Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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167
FXUS62 KRAH 041816
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
230 PM EDT WED MAY 4 2016

.SYNOPSIS...
A LOW PRESSURE TROUGH WILL LINGER OVER THE REGION THROUGH FRIDAY AS
A POTENT UPPER LEVEL LOW DIGS SOUTHEAST FROM THE OHIO VALLEY INTO
THE CAROLINAS.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 1030 AM WEDNESDAY...

TODAY: A DRIER LOW-LEVEL AIRMASS HAS ADVECTED INTO CENTRAL NC THIS
MORNING...IN THE WAKE OF A FRONT CURRENTLY LOCATED ALONG THE
CAROLINA COAST. THOUGH STEEP MID-LEVEL LAPSE RATES REMAIN IN
PLACE...LOW-LEVEL MOISTURE/HEATING ARE EXPECTED TO BE INSUFFICIENT TO
SUPPORT CONVECTION IN CENTRAL NC...PARTICULARLY GIVEN THE ABSENCE OF
ANY COMPACT/FOCUSED DPVA. EXPECT A HIGHER LIKELIHOOD OF SUBSIDENCE
OVER THE AREA AS PRIOR SHORTWAVE ENERGY LIFTS NORTHEAST OFFSHORE THE
MID-ATLANTIC COAST. A POSSIBLE EXCEPTION MAY BE FAR E/SE PORTIONS OF
THE COASTAL PLAIN IN CLOSER VICINITY TO RICHER MOISTURE...THOUGH
MOST SHOWER ACTIVITY WILL LIKELY REMAIN FURTHER EAST IN COASTAL NC.
EXPECT HIGHS IN THE UPPER 60S TO LOWER 70S.

TONIGHT: DESPITE DRIER LOW-LEVELS...CHANCES FOR SHOWER ACTIVITY WILL
INCREASE AFTER MIDNIGHT TONIGHT IN ASSOC/W COOLING /STEEPENING LAPSE
RATES/ ALOFT AND DPVA ATTENDANT SMALL AMPLITUDE WAVES ROTATING
AROUND THE EASTERN PERIPHERY OF AN UPPER LEVEL LOW DIGGING SOUTHEAST
FROM THE OH VALLEY TO THE SOUTHERN APPALACHIANS (NEAR THE TRI-
CITIES) BY 12Z THU. EXPECT LOWS RANGING FROM THE UPPER 40S (NW) TO
MID 50S (SE). -VINCENT

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 1045 AM WEDNESDAY...

THU/THU NIGHT: A POTENT UPPER LEVEL LOW WILL TRACK ACROSS CENTRAL NC
DRYING THE DAY THU. AS IS TYPICAL IN SUCH A SETUP...EXPECT SCT TO
NUMEROUS CONVECTION AS STEEPENING LAPSE RATES ALOFT AID DIURNAL
DESTABILIZATION...WITH THE GREATEST COVERAGE IN `BOUTS` ATTENDANT
POTENT SHORTWAVE ENERGY /DPVA/ ROTATING AROUND THE UPPER LOW. ANY
UPDRAFT STRONG ENOUGH TO PRODUCE LIGHTNING WILL BE SUFFICIENT TO
PRODUCE SMALL HAIL GIVEN A LOWERING FREEZING LEVEL /COOLING ALOFT/.
DEEP LAYER SHEAR WILL GENERALLY BE TOO WEAK TO SUPPORT ORGANIZED
CONVECTION OVER CENTRAL NC THU AFTERNOON...EXCEPT IN THE NE COASTAL
PLAIN WHERE 0-6 KM SHEAR (OR 0-8 KM) VALUES WILL BE SUFFICIENT TO
SUPPORT SUPERCELLS...ESP IF WELL TIMED DPVA ROTATES INTO THAT REGION
DURING THE MID/LATE AFTERNOON. SUCH ACTIVITY WOULD BE CAPABLE OF
PRODUCING LARGE (1-2") HAIL...THOUGH THE THREAT WOULD BE SPATIO-
TEMPORALLY LIMITED TO THE FAR NE COASTAL PLAIN FOR SEVERAL HOURS
MID/LATE AFTERNOON. THE BEST POTENTIAL FOR SUPERCELLS WILL REMAIN
OUTSIDE OF CENTRAL NC IN FAR NORTHEAST NC AND SOUTHEAST VA. EXPECT
AREAS OF CONVECTION TO WRAP SOUTHWARD BACK INTO CENTRAL NC OVERNIGHT
AS THE UPPER LOW PIVOTS NE TOWARD THE DELMARVA AND SHORTWAVE ENERGY
DIGS SOUTHWARD INTO CENTRAL NC FROM VA. HIGHS WILL BE MODULATED BY
CONVECTION...RANGING FROM THE UPPER 50S NW TO LOW/MID 60S SE. LOWS
THU NIGHT ALSO MODULATED BY CONVECTION...RANGING FROM THE UPPER 40S
WEST TO NEAR 50F EAST. -VINCENT

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 230 PM WEDNESDAY...

