Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 100738 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 340 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 /THROUGH TONIGHT/...
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AS OF 340 AM THURSDAY... A MID LEVEL SHEAR AXIS AND ASSORTED PERTURBATIONS WILL DRIFT OVER THE REGION TODAY. THIS FEATURE HAS TRIGGERED/MAINTAINED SCATTER CONVECTION OVER CENTRAL NC DURING THE OVERNIGHT HOURS. AS THE ATMOSPHERE HEATS UP...CONVECTION SHOULD BECOME NUMEROUS. BASED ON MID LEVEL SHEAR AND ASSOCIATED SFC BOUNDARY PROJECTED TO LIE IN VICINITY HIGHWAY 1 CORRIDOR EXPECT BULK OF CONVECTIVE ACTIVITY TO OCCUR OVER THE SOUTHEAST HALF OF THE FORECAST AREA. THUS WILL TREND POPS FROM HIGH CHANCE IN THE NW TO HIGH END LIKELY OVER THE COASTAL PLAIN. BEST BULK SHEAR VALUES EXPECTED TO LIE JUST NORTH OF CENTRAL NC. STILL...BULK SHEAR 25-30KTS ACROSS THE NORTH COUPLED WITH MLCAPE VALUES IN THE 500-1000J/KG RANGE THIS AFTERNOON WILL SUPPORT THE POTENTIAL FOR ORGANIZED CONVECTION...MAINLY IN THE FORM OF BROKEN CONVECTIVE SEGMENTS (DUE TO WIND PROFILE DEEPLY UNIDIRECTIONAL). CANNOT RULE OUT AN ISOLATED STRONG-SEVERE STORM WITH THE HIGHEST THREAT TO THE N-NE OF RDU. MAIN HAZARD WILL BE LOCALLY EXCESSIVE RAINFALL. DEEP UNIDIRECTIONAL FLOW WILL LIKELY CAUSE SHOWERS/STORMS TO TRAIN REPEATEDLY ACROSS THE SAME LOCATION FOR A GOOD HOUR OR SO BEFORE DRIFTING E-SE. WITH THE SFC BOUNDARY IN VICINITY OF HIGHWAY 1...THE THREAT OF HEAVY RAIN WILL BE GREATEST IN VICINITY OF RALEIGH- DURHAM...ROCKY MOUNT...AND FAYETTEVILLE. EXTENSIVE CLOUDINESS AND INCREASING COVERAGE OF CONVECTION WILL LEAD TO MAX TEMPS SEVERAL DEGREES COOLER COMPARED TO THE PAST FEW DAYS. HIGH TEMPS MID 80S NORTH TO UPPER 80S/AROUND 90 SOUTH. TONIGHT...SCATTERED CONVECTION WILL BE MAINLY CONFINED TO THE COASTAL PLAIN AS THE MID LEVEL SHEAR AXIS DRIFTS SLOWLY E-SE. MIN TEMPS UPPER 60S NW TO LOWER 70S SE.
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&& .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
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AS OF 340 AM THURSDAY... MID LEVEL SHEAR AXIS AND ATTENDANT SFC BOUNDARY MAINTAINS A POSITION IN VICINITY OF THE COASTAL PLAIN FRIDAY. WITH AIR MASS STILL MOIST AND SLIGHT-MODERATELY UNSTABLE...EXPECT ANOTHER ROUND OF SCATTERED SHOWERS/THUNDERSTORMS WITH LOCALLY HEAVY RAIN TO OCCUR. SIMILAR TO TODAY...EXPECT GREATEST COVERAGE TO OCCUR EAST OF HIGHWAY 1. FARTHER NW...A SLIGHTLY DRIER MORE STABLE AIR MASS AND WEAK DOWNSLOPE FLOW IN THE WAKE OF THE MID LEVEL SHEAR AXIS WILL INHIBIT CONVECTIVE DEVELOPMENT. STILL...WITH HEATING EXPECT ISOLATED-SCATTERED CONVECTION DURING THE HEAT OF THE AFTERNOON. MAX TEMPS FAIRLY UNIFORM DUE TO CLOUDS/CONVECTION. MAX TEMPS 85-88. FRIDAY NIGHT...BULK OF CONVECTION WILL DIMINISH WITH LOSS OF HEATING THOUGH COULD SEE A FEW SHOWERS PERSIST PAST MIDNIGHT ALONG OUR EASTERN PERIPHERY DUE TO PRESENCE OF MID LEVEL SHEAR AXIS. MIN TEMPS UPPER 60S TO AROUND 70.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/... 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. && 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...WSS SHORT TERM...WSS LONG TERM...BSD AVIATION...WSS

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