Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 030854
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
354 AM EST WED FEB 3 2016

.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TODAY BRINGING WIDESPREAD SHOWERS
AND SOME THUNDERSTORMS THROUGH THE AFTERNOON. IN THE FRONTS
WAKE...DRY HIGH PRESSURE WILL BUILD IN AND PERSIST INTO THE WEEKEND.
A MOIST UPPER LEVEL DISTURBANCE WILL APPROACH THE CAROLINAS EARLY
NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
FRONTAL BAND OF PRECIP IS MOVING INTO THE CWFA ATTM...WITH NUMEROUS
UPSLOPE/UPGLIDE-INDUCED SHOWERS PRECEDING IT. SOME RELATIVELY
HEALTHY CONVECTION IS NOTED ACROSS NORTHERN ALABAMA AND SE TENN
ATTM...WITHIN AXIS OF (BARELY) POSITIVE SBCAPE. THE LATEST SHORT
TERM GUIDANCE INDICATES THIS CAPE AXIS WILL WEAKEN EVEN FURTHER AS
THE CONVECTIVE BAND MOVES EAST...WHERE IT WILL ENCOUNTER AN AIR MASS
THAT IS COOLER OWING TO RESIDUAL COLD POOL AND PRECEDING UPSLOPE
SHOWERS. NEVERTHELESS...A PROMINENT WARM FRONT/CAD BOUNDARY IS
LOCATED ROUGHLY ALONG THE I-85 CORRIDOR...WHERE SRH IS BEING
ENHANCED ABOVE AND BEYOND THE ALREADY-IMPRESSIVE ENVIRONMENTAL SRH.
SO THE SITUATION WILL BEAR CLOSE MONITORING LATER THIS MORNING.
ADDITIONALLY...WITH VERY STRONG LOW LEVEL JET OF 50-60 KTS
TRANSLATING ACROSS THE AREA...CONVECTIVE ELEMENTS COULD MIX DOWN
HIGHER MOMENTUM AIR INTO THE MTN VALLEYS AS THEY TRANSLATE ACROSS
THE WARM SECTOR PORTION OF THE HIGH TERRAIN OVER THE NEXT FEW HOURS.
OF EQUAL CONCERN IS THE HEAVY RAIN THREAT...IN LIGHT OF VIRTUALLY
OFF-THE-CHART PWATS...GOOD S/SE UPSLOPE FLOW IN THE LOWEST 5
KFT...AND THE POTENTIAL FOR CONVECTION TO ENHANCE RAINFALL RATES
LOCALLY. UPSLOPE SHOWERS HAVE ALREADY PRODUCED 0.5-1.5 INCHES OF
RAIN ACROSS THE BLUE RIDGE...WITH ANOTHER 1-2 INCHES TO COME...AND
AS MUCH AS 3 ADDITIONAL INCHES POSSIBLE NEAR THE SOUTHERN ESCARPMENT
IN NC. CONVECTION ALSO ADDS A BIT OF A WILD CARD TO THE SCENARIO...
SO OPTED TO ISSUE A FLASH FLOOD WATCH FOR THE BLUE RIDGE IN
NC...FROM TRANSYLVANIA COUNTY NORTHEAST TO AVERY/CALDWELL MTNS.

