Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 280512
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
110 AM EDT TUE APR 28 2015

.SYNOPSIS...HIGH PRESSURE WILL EXTEND INTO THE AREA FROM THE
NORTHWEST TODAY AND TONIGHT. MEANWHILE... LOW PRESSURE STRENGTHENING
ALONG THE GULF COAST TODAY WILL TRACK EAST THEN NORTHEAST OVER THE
SOUTHEAST STATES LATE TONIGHT THROUGH WEDNESDAY NIGHT... THEN SLOWLY
PULL OFF THE CAROLINA COAST THURSDAY.

&&

.NEAR TERM /TONIGHT/...
AS OF 1010 PM MONDAY...

A DEEP MID/UPPER LEVEL LOW CENTERED OFF THE NEW ENGLAND COAST THIS
EVENING CONTINUES TO PROVIDE THE AREA WITH CYCLONIC FLOW ALOFT...
WITH EMBEDDED S/W DISTURBANCES MOVING THROUGH THE MID-ATLANTIC INTO
THE CAROLINAS. ONE SUCH POTENT S/W IS EXPECTED TO SINK SOUTHWARD AND
INTO CENTRAL NC DURING THE EARLY MORNING HOURS OF TUESDAY.
HOWEVER... WITH THE COMBINATION OF WEAK LOW LEVEL COLD ADVECTION...
POOR DIURNAL TIMING.... AND LACK OF SIGNIFICANT MOISTURE (PW`S ARE
AROUND 0.4-0.5 INCHES... RESULTING IN PW`S OF AROUND 50% OF NORMAL)
NO PRECIP IS EXPECTED... WITH EVEN VERY LITTLE LOW TO MID CLOUD
COVER. IN FACT MOST OF THE CLOUD COVER OVERNIGHT WILL BE FROM SOME
HIGH CLOUD COVER STREAMING INTO THE AREA FROM CONVECTION NEAR THE
GULF COAST. PLAN TO INCREASE THE CLOUDS IN THE GRIDS ACROSS SOUTHERN
PORTIONS OF THE FA GIVEN THE CIRRUS. STILL THINK OVERNIGHT LOWS
SHOULD RANGE FROM THE UPPER 30S TO AROUND 40 ACROSS THE NORTHERN
RURAL LOCATIONS TO THE LOWER TO MID 40S ELSEWHERE... NEAR
STATISTICAL GUIDANCE.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 230 PM MONDAY...

TUESDAY AND TUESDAY NIGHT: DRY CONDITIONS WILL PERSIST DURING THE
DAY TUE...WITH HIGHS IN THE UPPER 60S TO NEAR 70F. A DRY SFC RIDGE
EXTENDING INTO THE REGION FROM THE NORTHWEST WILL GRADUALLY WEAKEN
TUE AFT/EVE INTO TUE NIGHT AS A POTENT SOUTHERN STREAM WAVE
PROGRESSES EAST ACROSS THE LOWER MS RIVER VALLEY...WITH AN ATTENDANT
SFC LOW DEEPENING ALONG THE GULF COAST. THE UPPER WAVE AND ATTENDANT
SFC CYCLONE WILL BECOME CLOSE TO MATURE /VERTICALLY STACKED/ OVER
PORTIONS OF THE DEEP SOUTH BY 12Z WED. EXPECT TOP-DOWN MOISTENING
OVERNIGHT...I.E. ADVECTION OF MID/UPPER LEVEL MOISTURE DOWNSTREAM OF
THE MATURE CYCLONE INTO CENTRAL NC BY ~MIDNIGHT... FOLLOWED BY
STRENGTHENING LOW-LEVEL WARM ADVECTION AND AN INCREASING CHANCE FOR
LIGHT RAIN IN THE SANDHILLS AND WEST/SW PIEDMONT BY SUNRISE WED.
GIVEN A RAPID INCREASE IN CLOUD COVER...EXPECT LOWS MARKEDLY WARMER
THAN PREVIOUS NIGHTS...IN THE UPPER 40S TO LOWER/MID 50S...COOLEST
IN THE WEST/SW PIEDMONT WHERE PRECIP WILL DRIVE TEMPS DOWNWARD VIA
EVAP COOLING JUST PRIOR TO SUNRISE. -VINCENT

