142
FXUS62 KGSP 201759
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
159 PM EDT SAT APR 20 2019
SYNOPSIS
AN UPPER LEVEL LOW PRESSURE CENTER LOCATED NEAR WEST VIRGINIA WILL
MOVE SLOWLY EAST THROUGH MONDAY. EXPECT A WARMING TREND AS AS THE
UPPER LOW MOVES AWAY FROM OUR AREA. WARM AND DRY HIGH PRESSURE WILL
BE IN CONTROL OF OUR WEATHER FOR MOST OF THE WEEK. RAIN CHANCES
INCREASE BY THE END OF THE WEEK AS A COLD FRONT MOVES INTO OUR AREA.
NEAR TERM /THROUGH SUNDAY/
AS OF 200 PM...CLOSED UPPER LOW IS NOW CENTERED ON THE SOUTHERN
APPALACHIANS, WITH AN AXIS OF VORTICITY ORIENTED ALONG THE I-26
CORRIDOR. ALONG AND AHEAD OF THIS AXIS, A SMALL AMOUNT OF SBCAPE
(PROBABLY 100 J/KG OR LESS) WIDESPREAD SHOWER ACTIVITY WILL
CONTINUE, PRODUCING A FEW HUNDREDTHS OF AN INCH OF RAIN BY THE
END OF THE DAY. ALL AREAS AT LEAST POTENTIALLY WILL SEE A FEW
SPRINKLES. RAP PROFILES SUGGEST THE CONVECTIVE LAYER REACHES UP
TO ICY TEMPS. THUS A FEW STRONGER CELLS PRODUCING GRAUPEL AND EVEN
MAYBE A LITTLE THUNDER CAN BE EXPECTED IN THE AREA NE OF I-26.
MORE DETAILS WILL BE INCLUDED WITH THE FULL AFTN PACKAGE WITHIN
THE NEXT HOUR.
SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/
AS OF 120 PM EDT SATURDAY...IT LOOKS LIKE WE WILL SEE A RETURN
TO WARMER TEMPERATURES DURING THE EARLY PART OF THE UPCOMING
WEEK. THE OLD UPPER LOW WILL ROTATE OFF THE MID-ATLANTIC COAST
ON SUNDAY NIGHT, ALLOWING SFC HIGH PRESSURE TO BUILD IN FROM THE
NW. THE ARRIVAL OF THE HIGH WILL PROVIDE US WITH ONE MORE COOL
MORNING ON MONDAY, BUT THE AIR MASS SHOULD MODIFY QUICKLY AS
A FLATTENING UPPER RIDGE BUILDS IN DURING THE DAY. AS A RESULT,
TEMPERATURES REBOUND ANOTHER 5-10 DEGREES COMPARED TO SUNDAY. AFTER
A MILD MONDAY NIGHT, THE TEMPS ON TUESDAY LOOK EVEN WARMER...ON
THE ORDER OF TEN DEGREES ABOVE NORMAL...WITH HIGH PRESSURE MOVING
OFF THE SOUTHEAST COAST. WE COULD EVEN HAVE A FEW SHOWERS POPPING
UP ALONG THE RIDGETOPS ACROSS THE MTNS OF NC IN THE AFTERNOON.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
AS OF 2PM EDT SATURDAY: EC AND GFS GENERALLY AGREE ON LOW POPS
THROUGH WED. NIGHT AS BROAD EASTERN UPPER RIDGE CONTINUES TO HOLD
SWAY. BY THURSDAY MORNING, THE GFS BEGINS TO WASH-OUT THE RIDGE AND
ALLOWS A WEAK FRONTAL BOUNDARY INTO THE MOUNTAINS, GIVING SOME
INCREASE IN RAIN CHANCES AT THAT TIME, WHICH LAST THROUGH SATURDAY
MORNING AS FRONT AND UPPER SOUTHERN-STREAM LOW ADVANCES INTO THE
REGION. EC, ON THE OTHER HAND, KEEPS THE RIDGE STRONGER THROUGH
