Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 220455
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1250 AM EDT TUE JUL 22 2014

.SYNOPSIS...AN UPPER LEVEL LOW PRESSURE SYSTEM WILL REMAIN OVER THE
GULF COAST STATES THROUGH MIDWEEK... RESULTING IN A MOIST FLOW OFF
THE ATLANTIC INTO NORTH CAROLINA. A COLD FRONT WILL APPROACH THE
REGION FROM THE NORTH LATE WEDNESDAY... THEN SETTLE SOUTHWARD
THROUGH NORTH CAROLINA ON THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 910 PM MONDAY...

ONLY ISOLATED SHOWERS REMAIN IN THE WELL TURNED OVER BOUNDARY LAYER.
ALTHOUGH IT CONTINUED TO BE EXTREMELY MOIST WITH DEW POINTS IN THE
70S... CONDITIONS HAD GREATLY STABILIZED BY EARLIER CONVECTION AND
THE ONSET OF CONVECTIVE INHIBITION. CONVECTION IS EXPECTED TO REMAIN
POSSIBLE... BUT MAINLY DIURNALLY DRIVEN - THEREFORE THE PREVIOUS
FORECAST OF ISOLATED TO SCATTERED SHOWERS OVERNIGHT WILL CONTINUE.
THE EASTERLY FLOW WILL ALSO CONTINUE TO ENSURE THAT THE DEW POINTS
REMAIN HIGH... WITH A HIGH LIKELIHOOD OF LOW STRATUS OVERNIGHT. LOWS
IN THE LOWER 70S.

&&

.SHORT TERM /TUESDAY THROUGH FRIDAY NIGHT/...
AS OF 305 PM MONDAY...

PRECIPITABLE WATER REMAINS HIGH AS WE KICK OFF THE DAY WITH IN-SITU
DAMMED AIRMASS ACROSS THE AREA. GUIDANCE HIGHS TOMORROW ON THE GFS
REACH THE LOW 90S...WHICH IS QUESTIONABLE GIVEN MORNING LOW
CLOUDINESS AND EAST TO NORTHEAST SURFACE FLOW. WILL TREND TOWARDS
MID 80S WITH MOSTLY CLOUDY SKIES. POP-WISE... THE UPPER LOW WILL
RETROGRADE BACK TO THE MISSISSIPPI DELTA AREA BY LATE
TUESDAY...MAINTAINING A CHANCE OF MAINLY DIURNAL
CONVECTION...ESPECIALLY IN THE SOUTHWEST. DEEPER RIDGING WILL
RETROGRADE INTO THE AREA TUESDAY NIGHT... VEERING THE LOW LEVEL
FLOW...WEAKENING THE ISENTROPIC LIFT TO ONLY SLIGHT CHANCE POPS.
WITH NO AIR MASS CHANGE...MINS AGAIN WILL BE AROUND 70.

AN UPPER LEVEL TROUGH WILL DIVE FROM THE WESTERN GREAT LAKES REGION
WEDNESDAY INTO THE SOUTHERN APPALACHIANS BY THURSDAY MORNING. THE
ASSOCIATED COLD FRONT WILL STAY WEST OF THE APPALACHIANS THROUGH
WEDNESDAY EVENING. THE AIR MASS ACROSS CENTRAL NC ON WEDNESDAY
AFTERNOON WILL BE WARM AND UNSTABLE WITH WEAK TO MODERATE
INSTABILITY VALUES OF AROUND 1000-2000 J/KG. THE AIR MASS WILL BE
MOIST WITH PRECIPITABLE WATER VALUES OF 1.75 TO 2.0 INCHES.
CONVECTIVE COVERAGE IS NOT EXPECTED TO BE OVERWHELMING AND LIKELY
MOST FOCUSED ACROSS THE COASTAL PLAIN...EAST OF THE PIEDMONT TROUGH
AND TO THE WEST ACROSS THE HIGHER TERRAIN. HIGH TEMPERATURES IN THE
88 TO 92 RANGE ARE SUPPORTED BY CONSENSUS THICKNESS VALUES AND IN
BETWEEN THE WARMER MAV AND COOLER MET GUIDANCE. SCATTERED CONVECTION
IS APT TO CONTINUE IN THE EARLY EVENING HOURS AND THEN BECOME
ISOLATED OVERNIGHT...AGAIN THE BEST COVERAGE IS EXPECTED ACROSS THE
COASTAL PLAIN AND PERHAPS MORE SO IN THE WESTERN PIEDMONT CLOSER TO
THE UPPER TROUGH AND AS CONVECTION INITIATED NEAR THE MOUNTAINS
MOVES EAST. OVERNIGHT LOWS SHOULD BE MODERATED BY CLOUD COVER AND
SOME MIXING AHEAD OF THE APPROACHING WITH LOWS IN THE LOWER 70S.

