Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

379
FXUS62 KGSP 062349
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
649 PM EST SAT FEB 6 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 SUNDAY/...
AS OF 640 PM EST...WATER VAPOR IMAGERY AND THE LATEST NEAR TERM
MODEL HEIGHT FIELDS SHOW THE CLOSED UPPER LOW PRESSURE SYSTEM
SPINNING ACROSS CENTRAL AL THIS EVENING. A BROAD REGION OF LOWERING
ALTOCUMULUS/STRATOCUMULUS HAS FANNED OUT EAST OF THIS TROUGH ACROSS
THE WESTERN CAROLINAS AND NORTHEAST GEORGIA...AND THE DEEPER
MOISTURE AND FORCING WITH THIS SYSTEM WILL LIKELY MAKE A CLOSE CALL
TO THE SOUTHEAST OVERNIGHT. THE 18Z NAM/GFS AND THE 12Z ECMWF HAVE
COME IN SLIGHTLY WETTER ACROSS THE EXTREME SOUTHEAST FRINGE OF THE
FORECAST AREA OVERNIGHT...PARTICULARLY ACROSS SOUTHEASTERN UNION NC.
THE MAIN ADJUSTMENT TO THE FORECAST HAS BEEN TO PUSH OVERNIGHT
SHOWER CHANCES THERE INTO A MORE SOLID 40 TO 50 PERCENT RANGE.
PROFILES EXHIBITING DEEPER ISOTHERMAL NEAR ZERO WET BULBS OVERNIGHT
STILL APPEAR TO SUPPORT A RAIN/SNOW MIX AT ONSET WITH A POSSIBLE
TRANSITION TO SNOW SHOWERS BEFORE ENDING. THIS SHOULD ONLY IMPACT
LOCATIONS SOUTHEAST OF CHARLOTTE DURING THE EARLY MORNING HOURS...IF
IT HAPPENS AT ALL...WITH THE REST OF THE FORECAST AREA REMAINING
DRY. HOWEVER...THE GRADIENT OF PRECIPITATION WILL BE VERY SHARP...SO
THE SITUATION WILL NEED TO BE CLOSELY MONITORED OVERNIGHT FROM
CHESTER TO MONROE AND POINTS SOUTHEAST FOR THE POSSIBILITY OF
HEAVIER SNOW SHOWERS. FORTUNATELY...SURFACE TEMPERATURES SHOULD
REMAIN JUST ABOVE FREEZING IN THIS AREA.

ON SUNDAY...THE UPPER TROUGH REACHING THE COASTAL WATERS WILL
RAPIDLY DEEPEN AN 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 /SUNDAY NIGHT 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 /00Z SUNDAY THROUGH THURSDAY/...
AT KCLT....A SOLID SHIELD OF LOWERING VFR CLOUDS WILL REMAIN OVER
THE AIRFIELD OVERNIGHT AS A STRONG UPPER LOW MOVES BY TO THE SOUTH.
THIS SYSTEM...AND THE ASSOCIATED STRONG CYCLOGENESIS OFFSHORE...WILL
CREATE SHOWER BANDS OVER THE COASTAL PLAIN AND CENTRAL PIEDMONT OF
THE CAROLINAS...WHICH COULD FLIRT WITH THE KCLT AIRFIELD FROM THE
SOUTHEAST OVERNIGHT. THE CURRENT EXPECTATION IS THAT ANY SHOWER
BANDS...OF RAIN OR SNOW...WILL REMAIN PRIMARILY SOUTHEAST OF A
CHESTER TO MONROE LINE AND NOT IMPACT THE AIRFIELD...BUT THIS WILL
NEED CLOSE MONITORING OVERNIGHT. OTHERWISE...NORTHERLY WINDS WILL
INCREASE AND BECOME GUSTY THROUGH SUNDAY. VFR CIGS WILL SCATTER FROM
THE WEST THROUGH LATE SUNDAY MORNING.

ELSEWHERE...VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD...WITH
LOWER ALTOCUMULUS CEILINGS FOR MOST OF THE EVENING HOURS AND EARLY
OVERNIGHT...SCATTERING FROM THE WEST THROUGH THE REST OF SUNDAY
MORNING. BREEZY NORTHERLY WINDS WILL PRODUCE SOME LOW END GUSTS AS
THE PASSING UPPER LOW GENERATES A DEEP LOW PRESSURE SYSTEM OFF THE
SOUTHEAST COAST. GUSTS INTO THE 20S WILL BE POSSIBLE AT KAVL...WITH
GUSTS 15 TO 20 KT FROM KHKY TO KGMU.

OUTLOOK...WEAK HIGH PRESSURE WILL REMAIN OVER THE REGION ON SUNDAY
NIGHT...BUT WITH SEVERAL ROUNDS OF STRONG UPPER LEVEL
DISTURBANCES...MOISTURE...AND REINFORCING COLDER AIR ARRIVING FROM
THE NORTHWEST MONDAY THROUGH WEDNESDAY. RESTRICTIONS WILL BE
POSSIBLE...ESPECIALLY IN THE MOUNTAINS...WHERE SNOW SHOWERS ARE MOST
LIKELY.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
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
SHORT TERM...NED
LONG TERM...ARK
AVIATION...HG



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.