDAY INTO
WEDNESDAY NIGHT. ADDITIONAL SCATTERED TO OCCASIONALLY NUMEROUS SNOW
SHOWERS ARE EXPECTED ALONG THE TN LINE...ESPECIALLY TUESDAY NIGHT
THRU WEDNESDAY AFTERNOON. THE REST OF THE AREA SHUD BE MOSTLY CLEAR
AND QUITE CHILLY. THICKNESSES AND 850 MB TEMPS BOTTOM OUT EARLY
WEDNESDAY...WITH STILL SOME CAA AND WINDS TO MAKE FOR SOME WIND
CHILL CONCERNS IN THE HIGH TERRAIN. ADDITIONAL SNOW ACCUMS SHUD BE
GENERALLY LIGHT...BUT SOME SORT OF WINTER WX OR WIND CHILL ADV WILL
LIKELY BE NEEDED UNTIL THINGS WIND DOWN. A REINFORCING COLD FRONT IS
EXPECTED TO ACCOMPANY THE NEXT SYSTEM...BUT THE MEDIUM RANGE MODELS
ARE IN DISAGREEMENT ON THE EXACT TIMING AND ON THE AMOUNT OF
MOISTURE WITH IT. FOR NOW...I WILL INTRODUCE A SLGT CHC OF SNOW
SHOWERS ALONG THE TN LINE FRIDAY THRU FRIDAY NIGHT. TEMPS WILL BE
ABOUT 15-20 DEGREES BELOW NORMAL ON WEDNESDAY...WITH WIND CHILLS
BELOW ZERO ABOVE ABOUT 3500 FT EARLY THURSDAY MORNING. THEN TEMPS
WILL MODERATE BACK TO ONLY A CATEGORY OR TWO BELOW NORMAL BY
FRIDAY...BEFORE THE NEXT SURGE OF COLD AIR BRINGING TEMPS BACK DOWN
5 TO 10 DEG BELOW NORMAL FOR SATURDAY.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AT KCLT....MID LEVEL CLOUDS WILL REMAIN OVER THE AIRFIELD THRU THE
MORNING AS A STRONG UPPER LOW MOVES TO AND UP THE CAROLINA COAST. A
BRIEF SNOW FLURRY IS POSSIBLE EARLY THIS MORNING...BUT EXPECT ANY
SNOW SHOWER BANDS WILL REMAIN PRIMARILY SOUTHEAST OF THE AIRFIELD.
MID LEVEL CLOUDS SCATTER OUT BY AFTERNOON WITH CLEARING SKIES INTO
THE EVENING. LIGHT NNE WINDS THIS MORNING INCREASE IN SPEED AND
BECOME GUSTY BY AFTERNOON. WINDS DIMINISH AND THRU NWLY THIS
EVENING.

ELSEWHERE...VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD...WITH
SOME MID LEVEL CLOUDS EARLY THIS MORNING...THEN CLEAR SKIES. LIGHT
NLY WIND BECOMES GUSTY THIS AFTERNOON WITH DIMINISHING WINDS THIS
EVENING. WINDS REMAIN NLY AT KAVL THIS EVENING ...BUT TURN WLY AT
KHKY AND W TO SW FOR THE UPSTATE SITES.

OUTLOOK...SEVERAL ROUNDS OF STRONG UPPER LEVEL DISTURBANCES...
MOISTURE...AND REINFORCING COLDER AIR ARRIVE FROM THE NORTHWEST
MONDAY THROUGH WEDNESDAY. RESTRICTIONS WILL BE POSSIBLE...ESPECIALLY
IN THE MOUNTAINS...WHERE SNOW SHOWERS ARE MOST LIKELY.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...SBK
NEAR TERM...HG/RWH
SHORT TERM...NED
LONG TERM...ARK
AVIATION...RWH


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