Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 021426 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1026 AM EDT TUE JUN 2 2015 .SYNOPSIS...A MID LEVEL LOW PRESSURE TROUGH AND SURFACE COLD FRONT OVER THE TENNESSEE VALLEY WILL MOVE SLOWLY EASTWARD THEN STALL OVER THE CAROLINAS THROUGH THE WORK WEEK... BRINGING UNSETTLED WEATHER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM TUESDAY... UPPER LEVEL LOW PRESSURE OVER THE TENNESSEE VALLEY AND SURFACE HIGH PRESSURE IN THE WESTERN ATLANTIC HAVE COMBINED TO BRING WET SOUTHERLY FLOW OUT OF THE EASTERN GULF OF MEXICO AND UP INTO THE AREA AHEAD OF A NEAR STATIONARY COLD FRONT IN THE WESTERN PART OF THE STATE. DIFFERENT FROM PRIOR DAYS...MANY INDICATIONS POINTING TO THE EASTERN HALF OF THE CWA BEING MORE FAVORABLE FOR CONVECTION THIS AFTERNOON/EVENING AS OPPOSED TO THE NW PIEDMONT WHICH HAS SEEN THE MAJORITY OF THE ACTION OVER THE PAST SEVERAL DAYS. A COUPLE REASONS FOR THIS. FIRST...WATER VAPOR AND UPPER AIR ANALYSIS AT MULTIPLE LEVELS POINT TO DRIER AIR ADVECTING INTO THE SOUTHWEST PIEDMONT WITH THE EXCEPTION OF 700 MB WHICH STILL SHOWS DEWPOINT DEPRESSIONS LESS THAN FIVE. ABOVE AND BELOW THIS LEVEL...CONDITIONS ARE MUCH DRIER AS OPPOSED TO SATURATED TO THE SURFACE WHICH WE HAVE SEEN IN RECENT DAYS. SECOND...PRE EXISTING SHOWERS THIS MORNING HAVE HELPED TO KEEP TEMPERATURES DOWN WHICH WILL LIMIT OUR INSTABILITY OVER THE WESTERN HALF OF THE CWA THIS AFTERNOON. FINALLY...THE SOUTHERN HALF OF THE COLD FRONT HAS MOVED A LITTLE MORE EASTWARD...AND THUS WILL PUSH THE BEST MOISTURE FROM THE SOUTH...FURTHER EAST. DIFFERENTIAL HEATING BOUNDARY VERY CLEAR IN THE OBSERVATIONS JUST EAST OF THE TRIANGLE WITH TEMPS IN THE UPPER 60S TO LOWER 70S TO THE WEST AND UPPER 70S TO NEAR 80 DEGREES IN THE EAST. THIS WILL BECOME THE FOCUS FOR CONVECTIVE INITIATION LATER IN THE DAY AND THEREFORE BELIEVE THE BEST CHANCE FOR SIGNIFICANT COVERAGE OF CONVECTION TO BE ALONG THE I- 95 CORRIDOR. SPC HAS THE AREA IN A MARGINAL RISK OF SEVERE WX WITH WET DOWNBURSTS BEING THE MOST LIKELY THREAT. RAP FORECAST REALLY AGREEING WITH THIS SCENARIO. DO NOT THINK WE WILL SEE WIDESPREAD SEVERE STORMS BUT SHEAR IS BETTER THAN PREVIOUS DAYS SO CERTAINLY THINK IT IS IN THE REALM OF POSSIBILITY. HIGHS IN THE UPPER 70S WEST TO MID 80S EAST. TONIGHT EXPECT SHOWERS AND STORMS TO LINGER INTO THE EARLY MORNING HOURS IN THE EAST WITH NOT MUCH WEST OF HIGHWAY 1. LOWS IN THE LOW 60S WEST TO UPPER 60S EAST. EXPECT GOOD CHANCES FOR FOG/LOW STRATUS ACROSS THE NORTHERN HALF OF THE CWA. