Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 220700
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
300 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 230 AM TUESDAY...

FOR TODAY/TONIGHT: WE ANTICIPATE ANOTHER ROUND OF DECENT
SHOWER/STORM COVERAGE WITHIN A MOIST AND VOLATILE AIR MASS... WITH
ONCE AGAIN THE POTENTIAL FOR POCKETS OF HEAVY RAIN. LATEST SURFACE
MAP SHOWS THE FRONTAL ZONE WINDING AROUND THE INTERIOR SOUTHEAST
STATES AND ACROSS COASTAL NC... LEADING TO A VERY LIGHT FLOW FROM
THE NE OR E INTO NC. THIS WILL KEEP LOW LEVEL ATLANTIC-SOURCE
MOISTURE PUMPING INTO THE AREA... AND ALOFT AS WELL AS THE DAMP
SURGE EAST AND NORTH OF THE GULF COAST LOW IS EASILY SEEN ON WATER
VAPOR IMAGERY... DRAWING IN DEEPER MOISTURE OFF FL AND THE BAHAMAS.
GOES SOUNDER PW VALUES ARE WIDESPREAD 2.0-2.5 OVER NC (HIGHEST
ACROSS SRN NC)... AND WHILE THE BLENDED TPW AND GSO UA VALUES ARE A
BIT LOWER THEY`RE STILL 120-150% OF NORMAL. MODELS SHOW THE HIGHER
PW CONTINUE TO SURGE TO THE WNW INTO CENTRAL NC ON THE CYCLONIC MID
LEVEL FLOW FROM THE SE AND E TODAY. IT IS POSSIBLE THAT THE BEST
COVERAGE COULD HOLD OVER ERN NC AS MODELS INDICATE THAT THE MAXIMUM
LOW LEVEL MOISTURE TRANSPORT WILL HOLD EAST OF THE FORECAST AREA
TODAY... ALONG AND EAST OF THE STATIONARY FRONTAL ZONE. BUT THIS
FRONTAL ZONE SHOULD DISSIPATE TODAY IN FAVOR OF A PIEDMONT TROUGH AS
THE OFFSHORE RIDGE BECOMES A BIT MORE DOMINANT WITH THE WESTWARD
NUDGE OF THE GULF UPPER LOW... AND FORECAST SOUNDINGS SHOW A DEEP
LCL-0C LAYER SUPPORTING WARM RAIN PROCESSES AND HIGH PRECIP
EFFICIENCY. WILL TAKE POPS UP TO 50-60%... SPREADING INTO THE SOUTH
FIRST THEN TOWARD THE NNW. COVERAGE SHOULD TAPER DOWN FAIRLY QUICKLY
TO ISOLATED DURING THE MID-LATE EVENING AS LOW LEVEL FLOW TAKES ON A
GREATER WESTERLY COMPONENT. WILL MAINTAIN A THREAT OF LOCALLY HEAVY
DOWNPOURS AND ISOLATED FLOODING CONCERNS IN THE HAZARDOUS WEATHER
OUTLOOK... GIVEN THE HIGH-PW AND HIGH PRECIP EFFICIENCY COUPLED WITH
THE ALREADY-WET GROUND MOST PLACES. MBE MOVEMENT SHOULD BE A BIT
GREATER THAN MONDAY... BUT WITH WEAK LOW-MID LEVEL WINDS... SOME
SLOWER CONVECTIVE CLUSTERS COULD STILL DROP HIGH RAIN TOTALS.
HOWEVER... OVERALL LOW COVERAGE OF THESE HIGHER TOTALS HOWEVER
PRECLUDE ISSUING A FLASH FLOOD WATCH AT THIS TIME. HIGHS 83-88. LOWS
TONIGHT 71-75 WITH MORE FOG/STRATUS DEVELOPMENT LATE. -GIH

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 240 AM TUESDAY...

FOR WED/WED NIGHT: THE SURFACE PATTERN WILL FEATURE A PIEDMONT
TROUGH AHEAD OF THE COLD FRONT PUSHING TOWARD THE SSE OVER THE OH
VALLEY... AS 850 MB FLOW BECOMES MAINLY WESTERLY. WE`LL SEE
IMPROVING DEEP LAYER SHEAR AS THE BROAD TROUGH DIGS OVER ERN
CANADA/THE GREAT LAKES/NORTHEAST WITH THE WESTERLIES INCHING
SOUTHWARD TOWARD NC... PROMPTING DECENT HEIGHT FALLS ALOFT OF 20-50
M. EXPECT REDUCED CLOUDINESS ON WED AS WE LOSE THE TAP OF DEEPER
BAHAMIAN MOISTURE WITH MID LEVELS EXHIBITING MINOR DRYING... AND
THIS SHOULD NOT ONLY PUSH UP TEMPS (THICKNESSES ARE PROJECTED TO BE
5-8 M HIGHER WED THAN TODAY) BUT SHOULD ALSO PUSH UP INSTABILITY...
AND THE SREF MEAN MLCAPE WED IS 1500-2000 J/KG ACROSS THE AREA. DEEP
LAYER SHEAR REMAINS MODEST HOWEVER... JUST AROUND 15-20 KTS AT
MOST... BUT NEVERTHELESS EXPECT A BIT MORE ORGANIZED SCATTERED
STORMS TO DEVELOP. WILL KEEP POPS AS CHANCE... FOCUSED ON THE
AFTERNOON/EVENING. HIGHS 89-93. STICKY LOWS OF 71-75 WED NIGHT...
WITH A CONTINUED THREAT OF ISOLATED SHOWERS/STORMS AS WE MAINTAIN
MARGINAL TO MODERATE INSTABILITY AHEAD OF THE FRONT. -GIH

