Whittier North Carolina Personal Weather Station - Area Forecast Discussion

000
FXUS62 KGSP 180004
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
804 PM EDT THU MAY 17 2012

.SYNOPSIS...
AN UPPER LEVEL LOW WILL FORM OVER SOUTH CAROLINA...AND WILL MOVE TO
THE NORTH CAROLINA COAST...WHERE IT WILL LINGER INTO EARLY NEXT
WEEK. HIGH PRESSURE WILL BUILD IN FROM THE NORTH AND REMAIN THROUGH
MONDAY. A COLD FRONT WILL APPROACH THE AREA FROM THE WEST ON
TUESDAY.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 800 PM...CONVECTION HAS DIMINISHED OUTSIDE OF THE MTNS WITH
THE LOSS OF HEATING BUT CONTINUES OVER THE MTNS. CANNOT RULE OUT AN
ISOLATED STORM OUTSIDE OF THE MTNS THIS EVENING...BUT BEST CHC WILL
BE TO OUR SE CLOSER TO THE UPPER LOW AND TROF. OTHER THAN THE
OUTLIER RAP... MESOSCALE MDLS SHOW BEST CHC FOR CONVECTION OVER THE
MTNS THRU MIDNIGHT THEN DISSIPATING BY MORNING. HAVE GONE THIS ROUTE
WITH POP GIVEN THE CURRENT CONDITIONS. UPDATED LOWS WITH THE LATEST
GUIDANCE WHICH SEEMS TO TAKE INTO ACCOUNT THE LINGERING CLOUDS
EXPECTED OVERNIGHT. THIS RAISES LOWS BY A COUPLE OF DEGREES IN MANY
LOCATIONS. EXPECT ONLY PATCHY FOG NEAR BODIES OF WATER OUTSIDE OF
THE MTNS WITH THE INCREASE IN LOW CLOUDS FROM THE EAST OVERNIGHT.
MTN VALLEYS WILL SEE PATCHY DENSE FOG...ESPECIALLY THE LITTLE TN
VALLEY.

PREVIOUS DISCUSSION...WATER VAPOR IMAGERY AND THE LATEST RAP MODEL
RUN SHOW A NE TO SW ORIENTED UPPER LOW STRETCHED OVER THE MIDLANDS
OF SOUTH CAROLINA...BACK ACROSS SOUTHEAST GEORGIA. A SPOKE OF PVA ON
THE WEST SIDE OF THE LOW IS HELPING TO ORGANIZE STRONG TO SEVERE
CONVECTION ACROSS THE SOUTHERN PART OF THE UPSTATE.
ELSEWHERE...OTHER STORMS WERE DEVELOPING OVER THE BLUE RIDGE OF NE
GA AND SW NC. SOMEWHAT DRIER AIR HAS PUSHED INTO THE NRN PIEDMONT
AND FOOTHILLS OF NE...BUT AREAS TO THE SOUTH REMAIN QUITE UNSTABLE
WITH SB-CAPE VALUES RUNNING FROM 1500-2000 J/JG. OUR LOCAL
WORKSTATION WRF...THE NCEP 4KM WRF AND THE HRRR ALL AGREE IN
DEVELOPING CONVECTION OVER MUCH OF THE UPSTATE...SOUTHERN NC MTNS
AND FOOTHILLS AND NE GA INTO THE EVENING HOURS. THIS WOULD BE
SIMILAR TO WHAT HAPPENED LAST NIGHT. CONFIDENCE IN THIS DEVELOPMENT
IS FAIRLY HIGH...AND POPS WILL BE PUSHED UP TO 50 PERCENT ACROSS THE
I-85 CORRIDOR AND UP INTO THE WRN NC FOOTHILLS FOR THE EVENING
HOURS. COOL MID-LEVEL TEMPS AND DRY AIR ALOFT WILL CONTINUE TO
SUPPORT SEVERE WIND AND HAIL EVENTS.

A BACK DOOR COLD FRONT WILL CROSS THE REGION LATE TONIGHT. THE NAM
MIXES DEWPOINTS INTO THE U40S TO L50S ACROSS THE NC FOOTHILLS AND
PIEDMONT AND THE ERN UPSTATE. THIS SHOULD FINALLY END THE THREAT OF
STORMS FOR THESE AREAS. BACK ACROSS THE MOUNTAINS...ESPECIALLY
CLOSER TO THE TN LINE...SCT CONVECTION SHOULD DEVELOP AGAIN TMRW
WHERE LLVL MOISTURE CONVERGENCE WILL BE MAXIMIZED.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AT 1430 EDT THURSDAY...A CLOSED UPPER LOW...PART OF AN EAST COAST
REX ...WILL BE LOCATED NEAR THE NC COAST ON FRIDAY NIGHT AND
SATURDAY. ON SUNDAY THIS FEATURE RETROGRADES SLIGHTLY INLAND. THE
MODELS SHOW DRIER AIR MOVING SW INTO OUR AREA ON THE BACK SIDE OF
THE LOW FRIDAY NIGHT AND SATURDAY....WHILE SOME MOISTURE LINGERS
ALONG THE BLUE RIDGE. ON SATURDAY NIGHT THE NAM SHOWS MOISTURE
SPREADING WEST ACROSS THE INTERSTATE 77 CORRIDOR TO THE NC BLUE
RIDGE...WHILE THE GFS REMAINS RATHER DRY UNTIL SUNDAY NIGHT.

