Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 291045
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
645 AM EDT WED JUL 29 2015

.SYNOPSIS...
HIGH PRESSURE WILL PERSIST OVER THE REGION TODAY...WITH TEMPERATURES
REMAINING ABOVE NORMAL. A WEAK COLD FRONT WILL APPROACH THE AREA
FROM THE NORTHWEST ON THURSDAY AND SETTLE SOUTHEAST OF THE REGION ON
FRIDAY. THE FRONT AND ASSOCIATED DEEPER MOISTURE WILL LIKELY REMAIN
CONFINED TOWARD THE SOUTHEAST COASTLINE THROUGH THE WEEKEND...WITH
SLIGHTLY COOLER TEMPERATURES OVER THE WESTERN CAROLINAS AND
NORTHEAST GEORGIA. LOW LEVEL MOISTURE WILL SLOWLY RETURN EARLY NEXT
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 635 AM...I WILL UPDATE THE FORECAST TO FINE TUNE FOG MENTION
TO LATEST OBSERVATIONS. OTHERWISE...IT APPEAR THAT CLOUD COVER WILL
INCREASE STEADILY WITH THE FORMATION OF STRATUS OVER THE NEXT TWO
HOURS. I WILL UPDATE THE SKY FORECAST.

AS OF 325 AM...RECENT WATER VAPOR IMAGES INDICATED A LARGE MCS AND
VORT MAX TRACKING SE ACROSS THE CORN BELT. IN ADDITION...ANOTHER
DISTURBANCE WILL TRACKING ACROSS THE AL/TN STATE LINE. THESE
FEATURES SHOULD CONTINUE TO MOVE SSE...AROUND A LARGE MID LEVEL HIGH
CENTERED OVER THE SOUTHERN PLAINS. BASED ON THE MID LEVEL PATTERN
AND NEAR TERM GUIDANCE...THE SYSTEM TRACKING FROM THE NW MAY REACH
THE SOUTHERN APPALACHIAN REGION THIS EVENING. THE ENVIRONMENT ACROSS
THE WESTERN CAROLINAS AND NE GA WILL CHANGE LITTLE FROM TUESDAY
AFTERNOON. FORECAST SOUNDING INDICATE THAT CAPES SHOULD PEAK BETWEEN
1500-2000 J/KG...SHEAR WILL REMAIN WEAK...AND LLVL DEWPOINTS WILL
REMAIN IN THE U60S TO L70S. CAMS AND OPERATIONAL MODELS INDICATE
THAT CONVECTION WILL INITIATE ACROSS THE EAST FACING SLOPES EARLY
THIS AFTERNOON...THEN TRACK EAST. ADDITIONAL SHRA AND TSRA MAY
DEVELOP DURING THE EVENING HOURS AS THE MID LEVEL FEATURE APPROACHES
FROM THE NW. SPC DY 1 OUTLOOK KEEP THE CWA WITHIN THE GENERAL TSRA.
WE WILL HIGHLIGHT LIGHTNING...HEAVY DOWNPOURS...AND GUSTY WINDS IN
THE HWO. HIGH TEMPERATURES SHOULD RANGE WITHIN 1 TO 2 DEGREES FROM
VALUES OBSERVED YESTERDAY.

TONIGHT...CONVECTION SHOULD GENERALLY DISSIPATE AFTER MIDNIGHT. IT
APPEARS THAT WAVES OF HIGH/DEBRIS CLOUDS WILL REMAIN ACROSS THE
REGION THROUGH THE OVERNIGHT HOURS. I WILL FOLLOW THE TREND OF THE
PAST SEVERAL NIGHTS...INDICATING PARTLY CLOUDY SKY...LIGHT TO CALM
WIND...AND PATCHES OF FOG. LOWS ARE FORECAST TO RANGE FROM THE U60S
WITHIN THE MTN VALLEYS TO L70S EAST.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM EDT WEDNESDAY...THE BROAD RIDGE OF HIGH PRESSURE OVER
THE SOUTHERN CONUS EARLY THURSDAY WILL CONTINUE TO RETROGRADE
WESTWARD THROUGH THE SHORT TERM PERIOD. UPPER HEIGHTS WILL BEGIN TO
FALL OVER THE EAST ON THURSDAY...ALLOWING A COLD FRONT TO ARRIVE
FROM THE NORTHWEST. DEEPER MOISTURE ALONG THE IMMEDIATE FRONTAL ZONE
WILL SLIDE INTO THE NC MTNS FROM 12Z TO 18Z...WITH THE BOUNDARY
ENCOUNTERING ADDITIONAL INSTABILITY AND LOW LEVEL DCAPE EAST OF THE
MOUTAINS THROUGH THURSDAY AFTERNOON AND EVENING. HOWEVER...FRONTAL
ZONE FORCING WILL BATTLE DRIER AIR ARRIVING FROM THE NW TO LIMIT
COVERAGE SOMEWHAT. WILL STILL FEATURE SOLID CHANCE POPS FOR
CONVECTION GIVEN THE STEEPENING LAPSE RATES ALOFT. EXPECT ONE MORE
DAY OF ABOVE CLIMO MAXES AHEAD OF THE FRONTAL ZONE.

