AP-NC--GSP-NC W Cntrl Area Forecast Discussion, NC

000

FXUS62 KGSP 151421

AFDGSP

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC

1021 AM EDT WED JUL 15 2015

.SYNOPSIS...

A COLD FRONT WILL MOVE THROUGH THE AREA TODAY. FOLLOWING THE

FRONT...SURFACE HIGH PRESSURE WILL DRY OUT THE REGION AS AN UPPER

LEVEL RIDGE BUILDS IN FROM THE WEST...BRINGING WITH IT A RETURN

TO ABOVE NORMAL TEMPERATURES.

&&

.NEAR TERM /THROUGH TONIGHT/...

AT 1015 AM EDT...NO BIG CHANGES TO THE GOING FORECAST FOR TODAY.

TROUGH/WEAK FRONT ANALYZED FROM CENTRAL NC THROUGH THE UPSTATE INTO

NE GA AT 14Z. 12Z NAM SETTLES THE BOUNDARY SLOWLY SOUTHWARD INTO THE

SC MIDLANDS BY LATE AFTERNOON. THE NAM AND HRRR SHOW ISOLATED

CONVECTION FIRING OVER THE SOUTHERN UPSTATE EARLY THIS AFTERNOON SO

WILL CONTINUE THE ISOLATED POPS THERE. ALSO...THE MODELS SHOW

ISOLATED UPSLOPE SHOWERS ALONG THE TN LINE SO ISOALTED POPS LOOK

GOOD THERE. UPDATED TEMPS/DEWPOINTS WITH LATEST CONSHORT DATA WHICH

BUMPED MAX TEMPS UPWARD A DEGREE OR SO.

630 AM UPDATE...NO MAJOR CHANGES MADE TO THE GRIDS. POPS WERE

TEMPERED DOWN SRN ZONES AS LAST OF VORT PRECIP PUSHES SOUTH. TEMPS

AND TD/S REQUIRED ONLY MINOR TWEAKS WITH SFC WINDS PROVIDING MODEST

MIXING.

AS OF 255 AM EDT WEDNESDAY...AN UPPER LEVEL TROF WILL CONTINUE TO

SWING EAST THROUGH THE DAY WITH THE AXIS PASSING EAST OF THE CWFA BY

16Z/17Z. HEIGHTS WILL BEGIN TO RISE FAIRLY QUICKLY THROUGH THE

AFTERNOON WITH A STRONG H5 HIGH OVER TX NUDGING EAST. LOW LEVEL

MOISTURE SOURCES WILL BE LIMITED...WITH THE BEST POOLING ACROSS THE

MTN SPINE AIDED BY MECH LIFT AND SOME LINGERING MOISTURE SOUTH ALONG

A WEAKENING THETA/E BNDRY FROM CURRENT PRECIP SHIELD ADVANCING

SOUTH. THERE SHOULD BE ENUF LIFT ACROSS THE FAR WRN MTNS FOR

ISOL/SCT -SHRA AND PERHAPS A COUPLE TSTMS. THE SAME GOES FOR THE SRN

ZONES WHERE H5 VORT ENERGY WILL INTERACT WITH THE BNDRY AND PRODUCE

SHORT-LIVED WEAK CONVECTION BEFORE A SUBS INVERSION LIMITS CLOUDS

TO FAIR WX CU MOST LOCALES. WITH DEEP NW/LY FLOW...GOOD MIXING AND

DOWNSLOPE HEATING WILL LOWER SFC TD/S THROUGH THE AFTERNOON.

THUS...THE DAY WILL FEEL A LITTLE DRIER THAN THE PAST FEW DAYS WITH

LOW END GUSTS DEVELOPING BY MID AFTERNOON. THE OVERNIGHT WILL REMAIN

DRY AS THE MLVL FLOW MAINTAINS A N/LY SUBS PATTERN. AT THE SFC... A

RELATIVELY TIGHT PGRAD WILL SLOWLY WEAKEN AS A TROF AXIS SHIFTS

TOWARD THE COAST. SO...WITH SOME WIND AND WEAK SFC-BASED

INVERSIONS...LOWS WILL BE HELD NEAR SEASONAL LEVELS.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...

AS OF 230 AM WEDNESDAY...THE 00Z MODEL RUNS SHOW A TREND TOWARD MORE

CONVECTIVE COVERAGE FOR LATE IN THE WEEK...IN SPITE OF THE RETURN OF

THE UPPER RIDGE FROM THE WEST AND THE LACK OF LARGE SCALE FORCING.

THAT BEING SAID...ON THURSDAY AFTERNOON THERE DOES NOT APPEAR TO BE

ANYTHING IN THE MODEL GUIDANCE TO DISCOURAGE DEEP CONVECTION EITHER.

