Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KRAH 210801
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
400 AM EDT THU MAY 21 2015

.SYNOPSIS...LOW PRESSURE WILL TRACK EAST ALONG A QUASI-STATIONARY
FRONT OVER NC TODAY. WEAK HIGH PRESSURE WILL FOLLOW FOR TONIGHT AND
FRI.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 345 PM WEDNESDAY...

OVERVIEW: MINOR SHORTWAVE ENERGY TRACKING INTO CENTRAL NC FROM THE
WEST LATE TONIGHT WILL PROGRESS EAST TO THE NC/VA COAST BY 18Z THU
AFTERNOON AND OFFSHORE SHORTLY THEREAFTER. MEANWHILE...POTENT
SHORTWAVE ENERGY DIGGING INTO THE UPPER MS RIVER VALLEY TONIGHT WILL
TRACK INTO THE OH VALLEY DURING THE DAY THU...PROGRESSING TO THE MID-
ATLANTIC COAST THU NIGHT. A SFC LOW CENTERED IN VICINITY OF
CHARLOTTE AT 12Z THU WILL TRACK EAST ALONG A NORTHWARD MOVING WARM
FRONT (FRONT WILL STALL NEAR THE HWY 64 CORRIDOR)...PROGRESSING TO
KINSTON/KENANSVILLE BY 18Z AND OFFSHORE BY 00Z...THOUGH A WEAK SFC
TROUGH WILL LIKELY PERSIST OVER CENTRAL NC IN RESPONSE TO HEIGHT
FALLS ATTENDANT POTENT SHORTWAVE ENERGY TRACKING EASTWARD THROUGH
THE OH VALLEY INTO THE MID-ATLANTIC.

MORNING: PRECIPITATION ASSOC/W WARM ADVECTION AND ELEVATED
INSTABILITY ON THE EASTERN PERIPHERY OF THE SFC-H85 LOW THU MORNING
WILL LIFT NORTHWARD INTO VA BY 15-18Z. ELEVATED SHOWERS MAY PERSIST
ACROSS THE NORTHERN PIEDMONT AND NE COASTAL PLAIN IN VICINITY OF THE
VA BORDER EARLY THU AFTERNOON...HOWEVER...WIDESPREAD ELEVATED
CONVECTION WILL LIFT NORTHWARD THROUGH CENTRAL VA TO THE DELMARVA
COAST BY MID AFTERNOON...IN CONCERT WITH THE BEST WARM ADVECTION AND
IN CLOSER VICINITY TO STRONGER DPVA/HEIGHT FALLS ASSOC/W SHORTWAVE
ENERGY TRACKING EASTWARD THROUGH THE OH VALLEY.