THE UPPER TROUGH REACHES THE SOUTHERN APPALACHIANS ON THURSDAY
MORNING AS THE COLD FRONT SLOWLY MOVES FROM THE FOOTHILLS INTO THE
PIEDMONT DURING THE MORNING AND AFTERNOON. THE AIR MASS ACROSS
CENTRAL NC IS POSSIBLY EVEN MORE MOIST THAN ON WEDNESDAY WITH
PRECIPITABLE WATER VALUES AROUND OR IN EXCESS OF 2 INCHES. EXPECT A
GOOD AMOUNT OF CLOUD COVER WHICH MAY LIMIT INSTABILITY A BIT. THE
APPROACHING TROUGH WILL RESULT IN STRONGER FLOW ALOFT AND BULK SHEAR
VALUES WILL INCREASE INTO THE 20-30 KTS RANGE AND SUPPORT MORE
CONVECTIVE STORM ORGANIZATION AND A SLIGHTLY ELEVATED SEVERE THREAT.
POPS HAVE BEEN INCREASED TO THE HIGH CHANCE CATEGORY. MAX TEMP
GUIDANCE IS EVEN WARMER COMPARED TO WEDNESDAY WITH THE WARMER MAV
GUIDANCE SUGGESTING S HIGHS IN THE 94-95 RANGE AT RDU AND FAY. NOT
READY TO GO THAT HIGH BUT WE HAVE INCREASED MAX TEMPS A BIT AND IF
CLOUDS COVER IS LESS THAN EXPECTED...WARMER TEMPERATURES AND
INCREASED INSTABILITY CAN BE EXPECTED. THE THUNDERSTORM THREAT
CONTINUES INTO THURSDAY EVENING WITH THE BEST COVERAGE IN THE EAST.
HIGHS THURSDAY SHOULD RANGE IN THE 88 TO 93 RANGE WITH LOWS IN THE
UPPER 60S TO LOWER 70S.

THE FRONT SLOWLY CLEARS CENTRAL NC FRIDAY AFTERNOON AND THEN STALLS
ALONG THE NC COAST AND EXTENDS BACK INTO CENTRAL SC BY LATE FRIDAY
NIGHT. A CONTINUED THREAT OF SHOWERS AND THUNDERSTORMS PERSISTS ON
FRIDAY WITH THE GREATEST CHANCES ACROSS THE COASTAL PLAIN. HIGHS
WILL BE NOTICEABLY COOLER THAN ON THURSDAY WITH FRIDAY MAXES IN THE
MID TO UPPER 80S. LOWS WILL RANGE IN THE MID 60S TO THE NORTHWEST
AND UPPER 60S TO THE SOUTHEAST. -BLAES

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 320 PM MONDAY...

