Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 030802 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 400 AM EDT TUE MAY 3 2016 .SYNOPSIS...
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LOW PRESSURE WILL MOVE OFF THE MIDDLE ATLANTIC COAST EARLY TODAY. A SECONDARY WAVE OF LOW PRESSURE WILL DEVELOP ALONG THE TRAILING COLD OVER NC THIS AFTERNOON AND EVENING...BEFORE MOVING SLOWLY TO THE COAST AND OFFSHORE LATE TONIGHT AND WED.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 400 AM TUESDAY... AN AREA OF LOW PRESSURE NOW OVER MD WILL MOVE OFFSHORE EARLY TODAY. A SECONDARY LOW WILL DEVELOP OVER SOUTHERN VA/CENTRAL NC ALONG A TRAILING LEE SURFACE TROUGH AND SYNOPTIC COLD FRONT THAT WILL STRETCH THROUGH THE WESTERN CAROLINAS THIS AFTERNOON...IN RESPONSE TO HEIGHT FALLS /INCREASING LARGE SCALE FORCING FOR ASCENT/ ACCOMPANYING A POSITIVELY-TILTED TROUGH EVOLVING FROM SOUTHEAST CANADA TO THE CENTRAL PLAINS. SHOWERS AND A COUPLE OF ISOLATED MINI-SUPERCELLS OVER BOTH DILLON AND SUMTER COUNTY SC --ON THE LEAD OUTFLOW BOUNDARY AND IN A HSLC ENVIRONMENT CHARACTERIZED BY STRONG LOW LEVEL SHEAR /35 KTS OF 0-1 KM BULK AND 200-250 M2/S2 EFFECTIVE SRH/ AND AMIDST 35-40 KTS OF MID LEVEL FLOW PER REGIONAL VWP DATA...WILL MOVE NORTHEAST ACROSS EAST- CENTRAL NC DURING THE NEXT SEVERAL HOURS. ASSOCIATED MESO-VORTICES WILL BE CAPABLE OF PRODUCING LOCALLY DAMAGING WIND GUSTS AND/OR A WEAK TORNADO AS THEY TRACK NORTHEAST ACROSS CUMBERLAND/SAMPSON/WAYNE COUNTIES THROUGH AROUND 11Z. A COMPOSITE OUTFLOW BOUNDARY FROM WIDESPREAD CONVECTION FROM THE DELMARVA TO WESTERN NC WILL LIKELY INTERCEPT THE STORMS AND SERVE AS THE NORTHERN BOUND FOR THE SEVERE THREAT. OTHERWISE...PERSISTENT ANA-EFFECTIVE FRONTAL RAIN ON THE COOL SIDE OF THE OUTFLOW(S)...AT TIMES MODERATE TO HEAVY...MAY LEAD TO VERY LOCALIZED FLOODING. ALL OF THIS ACTIVITY SHOULD MOVE NORTHEAST OF CENTRAL NC WITH THE PASSAGE OF THE PARENT MID LEVEL DISTURBANCE NOW CROSSING EASTERN GA/WESTERN SC...BETWEEN 12-15Z. MUCH LIKE PREVIOUS DAYS...THE ATMOSPHERE WILL THEN DESTABILIZE WITH PARTIAL SUNSHINE...AND RISING TEMPERATURES TO NEAR 80 DEGREES...IN THE WAKE OF THE EARLY MORNING ACTIVITY...AND CONSEQUENTLY SET THE STAGE FOR THE RE-DEVELOPMENT OF SCATTERED TO NUMEROUS STORMS THAT WILL DEVELOP OVER WEST-CENTRAL NC - ALONG THE AFOREMENTIONED LEE SURFACE TROUGH AND/OR SYNOPTIC COLD FRONT. THESE STORMS WILL THEN CROSS CENTRAL NC THIS AFTERNOON AND EVENING. MID LEVEL FLOW AND ASSOCIATED EFFECTIVE SHEAR WILL STEADILY INCREASE FROM THE WEST INTO THE 40-60 KT RANGE WITH THE APPROACH OF THE AFOREMENTIONED UPPER TROUGH. THE CHARACTER OF THE STRONG SHEAR...INDICATED BY LONG/STRAIGHT HODOGRAPHS FROM THE SFC-6 KM...WILL FAVOR SPLITTING SUPERCELLS - ONES CAPABLE OF PRODUCING LARGE HAIL (SOME POSSIBLY VERY LARGE) AND WESTERLY WIND GUSTS UP TO 60-70 KTS. THE FRONTAL ZONE AND EMBEDDED WAVE OF LOW PRESSURE...AND ASSOCIATED DEEP MOISTURE AND SHOWERS...WILL MOVE GRADUALLY EAST OVERNIGHT... WITH JUST A LINGERING SLIGHT-LOW CHANCE OF SHOWERS EAST OF I-95 BY WED MORNING. DRY ELSEWHERE. COOLER WITH LOWS IN THE MID-UPPER 50S.