WEDNESDAY AND WEDNESDAY NIGHT: MODELS ARE IN FAIRLY GOOD AGREEMENT
WITH THE APPROACH OF THE TIMING AND STRENGTH OF THE MID/UPPER LOW AS
IT IS FORECAST TO TRACK OUT OF THE SOUTHERN PLAINS TOWARD THE
MISSISSIPPI VALLEY REGION TOWARD OUR REGION BY MID WEEK. COOL DRY
SURFACE HIGH PRESSURE IS INITIALLY FORECAST TO EXTEND FROM THE GREAT
LAKES SOUTH INTO THE CAROLINAS TUESDAY NIGHT AND WEDNESDAY. THE HIGH
IS FORECAST TO BE FAIRLY WEEK (1020 MB OR SO)... BUT WILL DEPOSIT
PLENTY OF DRY AIR OVER THE REGION BEFORE THE RAIN BEGINS WEDNESDAY
TO LEAD TO EVAPORATIVE COOLING AND AT LEAST A HYBRID COLD AIR
DAMMING RESUME WEDNESDAY AFTERNOON AND NIGHT. AS IT APPEARS WITH THE
RECENT MODELS RUNS... CONSENSUS IS FOR INCREASING CLOUDINESS TUESDAY
NIGHT WITH LOWS IN THE UPPER 40S TO LOWER 50S. THEN RAIN LIKELY
DEVELOPING FROM SOUTHWEST TO NORTHEAST WEDNESDAY. HIGHS WILL DEPEND
ON THE RAIN ARRIVAL. EXPECT GENERALLY 50S WEST TO SOME LOWER 60S
EAST. RAIN NOW APPEARS LIKELY WEDNESDAY AFTERNOON AND NIGHT. LOWS 50-
55 WEDNESDAY NIGHT.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 140 PM MONDAY...

...DAMP AND CHILLY THURSDAY FOLLOWED BY A MODERATION AND DRYING THIS
WEEKEND...

MODELS ARE FINALLY IN GOOD OVERALL AGREEMENT IN BRINGING A STORM
SYSTEM UP ALONG THE SOUTHEAST AND MID-ATLANTIC COAST THURSDAY INTO
FRIDAY. THIS IS A PATTERN THAT MORE RESEMBLES THE COLD SEASON THAN
THE WARM SEASON AND ONE THAT WILL ONLY MODIFY SLOWLY INTO THE
WEEKEND GIVEN THE COOL/RAINY CONDITIONS AND NE FLOW EXPECTED WITH
THE COASTAL STORM.

THE COASTAL LOW PRESSURE IS FORECAST TO START THE DAY NEAR THE SC/NC
COAST AROUND 12Z/THURSDAY... THEN DEEPEN AS IT MOVES NE TO ALONG AND
OFF THE MID-ATLANTIC TO NEW ENGLAND COAST BY 12Z/FRIDAY. THIS STORM
TRACK FAVORS A COOL STABLE NE FLOW ACROSS OUR REGION WITH STRATIFORM
RAIN AND IS NOT FAVORABLE FOR SEVERE STORMS AS THE WARM SECTOR IS
EXPECTED TO BE WELL SOUTH AND EAST (OFFSHORE). MODELS HAVE TRENDED A
BIT WESTWARD WITH THE MID/UPPER LOW POSITION IN THE PAST FEW RUNS...
AND THIS IN TURN ALLOWS A MORE WESTWARD TRACK OF THE COASTAL LOW
ALLOWING FOR WIDESPREAD QPF ON THE ORDER OF 1-2 INCHES.

SENSIBLE WEATHER SHOULD BE FOR THE STEADY AND HEAVIER RAIN TO FALL
INTO A PART OF THURSDAY... THEN GRADUALLY TAPER OFF AS THE COASTAL
LOW PULLS UP THE COAST LEAVING BEHIND A CHILLY NE FLOW... AREAS OF
LIGHT RAIN.... DRIZZLE... AND OVERCAST LOW CLOUDINESS DURING THE
DAY. TEMPERATURES SHOULD ONLY REACH THE UPPER 50S AND 60S (MOST
LIKELY A GOOD 15 DEGREES BELOW THE NORMAL). THEN DEPENDING ON THE
MID/UPPER LOW TRACK GIVEN POTENTIAL INTERACTION WITH THE POLAR
JET... EITHER SLOW CLEARING THURSDAY NIGHT AND BECOMING PARTLY SUNNY
FRIDAY OR... IF THE TRACK IS OVERHEAD THERE WILL BE A CONTINUED
CHANCE OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS WITH COLD AIR
ALOFT AND SURFACE HEATING FRIDAY. REGARDLESS... TEMPERATURES WILL
REMAIN COOL. HIGHS FRIDAY GENERALLY EXPECTED TO REACH 65-70 WITH THE
LOW LEVEL FLOW FROM THE NORTH.