THE COLD FRONT LINGERS SOUTH OF OUR AREA ON SATURDAY WITH HIGH
PRESSURE EXTENDING INTO THE REGION. SATURDAY SHOULD BE THE BETTER
DAY OF THE WEEKEND WITH A LIMITED THREAT OF CONVECTION...MAINLY
ACROSS THE SOUTHWESTERN PIEDMONT...SANDHILLS AND SOUTHERN COASTAL
PLAIN DURING THE TYPICAL AFTERNOON/EVENING PERIOD. ANOTHER UPPER
LEVEL TROUGH AND ASSOCIATED COLD FRONT APPROACHES ON SUNDAY AND
BRINGS AN INCREASED THREAT OF MAINLY AFTERNOON AND EVENING
THUNDERSTORMS. GUIDANCE DIFFERS ON MONDAY WITH THE ECMWF BRINGER THE
UPPER TROUGH THROUGH FASTER THAN THE GFS...FOR NOW WILL OPT FOR THE
DRIER ECMWF SOLUTION AND DECREASE POPS FOR MONDAY. TEMPERATURES
DURING THE LONG TERM RETURN TO MORE SEASONABLE VALUES WITH HIGHS IN
THE MID 80S TO AROUND 90 AND MORNING LOWS IN THE UPPER 60S TO LOW
70S. -BLAES

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1250 AM TUESDAY...

ABOVE-AVERAGE CONFIDENCE IN PREVAILING IFR TO LIFR CONDITIONS UNTIL
AROUND 12Z OR 13Z AT ALL TAF AIRFIELDS. CIGS AND VSBYS CURRENTLY SIT
AT VFR OR MVFR... BUT CIGS ARE EXPECTED TO DROP TO IFR/LIFR BY 07Z
OR 08Z... WITH MAINLY MVFR VSBYS. CIGS SHOULD RISE SLOWLY TO MVFR BY
15Z WITH VSBYS CLIMBING TO VFR... THEN MVFR CIGS SHOULD RISE TO VFR
BY 17Z OR 18Z. ISOLD SHOWERS THROUGH MID MORNING WILL LIKELY GIVE
WAY TO GREATER COVERAGE OF SHOWERS AND STORMS AS INSTABILITY
INCREASES WITH RISING AND DEEPENING MOISTURE... ALTHOUGH AS WAS THE
CASE YESTERDAY... THE DIFFICULTY LIES IN TRYING TO DETERMINE WHICH
SITE WILL SEE THE BEST CHANCE FOR SHOWERS/STORMS. IT LOOKS LIKE FAY
COULD SEE THE FIRST DEVELOPMENT OF SHOWERS/STORMS BY THE NOON
HOUR... WITH ACTIVITY THEN SPREADING TO THE NORTH AND NW TO THE REST
OF THE TAF SITES AND INCREASING IN COVERAGE THROUGH THE EARLY/MID
AFTERNOON. OVERALL COVERAGE SHOULD BE A LITTLE LESS THAN WE SAW
MONDAY. CIGS SHOULD HEAD BACK DOWN TO MVFR AFTER SUNDOWN.

LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING... WITH DEW POINTS STILL
HIGH... IFR CONDITIONS ARE LIKELY ONCE AGAIN AFTER 08Z AT ALL
SITES... LASTING THROUGH 13Z WED MORNING. THE FRONTAL ZONE ACROSS
ERN NC WILL HAVE DISSIPATED WITH SURFACE WINDS MAINLY FROM THE SW
WED AHEAD OF THE COLD FRONT APPROACHING FROM THE NORTH AND SLIGHTLY
DRIER AIR... SO CLOUD BASES SHOULD RISE TO VFR BY 15Z WED MORNING.
VFR CONDITIONS ARE LIKELY TO HOLD THROUGH FRONTAL PASSAGE ON THU
(ALTHOUGH SUB-VFR CONDITIONS WITHIN STORMS ARE POSSIBLE THU
AFTERNOON/EVENING). EXPECT VFR CONDITIONS TO LAST THROUGH SAT WITH
WEAK HIGH PRESSURE BUILDING IN. -GIH

&&

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

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...32
SHORT TERM...BLAES
LONG TERM...BLAES/DJF
AVIATION...HARTFIELD



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