THE FRONTAL BAND IS MOVING EAST WITH A BIT MORE MOMENTUM THAN
ADVERTISED BY 00Z GUIDANCE. IN FACT...IT WILL LIKELY BE RAINING
ACROSS ROUGHLY THE WESTERN 2/3 OF THE FORECAST AREA BY SUNRISE. THE
LATEST MESOSCALE/CONVECTION ALLOWING MODEL OUTPUT ACTUALLY BLAST THE
FRONTAL BAND THROUGH THE AREA...PUSHING IT EAST OF I-77 BY 00Z. THIS
MAY BE A BIT TOO FAST...BUT IT DOES CALL INTO QUESTION HOW MUCH
HEATING/BUOYANCY WILL BE REALIZED LATER TODAY...DESPITE NAM/GFS
DEPICTION OF AROUND 500 J/KG SBCAPE ACROSS THE PIEDMONT THIS
AFTERNOON. PER THE NAM AND THE GFS...THE SEVERE HAZARDS IN
ENVIRONMENTS WITH REDUCED BUOYANCY (SHERB) EXPERIMENTAL PARAMETER IS
AT NEARLY THE OPTIMAL VALUE FOR IDENTIFYING POTENTIALLY SIGNIFICANT
SEVERE HIGH SHEAR/LOW CAPE ENVIRONMENTS. INDEED...IF WE ARE ABLE TO
REALIZE AS MUCH INSTABILITY AS DEPICTED IN THE LATEST GUIDANCE...
GIVEN THE HIGH DEGREE OF SHEAR...AN ORGANIZED SEVERE CONVECTIVE
THREAT WILL EXIST...WITH THE POTENTIAL FOR DAMAGING STRAIGHT LINE
WINDS/ DOWNWARD MOMENTUM FLUX AND ISOLATED TORNADOES. THE HIGHEST
RISK FOR SUCH WILL BE EAST OF THE I-85 CORRIDOR...FROM LATE MORNING
ON.

NEEDLESS TO SAY...ALL LOCALES RECEIVE A 100 POP FOR TODAY... WITH
POPS RAMPING DOWN SOMEWHAT QUICKLY THIS EVENING. THE NAM IS SLOWER
WITH MOVING THE PRECIP EAST THIS EVENING THAN THE OTHER OPERATIONAL
MODELS...AS IT TENDS TO DEVELOP A WEAK SURFACE LOW ACROSS THE
PIEDMONT...QUITE A BIT FARTHER INLAND THAN THE OTHER MODELS. BUT
AGAIN EVEN THE 06Z NAM IS BEHIND THE CURVE IN BEING MUCH TOO SLOW TO
MOVE THE FRONTAL BAND INTO THE FORECAST AREA THIS MORNING. THEREFORE
LEANED THE FORECAST TOWARD THE FASTER SOLUTIONS.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 200 AM EST WEDNESDAY...THE SHORT TERM PERIOD INITIALIZES
ON THURSDAY MORNING AS THE UPPER PATTERN FEATURES A NEARLY FULL
LATITUDE UPPER TROF SLIDING ACROSS THE PLAINS STATES...WHILE
BROAD/COOL HIGH PRESSURE SPILLS ACROSS THE MS RIVER VALLEY.
CLOSER TO HOME...AN OLD COLD FRONTAL AXIS STALLED ALONG THE ATLANTIC
COAST WILL PROVIDE A FOCUS SHOWERS AS MODELS FAVOR A SERIES OF
WEAK WAVES TRAVERSING THE BOUNDARY THROUGH THE DAY ON THURSDAY.
THE PRIMARY IMPACTS FROM SAID ACTIVITY WILL LIKELY REMAIN EAST
OF THE FCST AREA...HOWEVER WILL KEEP POPS IN THE CHANCE RANGE
SOUTH/EAST OF I85/I77 RESPECTIVELY.