FINALLY... A MODERATING TREND IS EXPECTED OVER THE WEEKEND INTO
EARLY NEXT WEEK AS THE STORM DEPARTS AND HIGH PRESSURE IS FORECAST
TO BUILD OVERNIGHT. LOWS SHOULD MODERATE FROM THE MID 40S TO LOWER
50S SATURDAY INTO THE MID AND UPPER 50S MONDAY. HIGHS SHOULD REACH
CLOSE TO NORMAL LEVELS BY SUNDAY OR MONDAY (UPPER 70S TO LOWER
80S).

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 110 AM TUESDAY...

VFR CONDITIONS ARE LIKELY ACROSS CENTRAL NC THROUGH 06Z TONIGHT.
SPRAWLING HIGH PRESSURE WILL EXTEND INTO THE FORECAST AREA FROM THE
NORTHWEST TODAY INTO TONIGHT...  BRINGING FAIRLY DRY AIR NEAR THE
SURFACE... ENSURING UNRESTRICTED VSBYS. WE WILL SEE SOME HIGH CLOUDS
STREAMING IN FROM THE SW THROUGH THE PERIOD... ESPECIALLY TONIGHT...
AS LOW PRESSURE FORMING OVER THE CENTRAL GULF COAST STARTS TO TRACK
SLOWLY TO THE EAST-NORTHEAST... WHILE UPPER LEVEL LOW PRESSURE
APPROACHES FROM THE WEST. WE`LL ALSO HAVE A FEW MID CLOUDS THIS
MORNING... MAINLY OVER THE NRN/ERN TERMINALS (RDU/RWI/FAY)...
RESULTING FROM AN UPPER DISTURBANCE DROPPING SOUTHWARD ALONG THE
MIDATLANTIC COAST. ANY CIGS WILL BE VFR... ABOVE 10 000 FT AGL.
WINDS WILL BE LIGHT AND MAINLY FROM THE NORTH AND NE.

LOOKING BEYOND 06Z TONIGHT... HIGH CLOUDS WILL THICKEN AND LOWER
LATE TONIGHT AS THE LOW PRESSURE MOVES INTO THE SOUTHEAST STATES...
AND CLOUDS BASED AROUND 4000 FT AGL ARE LIKELY TO MOVE IN FROM THE
SW LATE TONIGHT... HOWEVER CIGS WILL REMAIN VFR THROUGH DAYBREAK
WED. THE COMBINATION OF APPROACHING LOW PRESSURE TROUGH ALOFT FROM
THE WEST AND THE SURFACE LOW CROSSING THE SOUTHEAST STATES WILL LEAD
TO LOWERING CIGS AND INCREASING RAIN CHANCES FROM THE SOUTHWEST
WED... LASTING INTO THU. SUB-VFR CIGS ARE POSSIBLE LATE WED INTO
THU... HOWEVER CONFIDENCE IS NOT HIGH... AS THE WORST AVIATION
CONDITIONS MAY HOLD TO OUR SOUTH DURING THIS PERIOD. AVIATION
INTERESTS SHOULD MONITOR LATER FORECASTS AND CONDITIONS. THE CHANCE
OF IFR CONDITIONS INCREASES LATE THU NIGHT INTO FRI AS UPPER LEVEL
LOW PRESSURE MOVES IN FROM THE NW. THE DEPARTURE OF THE LOW PRESSURE
TO OUR EAST LATE FRI WILL BRING IMPROVING CONDITIONS BACK TO VFR
LATE FRI THROUGH SAT AS HIGH PRESSURE BUILDS IN FROM THE WEST. -GIH


&&

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

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...BSD
SHORT TERM...VINCENT/BADGETT
LONG TERM...BADGETT
AVIATION...HARTFIELD


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