AND...ON A TYPICAL DAY IN THE SUMMERTIME...IT IS DIFFICULT TO KEEP

CONVECTION FROM DEVELOPING ON THE RIDGETOPS GIVEN SUFFICIENT

MOISTURE AND NOTHING THAT ACTS TO PREVENT IT. WILL FOLLOW THE NEW

NAM AND PUT A SMALL PRECIP CHANCE MAINLY OVER THE HIGHEST ELEVATIONS

FOR THE AFTERNOON...AND THEN GET RID OF IT WITH LOSS OF HEATING

THURSDAY EVENING. ON FRIDAY...THE UPPER PATTERN DOES NOT CHANGE

APPRECIABLY WITH THE ANTICYCLONE CENTERED OVER ERN TX/LA...BUT THE

SFC HIGH TO THE NE SEEMS A BIT STRONGER. THE MODELS DEVELOP A WEAK

E/SE FLOW IN THE BOUNDARY LAYER WHICH ADVECTS MOISTURE INTO THE

REGION. THE RESULT IS MORE PRECIP DEVELOPMENT IN THE MODEL. AGAIN...

GIVEN NOTHING TO DISCOURAGE THIS...I EXPECT THERE WILL BE A BIT MORE

COVERAGE THAN PREVIOUSLY EXPECTED...SO PRECIP CHANCES WERE NUDGED

UPWARD A BIT WHICH BRINGS THE PROBABILITY INTO THE CHC RANGE NEAR

THE BLUE RIDGE IN THE AFTERNOON. THE CHANCES FOR ANYTHING BEYOND

GARDEN VARIETY THUNDERSTORMS APPEARS VERY LOW. TEMPS BOTTOM OUT NEAR

NORMAL ON THURSDAY AND THEN BEGIN A CLIMB BACK ABOVE NORMAL STARTING

ON FRIDAY.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...

AS OF 315 AM WEDNESDAY...STILL NO BIG SURPRISES NOTED IN THE LATEST

MEDIUM RANGE GUIDANCE. THE SLOW WESTWARD DRIFT OF THE UPPER

ANTICYCLONE BACK TOWARD THE SRN PLAINS WILL KEEP THE WESTERN

CAROLINAS ON ITS PERIPHERY...AND THUS AWAY FROM ITS SUPPRESSIVE

AFFECTS. THAT SHOULD ALLOW FOR MAINLY DIURNAL SHOWERS AND

THUNDERSTORMS TO DEVELOP EACH DAY GIVEN SUFFICIENT LOW LEVEL

MOISTURE. TEMPS ABOVE NORMAL LOOK LIKE A GOOD BET...BUILDING EACH

DAY TO A PEAK MOST LIKELY ON MONDAY. THE ECMWF SOLUTION SUGGESTS

THAT A SHORT WAVE PASSING TO THE NORTH ON TUESDAY WILL BRING A

WEAKENING COLD FRONT DOWN ACROSS THE AREA THAT WOULD ENHANCE PRECIP

CHANCES AND DROP TEMPS BACK DOWN A BIT. HOWEVER...THE GFS SHOWS THE

UPPER WAVE MUCH FARTHER N AND KEEPS ANY BOUNDARY WELL TO OUR N. WILL

NOT MAKE ANY SIGNIFICANT CHANGES TO THE MEDIUM RANGE AT THIS TIME...

AND THINK EVEN WITHOUT THE FRONT THE COVERAGE OF STORMS WILL

INCREASE A BIT EACH DAY ANYWAY.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...

AT KCLT...VFR CONDS THROUGH THE TAF PERIOD. THE UPPER TROF AXIS WILL

CROSS EAST OF THE TERMINAL AFT 16Z AND SUPPRESSIVE DYNAMICS WILL

ALLOW ONLY FAIR WX CU THROUGH THE AFTERNOON. NO CIG/VSBY CONCERNS

OVERNIGHT AS WINDS REMAIN UP DUE TO A RELATIVELY TIGHT PGRAD. WINDS

WILL BECOME ALIGNED NW/LY WITH LOW END GUSTS ARND NOON AND THEN N/LY

ARND 00Z AS BROAD SFC TROF PUSHES SOUTHEAST.

ELSEWHERE...VERY SIMILAR TAFS TO KCLT WITH KAVL HAVING THE BEST

POTENTIAL FOR LATE PERIOD VSBY CONCERNS. OTHERWISE...FAIR WX CU WILL

DEVELOP THIS AFTERNOON WITH LOW END GUSTS. GENERALLY A NW/LY DIR ALL

SITES WITH WINDS PERSISTING OVERNIGHT IN A RELATIVELY TIGHT PGRAD.

OUTLOOK...BUILDING UPPER RIDGING WILL PERSIST THROUGH WEEKS END

LEADING TO LOWER PRECIP/RESTRICTION CHANCES. THESE CHANCES WILL

INCREASE OVER THE WEEKEND AS SAID RIDGE RETROGRADES LEADING TO

INCREASING DIURNAL SHRA/TSRA CHANCES AND THUS MORNING FOG/STRATUS AS

WELL.

CONFIDENCE TABLE...

14-20Z 20-02Z 02-08Z 08-12Z

KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%

KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%

KAVL MED 73% HIGH 100% HIGH 100% HIGH 87%

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 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...DEO

NEAR TERM...LG/SBK

SHORT TERM...PM

LONG TERM...PM

AVIATION...SBK

Delivered by Weather Underground Inc. Wed Jul 15 2015 10:22AM EDT