BEYOND THAT...THE ABOVE MENTIONED UPPER TROF AXIS AND EMBEDDED
SHORT WAVE WILL SLIDE THROUGH THE SOUTHERN APPALACHIANS INTO
FRIDAY MORNING EFFECTIVELY PUSHING THE STALLED FRONT OUT TO
SEA.  AS A RESULT...THE FCST WILL DRY OUT AS THE HIGH PRESSURE
INTRUDES AT THE SURFACE BENEATH SHORTWAVE RIDGING ALOFT ON FRIDAY.
MEANWHILE...ANOTHER H5 SHORTWAVE IS PROGGED TO DIG ACROSS SOUTHERN
PLAINS INTO SATURDAY MORNING WITH A REGION OF SURFACE CYCLOGENESIS
EXPECTED TO DEVELOP IN THE NORTHERN GULF OF MEXICO...POTENTIALLY
SETTING UP AN ACTIVE PATTERN FOR THE START OF THE NEW WORK WEEK.
TEMPERATURES THROUGH THE PERIOD WILL BE GENERALLY A FEW DEGREES
BELOW NORMAL.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
FAIRLY GOOD AGREEMENT IS HAD BTW THE OP MODELS AND ENS MEANS WITH
THE OVERALL SYNOPTIC PATTERN THROUGHOUT MOST OF THE EXT PERIOD.
HEMISPHERIC CHARTS SHOW A TIGHT HEIGHT GRADIENT ACROSS THE NRN ATL
WITH LITTLE MERIDIONAL BLOCKING POTENTIAL...THUS EXPECT PROGRESSIVE
SYSTEMS TO PERSIST ACROSS THE SE/RN CONUS.

FLAT RIDGING WILL REMAIN OVER THE AREA SAT WITH WEAK AND DRY SFC
HIGH PRESSURE TRANSITIONING OFF THE ATL COAST. CLOUD COVER INCREASES
IN THE AFTERNOON AS DIFL FLOW ALOFT INCREASES AHEAD OF A DIGGING
S/W. SO...WILL EXPECT NOMINAL WARMING WITH HIGHS RIGHT AROUND
NORMAL. THE PATTERN BEGINS TO CHANGE SAT NIGHT AS A COASTAL LOW
DEVELOPS AND REMAINS OFF THE CAROLINA COAST THROUGH THE DAY SUN.
WITH THE PLACEMENT OF THE UPPER TROF...THE COASTAL LOW SHOULD
MAINTAIN CLOSELY WRAPPED PRECIP AND TRACK FAR ENUF EAST FOR LITTLE
IN THE WAY OF POP CONCERNS FOR THE FA. THIS COULD CHANGE ACROSS THE
ERN ZONES AS WE NEAR THE EVENT AND THICKNESSES WOULD SUPPORT A -SN
OR A MIXED P/TYPE SITUATION SUN NIGHT.

MONDAY SHOULD REMAIN MOSTLY DRY ACROSS THE CWFA WITH THE NEXT S/W
DIVING INTO THE BASE OF THE MEAN TROF MON NIGHT THROUGH THE PERIOD.
THE MODELS CONTINUE TO SUPPORT THE REINFORCING CP AIRMASS IDEA AND
THIS WILL SET THE STAGE FOR WINTRY PRECIP BEGINNING ACROSS THE MTNS
LATE MON INTO TUE. WITH STRONG DYNO OMEGA CROSSING AND JUST ENUF LOW
TO MID LEVEL MOISTURE...SNOW SHOWERS COULD BREAK HIGH TERRAIN
CONTAINMENT INTO THE NC/SC PIEDMONT. TOO EARLY TO SPECULATE ON
ACCUMS...BUT THE EVENT LOOKS PROGRESSIVE AND LOW END OUTSIDE THE
MTNS.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...IFR CIGS HAVE RETURNED IN ASSOCIATION WITH MOIST LOW LEVEL
LIFT WITHIN SE FLOW REGIME. THE GOOD NEWS IS IT APPEARS THAT VISBY
IS NOT GOING TO BE AS PROBLEMATIC AS PREVIOUSLY ANTICIPATED...AS THE
STOUT SE WINDS SHOULD PREVENT ANY BR/FG FROM DEVELOPING.
HOWEVER...VISBY IS EXPECTED TO DETERIORATE AFTER SUNRISE...AS RAIN
ASSOCIATED WITH A COLD FRONT OVERSPREADS THE AREA FROM THE WEST.
EXPECT VISBY PRIMARILY IN THE 2-3SM RANGE...WITH BRIEF PERIODS OF
LOWER VISBY POSSIBLE IN HEAVY RAIN. IN TERMS OF CIGS...WILL FORECAST
THEM TO REMAIN AROUND 006 (GIVE OR TAKE 100 FT) THROUGH THE
AFTERNOON... ALTHOUGH WOULD NOT BE AT ALL SURPRISED TO SEE THEM LIFT
TO MVFR BY AROUND 18Z. ISOLATED THUNDER WILL BE POSSIBLE DURING THE
AFTERNOON...AND HAVE ACTUALLY BACKED UP THE PROB30 TO 18Z. WINDS
WILL GRADUALLY TURN TOWARD THE S AND SW AT 10-15 KTS...WITH GUSTS
AROUND 20 KTS POSSIBLE AT JUST ABOUT ANY TIME. PRECIP CHANCES WILL
DIMINISH DURING THE EVENING...CONCURRENT WITH RATHER QUICK
IMPROVEMENT IN FLT CONDITIONS.