A SHARPENING UPPER TROUGH WILL THEN DEVELOP SWD FROM A HUDSON BAY
CANADA CYCLONE INTO THE SOUTHEAST U.S. BY FRIDAY. MUCH DRIER AIR
WILL ALSO START TO ARRIVE FROM THE N AS SFC HIGH PRESSURE MOVES EAST
FROM THE LOWER OH VALLEY. TEMPERATURES WILL FALL CLOSER TO
CLIMO...WITH ISOLD SHOWER CHANCES MAINLY OVER THE SOUTHEAST PART OF
THE AREA.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM EDT WEDNESDAY...A WESTERN RIDGE/EASTERN TROUGH PATTERN
WILL REMAIN IN PLACE DURING THE SATURDAY THROUGH TUESDAY PERIOD.
MOISTURE WILL REMAIN FOCUSED MAINLY ALONG THE FRONT TO THE
SOUTHEAST...WITH THE NUMERICAL MODELS TRENDING TOWARD CONFINING THE
DEEPEST MOISTURE TO THE IMMEDIATE SOUTHEAST COASTLINE THROUGH THE
WEEKEND. A WEAKLY REINFORCING COLD FRONT WILL APPROACH FROM THE NW
SATURDAY NIGHT...BUT LIKELY STALL OR DISSIPATE JUST AS IT REACHES
THE FORECAST AREA. MEANWHILE...NUMEROUS SHORTWAVES WILL MOVE THROUGH
THE MEAN TROUGH DURING THE PERIOD. THESE WILL BE HARD TO TIME AND
GENERALLY HAVE LIMITED MOISTURE TO WORK WITH. WILL FEATURE A MOSTLY
DIURNAL TREND ON ANY LOW END AFTN/EVENING POPS EACH DAY. STEEP 850
TO 500 MB LAPSE RATES LINGER OVER THE AREA UNDER THE TROUGH
AXIS...BUT WITH SURPRISINGLY LITTLE CAPE KEEPING ANY CONVECTION
FAIRLY SHALLOW. TEMPERATURES WILL BE COOLER THROUGH THE
WEEKEND BEFORE SLOWLY REBOUNDING EARLY NEXT WEEK.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...WET GROUND AND NEARLY SATURATED BL CONDITIONS ARE
WIDESPREAD ACROSS THE NC PIEDMONT THIS MORNING. SIMILAR TO
TUESDAY...EARLY MORNING HEATING SHOULD RESULT IN MVFR CEILINGS
THROUGH LATE MORNING. A SWEEPING MID LEVEL SHORTWAVE WILL APPROACH
THE REGION THIS AFTERNOON AND EVENING...LIKELY TRIGGERING CLUSTERS
OF TSRA. USING THE EXAMPLE FROM TUESDAY...I WILL INCLUDE A TEMPO FOR
TSRA FROM 19Z THROUGH 23Z. WINDS SHOULD FAVOR A SOUTH DIRECTION
THROUGH THE DAYLIGHT HOURS...LIKELY REMAINING LESS THAN 5 KTS.
BKN050 TO 060 CLOUDS ARE FORECAST TO PERSIST THROUGH THE OVERNIGHT
HOURS.

ELSEWHERE...OVERALL CONDITIONS SHOULD FOLLOW THE TIMING OF CLT. KAVL
AND KHKY SHOULD SEE THE GREATEST POTENTIAL FOR FOG AND LOW CLOUDS
EARLY THIS MORNING. KGMU AND KGSP MAY SEE PERIOD OF LIFR/IFR
CEILINGS THROUGH 14Z. OTHERWISE...THE ENVIRONMENT SHOULD YIELD
MORNING MVFR STRATUS...MIXING TO VFR CU BY MID DAY.  A SWEEPING MID
LEVEL SHORTWAVE WILL APPROACH THE REGION THIS AFTERNOON...LIKELY
TRIGGERING CLUSTERS OF TSRA. USING THE EXAMPLE FROM TUESDAY...I WILL
INCLUDE EITHER A TEMPO OR PROB30 FOR TSRA FROM 19Z THROUGH 23Z.

OUTLOOK...AN UPPER LEVEL TROUGH WILL AMPLIFY ACROSS THE ATLANTIC
STATES LATE IN THE WEEK...WITH THE LIKELY PASSAGE OF A COLD FRONT ON
FRIDAY. THE POTENTIAL FOR CONVECTION WILL INCREASE THROUGH
FRIDAY...THEN DECREASE BEHIND THE FRONT ON SATURDAY.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       HIGH  87%     HIGH  97%     HIGH 100%     HIGH 100%
KGSP       LOW   43%     HIGH  97%     HIGH 100%     HIGH 100%
KAVL       MED   61%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH  86%     HIGH  94%     HIGH 100%     HIGH 100%
KGMU       LOW   54%     HIGH  84%     HIGH 100%     HIGH 100%
KAND       MED   70%     HIGH  81%     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...HG
NEAR TERM...NED
SHORT TERM...HG
LONG TERM...HG
AVIATION...NED



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