AFTERNOON: PRIMARY FCST PROBLEM REVOLVES AROUND WHETHER OR NOT
CONVECTION WILL RE-DEVELOP THU AFTERNOON...AND IF SO...COVERAGE/
INTENSITY...IN ADDITION TO HIGH TEMPS. RICH LOW-LEVEL MOISTURE WILL
ADVECT NORTHWARD INTO CENTRAL NC ALONG THE EASTERN PERIPHERY OF THE
SFC LOW THU AFTERNOON AS THE BOUNDARY STALLED TO THE SOUTH LIFTS
NORTHWARD TO THE HWY 64 CORRIDOR AS A WARM FRONT...PARTICULARLY IN
THE SANDHILLS AND SE COASTAL PLAIN WHERE DEWPOINTS WILL APPROACH
UPPER 60S TO NEAR 70F AND FCST SOUNDINGS SUGGEST MODERATE DIURNAL
DESTABILIZATION. WITH DPVA EXITING BY EARLY AFTERNOON AND ADDITIONAL
SHORTWAVE ENERGY TOO FAR REMOVED FROM CENTRAL NC (OH VALLEY)...
FORCING FOR ASCENT WILL LARGELY BE CONFINED TO LOW-LEVEL CONVERGENCE
INVOF THE SFC LOW TRACKING EAST ALONG OR JUST SOUTH OF THE HWY 64
CORRIDOR. THOUGH WEAK/SHALLOW LOW-LEVEL CONVERGENCE ATTENDANT SFC
TROUGHING WILL PERSIST THROUGH THE AFTERNOON...12Z GUIDANCE SUGGESTS
THE BEST LOW-LEVEL CONVERGENCE (CENTER OF SFC LOW) WILL PROGRESS
EAST OF THE I-95 CORRIDOR PRIOR TO PEAK HEATING (~18Z).
FURTHERMORE...FCST SOUNDINGS INDICATE SIGNIFICANT DRYING AOA 700 MB
FROM WEST-EAST THU AFTERNOON. GIVEN A TEMPORAL DISCONNECT BETWEEN
THE BEST LOW-LEVEL FORCING/ DIURNAL DESTABILIZATION AND THE PRESENCE
OF AN INCREASINGLY HOSTILE THERMODYNAMIC ENVIRONMENT (ENTRAINMENT OF
DRY AIR AOA 700 MB)... IT IS POSSIBLE THAT AFTERNOON DEVELOPMENT
WILL BE LIMITED TO SCATTERED SHOWER ACTIVITY OR POSSIBLY PRECLUDED
ALTOGETHER. HOWEVER... UNCERTAINTY PERSISTS WITH REGARD TO THE
PRECISE EVOLUTION OF THE APPROACHING SHORTWAVE/ATTENDANT SFC-
LOW...AND A NARROW TEMPORAL/ SPATIAL WINDOW FAVORING THE DEVELOPMENT
OF DEEP CONVECTION CANNOT BE ENTIRELY RULED OUT BETWEEN ~18-21Z IN
THE SE COASTAL PLAIN. DEEP LAYER SHEAR WOULD BE SUFFICIENT FOR
SUPERCELLULAR ORGANIZATION AND AN ATTENDANT POTENTIAL FOR SEVERE
WIND/HAIL...SHOULD DEEP CONVECTION DEVELOP. WITH THE ABOVE IN
MIND...OVERALL SVR THREAT (AND ANY TOR POTENTIAL) IS EXPECTED TO BE
CONFINED TO COASTAL NC WHERE SFC-BASED CONVECTION IS MOST LIKELY TO
OCCUR AND WHERE LOW-LEVEL SHEAR WILL BE MOST FAVORABLE ON THE
EASTERN PERIPHERY OF THE SFC-H85 LOW. EXPECT HIGHS RANGING FROM THE
LOWER/MID 70S N/NW TO MID 80S SE.

THURSDAY NIGHT: EXPECT CLEARING SKIES AS A DRIER AIRMASS ADVECTS
INTO THE REGION IN THE WAKE OF THE DEPARTING LOW. LOWS IN THE LOWER
50S.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 355 AM THURSDAY...

A TROUGH ALOFT WILL AMPLIFY ACROSS THE NORTHEAST AND MIDDLE ATLANTIC
STATES FRI...THEN OFFSHORE FRI NIGHT. DESPITE THE AMPLIFICATION OF
THE TROUGH...HEIGHT RISES ALOFT AND ASSOCIATED SUBSIDENCE WILL BE
UNDERWAY OVER VA AND THE CAROLINAS...IN THE WAKE OF A LEAD SHORTWAVE
TROUGH FORECAST TO CROSS THE MIDDLE ATLANTIC STATES TONIGHT. SURFACE
HIGH PRESSURE WILL CONSEQUENTLY BUILD EAST FROM THE TN VALLEY ON FRI
IN ASSOCIATION WITH THE LEAD MIDDLE ATLANTIC SHORTWAVE TROUGH...
FOLLOWED BY THE PASSAGE OF A DRY COLD FRONT RESULTING FROM THE
LARGER SCALE TROUGH AMPLIFICATION OVER THE NORTHEAST. TEMPERATURES
WILL BE IN THE 70S ON FRI...WITH LOWER HUMIDITY VALUES OWING TO
SURFACE DEWPOINTS IN THE 40S. TEMPERATURES FRI NIGHT WILL LIKELY
VARY WILDLY...WITH PE-FRONTAL RADIATIONAL COOLING INITIALLY; THEN
MIXING AND ASSOCIATED WARMING WITH FROPA; AND ENDING WITH CAA
LATE...WITH LOWS BY THE END OF THE NIGHT IN THE 50S.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 220 AM THURSDAY...

