Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 261801 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 201 PM EDT TUE MAY 26 2015 .SYNOPSIS...
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THE WESTERN EXTENT OF BROAD SURFACE HIGH PRESSURE...AND A SEASONABLY MOIST AIR MASS...WILL PREVAIL OVER THE REGION FOR THE WORK WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/... AS OF 1030 AM TUESDAY... THE LATEST UPPER-AIR ANALYSIS SHOWED THE WEST PART OF RIDGING SURFACE AND ALOFT OVER THE CAROLINAS...AND THE LATEST SATELLITE WATER VAPOR IMAGES SHOWS AMPLE MID-LEVEL DRY AIR ALONG THE CAROLINA COAST. DURING THE MORNING...THE SPC MESOANALYSIS HAS SHOWN A GRADUAL INCREASE IN PRECIPITABLE WATER VALUES OVER AND EAST OF THE COASTAL PLAIN...IN CONCERT WITH THE RAP WHICH FORECASTS OVERALL PRECIPITABLE WATER VALUES OF AROUND 1.5 INCHES OVER CENTRAL NORTH CAROLINA BY 00Z. WHILE FORECAST SOUNDINGS ARE FAIRLY STABLE...THE RAP DOES FORECAST AFTERNOON MLCAPE IN THE LOWEST 3KM TO 500J/KG OR LESS. 850MB LIFT IS GREATEST TOWARD KFAY AND KCTZ EARLY THIS AFTERNOON... WHERE THE LATEST REGIONAL RADAR IMAGES SHOW ISOLATED TO SCATTERED SHOWERS NEAR AND JUST NORTH OF KILM. THE HRRR WRF GUIDANCE IS DOING WELL WITH THIS MODEST CONVECTION...AND DESPITE ONLY MODEST INSTABILITY...IN THE MOISTURE ADVECTION THE HRRR WRF DOES SHOW MOSTLY ISOLATED SHOWERS SLOWLY MOVING NORTH ACROSS THE KFAY AND KCTZ AREAS TO NEAR KRDU AND KRWI BY LATE IN THE DAY. FARTHER WEST...RAP SOUNDINGS SHOW DECENT CIN THROUGH MUCH OF THE DAY...AND ANY ISOLATED SHOWER OR STORM MAY HOLD OFF AS WELL UNTIL VERY LATE IN THE DAY GIVEN THE WEAK LIFT AND LIMITED FORCING. HIGH TEMPERATURES IN THE MID TO UPPER 80S WITH A FEW WIND GUSTS IN THE TEENS KNOTS WITH MIXING DURING THE DAY...925MB AND 850MB WINDS TO 15KT. CONVECTION SHOULD BE LARGELY DIURNALLY DRIVEN...BUT WILL KEEP A SLIGHT CHANCE ACROSS THE WESTERN PIEDMONT OVERNIGHT WHERE THE POTENTIAL FOR GLANCING SHOT DPVA ATTENDANT TO UPPER DISTURBANCES IS HIGHEST. LOWS IN THE MID TO UPPER 60S. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 300 AM TUESDAY... MODELS GENERALLY AGREE THAT THE MID/UPPER LEVEL RIDGE MAY WEAKEN A BIT WHILE DRIFTING EVER SO SLIGHTLY EASTWARD OVER THE WESTERN ATLANTIC. FACTORS CONTRIBUTING TO RAIN CHANCES TODAY(DAYTIME HEATING AND RESULTANT DESTABILIZATION...POTENTIAL FOR SHORTWAVE DISTURBANCES ALOFT...AND SEABREEZE BOUNDARY) WILL ESSENTIALLY GOVERN RAIN CHANCES AGAIN ON WEDNESDAY...BUT PERHAPS WITH MORE EQUITABLE RAIN CHANCES EASTWARD INTO CENTRAL PIEDMONT. HIGHER RAIN CHANCES AND CLOUD COVER MAY KNOCK A DEGREE OR TWO OFF OF DAYTIME HIGHS. HIGHS IN THE LOWER/80S NORTHWEST TO MID/UPPER 80S SOUTHEAST. LOWS IN THE MID/UPPER 60S. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 320 AM TUESDAY... STRONG UPPER LEVEL RIDGING ALONG THE SOUTHEAST COAST SHOWS SOME SIGNS OF WEAKENING BY THURSDAY BUT IS STILL STRONG ENOUGH TO DEFLECT THE SHORTWAVE CURRENTLY OVER THE CENTRAL PLAINS NORTH TOWARD THE GREAT LAKES AND KEEP THE ASSOCIATED FRONTAL ZONE TO OUR NORTHWEST. THOUGH FORCING OVER CENTRAL NC WILL BE WEAK ON THURSDAY...A WEAK REMNANT SHEAR AXIS AMIDST PW OVER 1.5 INCHES AND 600 TO 1200 J/KG OF MLCAPE...HIGHEST OVER THE WESTERN PIEDMONT...SHOULD LEAD TO INCREASED...THOUGH STILL SCATTERED COVERAGE OF AFTERNOON SHOWERS/STORMS. SHEAR WILL BE WEAK WITH THE UPPER TROUGH AND STRONGEST WESTERLIES WELL WEST OF THE MOUNTAINS...SO SEVERE STORMS WILL BE LIMITED. THE UPPER RIDGE THEN LOOKS TO BUILD BACK SLIGHTLY FRIDAY INTO THE WEEKEND WITH A LITTLE DRIER AIR ACTUALLY FORECAST TO FILTER IN FROM THE EAST ON FRIDAY. THUS EXPECT MAINLY ISOLATED SHOWERS AND STORMS FRIDAY AND SATURDAY AS THE AIRMASS SLOWLY RE-MOISTENS THROUGH THE WEEKEND. ANOTHER SHORTWAVE AND COLD FRONT ARE FORECAST TO MOVE INTO THE MIDWEST STATES EARLY NEXT WEEK...AND WHILE IT IS UNCERTAIN WHETHER THAT FRONT WILL MAKE IT ALL THE WAY INTO NC AS WELL...THE CHANCES OF CONVECTION WILL INCREASE FROM NORTH TO SOUTH SUNDAY THROUGH TUESDAY. THICKNESSES ARE PROJECTED TO BE NEARLY UNCHANGED THROUGH THE PERIOD...WITH HIGHS MOSTLY IN THE MID TO UPPER 80S NEARLY EVERYDAY...WITH SOME AREAS IN THE SOUTH REACHING 90 ON SATURDAY. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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AS OF 200 PM TUESDAY... FOR THE 18Z VALID TAF PERIOD...VFR CONDITIONS OUTSIDE OF ANY MOSTLY ISOLATED...DEEP CONVECTION SHOULD PERSIST THROUGH MUCH OF TONIGHT. AS OF THIS WRITING...ISOLATED TO SCATTERED SHOWERS WERE NOTED TOWARD KCTZ...AND DURING THIS EVENING WITH A WEAK SHORTWAVE MOVING NORTH OVER THE WESTERN CAROLINAS...ISOLATED TO SCATTERED SHOWERS MAY OCCUR MORE TOWARD THE TRIAD. THERE EXISTS A MODEST PROBABILITY OF IFR CONDITIONS IN LOW CLOUDS OVERNIGHT. SREF MODEL PROBABILITIES OF SUCH ARE HIGH ESPECIALLY WEST OF INTERSTATE 95...HOWEVER...THE STATISTICAL GUIDANCE IS NOT AS BULLISH AND MODEL SOUNDINGS FROM THE GFS AND NAM DIFFER AS TO THE POTENTIAL OF LOW CLOUDS LATE. SINCE LOW CLOUDS OCCURRED MAINLY TOWARD THE YADKIN RIVER AND THE TRIAD EARLY THIS MORNING...THE OVERALL AIR MASS HAS MOISTENED...AND 925MB WINDS SHOULD BE FAVORABLE OVERNIGHT...HAVE FORECAST IFR CONDITIONS BY 10Z IN THE TRIAD AND AT KRDU...WITH TEMPORARY CONDITIONS OF SUCH AT KFAY AND KRWI WHERE CONFIDENCE CURRENTLY IS NOT AS HIGH WITH LIGHTER 925MB WINDS AND LESSER PROBABILITIES EVEN ON THE AGGRESSIVE SREF. DURING WEDNESDAY MORNING...ANY IFR CONDITIONS SHOULD LIFT AT LEAST INTO MVFR...WITH SCATTERED SHOWERS BEGINNING TO DEVELOP TOWARD THE END OF THE TAF PERIOD. ANY SOUTHWEST WIND GUSTS SHOULD BE LIMITED TO THE LOWER TO MID TEENS KNOTS WITH MIXING WEDNESDAY AND BE BRIEF. BEYOND THE 18Z VALID TAF PERIOD...THE LATEST MODEL SOUNDINGS SUGGEST THAT LOW CLOUDS ARE POSSIBLE AGAIN THURSDAY MORNING...THOUGH WITH A BETTER PROBABILITY TOWARD KFAY AND KRWI RELATIVE TO THE REST OF CENTRAL NORTH CAROLINA. ISOLATED TO SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS ARE ALSO POSSIBLE. LOWEST CHANCES OF THOSE APPEAR TO BE SATURDAY WHEN THE AIR MASS IS RELATIVELY MORE STABLE COMPARED TO OTHER DAYS.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...DJF/CBL SHORT TERM...CBL LONG TERM...BLS AVIATION...DJF

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