POPS WILL INITIALLY BE QUITE LOW AND FOCUSED ALONG THE BLUE
RIDGE...THEN WILL INCREASE SLIGHTLY FROM THE EAST TOWARD SUNDAY...
BUT REMAINING RATHER LOW AS CONFIDENCE IS LIMITED ON THE AMOUNT AND
TIMING OF MOISTURE ENCROACHMENT FROM THE EAST. TEMPERATURES WILL
GENERALLY BE SLIGHTLY BELLOW NORMAL UNDER THE UPPER LOW HEIGHT
ANOMALY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AT 1430 EDT THURSDAY...A LONGWAVE TROUGH WILL PROGRESS ACROSS THE
EASTERN USA FROM MONDAY THROUGH WEDNESDAY...PROGRESSING OFFSHORE ON
THURSDAY WHEN A LONGWAVE RIDGE AXIS CROSSES THE MS RIVER VALLEY. A
CLOSED UPPER LOW WILL REMAIN NEAR THE CAROLINA COAST ON MONDAY. THIS
LOW FILLS AND DRIFTS NORTHEAST ON TUESDAY. A SHORTWAVE TROUGH DROPS
SOUTHEAST OVER THE SOUTHERN APPALACHIANS LATE TUESDAY...MOVING OFF
TO THE EAST ON WEDNESDAY.

SURFACE HIGH PRESSURE WILL BE OVER OUR ARE ON MONDAY...BETWEEN A
COASTAL LOW AND A COLD FRONT IN THE MS RIVER VALLEY. CONFIDENCE IS
LIMITED ON THE WESTERN EXTENT OF MOISTURE THAT WILL WRAP AROUND THE
COASTAL LOW TOWARD THE SOUTHERN APPALACHIANS...AND THE RESULTANT
POPS. THE COLD FRONT TO OUR WEST REACHES THE SOUTHERN APPALACHIANS
ON TUESDAY WHILE WEAKENING...WITH THE REMAINS OF THE BOUNDARY
SUPPORTING LENDING SUPPORT TO AT LEAST SMALL POPS. WEDNESDAY AND
THURSDAY FIND OUR AREA UNDER WEAK HIGH PRESSURE...BUT THE MODELS
DEPICT SOME AMOUNT OF LINGERING MOISTURE...OSTENSIBLY ASSOCIATED
WITH THE REMAINS OF THE FORMER FRONT. WITH GULF INFLOW EVENTUALLY
SETTING UP TO OUR WEST...SMALL POPS WILL BE MAINTAINED INTO
THURSDAY...ESPECIALLY IN  THE WEST. TEMPERATURES WILL BE SLIGHTLY
ABOVE NORMAL IN MINOR HEIGHTS RISES BEHIND THE DEPARTING UPPER LOW.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AT KCLT...EXPECT ANY SIGNIFICANT CONVECTION TO REMAIN EAST AND SOUTH
OF THE AIRFIELD THIS EVENING BEFORE DISSIPATING OVERNIGHT. CANNOT
RULE OUT A ROGUE CELL DEVELOPING...BUT CHC TOO LOW FOR MENTION ATTM.
EXPECT LOW VFR THEN MVFR TO MOVE IN ON THE LOW LEVEL ELY FLOW AS
MOISTURE INCREASES OVERNIGHT. THIS SHUD LIFT QUICKLY AFTER SUNRISE.
HOWEVER...GUSTY NNE WINDS DEVELOP AS MIXING TAPS THE STRONGER ELY
FLOW JUST ABOVE THE SFC. THE GUSTS SHUD DIMINISH AROUND NOON WITH
SCT HIGH BASED CU DEVELOPING. DRIER ATMOS MOVING IN SHUD SQUELCH ANY
CONVECTION.

ELSEWHERE...BEST CHC FOR ANY CONVECTION THIS EVENING WILL BE AT
KAVL...BUT CANNOT COMPLETELY RULE OUT A ROGUE CELL ELSEWHERE.
CONVECTION WILL LINGER THRU MIDNIGHT THEN DISSIPATE BEFORE DAYBREAK.
EXPECT LOW VFR THEN MVFR TO DEVELOP TOWARD MORNING ON ELY LOW LEVEL
FLOW AND INCREASING MOISTURE. KAVL HAS THE BEST CHANCE FOR ANY MVFR
FOG OVERNIGHT. EXPECT THE MVFR TO LIFT SHORTLY AFTER DAYBREAK.
HOWEVER...GUSTY NELY WINDS WILL DEVELOP OVER THE SC SITES AS MIXING
TAPS THE STRONGER WINDS JUST ABOVE THE SFC...LESS WIND KAVL/KHKY.
GUSTS DIMINISH FOR THE AFTERNOON WITH HIGH BASED CU DEVELOPING. KAVL
HAS THE BEST CHC FOR ANY DIURNAL CONVECTION...BUT CHC TOO LOW TO
INCLUDE ATTM.

OUTLOOK...DRYING OVER THE WEEKEND SHUD KEEP A LID ON CONVECTION.
MRNG FOG WILL BE PSBL...ESP MTN VALLEYS AND NEAR LAKES/RIVERS.

AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...

WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM

&&

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

&&

$$
SYNOPSIS...JAT
NEAR TERM...MCAVOY/RWH
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...RWH

NWS GSP Office Area Forecast Discussion