Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 080137
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
937 PM EDT TUE JUL 7 2015

.SYNOPSIS... A RIDGE OF HIGH PRESSURE WILL GRADUALLY BUILD OVER THE
SOUTHEAST AND STRENGTHEN THROUGH THE REMAINDER OF THE WORK WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 PM TUESDAY...

CONVECTION WAS VERY ISOLATED THIS AFTERNOON/EVENING AS VERY LITTLE
IN THE WAY OF FORCING WAS/IS PRESENT OVER THE REGION. THE LITTLE BIT
OF CONVECTION THAT DID DEVELOP EARLIER...QUICKLY DISSIPATED WITH THE
LOSS OF DAYTIME HEATING. OVERALL...DRY CONDITIONS AND MOSTLY CLEAR
SKIES ARE EXPECTED OVERNIGHT...AS A WEAK SHEAR AXIS SLOWLY EXITS THE
REGION TO THE EAST AND A MID LEVEL RIDGE SLOWLY STARTS TO BUILD
TOWARDS THE AREA. OVERNIGHT LOWS WILL CONTINUE TO BE SIMILAR TO
PREVIOUS NIGHTS...GENERALLY UPPER 60S TO LOWER 70S.

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 235 PM TUESDAY...

THE SUBTROPICAL RIDGE WILL STRENGTHEN DURING THE PERIOD WITH RISING
HEIGHTS AND THICKNESSES. A SHORTWAVE TROUGH IN THE GREAT LAKES EARLY
WEDNESDAY SHEARS NORTHEAST ATOP THE RIDGE ON WEDNESDAY. THE
ASSOCIATED COLD FRONT SETTLES NORTH OF OUR AREA IN AN EAST TO WEST
AXIS ACROSS THE MID ATLANTIC AND OHIO VALLEY. WITH THE UPPER FLOW
PARALLEL TO THE FRONTAL POSITION IS UNLIKELY TO MAKE MUCH
SOUTHWARD PROGRESS. A SERIES OF UPPER-LEVEL DISTURBANCES IS PROGGED
TO RIDE AROUND THE RIDGE IN PROXIMITY OF THE FRONT ON WEDNESDAY INTO
THURSDAY ENHANCING AREA OF CONVECTION TO OUR NORTHWEST AND NORTH.

THE AIR MASS ACROSS CENTRAL NC WILL BE SLIGHTLY MORE UNSTABLE THAN
PREVIOUS DAYS...ESPECIALLY IN THE EASTERN PIEDMONT AND SANDHILLS.
PRECIPITABLE WATER VALUES ALSO REBOUND AND RANGE BETWEEN 1.6 AND 1.9
INCHES BY LATE WEDNESDAY. THE RESULT WILL BE AN AIRMASS MORE
THERMODYNAMICALLY FAVORABLE FOR CONVECTION BUT STILL LACKING A WELL
DEFINED TRIGGER. CONVECTION WILL LIKELY INITIATE IN LOCALIZED
CONVERGENCE FROM DIFFERENTIAL HEATING AND NEAR THE SEABREEZE IN THE
EARLY TO MID AFTERNOON. MOST CONVECTION ALLOWING MODELS CONTINUE
SUGGEST THAT CONVECTION THAT ORIGINATES IN THE MOUNTAINS MAY
ORGANIZE INTO A BROKEN OUTFLOW DOMINATED CONVECTIVE LINE THAT MOVES
INTO CENTRAL NC VERY LATE IN THE AFTERNOON AND EVENING. BULK SHEAR
VALUES ARE PROGGED TO BE WEAK...LIKELY RANGING BETWEEN 10 AND 15 KTS
INDICATIVE OF POOR STORM ORGANIZATION AND LIMITED SEVERE WEATHER
THREAT. STILL...WE HAVE ADJUSTED POPS UPWARD SLIGHTLY AND ATTEMPTED
TO INCLUDE THE ABOVE STORM MORPHOLOGY IN THE POP GRIDS. HIGHS WILL
RANGE BETWEEN 89 IN THE TRIAD TO 95 IN THE SANDHILLS. LOWS WILL
RANGE BETWEEN 68 AND 73. -BLAES
&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS OF 155 PM TUESDAY...