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 315 AM TUESDAY... ATMOSPHERE CHANGES LITTLE WEDNESDAY/WEDNESDAY NIGHT DUE TO THE NEARLY STATIONARY UPPER LOW TO OUR WEST AND THE RIDGE TO OUR EAST. LOBES OF VORTICITY ROTATING AROUND THE LOW WILL CAUSE PERIODS OF SHOWERS AND STORMS WITH COVERAGE ENHANCED BY AFTERNOON HEATING. SIMILAR TO TODAY...RAINFALL RATES OF 1-2 INCHES PER HOUR MAY LEAD TO NUISANCE FLOODING OF STREETS/LOW LYING AREAS. SINCE FLOODING IS EXPECTED TO BE MINOR AND LIMITED IN SCOPE...NOT ANTICIPATING THE NEED FOR A FLOOD WATCH AT THIS TIME. NEAR SFC NELY FLOW BEHIND THE SLOW MOVING SFC COLD FRONT THAT SHOULD IN VICINITY OF HIGHWAY 64 WILL ADVECT SLIGHTLY COOLER AIR INTO THE NORTHERN COUNTIES. THIS LOW LEVEL CAA ALONG WITH PERIODS OF SHOWERS AND EXTENSIVE CLOUDINESS WILL RESULT IN HIGH TEMPS IN THE 70S OVER MOST OF THE REGION WITH NEAR 80/LOWER 80S CONFINED TO THE FAR SOUTH-SE. THE THREAT FOR SHOWERS AND STORMS WILL CONTINUE INTO WEDNESDAY NIGHT THOUGH COVERAGE SHOULD BEGIN TO WANE AFTER 03Z-05Z AS ATMOSPHERE UNDERGOES USUAL NOCTURNAL STABILIZATION. MIN TEMPS LOWER 60S NORTH TO MID 60S SOUTH. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 250 AM TUESDAY... THURSDAY THROUGH FRIDAY NIGHT: SURFACE HIGH PRESSURE IS EXPECTED TO EXTEND SOUTHWARD AND INTO PORTIONS OF CENTRAL NC STILL ON THURSDAY. HOWEVER... THE CENTER OF THE HIGH IS EXPECTED TO BE MOVING OFF THE NORTHEAST U.S. COAST ON THURSDAY. THIS SHOULD YIELD A MODERATING AIRMASS SOME. HOWEVER... WITH PLENTIFUL MOISTURE AND A LINGERING NORTHERLY FLOW OVER MOST OF THE AREA EXPECT WE WILL ONCE AGAIN SEE BELOW NORMAL TEMPS ACROSS CENTRAL NC... WITH HIGHS RANGING FROM THE LOWER TO MID 70S NW TO THE LOWER 80S SE. THE MID LEVEL LOW ON THURSDAY WILL SLOWLY WOBBLE EASTWARD FROM THE NC MOUNTAINS AND EVENTUALLY MAKE IT TO THE COASTAL PLAIN ON FRIDAY. THIS SHOULD CONTINUE TO GIVE US A GOOD CHANCE OF SHOWERS AND STORMS ON THURSDAY INTO THURSDAY EVENING (SCATTERED TO NUMEROUS)... WITH THE BETTER CHANCES ON FRIDAY ACROSS THE EASTERN HALF OF THE FORECAST AREA AS THE MID LEVEL LOW MOVES ACROSS THE CWA. HOWEVER... OVERALL DEEP SHEAR WILL REMAIN WEAK... WITH SURFACE INSTABILITY WEAK TO MODEST AT BEST. THUS... ANY SEVERE THREAT SHOULD REMAIN ISOLATED DURING THIS TIME... WITH LOCALIZED FLASH FLOODING (ESPECIALLY IN URBAN AREAS AND LOCATIONS THAT HAPPEN TO RECEIVE SEVERAL ROUNDS OF HEAVY PRECIP) BEING THE MAIN HAZARDOUS WEATHER THREAT DURING THIS TIME FRAME. TEMPS SHOULD REBOUND A BIT ON FRIDAY WITH A CONTINUED MODERATING AIRMASS... WITH HIGHS GENERALLY IN THE LOWER 80S. LOWS THURSDAY AND FRIDAY NIGHT GENERALLY IN THE MID 60S. SATURDAY THROUGH MONDAY: UNSETTLED FORECAST CONTINUES INTO NEXT WEEKEND. WITH THE PASSAGE OF A NORTHERN STREAM DISTURBANCE TO THE NORTH OF THE AREA ON FRIDAY NIGHT INTO SATURDAY... ANOTHER TRAILING OR BACKDOOR COLD