Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 052015 RRA AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 415 PM EDT TUE MAY 5 2015 .SYNOPSIS...BERMUDA HIGH PRESSURE WILL EXTEND INTO OUR REGION THROUGH MID WEEK. AN AREA OF LOW PRESSURE WILL FORM NEAR THE BAHAMAS AND MEANDER OFF THE SOUTHEAST COAST DURING THE MIDDLE OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 PM TUESDAY... HIGH PRESSURE WILL CONTINUE TO RIDGE WESTWARD INTO CENTRAL NC...EVEN AS THE HIGH SHIFTS OFFSHORE. SKIES WILL GENERALLY BE CLEAR...WITH SOME INCREASING CLOUDS IN THE FAR SOUTHEAST TOWARD DAYBREAK WEDNESDAY. EXPECT WINDS TO BECOME LIGHT AND VARIABLE OVERNIGHT. MILD LOWS TONIGHT...MAINLY IN THE MID TO UPPER 50S. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 240 PM TUESDAY... A WEAK SURFACE TROUGH WILL STALL TO THE NORTH ON WEDNESDAY NIGHT... WITH HIGH PRESSURE OVER THE NE U.S. AND OFF THE CAROLINA COAST. THE BIGGER FEATURE WILL BE THE CLOSED LOW DEVELOPING OFF THE EAST FLORIDA COAST...WHICH IS EXPECTED TO MOVE NORTH-NORTHEAST TOWARD THE CAROLINAS THROUGH WEDNESDAY NIGHT. FOR NOW...IT APPEARS THAT THE SYSTEM WILL STAY TO THE SOUTH THROUGH WEDNESDAY NIGHT...WITH THE MAIN IMPACT OVER CENTRAL NC BEING INCREASING CLOUDINESS FROM THE SE AND AN INCREASE IN AFT/EVE WINDS. THERE IS A SLIGHT CHANCE FOR SOME SHOWERS/STORMS TO DEVELOP IN THE AFT/EVE ALONG THE STALLED BOUNDARY TO THE NORTH...BUT EXPECT MOST OF THE ACTIVITY TO STAY TO THE NORTH AND NORTHWEST OF CENTRAL NC. WITH LITTLE TO NO CHANGE IN AIRMASS... AND BERMUDA HIGH PRESSURE CONTINUING TO RIDGE INTO THE AREA... EXPECT HIGHS IN THE LOW TO MID 80S. WITH THE INCREASING CLOUDS OVERNIGHT AND SOME WEAK WAA...LOWS WILL BE A FEW DEGREES WARMER THAN PREVIOUS NIGHTS...MAINLY IN THE UPPER 50S. && .LONG TERM /THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
AS OF 415 PM TUESDAY... THE MAIN FORECAST PROBLEM THROUGH THE PERIOD REMAINS THE EVOLUTION OF AN AREA OF LOW PRESSURE...WITH POSSIBLE SUB-TROPICAL CHARACTERISTICS...FORECAST TO FORM NEAR THE BAHAMAS AND DRIFT NEAR THE SOUTHEAST US COAST THROUGH THE END OF THE WEEK. WHILE TWO MODEL CAMPS REMAIN...WITH SOLUTIONS RANGING FROM THE NCEP ONES ON THE WESTERN SIDE OF THE GUIDANCE ENVELOPE TO MORE EASTERN ONES DEPICTED BY THE NON-NCEP MODELS...THE SPREAD HAS SIGNIFICANTLY DECREASED IN THE PAST 24 HOURS. THE DECREASING MODEL SPREAD RESULTS FROM A WESTWARD SHIFT IN THE NON-NCEP GUIDANCE...INCLUDING THE 12Z OP ECMWF...WHICH YIELDS RELATIVE INCREASED FORECAST CONFIDENCE IN A CLOSER TO THE CAROLINAS COAST MEANDER OF THE LOW THROUGH THE WEEKEND. HOWEVER...NO SOLUTION IS TRULY OFF THE TABLE...SINCE THE STEERING FLOW FOR THE LOW IS FORECAST TO BECOME QUITE WEAK ON THE SOUTHERN PERIPHERY OF A PERSISTENT RIDGE ALOFT OVER THE EAST COAST. IN FACT...THE RIDGE...IN CONJUNCTION WITH AN ELONGATED UPPER LOW ANALYZED THIS MORNING FROM THE SE STATES TO THE YUCATAN