Funnel Cloud in North Carolina, April 30, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
156 PM EDT TUE APR 30 2013

.SYNOPSIS...
A RIDGE OF COOL HIGH PRESSURE WILL STRENGTHEN ATOP THE REGION
THROUGH MIDWEEK AND LINGER INTO THE UPCOMING WEEKEND. THIS HIGH WILL
PUMP SUFFICIENT GULF AND ATLANTIC MOISTURE INTO THE AREA ALLOWING
FOR A CHANCE OF SHOWERS DURING MUCH OF THIS PERIOD.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 145 PM EDT TUESDAY...CIGS ARE LIFTING ACROSS THE FA...WHICH
REFLECTS THE CLOUD TREND IN THE GRIDS PRETTY WELL. SOME SHRA ARE
DEVELOPING OVER THE FOOTHILLS...AND I EXPECT MORE TO DEVELOP THERE
AND ACROSS THE THE HIGHER ELEVATIONS OF THE MTNS OVER THE NEXT
COUPLE HOURS. AT THIS TIME I DON/T THINK WE WILL SEE ANY
THUNDERSTORMS THIS AFTN.

AS OF 1025 AM EDT TUESDAY...FOG HAS LIFTED BUT AND EXTENSIVE DECK OF
STRATUS CONTINUES OVER THE FORECAST AREA ROUGHLY ALONG AND EAST OF A
LINE FROM GREENWOOD TO GREENVILLE AND ASHEVILLE. SKY GRIDS HAVE BEEN
ALTERED TO REFLECT THIS. OTHERWISE THE GRIDS ARE IN GOOD SHAPE.

AS OF 650 AM...ISOLATED SHOWERS REFUSE TO RELENT ACROSS THE
NORTHEAST ZONES THIS MORNING...SO SHOWER CHANCES HAVE BEEN EXTENDED
YET A COUPLE MORE HOURS. OTHERWISE...DENSE FOG CONTINUES ACROSS MUCH
OF THE SOUTHERN HALF OF THE AREA...AND THE CHARLOTTE METRO AREA WAS
RECENTLY ADDED TO THE DFA. OTHERWISE...THE FORECAST SUITE HAS BEEN
UPDATED BASED UPON OBSERVATIONAL TRENDS.

PREVIOUS DISCUSSION...
VISBY OF 1/4SM OR LESS HAS BECOME FAIRLY WIDESPREAD OVER OUR LOWER
PIEDMONT ZONES EARLY THIS MORNING. ALTHOUGH VISBY CLOSER TO THE I-85
CORRIDOR HAS BEEN SLOWER TO TANK...I REALLY SEE NO REASON WHY THEY
SHOULDNT FOLLOW SUIT...SO A DENSE FOG ADVISORY WILL BE ISSUED FOR
THE UPSTATE AND NORTHEAST GEORGIA ZONES SOUTH OF I-85 (AS WELL AS
UNION COUNTY NC). MEANWHILE...AREAS OF HIGHER BASED STRATOCU
DEVELOPING IN THE EASTERLY LOW LEVEL FLOW SEEM TO BE HOLDING TEMPS
HIGH ENOUGH TO PRECLUDE FOG PROBLEMS OVER MUCH OF WESTERN NC.
OTHERWISE...A FEW PESKY SHOWERS PERSIST ACROSS NORTHEAST PORTIONS OF
THE CWA. THESE ARE NOT MOVING MUCH (IF AT ALL) IN THE WEAK DEEP
LAYER FLOW...AND COVERAGE HAS GRADUALLY BEEN DECREASING. SLIGHT
CHANCE POPS SHOULD SUFFICE FOR A COUPLE MORE HOURS.

