Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 201125 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 725 AM EDT SUN APR 20 2014 .SYNOPSIS...LOW PRESSURE OFF THE SOUTH CAROLINA COAST WILL CONTINUE MOVING SLOWLY TO THE NORTHEAST TODAY... AS COOL HIGH PRESSURE NOSES INTO THE REGION FROM THE NORTHEAST. THE OFFSHORE LOW WILL MOVE OUT OVER THE ATLANTIC TONIGHT AND MONDAY... AS MILD HIGH PRESSURE BUILDS INTO THE AREA FROM THE SOUTHWEST THROUGH TUESDAY. && .NEAR TERM /THROUGH MONDAY NIGHT/... AS OF 235 AM SUNDAY... FOR TODAY/TONIGHT: BROKEN BANDS OF PATCHY VERY LIGHT RAIN AND DRIZZLE CONTINUE TO PROPAGATE TO THE WSW ACROSS THE CENTRAL/SRN CWA THIS MORNING... FED BY CONFLUENT LOW LEVEL ONSHORE FLOW AROUND LOW PRESSURE LOCATED OFF THE SC COAST. AS THIS LOW MAKES ONLY SLOW PROGRESS GENERALLY TOWARD THE NE TODAY/TONIGHT... THIS FETCH OF ATLANTIC MOISTURE THROUGH A DEEP LAYER SHOULD ALLOW FOR A CONTINUED RISK OF PATCHY AND MOSTLY TRACE AMOUNTS OF PRECIP OVER THE ERN AND SRN CWA. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THIS PATTERN... DEPICTING A GRADUAL DISSOLUTION OF THE 925-700 MB MASS CONVERGENCE OVER THE NW CWA WITH THE FOCUS OF DEEPER MOISTURE AND LIGHT PRECIP SHIFTING TO THE SOUTHEAST. LATEST MODELS SHOW A FAIRLY SHARP NW EDGE TO THE DEEPER MOISTURE... SUGGESTING THAT THERE WILL BE A TIGHT GRADIENT IN CLOUDS AND LIGHT PRECIP POTENTIAL TODAY THAT IS DIFFICULT TO PINPOINT... AND THESE CLOUDS (OR LACK OF SAME) WILL IMPACT TODAY`S HIGH TEMPS. HAVE CHOSEN TO FOLLOW THE PATTERN OF THE SREF PROBABILITIES OF ANY MEASURABLE RAIN... KEEPING A HIGH CHANCE OF LIGHT RAIN OR DRIZZLE (LIKELY POPS TO START THEN TRENDING DOWN TO CHANCE THROUGH THE DAY) ROUGHLY SE OF A LINE FROM KIXA TO KRDU TO KAFP... WITH A TREND TO NO CHANCE NW OF THIS LINE AND GREATER SUNSHINE. ACCORDINGLY... WITH MORE SOLAR INSOLATION EXPECTED ACROSS THE FAR NRN AND NW CWA... HAVE NUDGED UP HIGHS A BIT THERE... WHILE KEEPING THEM STEADY OR A DEGREE OR SO LOWER IN THE FAR ERN CWA WHERE THERE SHOULD BE ONLY A BRIEF WINDOW OF PARTIAL SUNSHINE THIS AFTERNOON. HIGHS 60 EAST TO 68 NW. WITH THE MSLP GRADIENT STAYING TIGHT ESPECIALLY FROM THE TRIANGLE SOUTH AND EAST... EXPECT THE STEADY BRISK AND OCCASIONALLY GUSTY WINDS TO CONTINUE TODAY... MOST MARKEDLY IN THE ERN CWA. THE PARENT HIGH CENTERED OFF THE NEW ENGLAND COAST CONTINUES PROGRESSING EASTWARD AND ITS NARROW RIDGE SW THROUGH CENTRAL NC STEADILY WEAKENS... AND AS THE OFFSHORE CYCLONE CONTINUES MOVING NE... EXPECT OUR SURFACE WINDS TO BACK SLIGHTLY TO A MORE NNE DIRECTION... DRAWING IN INCREASINGLY DRY LOW LEVEL AIR INTO CENTRAL NC. BUT THERE IS CONSIDERABLE MODEL DISCREPANCY AS TO THE DEGREE OF REMAINING LOW LEVEL MOISTURE OVER THE ERN CWA... WITH THE NAM SHOWING THICK CLOUDS ROLLING BACK IN LATE AFTERNOON THROUGH THE NIGHT WITH LOWERING BASES... WHILE