FRIDAY MORNING, WITH A MORE PRONOUNCED SOUTHERN STREAM WAVE
BEGINNING TO POP PRECIP ON FRIDAY. RESULTING BLEND WILL BE SOME
INCREASE IN SHOWER POSSIBILITIES BEGINNING THURSDAY, AND LASTING
THROUGH SATURDAY MORNING. RIDGE WILL GIVE ABOVE NORMAL TEMPS. UNTIL
PRECIPITATION DEVELOPS LATE IN THE FORECAST. LOW TEMPERATURES ARE
SOMEWHAT MORE UNCERTAIN DUE TO DIFFERENCES OF OPINION IN THE AMOUNT
OF MOISTURE RETAINED UNDER THE RIDGE, AND CONSIDERABLE DIFFERENCES
IN MODEL INDICATIONS OF HOW MUCH MOISTURE ADVANCES AHEAD OF THE NEXT
SYSTEM LATE IN THE WEEK. NONETHELESS, LOWS SHOULD BE AT OR ABOVE
SEASONAL NORMALS THROUGHOUT THE FORECAST, KEEPING ANY FROST OUT OF
THE PICTURE. WINDS SHOULD BE FAIRLY LIGHT UNDER THE RIDGE WED. INTO
THURS., AND MAY PICKUP AS SURFACE LOW BEGINS TO IMPACT THE REGION
LATE IN THE FORECAST.
GFS DEVELOPS MEAGER CAPE THURS. - FRI., GIVING SOME CHANCE FOR
THUNDER WITH THE LATE-PERIOD FRONT; HOWEVER, IF THE EC IS CORRECT
WITH A STRONGER LOW AND AN OPEN GULF, BETTER INSTABILITY AND A
CHANCE FOR STRONGER STORMS COULD DEVELOP FOR FRIDAY.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: AN UPPER LOW SKIRTING BY THE REGION WILL
PROVIDE ENHANCED LAPSE RATES AND FORCING, GENERATING LIGHT SHOWERS
ACROSS THE PIEDMONT THIS AFTERNOON. SOME OF THESE SHRA WILL BRING
MVFR CIGS/VSBY. OCCASIONAL BRISK GUSTS COULD OCCUR IN THEIR VICINITY
AS WELL. THE POSSIBILITY OF LIGHT NONCONVECTIVE PRECIP WILL PERSIST
ACRS THE MOUNTAINS INTO TONIGHT. VERY HIGH ELEVATIONS WILL SEE
LIGHT SNOWFALL THIS AFTN/EVENING, BUT MOST LIKELY NOT REACHING
THE VALLEYS OR KAVL. CLOUDS WILL BECOME MORE SPARSE AFTER SUNSET
EAST OF THE MTNS. WHILE CONDITIONS WILL REMAIN VFR THEREAFTER,
SOME CONGESTED CUMULUS MAY REDEVELOP IN THE LATE MORNING TOMORROW,
ALBEIT WITH NEAR-ZERO CHANCE OF PRECIP. WINDS WILL REMAIN SW AND
SOMEWHAT GUSTY THIS AFTN, VEERING TO NW OVERNIGHT.
OUTLOOK: VFR CONDS ARE EXPECTED TO PREVAIL THRU EARLY NEXT WEEK.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 100% HIGH 99% HIGH 100% HIGH 100%
KGSP HIGH 93% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 85% HIGH 85% MED 69% HIGH 94%
KHKY HIGH 98% HIGH 99% HIGH 100% HIGH 100%
KGMU HIGH 90% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 89% 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:
WWW.WEATHER.GOV/GSP/AVIATION
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...DEO
NEAR TERM...WIMBERLEY
SHORT TERM...PM
LONG TERM...WJM
AVIATION...WIMBERLEY
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page