ON THURSDAY...THE SUBTROPICAL RIDGE RETROGRADING ACROSS THE
SOUTHEAST WILL SUPPRESS THE WESTERLIES WELL NORTH OF THE
AREA...LEAVING US ONLY A SLIGHT CHANCE OF CONVECTION ACROSS THE
NORTHERN TIER COUNTIES. HIGHS ARE STILL ON TRACK FOR LOW AND MID 90S
WITH STRONG INSOLATION. AMPLIFICATION OF THE UPPER RIDGE INTO THE
MIDWEST WILL TIP THE FLOW NORTHWESTERLY ON FRIDAY...PROVIDING
FAVORABLE STEERING FLOW FOR ADVECTION OF UPSTREAM CONVECTION ACROSS
THE OHIO VALLEY INTO THE NORTHERN TIER COUNTIES...WITH SLIGHTLY
BETTER CHANCES (ALBEIT STILL A CLIMATOLOGICAL 30 PERCENT) IN THE
NORTHEAST PIEDMONT AND NORTHERN COASTAL PLAIN. NO CHANGE OF
AIRMASS...BUT INCREASED DEBRIS CLOUDINESS IN THE NORTHWEST FLOW
ACROSS THE NORTHERN TIER COULD NIP A COUPLE OF DEGREES OFF THE
AFTERNOON HIGH...WILL MAINTAIN A FORECAST OF AROUND 90 NORTH TO 96
SOUTH.

RIDGE CONTINUES TO BUILD IN THE MIDWEST OVER THE WEEKEND...RESULTING
IN STRONGER NORTHWEST FLOW. THIS WILL MAINTAIN A POP GRADIENT
FAVORING THE NORTHEAST...WHILE THE SOUTHWEST PIEDMONT COULD BE DRY
THROUGH TUESDAY. IN ADDITION...THE CHANCE FOR NON-DIURNAL CONVECTION
WILL BE INCREASING DUE TO THE POTENTIAL FOR IMPULSES ORIGINATING
FROM DIURNALLY ENHANCED MCS ACTIVITY OVER THE OHIO VALLEY TO MOVE
INTO THE AREA OVERNIGHT. IT IS DIFFICULT TO PINPOINT A MORE
FAVORABLE TIME SLOT FOR INCREASED CONVECTIVE ACTIVITY AT THIS POINT
GIVEN LOW CONFIDENCE IN FORECASTING UPSTREAM MESOSCALE
FEATURES...THUS WILL MAINTAIN NEAR CLIMATOLOGICAL POPS FOR THE
MEANTIME. SIMILARLY...HIGHS EACH DAY WILL BE PERSISTENCE BARRING
DEBRIS CLOUDINESS AND EARLY DAY CONVECTION...IN THE LOW TO MID
90S...WITH SOME UPPER 90S POSSIBLE IN THE SOUTH.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AS OF 708 PM TUESDAY...

LOSS OF DAYTIME HEATING HAS BROUGHT AN ABRUPT END TO THE ISOLATED
SHOWERS AND STORMS. FCST SOUNDINGS MOS STATISTICAL GUIDANCE SUGGESTS
GENERALLY VFR CONDITIONS WITH LITTLE IN THE WAY OF STRATUS OR FOG
OVERNIGHT. LOW LEVEL FLOW AT THE TOP OF THE LOW LEVEL INVERSION
INCREASES OVERNIGHT WITH A SOUTHWESTERLY WIND AT 25-30KTS AT 1500 FT
JUST OUTSIDE OF LLWS CRITERIA SO WILL OMIT THAT FROM THE TAF AS
WELL. THE FIRST HALF OF WEDNESDAY WILL FEATURE VFR CONDITIONS WITH
THE REDEVELOPMENT OF SCT CUMULUS AT AROUND 4-5KT AND SOME MID-HIGH
LEVEL BKN DEBRIS CLOUDINESS FROM UPSTREAM CONVECTION.

OUTLOOK...A RIDGE OF HIGH PRESSURE WILL BUILD OVER THE SOUTHEAST
THROUGH THE PERIOD SETTING UP A TYPICAL SUMMERTIME PATTERN. VFR
CONDITIONS ARE EXPECTED TO DOMINATE OUTSIDE OF MAINLY ISOLATED
AFTERNOON OR EVENING THUNDERSTORMS AND PATCHY FOG AROUND DAYBREAK.


&&

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

&&

$$

SYNOPSIS...BLAES
NEAR TERM...KRD
SHORT TERM...BLAES
LONG TERM...MLM
AVIATION...CBL/BLAES



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