COOL POOL ALOFT WILL MAINTAIN MID LEVEL INSTABILITY WITH LAPSE RATES
GREATER THAN 6C/KM...BUT THUNDER WILL BE DAMPENED BY WEAK SHEAR
PROFILE AND MINIMAL DIFFLUENCE ALOFT. EXPECT WRAP AROUND SHOWERS TO
DEVELOP AND STREAM SOUTH INTO THE AREA THROUGH MUCH OF THE DAY AS
THE CUTOFF LOW LIFTS NORTH...WITH COVERAGE AT A MINIMUM OVER THE
SOUTHWEST AND WILL BE PROGRESSIVELY DIMINISHING THROUGHOUT THE DAY
IN THE NORTHEAST. TEMPS WILL BE COOL WITH CLOUD COVERAGE AND COLD
RAIN...WILL STALL IN THE MID 60S OVER MOST OF THE AREA. LINGERING
SHOWERS WILL END IN THE FAR NORTHEAST BY MIDNIGHT WITH MINS AROUND
50 SATURDAY MORNING.

THE LARGER UPPER TROF WILL SLOWLY MOVE EAST OF THE ATLANTIC COAST
THROUGH LATER SATURDAY WITH DECREASING CLOUDINESS ASSOCIATED WITH
THE EXITING CUTOFF LOW LINGERING IN THE EAST INTO AFTERNOON. HIGHS
WILL BENEFIT FROM A LITTLE MORE SUN AND RISING HEIGHTS BEHIND THE
LOW...WITH HIGHS MOSTLY IN THE MID 70S. A DRY BACKDOOR FRONT WILL BE
SAGGING SOUTH ON SUNDAY...WHERE IT WILL STALL IN THE VICINITY OF THE
NC/VA BORDER AS IT ALIGNS PARALLEL TO THE PREVAILING FLOW.
A FEW SHOWERS COULD FORM ALONG THE FRONTAL ZONE ACROSS THE NORTHERN
COUNTIES...BUT NOT CONFIDENT ENOUGH TO PAINT THEM IN YET. CLOUDINESS
WILL BE THE MAJOR IMPACT AS DOWNSLOPE FLOW WILL AID IN BOOSTING
HIGHS TO NEAR 80.

THE FRONT WILL BE EDGED NORTH OF THE AREA AS WE TRANSITION TO A
RETURN FLOW REGIME WITH WEAK RIDGING ALOFT ASSISTING A MILD WARMING
TREND MONDAY THROUGH WEDNESDAY. HIGHS AROUND 80 MONDAY WILL WARM TO
THE LOW AND MID 80S BY WEDNESDAY.

&&

.AVIATION /18Z WEDNESDAY THROUGH SUNDAY/...
AS OF 1030 AM WEDNESDAY...

ONCE SUB-VFR CEILINGS LIFT AT EASTERN TERMINALS...VFR CONDITIONS
WILL PREVAIL THROUGH THIS EVENING IN ASSOC/W A DRIER LOW-LEVEL
AIRMASS IN PLACE OVER THE REGION. EXPECT ANY DIURNAL CU TO BE BASED
AT 4-5 KFT THIS AFTERNOON. EXPECT DETERIORATING CONDITIONS AT THE
TRIAD TERMINALS BY OR SHORTLY AFTER MIDNIGHT TONIGHT AS SHOWERS
DEVELOP IN ADVANCE OF AN APPROACHING UPPER LEVEL LOW. SUB-VFR
CONDITIONS WILL BECOME INCREASINGLY LIKELY AT THE EASTERN TERMINALS
BY THE END OF THE TAF PERIOD AS THE UPPER LEVEL LOW APPROACHES THE
CAROLINAS.

LOOKING AHEAD: EXPECT ADVERSE AVIATION CONDITIONS AT ALL TERMINALS
THU INTO THU NIGHT IN ASSOC/W NUMEROUS SHOWERS AND SCT THUNDERSTORMS
(ANY OF WHICH COULD PRODUCE SMALL HAIL) OVER CENTRAL NC IN ASSOC/W
THE UPPER LEVEL LOW OVER THE REGION. CONDITIONS WILL BEGIN TO
IMPROVE ON FRIDAY AS THE UPPER LOW SHIFTS TOWARD THE DELMARVA/ MID-
ATLANTIC COAST...WITH VFR CONDITIONS FRI NIGHT THROUGH THE UPCOMING
WEEKEND. -VINCENT

&&

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

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT/
LONG TERM...MLM
AVIATION...VINCENT



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