LATER TODAY...FORECAST SOUNDINGS FEATURE SOME POSITIVE CAPE...BUT
THEY ARE GENERALLY CAPPED BY A SUBSIDENCE INVERSION NEAR 10 KFT. THE
COMBINATION OF EASTERLY FLOW AND DIFFERENTIAL HEATING COULD RESULT
IN A FEW SHOWERS DEVELOPING BENEATH THE CAP THIS AFTERNOON ACROSS
THE HIGHER TERRAIN...SO SLIGHT/LOW CHANCE POPS WILL BE ADVERTISED
LATE THIS AFTERNOON THROUGH THIS EVENING. ALTHOUGH CLOUDS SHOULD
SCATTER OUT BY THIS AFTERNOON...ABUNDANT LOW LEVEL MOISTURE SHOULD
SPELL A RETURN OF STRATUS/POSSIBLE FOG LATE TONIGHT. TEMPS SHOULD
AVERAGE VERY CLOSE TO CLIMO THROUGH THE PERIOD.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
DEEP RIDGING WILL EXTEND DOWN THE EAST COAST AT THE START OF THE NEAR
TERM. THROUGHOUT THE COLUMN WEAK FLOW WILL PREVAIL AND NO SIGNIFICANT
SYNOPTIC FORCING WILL BE PRESENT OVER THE CAROLINAS AND NE GA.
CONFLUENT UPPER LEVEL PATTERN IN EXIT REGION OF THE UPPER RIDGE
COMBINED WITH THE EASTERLY LOW LEVEL FLOW WILL SET UP CAD OVER OUR
AREA WHICH WILL LAST THROUGH THE REST OF THE PERIOD...WITH A WEAK
BACKDOOR FRONT BEGINNING TO PUSH ACROSS WEDNESDAY.  CAPPING
SUBSIDENCE/WEDGE INVERSION SEEN ON PROG SOUNDINGS WED SO EVEN DIURNAL
CONVECTION LOOKS UNLIKELY...WITH THE QPF SHOWN ON GFS NOT BELIEVABLE
GIVEN THE SHALLOW MOISTURE. AS THAT WEAK FRONT PUSHES ACROSS THE AREA
IT PRODUCES SLIGHT ISENTROPIC LIFT.  SOME CLOUD COVER COULD RESULT
BUT WILL GO WITH DRY FCST. WITH THE ELY FLOW CONTINUING INTO WED
NIGHT AND DEEPENING MOISTURE PRECIP BECOMES BELIEVABLE. CONDITIONS
REMAIN LARGELY THE SAME GOING INTO THURSDAY...BUT THE BEST MOISTURE
PUSHES SOUTHWEST ACROSS THE AREA WITH THE BACKDOOR FRONT. POPS
DIMINISH SOMEWHAT THU NIGHT. QPF THROUGH THE PERIOD WILL BE LIGHT
GIVEN WEAK FORCING AND RELATIVELY SHALLOW SATURATED LAYER...WITH
6-HOUR AMOUNTS OF UP TO A FEW HUNDREDTHS. GIVEN MOSTLY CLOUDY SKIES
AND WEDGE...LEANING TOWARD A RAW MODEL BLEND FOR TEMPS WITH FEW
DIFFERENCES NOTED BETWEEN GFS/NAM.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
SFC RIDGE WILL REMAIN IN PLACE ALONG THE EAST COAST FOR MOST OF THE
EXTENDED/MEDIUM RANGE PERIOD AS OMEGA BLOCK DEVELOPS BY LATE
FRI...WITH THE RIDGE STUCK BETWEEN A DEEP CUTOFF PLAINS LOW AND A
BROAD WESTERN ATLANTIC TROUGH. THUS OUR REGION SHOULD REMAIN UNDER A
CAD WEDGE AND IN A RATHER WET AND COOL PATTERN FRIDAY AND INTO THE
WEEKEND.