ELSEWHERE...OCCL RAIN CAN BE EXPECTED AT THE TERMINALS OVER THE NEXT
FEW HOURS...FOLLOWED BY MORE PERSISTENT AND INCREASING RAINFALL
RATES BY AROUND SUNRISE...AND CONTINUING THROUGH A GOOD PART OF THE
DAY. THE GOOD NEWS IS VISBY IS NOT EXPECTED TO BE AS LOW AS
PREVIOUSLY FORECAST...AS THE INCREASING S/SE WINDS HAVE GENERALLY
CLEARED OUT MUCH OF THE BR. HOWEVER...OCCL 2-3SM VISBY IN RAIN WILL
CONTINUE THROUGH THE EARLY MORNING...WITH VISBY EXPECTED TO BECOME
MORE PERSISTENT IN THIS RANGE...WITH OCCL LOWER VISBY IN MODERATE TO
HEAVY RAIN. THUNDER CHANCES WILL INCREASE AT THE TERMINALS BY LATE
MORNING...AND PROB30S ARE CARRIED AT ALL LOCATIONS INTO THE
AFTERNOON. OTHERWISE...CIGS ARE EXPECTED TO SETTLE AT AROUND 005 BY
DAYBREAK. THE FORECAST CARRIED THESE THROUGH MUCH OF THE DAY...BUT
WOULD NOT BE SURPRISED TO SEE THEM LIFT TO MVFR BY EARLY AFTERNOON.
PRECIP CHANCES WILL DIMINISH DURING THE EVENING...CONCURRENT WITH
RATHER QUICK IMPROVEMENT IN FLT CONDITIONS.

OUTLOOK...IN THE WAKE OF THE FRONT...LARGE HIGH PRESSURE WILL BUILD
ACROSS THE REGION THROUGH THE WEEKEND...PROVIDING UNRESTRICTED
CONDITIONS.

CONFIDENCE TABLE...

            09-15Z        15-21Z        21-03Z        03-06Z
KCLT       HIGH 100%     HIGH  85%     MED   68%     HIGH  84%
KGSP       HIGH  94%     HIGH  89%     HIGH  82%     HIGH 100%
KAVL       HIGH  94%     HIGH  90%     HIGH  83%     HIGH 100%
KHKY       HIGH  94%     HIGH  81%     MED   62%     HIGH 100%
KGMU       HIGH  94%     HIGH  92%     MED   78%     HIGH 100%
KAND       HIGH  94%     HIGH  87%     HIGH  80%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE 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...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NCZ033-049-050-053-
     064-065-501-503-505-507-509.
     WIND ADVISORY UNTIL 10 AM EST THIS MORNING FOR NCZ033-048>052-
     058-059-062>064.
SC...NONE.

&&

$$
SYNOPSIS...SBK
NEAR TERM...JDL
SHORT TERM...CDG
LONG TERM...SBK
AVIATION...JDL


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