FRONT MAY AGAIN SINK SOUTHWARD INTO CENTRAL NC. THIS COMBINED WITH A CONTINUED WEAK MID LEVEL TROUGH REMAINING ACROSS THE REGION AND POSSIBLY ADDITIONAL S/W ENERGY DROPPING SOUTHEASTWARD AND INTO THE BACK SIDE OF THE WEAK MID LEVEL TROUGH OVER THE AREA (AS SHOWN ON THE LATEST ECWMF... WHICH WOULD ENHANCE COVERAGE OF SHOWERS AND STORMS EVEN MORE) SHOULD RESULT IN AT LEAST CHANCES FOR AFTERNOON AND EVENING SHOWERS AND STORMS. STILL A LITTLE TO EARLY TO TELL HOW FAR SOUTH THIS POSSIBLE FRONT WILL MAKE IT. THUS... WILL CONTINUE TO STICK CLOSE TO WPC FOR TEMPS...WITH HIGH TEMPS NEAR TO SLIGHTLY BELOW NORMAL FOR EARLY JUNE AND LOWS NEAR NORMAL. YET ANOTHER DISTURBANCE IS EXPECTED TO TRACK FROM THE CENTRAL AND NORTHERN PLAINS ON SATURDAY INTO THE GREAT LAKES REGION BY LATE SUNDAY INTO MONDAY MORNING. THIS WILL EVENTUALLY SEND ANOTHER FRONT TOWARDS CENTRAL NC LATE MONDAY FROM THE WEST. THUS... WILL CONTINUE TO KEEP CHANCE POPS IN FOR DAY 7 IN THE FORECAST WITH NEAR NORMAL TEMPS. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 735 AM TUESDAY... A VERY MOIST AIR MASS OVER THE CAROLINAS COUPLED WITH THE APPROACH OF A LOW PRESSURE SYSTEM AND ITS ATTENDANT SFC COLD FRONT WILL RESULT IN ADVERSE AVIATION CONDITIONS ACROSS MUCH OF CENTRAL NC THROUGH WEDNESDAY NIGHT. THIS MORNING...SHOWERS WILL BECOME A LITTLE MORE NUMEROUS OVER THE PIEDMONT AND POSSIBLY OVER THE SANDHILLS AS A PERTURBATION ALOFT LIFTS NWD ACROSS THE REGION. THESE SHOWERS AND ISOLATED STORMS WILL CAUSE PERIODS OF MVFR CEILINGS/VISIBILITY. HEATING OF THE MOIST AND SLIGHTLY UNSTABLE ATMOSPHERE THIS AFTERNOON WILL CAUSE NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS TO DEVELOP WITH THE GREATEST CONCENTRATION EXPECTED OVER THE EASTERN HALF OF CENTRAL NC. THIS BATCH OF CONVECTION MAY IMPACT KRDU...KFAY AND KRWI. THE AREAS OF CONVECTION WILL BE SLOW TO DIMINISH TONIGHT AS A SFC COLD FRONT DRIFTS SOUTHWARD INTO OUR AREA. THIS FEATURE WILL LIKELY AID TO MAINTAIN A FEW SHOWERS AND STORMS WELL INTO THE NIGHT. THE UNSETTLED WEATHER PATTERN WILL CONTINUE WEDNESDAY INTO THURSDAY AS THE ATMOSPHERE WILL MAINTAIN ITS MOIST AND SLIGHTLY UNSTABLE CHARACTER. THIS WILL CAUSE PERIODS OF MVFR/IFR CONDITIONS DUE TO CEILINGS AND CONVECTION. CONDITIONS WILL BEGIN TO SLOWLY IMPROVE FRIDAY AND SATURDAY AS THE ATMOSPHERE BECOMES SLIGHTLY DRIER. THIS WILL LEAD TO FEWER SHOWERS AND STORMS DURING THE HEAT OF THE AFTERNOON-EARLY EVENING. HOWEVER...THERE IS STILL A GOOD PROBABILITY OF EARLY MORNING MVFR/IFR CEILINGS AND VISIBILITY BOTH MORNINGS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...ELLIS SHORT TERM...WSS LONG TERM...BSD AVIATION...WSS

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