Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 090714 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 313 AM EDT WED JUL 9 2014 .SYNOPSIS...A SURFACE TROUGH WILL PERSIST OVER CENTRAL NORTH CAROLINA TODAY. A WEAKENING COLD FRONT WILL MOVE INTO OUR REGION THURSDAY...THEN DRIFT TOWARD THE COAST FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 PM TUESDAY... WEAK CONVECTION AIDED BY A SMALL MCV MOVING SOUTH OF MARTINSVILLE IS MOVING THROUGH THE TRIAD AND HAS MUSTERED UP A COUPLE OF 40 MPH GUSTS BUT NOT MUCH MORE. THIS SHOULD EVENTUALLY DIE OUT AS THE ENVIRONMENT BECOMES LESS FAVORABLE TO THE EAST BUT SOME LIGHT RAIN COULD MAKE IT AS FAR EAST AS THE TRIANGLE BUT THAT IS ABOUT IT. WINDS WILL STAY UP A LITTLE OVERNIGHT AT 5-10 KTS OUT OF THE SOUTHWEST. RELATIVE HUMIDITY CROSS SECTIONS AND ATMOSPHERIC SOUNDINGS ARE VERY DRY AT LOW LEVELS AND NOT MUCH FOG OR LOW STRATUS IS EXPECTED OVERNIGHT TONIGHT. IT WILL BE A WARM NIGHT AS TEMPERATURES ARE NOT EXPECTED TO GET MUCH LOWER THAN THE LOWER 70S. && .SHORT TERM /WEDNESDAY AND THURSDAY NIGHT/... AS OF 255 PM TUESDAY... BOTH THE NAM AND THE GFS FORECAST A MODEST BUT WEAKENING MID-LEVEL SHORTWAVE MOVING THROUGH CENTRAL NORTH CAROLINA WEDNESDAY...FOLLOWED BY ANOTHER MID-LEVEL WAVE WEDNESDAY NIGHT. ADVECTION OF K INDICES CONTINUES OVERNIGHT...WITH VALUES AT OR ABOVE 30 ACROSS CENTRAL NORTH CAROLINA FOR THE DAY WEDNESDAY. THE SOUTHWEST FLOW ALOFT THAT OCCURS OVER CENTRAL NORTH CAROLINA AS THE MID-LEVEL TROUGH SHARPENS TO OUR WEST SHOULD KEEP MOISTURE IN PLACE THROUGH AND BEYOND THIS PERIOD...WITH PERIODS OF LIFT IN ASSOCIATION WITH MID-LEVEL FORCING...A SURFACE TROUGH...AND THE APPROACHING FRONT FROM THE NORTHWEST FOR ISOLATED-TO-SCATTERED SHOWERS AND THUNDERSTORMS. NAM AND GFS BUFR SOUNDINGS ARE SOMEWHAT MOIST IN CENTRAL NORTH CAROLINA WEDNESDAY INTO WEDNESDAY NIGHT...MOST SO TOWARD THE TRIAD AND LEAST SO TOWARD KFAY. CHANCES FOR PRECIPITATION WEDNESDAY WILL BE GRADUATED AS SUCH...HIGHEST IN THE NORTHWEST PIEDMONT AND TOWARD THE VIRGINIA BORDER...LEAST IN THE SOUTHERN COASTAL PLAIN. BY WEDNESDAY NIGHT...WITH FORECAST LIFT AND INSTABILITY SHIFTING EAST...SIMILAR CHANCES FOR SHOWERS AND THUNDERSTORMS WILL EXIST ACROSS CENTRAL NORTH CAROLINA...HIGHEST NORTHEAST CLOSER TO THE SURFACE BOUNDARY. 1000-500MB LAPSE RATES ARE NOT VERY STRONG NORTH AND NORTHWEST OF THE TRIANGLE...ONLY FORECAST BY THE GFS TO JUST UNDER 6C/KM. FARTHER SOUTH...WHERE THERE IS POTENTIAL FOR BETTER HEATING...THOSE LAPSE RATES ARE NEAR 7C/KM. IT MAY BE OVER THE NORTHEAST PIEDMONT AND THE NORTHERN COASTAL PLAIN...WHERE THE BEST COMBINATION OF 0-3KM SHEAR...INSTABILITY...MOISTURE...AND LIFT RESIDE WEDNESDAY AFTERNOON...WHERE THE STRONGER STORMS MAY OCCUR. THE ARW WRF SUGGESTS THIS...BUT NOT CONFIDENT ENOUGH AT THIS TIME TO BE THAT SPECIFIC IN THE HAZARDOUS WEATHER OUTLOOK. SPC DAY TWO OUTLOOK SHOWS A FIVE PERCENT OUTLOOK FOR ALL OF CENTRAL NORTH CAROLINA FOR WEDNESDAY...AND WILL RETAIN THE CURRENT WORDING IN THE HWO. SREF GUIDANCE AND BUFR SOUNDINGS SUGGEST GOOD POTENTIAL FOR DECENT CLOUD COVER FOR MUCH OF WEDNESDAY IN THE NORTHWEST PIEDMONT...AND HIGH TEMPERATURES ON WEDNESDAY WILL HAVE A GRADIENT FROM THE MID TO UPPER 80S OVER THE IMMEDIATE TRIAD TO AROUND 95 TOWARD KFAY. SURFACE WINDS SHOULD GUST TO AROUND 20KT AT TIMES TOWARD KFAY WEDNESDAY IN BETTER HEATING...WITH LESSER GUSTS OUTSIDE OF ANY DEEP CONVECTION ELSEWHERE. OVERNIGHT LOWS WEDNESDAY NIGHT 68 TO 74. && .LONG TERM /FRIDAY THROUGH TUESDAY/...
