Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 100719 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 317 AM EDT THU JUL 10 2014 .SYNOPSIS...A WEAKENING COLD FRONT WILL MOVE INTO THE AREA TODAY THEN DRIFT TOWARD THE COAST FRIDAY. WEAK HIGH PRESSURE WILL SETTLE OVER THE REGION SATURDAY. && .NEAR TERM /OVERNIGHT/... AS OF 1045 PM WEDNESDAY... CYCLONIC FLOW ALOFT WILL PREVAIL ACROSS THE REGION OVERNIGHT... FOSTERING A POTENTIAL FOR DPVA ASSOCIATED WITH SMALL AMPLITUDE DISTURBANCES TRACKING EAST FROM THE TN/OH VALLEY INTO THE MID- ATLANTIC AND NORTH CAROLINA. GIVEN THE PRESENCE OF MARGINAL NOCTURNAL INSTABILITY (500-1000 J/KG MUCAPE) AND THE PRESENCE OF A SHORTWAVE JUST UPSTREAM OVER TN/KY (PER RAP DATA AND WV IMAGERY)... WILL CONTINUE TO INDICATE A SLIGHT CHANCE OF SHOWERS/STORMS THROUGHOUT THE NIGHT. EXPECT LOWS IN THE LOWER 70S. -VINCENT && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 230 PM WEDNESDAY... SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR AGAIN ON THURSDAY AS A SERIES OF WEAK DISTURBANCES MOVE NE ACROSS OUR AREA IN ADVANCE OF THE MID-LEVEL TROUGH AXIS TO OUR WEST. AT THE SFC...THE COLD FRONT CURRENTLY TO OUR NW WILL DROP SOUTH AND MERGE WITH THE PIEDMONT TROUGH...PROVIDING A LOW LEVEL FOCUS FOR CONVECTION INITIATION. NOTED THAT GUIDANCE SHOWS AN AXIS OF HIGH PWAT (AROUND 2 INCHES) WILL PERSIST ACROSS THE EASTERN 2/3 OF OUR CWA DURING THE AFTERNOON INTO THE EVENING...TRENDING LOWER TO AROUND 1.5 INCHES ACROSS THE TRIAD. MEANWHILE...DEEP LAYER SHEAR WILL BE SIMILAR TO TODAY...25KT OR LESS. THUS...WHILE WE CAN`T RULE OUT THE POTENTIAL FOR AN ISOLATED STRONG WIND GUST OR TWO...THE MAIN IMPACTS MAY INSTEAD BE HEAVY RAIN INVOF OF THE BELT OF HIGH PWAT...AND THE POTENTIAL FOR LOCALIZED POOR DRAINAGE FLOODING WITH ANY OF THE SLOWER CELLS OR LOCATIONS THAT SEE REPETITIVE DOWNPOURS. GIVEN THIS MOISTURE PROFILE...LOOK FOR THE BEST COVERAGE AND THUS HIGHEST POPS TO BE EAST OF THE TRIAD. SIMILAR TO TODAY...HIGHS WILL BE DEPENDENT ON CLOUD COVERAGE...WHICH MAY BE MORE WIDESPREAD ACROSS OUR CWA TOMORROW COMPARED TO TODAY. HIGHS IN THE MID-UPR 80S AND LOWS THURSDAY NIGHT IN THE UPPER 60S TO AROUND 70. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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AS OF 310 AM THURSDAY... SATURDAY THROUGH SUNDAY NIGHT: THE WEAK MID LEVEL TROUGH AXIS IS PROGGED TO PUSH TO THE EAST AND SOUTH OF CENTRAL NC BY SATURDAY MORNING. AT THE SURFACE THE LINGERING WEAK SURFACE TROUGH ACROSS EASTERN NC IS EXPECTED TO SLOWLY RETROGRADE WESTWARD ACROSS THE PIEDMONT (REMAINING VERY WEAK)... AS THE MID LEVEL RIDGE OVER THE SOUTHERN PLAINS AND INTERMOUNTAIN WEST IS EXPECTED TO NUDGE EASTWARD AND INTO OUR AREA. THIS COUPLED WITH DRIER AIR BEHIND THE DEPARTING MID LEVEL TROUGH AND LACK OF A GOOD TRIGGER WILL LEAD TO GENERALLY ISOLATED CONVECTION ON SATURDAY... WITH THE BEST CHANCE ACROSS OUR FAR EAST/SOUTHEAST (BEST REMAINING MOISTURE AND WEAK CONVERGENCE EARLY IN THE AFTERNOON). WITH AFTERNOON LOW LEVEL THICKNESS VALUES EXPECTED TO BE AROUND 1420 METERS AND LACK OF GOOD CONVECTIVE COVERAGE THINK WE WILL SEE TEMPS AT LEAST CLIMB INTO THE UPPER 80S/NEAR 90 NORTH/NORTHWEST TO THE LOWER 90S SOUTH. EXPECT GENERALLY DRY CONDITIONS OVERNIGHT. HOWEVER... WITH CENTRAL NC ON THE PERIPHERY OF THE MID LEVELE RIDGE AND MOISTURE EXPECTED TO BE INCREASE CANNOT COMPLETELY RULE OUT A WEAK PERTURBATION MOVING THROUGH THE MID LEVEL FLOW AND SETTING OFF A FEW ISOLATED SHOWERS/STORMS. EXPECT LOWS SUNDAY MORNING WILL BE IN THE UPPER 60S TO LOWER 70S. CHANCES FOR SHOWERS AND STORMS WILL INCREASE A BIT ON SUNDAY... ALTHOUGH STILL LOW CHANCE/SLIGHT CHANCE POPS AT THIS TIME. EXPECT WE WILL BEGIN