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&& .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 345 PM MONDAY... APPEARS HIGHLY LIKELY THAT ANOTHER ROUND OF CONVECTION WILL AFFECT CENTRAL NC TUESDAY AFTERNOON AND TUESDAY NIGHT WITH POTENTIAL FOR A FEW SEVERE STORMS. MAIN FOCUS FOR CONVECTIVE DEVELOPMENT WILL LIKELY BE ALONG AND EAST OF HIGHWAY 1 WHERE REMNANT OUTFLOWS FROM TONIGHT`S CONVECTION SHOULD RESIDE. ALSO...CONVECTION MAY NOT DEVELOP UNTIL VERY LATE IN THE DAY OR DURING THE EVENING HOURS AS BETTER SUPPORT ALOFT CROSSES OUR REGION AT THAT TIME. BULK SHEAR COULD BE AS HIGH AS 45-50KTS TUESDAY AFTERNOON WITH MLCAPE AROUND 1000 J/KG. THIS SUGGEST POTENTIAL FOR BROKEN BANDS OF STRONG STORMS WITH BOWING SEGMENTS. THOSE CELLS WITH STRONG/SUSTAINED UPDRAFTS COULD PRODUCE LARGE HAIL. CAVEAT TO THIS IS THAT THERE IS A POSSIBILITY THAT LINGERING/DIMINISHING SHOWERS FROM CONVECTION TONIGHT MAY PERSIST OVER THE EASTERN COUNTIES TUESDAY MORNING. THIS WILL INITIALLY INHIBIT THE ATMOSPHERE FROM DESTABILIZING UNTIL LATE N THE DAY. SIMILAR TO CONCERNS FOR TODAY...SHOWERS/STORMS WILL BE EFFICIENT RAIN PRODUCERS...LEADING TO LOCALLY HEAVY/EXCESSIVE RAINFALL. FOR TUESDAY/TUESDAY...WILL HAVE HIGHEST POPS ALONG AND EAST OF HIGHWAY 1 THOUGH A DECENT CHANCE FOR CONVECTION WILL STILL EXIST IN THE WEST. SIMILAR TO TONIGHT... EXPECT CONVECTION TO PERSIST WELL INTO TUESDAY NIGHT AS A SLOW MOVING COLD FRONT APPROACHES AND EVENTUALLY ENTERS THE AREA. MAX TEMPS TUESDAY DEPENDENT UPON THE EXTENT OF CLOUDS/REMNANT SHOWERS IN THE MORNING. BELIEVE THAT THERE WILL BE SOME EXTENSIVE CLOUDINESS THROUGH 9 AM...THEN LOW CLOUDS SHOULD LIFT/DISSIPATE THEREAFTER. MAX TEMPS TUESDAY MID 70S NW TO AROUND 80 EAST. MIN TEMPS TUESDAY NIGHT MID-UPPER 50S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 220 PM MONDAY... THE MAIN WEATHER STORY IN THIS PERIOD WILL BE A CLOSED LOW PROGGED TO DROP SOUTH ACROSS THE GREAT LAKES ON WEDNESDAY AND MOVE ACROSS THE CAROLINAS ON THURSDAY INTO EARLY FRIDAY. THE MAIN IMPACT OF THIS PATTERN WILL BE BELOW NORMAL TEMPS THURSDAY THROUGH FRIDAY MORNING...BEFORE THE AIRMASS REBOUNDS AS THE TROUGH DEPARTS TO OUR EAST ON FRIDAY. IN TERMS OF PRECIP CHANCES...LOOK FOR THE BEST CHANCE FOR RAIN WEDNESDAY NIGHT WITH THE PASSAGE