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AS OF 310 AM WEDNESDAY... FRIDAY THROUGH SUNDAY NIGHT: THE WEAK MID LEVEL TROUGH IS EXPECTED TO PUSH TO THE EAST OF CENTRAL NC LATE FRIDAY AFTERNOON/EVENING... WITH THE WEAK SURFACE TROUGH STALLING ACROSS THE COASTAL PLAIN LATE FRIDAY AFTERNOON/EVENING. BEHIND THE MID LEVEL TROUGH... WE SHOULD SEE DRIER MID/UPPER LEVEL AIR. THUS... WILL LOWER POPS IN THE WEST/NORTHWESTERN PIEDMONT TO SLIGHT CHANCE FRIDAY. EXPECT THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS THE COASTAL PLAIN AND SANDHILLS (WHERE THE BEST INSTABILITY AND WEAK SURFACE CONVERGENCE WILL BE DURING THE AFTERNOON... AND BETTER MOISTURE AS MENTIONED ABOVE). DEEP LAYER SHEAR LOOKS TO BE LESS THAN 20 KTS WHERE THE BEST INSTABILITY IS EXPECTED (ACROSS COASTAL PLAIN/SANDHILLS) FRIDAY AFTERNOON/EVENING. THUS... EXPECT ANY SEVERE THREAT WILL BE QUITE MARGINAL AT BEST. HOWEVER... EXPECT WE COULD SEE SOME ISOLATED STRONG TO SEVERE STORMS... WITH THE MAIN THREAT FROM DAMAGING DOWNBURST WINDS. GIVEN THE LINGERING HIGH PW`S ACROSS OUR EASTERN COUNTIES... A LOCALIZED FLASH FLOODING THREAT CANNOT BE RULED OUT... ESPECIALLY WITH A FAIRLY WEAK STEERING FLOW. EXPECT HIGH TEMPS WILL GENERALLY BE IN THE UPPER 80S... WITH PERHAPS EVEN A FEW MID 80S ACROSS OUR FAR EAST WHERE CLOUDS/SCATTERED CONVECTION WILL HELP LIMIT INCOMING SOLAR RADIATION. ANY LINGERING CONVECTION LATE FRIDAY EVENING SHOULD GENERALLY PUSH TO THE EAST/SOUTHEAST OF THE AREA AND/OR DISSIPATE WITH THE LOSS OF HEATING. LOWS SATURDAY MORNING ARE EXPECTED TO BE IN THE UPPER 60S TO LOWER 70S. MID LEVEL FLOW WILL BECOME MORE NORTHWESTERLY TO WEST-NORTHWESTERLY OVER THE WEEKEND... WITH THE POTENTIAL OF UPSTREAM CONVECTION/MCV`S TO TRACK ACROSS CENTRAL NC. THE LATEST GUIDANCES HAS SHIFTED THE MORE ACTIVE DAY TO SUNDAY NOW... AS THE MID/UPPER LEVEL TROUGH BEGINS TO AMPLIFY ACROSS THE UPPER MIDWEST/NORTHERN PLAINS AND GREAT LAKES REGION. GIVEN SUCH DISTURBANCES IN NORTHWEST FLOW ARE HARD TO TRACK WILL LIMIT POPS TO LOW END CHANCE FOR THE WEEKEND... HIGHEST ON SUNDAY. LOW LEVEL THICKNESS VALUES ARE EXPECTED TO SLOWLY INCREASE THIS WEEKEND. THIS WILL RESULT IN HIGH TEMPS IN THE UPPER 80S TO LOWER 90S SATURDAY TO THE LOWER 90S SUNDAY (TO PERHAPS EVEN SOME MID 90S ACROSS THE SOUTH). LOW TEMPS ARE EXPECTED TO GENERALLY BE AROUND 70/LOWER 70S. MONDAY AND TUESDAY: A DEEP TROUGH IS EXPECTED TO DEVELOP ACROSS THE EASTERN HALF OF THE COUNTRY EARLY NEXT WEEK. THIS SHOULD RESULT