SATURDAY THROUGH WEDNESDAY: VERY LITTLE SIGNIFICANT WEATHER IS
EXPECTED DURING THE LONG TERM PERIOD WITH HIGH PRESSURE DOMINATING
THE PATTERN FOR MUCH OF THE PERIOD. INITIALLY...SURFACE HIGH
PRESSURE WILL BE TO THE NORTH OF THE AREA BRINING COOLER
NORTHEASTERLY FLOW TO CENTRAL NC FOR SATURDAY BEFORE THE HIGH SLIDES
OFFSHORE AND SETS UP EAST OF THE AREA. THIS WILL SHIFT WINDS TO
SOUTHERLY (ALTHOUGH LIGHT) AND BEGIN A WARMING TREND THAT WILL
CONTINUE THROUGH WEDNESDAY. INITIALLY...EXPECT TEMPERATURES IN THE
UPPER 70S TO NEAR 80 DEGREES ON SATURDAY BUT STEADILY RISING A FEW
DEGREES EACH DAY UP TO NEAR 90 DEGREES BY WEDNESDAY AFTERNOON. LOWS
WILL FOLLOW A SIMILAR PATTERN...RISING A COUPLE DEGREES EACH DAY
FROM THE UPPER 50S ON SATURDAY NIGHT UP TO THE UPPER 60S BY TUESDAY
NIGHT/WEDNESDAY MORNING.

MUCH OF THE PERIOD LOOKS DRY AS HIGH PRESSURE KEEPS MUCH OF THE
PRECIPITATION THREAT WELL AWAY FROM THE AREA. LATE IN THE PERIOD...A
FRONTAL SYSTEM WILL APPROACH FROM THE WEST AND THERE IS A LITTLE
DISCREPANCY ON TIMING BUT MODELS THIS MORNING LOOK TO HOLD OFF
PRECIPITATION WITH THIS FRONT A LITTLE LONGER THAN THE
PREVIOUS DAYS RUNS AND THEREFORE HAVE CUT BACK POPS ON TUESDAY AND
WEDNESDAY...INTRODUCING A SLIGHT CHANCE IN THE WEST ON TUESDAY
AFTERNOON AND THEN CHANCE IN THE WEST...SLIGHT CHANCE IN THE EAST ON
WEDNESDAY AFTERNOON.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 230 AM THURSDAY...

A WARM FRONT AND ASSOCIATED LIFT AND FOCUS FOR THE DEVELOPMENT OF
BOTH MVFR-IFR CEILINGS AND SCATTERED ELEVATED SHOWERS/STORMS WILL
CONTINUE TO RETREAT NORTH INTO CENTRAL NC THIS MORNING...WITH THE
RELATIVE BEST CHANCE OF SHOWERS AND STORMS AT GSO/INT/RDU THROUGH
15Z. A WAVE OF LOW PRESSURE WILL TRACK EAST ALONG THE FRONT...WHICH
IS EXPECTED TO STALL IN THE VICINITY OF A LINE FROM NEAR RDU TO RWI.
THE LOW PRESSURE WILL BE ACCOMPANIED BY A BAND OF THUNDERSTORMS THAT
WILL LIKELY DEVELOP NEAR THE TRIAD TERMINALS BETWEEN 15-17Z AND GAIN
STRENGTH AS IT MOVES EAST INTO AN INCREASINGLY UNSTABLE AIR MASS
DOWNSTREAM...PARTICULARLY SOUTH OF THE WARM FRONT -AT FAY- WHERE
DESTABILIZATION WILL BE MAXIMIZED. OTHERWISE...THE FRONT WILL ALSO
SERVE AS THE BOUNDARY BETWEEN CONTINUED MVFR-IFR CEILINGS TO THE
NORTH AND VFR CEILINGS AND A GUSTY S TO SW SURFACE WIND TO THE
SOUTH. WHILE THE ASSOCIATED SUB-VFR CEILINGS MAY LINGER AT NORTHERN
TAF SITES INTO HE AFTERNOON...OR EVENING EARLY EVENING AT
RWI...DRIER AIR WILL EVENTUALLY SETTLE SOUTH INTO OUR AREA IN THE
WAKE OF THE PASSING LOW PRESSURE SYSTEM...WITH AN ASSOCIATED RETURN
TO VFR CONDITIONS FOR TONIGHT.

OUTLOOK: VFR...UNDER THE INFLUENCE OF HIGH PRESSURE.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...26
NEAR TERM...BRV
SHORT TERM...26
LONG TERM...ELLIS
AVIATION...26



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.