THURSDAY AND THURSDAY NIGHT: AN UPPER LEVEL TROUGH WILL MOVE OVER
CENTRAL NC FROM THE WEST AND STALL OVER THE CAROLINAS. THE INITIAL
SURFACE FRONT WILL MOVE THROUGH MUCH OF CENTRAL NC THURSDAY AND
THURSDAY NIGHT. THE 00Z GFS INDICATES NC WILL BE SITUATED UNDER THE
RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET AND FORECASTS MID LEVEL
LAPSE RATES OF 6-6.5 C/KM. THE BEST INSTABILITY ON THURSDAY WILL BE
ALONG AND EAST OF THE FRONT...WITH MUCAPE AND MLCAPE VALUES FORECAST
FROM 1000 J/KG IN THE NW TO 2500 J/KG ALONG THE NC COAST. BULK SHEAR
IS ALSO FORECAST TO BE DESCENT TO GOOD...ESPECIALLY ALONG THE EAST
AND SE...WITH VALUES OF 25 TO 35 KTS...SUPPORTING MORE ORGANIZED
CONVECTION AND INCREASING POTENTIAL FOR STORM TO BECOME SEVERE...
ALTHOUGH THE LOW LEVEL SHEAR VALUES WILL BE RELATIVELY WEAK. THUS...
EXPECT THE MAIN SEVERE THREATS TO BE DAMAGING WINDS AND HAIL. HEAVY
RAIN WILL ALSO BE A THREAT ON THURSDAY GIVEN THE PWAT VALUES AROUND
2 INCHES. EXPECT HIGHS IN THE UPPER 80S NW TO LOW 90S SE AND
OVERNIGHT LOWS IN THE MID 60S TO LOW 70S. -KC

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 240 AM TUESDAY...

FRIDAY AND FRIDAY NIGHT: THE INITIAL SURFACE FRONT WILL MOVE THROUGH
MUCH OF CENTRAL NC THURSDAY AND THURSDAY NIGHT...WITH WINDS VEERING
AROUND TO THE NORTHWEST AND COOL HIGH PRESSURE BUILDING IN BEHIND IT
FOR FRIDAY. IT IS STILL UNCERTAIN HOW FAR THE COOLER AIR WILL MAKE
IT INTO THE AREA AS WEAK LOW PRESSURE IS EXPECTED TO SIT ALONG THE
CAROLINA COAST FRIDAY AND FRIDAY NIGHT. REGARDLESS...HIGHS ON FRIDAY
SHOULD BE 3-5 DEGREES COOLER THAN THURSDAY...MID TO UPPER 80. LOWS
IN THE MID 60S TO AROUND 70 DEGREES. GIVEN THE LINGERING SFC LOW
ALONG THE COAST AND THE FRONT STALLING IN THE VICINITY OF NC/VA...
THERE WILL BE THE CHANCE FOR ADDITIONAL SHOWERS AND STORMS ON FRIDAY
ACROSS THE SOUTHEAST. PWATS WILL DECREASE SIGNIFICANTLY THROUGHOUT
THE DAY FRIDAY...DOWN TO AROUND 1.00 TO 1.20 INCHES FRIDAY NIGHT AS
MID LEVEL DRY AIR IS ADVECTED INTO THE REGION.

SATURDAY THROUGH MONDAY: ALTHOUGH THERE MAY BE A LINGERING CHANCE
FOR SOME CONVECTION IN THE EAST SATURDAY WITH A SURFACE TROUGH
LINGERING ALONG THE CAROLINA COAST...EXPECT MAINLY DRY WEATHER FOR
MUCH OF THE AREA AS THE UPPER LEVEL TROUGH SHIFTS OFFSHORE. HIGHS
WILL BE GENERALLY IN THE UPPER 80S AND LOWS IN THE UPPER 60S TO LOW
70S. A SERIES OF UPPER LEVEL DISTURBANCES WILL APPROACH CENTRAL NC
FROM THE NW ON SUNDAY AND MONDAY. MEANWHILE...THE SURFACE TROUGH
WILL LINGER ALONG THE COAST AS A LOW DEEPENS OVER THE GREAT LAKES
EARLY NEXT WEEK AND ITS ASSOCIATED FRONT APPROACHES THE REGION FROM
THE OH/TN VALLEYS. THEREFORE...EXPECT CHANCES FOR AFT/EVE SHOWERS
AND STORMS WITH HIGHS GENERALLY IN THE UPPER 80S TO LOW 90S AND LOWS
IN THE MID 60S TO LOW 70S.

&&

.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...HARTFIELD
SHORT TERM...HARTFIELD/KC
LONG TERM...KC
AVIATION...HARTFIELD



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