THE GFS TRENDS TO MOSTLY CLEAR SKIES BUT INDICATES LOW STRATUS FORMING LATE TONIGHT WITHIN THE SURFACE-BASED STABLE LAYER. THERE ARE FEW HINTS AT THIS TIME AS TO WHICH SOLUTION IS BEST... AS THE INCOMING AIR ADVECTING IN THROUGH A DEEP LAYER IS COMING FROM THE RATHER DATA-SPARSE ATLANTIC OCEAN. BUT THE PATTERN WOULD SUGGEST THAT WE`LL MOST LIKELY SEE AT LEAST SOME RETURN OF CLOUDS IN THE ERN CWA THIS EVENING... AND WILL INDICATE THIS IN THE FORECAST. EXPECT MOSTLY CLEAR SKIES IN THE NW TRENDING TO MOSTLY CLOUDY SE TONIGHT... WITH ANY PATCHY DRIZZLE EXITING THE SE CWA EARLY. WITH THE LOW LEVELS REMAINING AT LEAST A LITTLE STIRRED AND POSSIBLE CLOUD COVER... HAVE UPPED LOWS JUST SLIGHTLY... TO 40-46. -GIH FOR MONDAY/MONDAY NIGHT: QUIET WEATHER ANTICIPATED BETWEEN STORM SYSTEMS. THE CHILLY HIGH TO OUR NE AS WELL AS THE OFFSHORE LOW SHOULD BE WELL AWAY FROM OUR REGION BY MONDAY MORNING... ALLOWING MID LEVEL SHORTWAVE RIDGING TO BUILD IN FROM THE WEST WITH A WEAK SURFACE RIDGE SETTLING BRIEFLY OVER THE GULF COAST AND INTERIOR SOUTHEAST STATES AHEAD OF THE NEXT COLD FRONT. WILL HAVE MOSTLY SUNNY SKIES... WITH ANY MORNING STRATUS QUICKLY MIXING OUT BOTH HORIZONTALLY AND VERTICALLY. THICKNESSES SUPPORT HIGHS OF 69-72. EXPECT MOSTLY CLEAR SKIES MUCH OF MONDAY NIGHT BUT TRENDING TOWARD FAIR SKIES WITH INCREASING HIGH CLOUDS AS THE TROUGH NOW OVER THE DESERT SOUTHWEST HEADS EASTWARD THROUGH THE MISS VALLEY. NEAR-NORMAL LOWS OF 49-53. -GIH && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... AS OF 300 AM SATURDAY... WITH THE DEPARTURE OF THE UPPER LOW ON MONDAY...THE LARGE SCALE FLOW WILL BECOME MUCH MORE PROGRESSIVE FOR THE UPCOMING WEEK. AN UPPER LEVEL TROUGH AND ASSOCIATED WEAK FRONTAL ZONE WILL CROSS CENTRAL NC TUESDAY AFTERNOON AND EVENING...AND THE MAIN FORECAST CONCERN DURING THIS PERIOD WILL BE MOISTURE RETURN AND WHETHER OR NOT CONVECTION IS ABLE TO MAKE IT ACROSS THE MOUNTAINS. SURFACE HIGH PRESSURE OVER THE SOUTHEAST US AND MOSTLY WEST-SOUTHWESTERLY MID-LEVEL FLOW SHOULD LIMIT SIGNIFICANT MOISTURE RETURN AHEAD OF THE FRONT. THUS...MODEL DEWPOINTS CAPE APPEAR TO BE TOO HIGH TUESDAY AFTERNOON. DRY ADIABATIC MIXING TO 900-850MB SUGGESTS HIGHS IN THE UPPER 70S TO AROUND 80. THIS WILL AID IN SOME WEAK DESTABILIZATION...BUT OVERALL THE THREAT OF MORE THAN JUST A FEW STRONG STORMS APPEARS LIMITED AND MOST LIKELY OVER WESTERN NC...WITH CONVECTIVE POTENTIAL BECOMING LESS FAVORABLE TO THE EAST AS THE FRONT MOVES TOWARD THE COAST TUESDAY EVENING. LOWS TUESDAY NIGHT IN THE LOW TO MID 50S. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 300 AM SATURDAY... WITHIN THE PROGRESSIVE FLOW ALOFT...CANADIAN HIGH PRESSURE WILL BRIEFLY BUILD OVER THE MID-ATLANTIC STATES AND CAROLINAS WEDNESDAY AND THURSDAY BEFORE SHIFT OFFSHORE BY THURSDAY NIGHT. THIS WILL LEAD TO A COUPLE DAYS OF HIGHS SLIGHTLY BELOW NORMAL IN THE UPPER 60S AND LOWER 70S...WITH RETURN FLOW AND WARMING FOR FRIDAY. ANOTHER FRONTAL SYSTEM WILL APPROACH ON FRIDAY...WITH A SLIGHTLY BETTER WINDOW FOR MOISTURE RETURN OFF THE GULF. HOWEVER...STRONGER DYNAMIC FORCING AGAIN LOOKS TO LIFT OFF TO THE NORTH AND BEST INSTABILITY LIKELY STAYS TO OUR SOUTH. THUS...THIS SYSTEM COLD BE ANOTHER ONE THAT BECOMES DRIER AS IT MOVES EAST OF THE MOUNTAINS. SLIGHT CHANCE POPS FOR NOW...WITH HIGHS MOSTLY IN THE 75-80 RANGE. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
AS OF 725 AM SUNDAY... HIGH AND MID LEVEL CLOUD DECKS AND SCT-BKN VFR STRATOCUMULUS WILL CONTINUE TO SPREAD TOWARD THE WEST-SOUTHWEST OVER NC... A RESULT OF THE COMBINATION OF STRONG LOW PRESSURE OFF THE SC COAST AND A NARROW WEDGE OF COOL HIGH PRESSURE NOSING INTO NC FROM THE NORTH. THESE VFR CLOUDS SHOULD PERSIST THROUGH THE DAY. CONFIDENCE IN THE DETAILS OF THE AVIATION FORECAST FOR CENTRAL NC IS LOW BEYOND 00Z THIS EVENING... DUE TO POOR MODEL PERFORMANCE REGARDING CLOUD HEIGHTS AND EXTENT IN THE LAST DAY OR SO AND LACK OF MODEL AGREEMENT ON A SOLUTION. BUT BASED ON EXTRAPOLATION OF UPSTREAM CONDITIONS AND THE MOST PLAUSIBLE MODEL SOLUTION... EXPECT CENTRAL NC TAF SITES TO SEE NO WORSE THAN VFR CLOUDS HOLD THROUGH THE DAY (LOWEST AT FAY/RWI)... WITH PATCHY SPRINKLES OR DRIZZLE POSSIBLE AT RWI. FAY HAS A CHANCE OF SEEING A TREND TO MVFR CIGS LATE TONIGHT INTO MONDAY MORNING. FORECAST CONFIDENCE DROPS THIS AFTERNOON WITH THE NAM SHOWING VFR CLOUDS RETURNING... AROUND 4 000 FT THICK... TRENDING SLOWLY DOWN TO MVFR THIS EVENING... WHILE THE GFS SHOWS MOSTLY CLEAR SKIES BY EVENING. PREFER THE PESSIMISTIC SOLUTION WITH GREATER CLOUD COVER... BUT TAFS WILL FEATURE CLOUDS HOLDING MAINLY VFR WITH A CHANCE OF MVFR TOWARD THE END OF THE FORECAST PERIOD. VSBYS SHOULD REMAIN PREDOMINANTLY VFR THROUGHOUT. SURFACE WINDS WILL REMAIN BRISK FROM THE NE AT 12-16 KT SUSTAINED WITH SPORADIC GUSTS TO 18-25 KTS AT ALL SITES THROUGH THE TAF FORECAST PERIOD. LOOKING BEYOND 12Z MONDAY MORNING... AS THE OFFSHORE LOW MOVES AWAY AND OUT TO SEA... VFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH MONDAY NIGHT... ALTHOUGH RWI/FAY MAY SEE A PERIOD OF OVC IFR STRATUS LATE TONIGHT THROUGH MID MORNING MONDAY. THE NEXT SYSTEM WILL IMPACT THE AREA ON TUESDAY... BRINGING ANOTHER CHANCE FOR RAIN AND ASSOCIATED ADVERSE AVIATION CONDITIONS. HOWEVER... THIS WILL BE A MUCH MORE PROGRESSIVE SYSTEM THAN THE CURRENT ONE... WITH CONDITIONS IMPROVING TO VFR LATE TUESDAY NIGHT INTO WEDNESDAY. VFR CONDITIONS SHOULD THEN PERSIST THROUGH THURSDAY AS HIGH PRESSURE DOMINATES. -GIH
-- End Changed Discussion --
&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...SMITH LONG TERM...SMITH AVIATION...HARTFIELD/KRD

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