OF THE SFC COLD FRONT (AS THE UPPER TROUGH IS DIVING SOUTHWARD ACROSS THE OHIO VALLEY)...AND THURSDAY AFTERNOON INTO EARLY FRIDAY AS THE UPPER TROUGH MOVES ACROSS OUR AREA. FOR THIS WEEKEND INTO MONDAY...RIGHT NOW FAIR WEATHER STILL APPEARS TO BE ON TRACK FOR THIS WEEKEND...ALTHOUGH WE`LL HAVE TO KEEP OUR EYES ON A COUPLE WEAK SHORT WAVES EMBEDDED IN THE NW FLOW ON THE BACK SIDE OF THE AFOREMENTIONED TROUGH...AS THESE FEATURES COULD BRIEFLY INCREASE THE CLOUDS ACROSS OUR AREA...AND PERHAPS BRING A FAST-MOVING AND BRIEF SHOWER OR TWO. TEMPS NEAR TO SLIGHTLY ABOVE NORMAL. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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AS OF 230 AM TUESDAY... AN AREA OF SHOWERS AND ISOLATED STORMS OVER SC --AND PARENT MID LEVEL DISTURBANCE-- WILL LIFT NORTHEAST AND INTERACT WITH A LINE OF SHOWERS AND TRAILING RAIN NOW SETTLING SOUTHEAST ACROSS CENTRAL NC. THE RESULT WILL BE WIDESPREAD SHOWERS/RAIN...AND ASSOCIATED SUB-VFR CONDITIONS THROUGHOUT CENTRAL NC THIS MORNING. THIS REGIME WILL MOVE NORTHEAST AND OUT OF CENTRAL NC...WITH A RETURN TO DRY VFR CONDITIONS...GENERALLY BETWEEN 12-16Z. MUCH LIKE PREVIOUS DAYS...THE ATMOSPHERE WILL DESTABILIZE WITH PARTIAL SUNSHINE IN THE WAKE OF THE EARLY MORNING ACTIVITY...AND CONSEQUENTLY SET THE STAGE FOR THE RE-DEVELOPMENT OF SCATTERED TO NUMEROUS STORMS THAT WILL CROSS CENTRAL NC THIS AFTERNOON AND EVENING. LARGE HAIL...INCLUDING SOME POSSIBLY VERY LARGE...AND WESTERLY WIND GUSTS UP TO 60-70 KTS --IN SPLITTING SUPERCELLS-- WILL POSE AN ADDED RISK BEYOND TYPICAL SUB-VFR CONDITIONS IN SHRA/TSRA. DESPITE THE LIKELIHOOD OF OCCURRENCE OF SUCH STORMS AND CONDITIONS OVER NC...THE ASSOCIATED PROBABILITY OF SUCH OCCURRENCES AT ANY GIVEN POINT/TAF SITE IS TOO LOW TO INCLUDE IN THE TAFS...AT LEAST UNTIL STORMS ULTIMATELY DEVELOP. MULTIPLE SLOW-MOVING WAVES OF LOW PRESSURE ARE FORECAST TO DEVELOP IN THE VICINITY OF THE MIDDLE ATLANTIC COAST MID-LATE WEEK...WITH ASSOCIATED SUB-VFR CEILINGS AND SHOWERS/STORMS THAT WILL GROW IN COVERAGE AND INTENSITY WITH HEATING EACH AFTERNOON - ESPECIALLY AT EASTERN TAF SITES.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...26 SHORT TERM...WSS LONG TERM...RAH AVIATION...26

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