IN THE INCREASING LIKELIHOOD OF SHOWERS AND STORMS EARLY NEXT WEEK AS A SURFACE COLD FRONT APPROACHES THE REGION FROM THE NORTHWEST... POSSIBLY MOVING INTO THE AREA ON TUESDAY. GIVEN WE ARE TALKING ABOUT DAY 6 AND 7 OF THE FORECAST WILL LIMIT POPS TO THE 30-40 PERCENT RANGE FOR NOW. AFTERNOON LOW LEVEL THICKNESS VALUES ARE PROGGED TO INCREASE TO AROUND 1430 METERS DURING THIS TIME. THIS WOULD SUPPORT AT LEAST HIGH TEMPS IN THE LOWER TO MID 90S... WITH PERHAPS SOME UPPER 90S. FOR NOW WILL LIMIT HIGH TEMPS TO THE LOWER 90S... TO A FEW MID 90S ACROSS THE SOUTH.... GIVEN THE INCREASED CHANCES FOR SHOWERS AND STORMS. LOWS DURING THE PERIOD ARE EXPECTED TO BE IN THE LOWER 70S... WITH EVEN SOME MID 70S POSSIBLE.
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&& .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 125 AM WEDNESDAY... VFR CONDITIONS WILL GENERALLY PERSIST THROUGH 18Z. AFTER 18Z...A SERIES OF UPPER LEVEL DISTURBANCES COUPLED WITH A SLOWLY WEAKENING SURFACE COLD FRONT WILL INCREASE THE THREAT FOR SCATTERED CONVECTION ACROSS CENTRAL NC. BETWEEN 20Z AND 01Z...THE THREAT FOR SCATTERED CONVECTION AND ASSOCIATED MVFR/IFR CEILINGS AND VISIBILITIES WILL BE GREATEST ON VICINITY OF THE TRIAD TERMINALS AS WELL AS KRDU. IN VICINITY OF THE STRONGER CONVECTION...WIND GUSTS UP TO 40KTS PROBABLE. THE ATMOSPHERE WILL REMAIN UNSETTLED TONIGHT THROUGH THURSDAY NIGHT AS THE SURFACE COLD FRONT GRADUALLY DRIFTS SEWD ACROSS THE REGION AND THE SERIES OF DISTURBANCES LIFT ACROSS THE REGION. WHILE CONVECTIVE COVERAGE AND INTENSITY WILL DWINDLE OVERNIGHT...ISOLATED TO SCATTERED SHOWERS AND T-STORMS WILL STILL OCCUR WELL PAST MIDNIGHT. THE CONVECTIVE ACTIVITY IS EXPECTED TO REACH ITS PEAK COVERAGE THURSDAY AFTERNOON AND EVENING WHEN SHOWERS AND THUNDERSTORMS ARE EXPECTED TO BE NUMEROUS. BETTER AVIATION CONDITIONS ANTICIPATED FRIDAY THROUGH SATURDAY AS A SLIGHTLY DRIER MORE STABLE AIR MASS ENCOMPASSES MOST OF THE REGION. SCATTERED AFTERNOON-EARLY EVENING CONVECTION WILL STILL BE PROBABLE IN VICINITY OF KFAY AND KRWI WHERE AVAILABLE MOISTURE AND LOW LEVEL INSTABILITY WILL BE BEST. BY SUNDAY...REMNANTS OF DECAYING THUNDERSTORM COMPLEXES ORIGINATING IN THE MIDWEST MAY BEGIN TO AFFECT CENTRAL NC...LEADING TO A BETTER CHANCE FOR SCATTERED CONVECTION AND ASSOCIATED MVFR CONDITIONS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...ELLIS SHORT TERM...DJF LONG TERM...BSD AVIATION...WSS

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