CHANNEL...WILL FAVOR THE DEVELOPMENT OF AT LEAST A BRIEF REX BLOCK...WHICH WOULD INDEED FAVOR SLOW AND ERRATIC MOTION OF ANY CYCLONE TRAPPED WITHIN IT. IT WILL LIKELY TAKE A KICKER SHORTWAVE TROUGH TO MIGRATE SLOWLY FROM THE PAC NW TODAY TO THE MS VALLEY EARLY NEXT WEEK TO FINALLY CAUSE THE LOW TO LIFT NE AND AWAY FROM THE NC/VA COASTS EARLY NEXT WEEK. WILL FOLLOW THE WPC-PREFERRED "COMPROMISE" SOLUTION BETWEEN THE TWO MODEL CAMPS INDICATED ABOVE...BEST ILLUSTRATED BY A 12Z GFS/EC BLEND...WHOSE RESPECTIVE MASS FIELDS ARE REALLY NOT TOO DISSIMILAR. THE RESULTANT SENSIBLE WEATHER IMPACTS WILL BE INCREASING CLOUDS AND PROBABILITY OF PRECIPITATION FROM THE SOUTH AND EAST BY LATE THU...WITH THE LATTER PROBABILITIES RANGING FROM CHANCE OVER THE COASTAL PLAIN AND EASTERN SANDHILLS TO SLIGHT CHANCE OVER THE PIEDMONT. WITH THE LOW NEARBY AND FORECAST TO MOVE LITTLE...LIKELY JUST TO THE SOUTH AND EAST OF CENTRAL NC...A PERSISTENCE FORECAST OF SIMILAR POP DISTRIBUTION -HIGHEST CHANCES SE AND LOWEST NW- WILL BE HARD TO BEAT THROUGH THE WEEKEND. PROVIDED THE TIMING OF THE KICKER WAVE REMAINS CONSISTENT...MON MAY BE THE RELATIVE DRIEST DAY OF THE PERIOD IN BRIEF SUBSIDENCE BEHIND THE LOW AND IN ADVANCE OF THE FRONTAL SYSTEM ASSOCIATED WITH THE KICKER WAVE...FORECAST TO ARRIVE ON SUN. TEMPERATURES HAVE BEEN ADJUSTED DOWNWARD...INTO THE 70S MAINLY OVER EASTERN AREAS...GIVEN THE EXPECTATION OF MORE CLOUDS AND HIGHER PRECIPITATION CHANCES WITH THE MORE WESTWARD FORECAST SOLUTIONS FOR THE LOW. IF THE LOW WERE TO STAY OFFSHORE AND FARTHER SE OF NC...THE AIR MASS WOULD SUPPORT LOWER TO MIDDLE 80S...AND SOME UPPER 80S PROBABLE BY TUE.
-- End Changed Discussion --
&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 115 PM TUESDAY... 24-HOUR TAF PERIOD: HIGH CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD AS BERMUDA HIGH PRESSURE RIDGES INTO THE CAROLINAS. WINDS WILL BE GENERALLY SOUTHWESTERLY AT 5-10 KTS THIS AFT/EVE...DECREASING TO 5 KTS OR LESS AND BECOMING VARIABLE OVERNIGHT. A FEW MID TO HIGH CLOUDS MAY DEVELOP DURING THE AFTERNOON HOURS...CLEARING OVERNIGHT. WINDS WILL BECOME MORE SOUTHERLY TO SOUTHEASTERLY ON WEDNESDAY. LOOKING AHEAD: THE BIGGEST AVIATION IMPACT WILL COME LATER IN THE WEEK OR INTO THE WEEKEND AS AN AREA OF LOW PRESSURE DEVELOPS OFF THE SOUTHEAST U.S. COAST. MODELS STILL DIFFER ON THE TRACK/LOCATION AND TIMING OF THIS SYSTEM AS IT PROGRESSES NORTHWARD...THUS CONDITIONS BEYOND THURSDAY STILL REMAIN FAIRLY UNCERTAIN. EVEN IF THE SYSTEM REMAINS OFFSHORE...ENHANCED EASTERLY ONSHORE FLOW COULD YIELD AN INCREASED THREAT FOR MORNING STRATUS/FOG. SHOULD THE SYSTEM MOVE ONSHORE...THERE WOULD BE AN INCREASED CHANCE FOR RAIN...STRONG WINDS...AND REDUCED AVIATION CONDITIONS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RAH NEAR TERM...RAH SHORT TERM...RAH LONG TERM...RAH AVIATION...RAH

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.