MODEL DIFFERENCES LEND LITTLE CONFIDENCE TO THE FORECAST FOR SUNDAY
NIGHT INTO THE EARLY WEEK. THE GFS KEEPS THE PLAINS LOW SEPARATED
FROM THE NORTHERN STREAM...SLOWLY SHIFTING INTO THE MISS VALLEY
MONDAY AND THEN IN POSITION TO MOVE TOWARD THE EAST COAST AND THE GSP
CWFA ONCE THE RIDGE SHIFTS OFFSHORE. THE 29/12Z EC FEATURES AN
AMPLIFYING TROUGH OVER WRN CANADA BY SUNDAY NIGHT WHICH ENVELOPS THE
CENTRAL CONUS LOW AND TAKES IT UP AND OVER THE EAST COAST
RIDGE...BASICALLY BREAKING DOWN THE BLOCK. BOTH THE 29/12 AND 30/00
CMC ENSEMBLES SUPPORT A MORE EC-LIKE SOLUTION. THE GFS/EC/CMC ALL
SHOW A FRONTAL BOUNDARY EXTENDING DOWN THE MISSISSIPPI VALLEY
SATURDAY AND MOVING EAST AS IT OCCLUDES. IF THE UPPER LOW WERE TO
TAKE A MORE NORTHERN TRACK PER THE EC...THIS FRONT WOULD LIKELY WASH
OUT AS THE EAST COAST RIDGE HELD STRONG. THE GFS WOULD TAKE THE FRONT
THROUGH THE SOUTHEAST SUPPORTING CHANCES OF SHOWERS AND THUNDERSTORMS
PER SBCAPE AND MODEST DEEP SHEAR.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AT KCLT...STRATUS IS FINALLY BREAKING UP INTO CELLULAR CU AROUND
KCLT...THOUGH IT WILL STILL TAKE ANOTHER HOUR OR SO FOR THE
TRANSITION TO BECOME COMPLETE. THIS MEANS CIGS SHOULD LIFT QUICKLY
THROUGH THE MVFR RANGE AND INTO THE IFR RANGE BY 19 UTC OR A LITTLE
AFTER. WINDS SHOULD VEER TO ESE/SE WITHIN THE HOUR AND STAY FROM
THAT DIRECTION UNTIL AFTER SUNSET. STRATUS IS LIKELY TO DEVELOP
AGAIN TONIGHT. TIMING IS A LITTLE IFFY AS THE NAM WOULD IMPLY IFR
CIGS DEVELOPING QUITE A BIT LATER THAN THE GFS. AT ANY RATE...I/VE
KEPT CIGS AT 1000 FEET STARTING AT 0900 UTC. BUT I SUSPECT LATER
SHIFTS WILL HAVE TO GO WITH SOMETHING LOWER. THE BNDRY LAYER FLOW
WILL ALSO INCREASE TOWARD SUNRISE WITH 10 TO 12 KT SUSTAINED NE
WINDS...POSSIBLY A LITTLE STRONGER

ELSEWHERE...A CUMULUS DECK SHOULD GRADUALLY RISE TO BETWEEN 3000 AND
4000 FEET ACROSS THE REGION THE REST OF THE AFTN. WINDS WILL VEER
AROUND TO ESE AT MANY SITES. LATER TONIGHT IFR STRATUS SHOULD RETURN
TO THE FOOTHILLS AND PIEDMONT AS INCREASING MOIST FLOW IN THE BNDRY
LAYER HELPS TO DEVELOP AND MAINTAIN A LOW DECK. AS HIGH PRESSURE
BUILDS INTO THE MID-ATLANTIC...THE WINDS SHOULD TURN OUT OF THE NE
AND INCREASE TO 10 TO 12 KTS ACROSS THE REGION LATER TONIGHT.

OUTLOOK...EARLY MORNING LOW CLOUDS AND FOG...WITH A SMALL CHANCE OF
AFTERNOON SHOWERS/THUNDERSTORMS EACH DAY THROUGH AT LEAST FRIDAY.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH  97%     HIGH  95%     MED   68%     MED   76%
KGSP       HIGH  98%     HIGH  88%     MED   64%     MED   76%
KAVL       HIGH  85%     HIGH  96%     HIGH  94%     HIGH  92%
KHKY       MED   77%     HIGH  85%     MED   72%     HIGH  86%
KGMU       HIGH 100%     HIGH  94%     MED   64%     HIGH  83%
KAND       HIGH 100%     HIGH  94%     MED   68%     HIGH  98%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

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

&&

SYNOPSIS...WIMBERLEY
NEAR TERM...JDL/MCAVOY
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...MCAVOY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1023 AM EDT TUE APR 30 2013

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-011430-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-ALEXANDER-
IREDELL-DAVIE-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-CATAWBA-
ROWAN-GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
HENDERSON-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-UNION NC-
CALDWELL MOUNTAINS-GREATER CALDWELL-BURKE MOUNTAINS-GREATER BURKE-
MCDOWELL MOUNTAINS-EASTERN MCDOWELL-RUTHERFORD MOUNTAINS-
GREATER RUTHERFORD-POLK MOUNTAINS-EASTERN POLK-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-GREATER OCONEE-
GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-CHEROKEE-YORK-
ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
1023 AM EDT TUE APR 30 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...PIEDMONT
NORTH CAROLINA...WESTERN NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.