TO SEE A FULL LATITUDE EASTERN U.S. TROUGH DEVELOP. WHILE THE MID LEVEL RIDGE WILL GENERALLY HOLD ACROSS OUR AREA ON SUNDAY... WE WILL SEE THE MID LEVEL RIDGE CENTER BEGIN TO RETREAT WESTWARD AND SETUP ACROSS THE WESTERN U.S. THIS COUPLED WITH INCREASING MOISTURE THROUGHOUT THE COLUMN AND A SHARPENING SURFACE TROUGH WILL LEAD TO A LITTLE BIT BETTER CHANCE OF SHOWERS AND STORMS FOR SUNDAY AFTERNOON/EVENING... WITH THE BEST CHANCES ACROSS THE NORTH/NORTHWEST PIEDMONT. AFTERNOON LOW LEVEL THICKNESS VALUES ARE EXPECTED TO RISE BY ANOTHER 5 TO 10 METERS OVER SATURDAY AFTERNOON. THUS... EXPECT WE WILL SEE HIGH TEMPS IN THE LOWER TO MID 90S (MAYBE EVEN A FEW UPPER 90S ACROSS THE SANDHILLS). LOWS MONDAY MORNING ARE EXPECTED TO BE GENERALLY IN THE LOWER 70S. MONDAY THROUGH WEDNESDAY: A DEEP TROUGH IS EXPECTED TO DEVELOP ACROSS THE EASTERN HALF OF THE COUNTRY EARLY NEXT WEEK... WITH A DEEP VORTEX EXPECTED TO DIVE SOUTHWARD OUT OF CANADA AND ACROSS THE NORTHERN PLAINS/UPPER MIDWEST AND GREAT LAKES REGION. THIS SHOULD RESULT IN THE INCREASING LIKELIHOOD OF SHOWERS AND STORMS EARLY NEXT WEEK ACROSS CENTRAL NC.... AS A STRONG COLD FRONT MOVES INTO THE AREA EARLY NEXT WEEK (LOOKING LIKE LATE TUESDAY INTO TUESDAY NIGHT OR EARLY WEDNESDAY). THUS... WILL SHOW CHANCES FOR SHOWERS AND STORMS INCREASING EARLY NEXT WEEK... PEAKING ON TUESDAY AFTERNOON/EVENING. WITH MODELS NOW SHOWING THE FRONT PUSHING TO THE SOUTH OF THE AREA ON WEDNESDAY WILL LOWER POPS... BUT STILL KEEPING AT LEAST A SLIGHT CHANCE NORTH TO CHANCE SOUTH MENTIONED AS WE ARE TALKING ABOUT DAY 7 OF THE FORECAST AND DEALING WITH AN ANOMALOUS SETUP FOR THIS TIME OF YEAR. IN FACT WE COULD EVEN SEE MORE OF AN ORGANIZED SEVERE THREAT AS MID LEVEL FLOW IS EXPECTED TO STRENGTHEN AS THE SYSTEM APPROACHES. HIGH TEMPS AHEAD OF THE FRONT MAY BE SUPPRESSED SOME BY CONVECTION... BUT STILL THINK LOWER TO MID 90S WILL STILL BE POSSIBLE ON MONDAY AND POSSIBLY TUESDAY (MAYBE A CATEGORY COOLER ON TUESDAY DEPENDING ON TIMING OF THE PRECIP/FRONT). HIGHS TEMPS WEDNESDAY WILL BE COOLER IF THE FRONT INDEED PUSHES THROUGH THE AREA. FOR NOW WILL GO WITH HIGHS IN THE MID TO UPPER 80S. LOWS EARLY TO MID NEXT WEEK ARE EXPECTED TO BE IN THE LOWER TO MID 70S IN ADVANCE OF THE FRONT AND UPPER 60S TO LOWER 70S ON WEDNESDAY MORNING.
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&& AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 105 AM THURSDAY... A MOIST AND UNSTABLE AIR MASS WILL SUPPORT THE DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS OVERNIGHT THROUGH THURSDAY NIGHT AS AN UPPER LEVEL TROUGH AND ATTENDANT SURFACE BOUNDARY MOVES ACROSS THE AREA. THE SHOWERS AND STORMS WILL BE MOST NUMEROUS DURING THE AFTERNOON AND EARLY EVENING HOURS. EXPECT MVFR/IFR VISIBILITIES AND CEILINGS IN VICINITY OF THE HEAVIER SHOWERS AND STORMS. AWAY FROM THE CONVECTION...EXPECT VFR CONDITIONS WITH SFC WINDS PREDOMINATELY WEST-SOUTHWEST AT LESS THAN 10 KTS. IMPROVING AVIATION CONDITIONS ANTICIPATED FRIDAY THROUGH SATURDAY AS A SLIGHTLY DRIER MORE STABLE AIR MASS COVERS MOST OF THE REGION. SCATTERED AFTERNOON-EARLY EVENING CONVECTION WILL STILL BE PROBABLE IN VICINITY OF KFAY AND KRWI FRIDAY WHERE AVAILABLE MOISTURE AND LOW LEVEL INSTABILITY WILL BE BEST COMPARED TO THE PIEDMONT. ANY CONVECTION SATURDAY IS EXPECTED TO BE ISOLATED. BY SUNDAY AND MONDAY ...REMNANTS OF DECAYING THUNDERSTORM COMPLEXES ORIGINATING IN THE MIDWEST MAY BEGIN TO AFFECT CENTRAL NC...LEADING TO A SLIGHTLY BETTER CHANCE FOR SCATTERED CONVECTION AND ASSOCIATED MVFR CONDITIONS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...VINCENT SHORT TERM...NP LONG TERM...BSD AVIATION...WSS

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