Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 031913 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 312 PM EDT MON AUG 3 2015 .SYNOPSIS... A STATIONARY FRONT WILL CONTINUE TO EXTEND THROUGH CENTRAL NORTH CAROLINA... FROM THE SANDHILLS THROUGH THE NORTHERN OUTER BANKS... THROUGH MIDWEEK. A COLD FRONT APPROACHING FROM THE NORTHWEST WILL STALL NEAR THE NORTH CAROLINA VIRGINIA BORDER EARLY WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 950 AM MONDAY... CURRENT FORECAST IS IN GOOD SHAPE. LATEST SURFACE ANALYSIS SHOWS THE DIFFUSE FRONTAL ZONE STILL BISECTING CENTRAL NC... WITH THE NOTABLY MORE SOUPY AIR TO ITS SW... AS NOTED BY BLENDED TPW IMAGERY SHOWING BELOW NORMAL PW OVER ALL BUT THE SE CWA. THE PATCHY STRATUS ACROSS THE ERN PIEDMONT/SANDHILLS/COASTAL PLAIN THIS MORNING IS GRADUALLY LIFTING AND BREAKING UP... AND ITS DISSIPATION SHOULD ALLOW FOR DECENT HEATING OVER MUCH OF THE CWA... UNTIL CUMULUS FORMATION EARLY THIS AFTERNOON. THE EXIT OF ONE LOOSELY ORGANIZED BATCH OF SHOWERS/STORMS MOVING NE OVER AND OFF THE SRN OUTER BANKS WILL LEAD TO A RELATIVE LULL IN POPS BUT THIS SHOULD BE QUICKLY SUPPLANTED BY ANOTHER WEAK WAVE MOVING E THEN NE THROUGH THE BASE OF THE MEAN MID LEVEL TROUGH. EXPECTATIONS ARE FOR LITTLE MORE THAN MARGINAL TO BRIEFLY MODERATE INSTABILITY THIS AFTERNOON WITH MUCAPE VALUES AROUND 1000 J/KG MAINLY ALONG/EAST OF I-95 THIS AFTERNOON... LIMITED BY PERSISTENT MOSTLY CLOUDY SKIES THERE... AND DEEP LAYER SHEAR IS PROJECTED TO BE MARGINAL AS WELL AT 20-25 KTS. WILL RETAIN THE LOW CHANCE POPS IN THE SE CWA TODAY. THESE CHANCES SHOULD DECREASE TONIGHT BUT NOT DISAPPEAR ENTIRELY GIVEN THE MOIST COLUMN AND POTENTIAL FOR ELEVATED INSTABILITY OVERNIGHT. THICKNESSES AND GUIDANCE TRENDS SUPPORT HIGHS OF 87-94... LOWEST IN THE FAR SE (CLINTON/MT OLIVE) AND WARMEST IN THE SW. LOWS TONIGHT STILL LOOK FITTING... 68-74... WITH NUMEROUS INDICATIONS OF STRATUS REDEVELOPMENT OVERNIGHT. -GIH && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 400 AM MONDAY... CENTRAL NC WILL REMAIN LARGELY SANDWICHED BETWEEN THE NEARLY STATIONARY FRONTAL ZONE OVER THE EASTERN CAROLINAS AND NORTHEAST DRIFTING AREA OF LOW PRESSURE ACROSS THE COASTAL CAROLINAS...AND A COLD FRONT FORECAST TO APPROACH FROM THE NORTHWEST AND STALL NEAR THE NC/VA STATE BORDER BY WED MORNING. THE RESULT WILL BE A CONTINUED CHANCE OF SHOWERS AND STORMS OVER THE COASTAL PLAIN...IN CLOSEST PROXIMITY TO THE STATIONARY FRONT. AND ELSEWHERE...THERE WILL BE A SLIGHT CHANCE OF A LATE AFTERNOON AND EVENING STORM FROM ACTIVITY THAT COULD EITHER DEVELOP IN-SITU INVOF A PIEDMONT SURFACE TROUGH AND/OR THAT WILL INITIATE UPSTREAM OVER THE MOUNTAINS AND INVOF THE AFOREMENTIONED FRONT...WHICH WOULD THEN PROPAGATE AWAY FROM THOSE FORCING MECHANISMS AND INTO THE NC PIEDMONT. CENTRAL NC WILL REMAIN JUST SOUTH OF THE MAIN BELT OF WESTERLIES...SO DEEP LAYER BULK SHEAR VALUES AT THIS LATITUDE ARE FORECAST TO BE ONLY MODEST...BETWEEN ABOUT 15-20 KTS - SUPPORTIVE OF MULTI-CELL STORM ORGANIZATION. FORECAST LOW LEVEL THICKNESS VALUES RISE ABOUT 5-10 METERS PER A CONSENSUS OF MODEL GUIDANCE...SUPPORTIVE OF LOWER TO MIDDLE 90S AREA- WIDE...WITH A FEW 97-98 DEGREE READINGS POSSIBLE FROM AFP TO FAY. LOWS GENERALLY 70 TO 75. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 305 PM MONDAY... OVERALL THE SYNOPTIC PATTERN THROUGHOUT THE LONG TERM PERIOD WILL FEATURE RIDGING OVER THE SOUTHWEST CONUS AND TROUGHING (WITH VARYING STRENGTHS) OVER THE EAST. GIVEN THIS UPPER LEVEL FLOW PATTERN... MUCH OF OUR WEATHER WILL BE DICTATED BY NUMEROUS SHORTWAVES (WHICH ARE IMPOSSIBLE TO ACCURATELY PREDICT THIS FAR OUT). BESIDES SEVERAL WEAKER DISTURBANCES DURING THE MIDDLE PART OF THE WEEK TRIGGERING WIDELY SCATTERED SHOWERS/STORMS...THE FIRST SIGNIFICANT SHORT WAVE IS PROGGED TO CROSS THE REGION LATE THURSDAY INTO FRIDAY. THE GFS AND ECMWF DIFFER QUITE SIGNIFICANTLY...WITH THE GFS MUCH WEAKER AND DISORGANIZED...WHILE THE ECMWF SPINS UP QUITE A STRONG LOW THAT CROSSES VIRGINIA BEFORE EXITING OFF OF THE DELMARVA COAST. GIVEN THAT THE ECMWF IS MORE SIMILAR TO THE NAM (AT LEAST THROUGH 84 HOURS)...WILL FOLLOW ITS SOLUTION MORE CLOSELY. THIS WOULD RESULT IN PRECIP CHANCES RAMPING UP LATE THURSDAY INTO FRIDAY WITH THE APPROACH OF THE DEEPER SHORT WAVE/SURFACE FRONT BEFORE DECREASING LATE FRIDAY NIGHT AS THE NEXT KICKER WAVE PUSHES THE FRONT EAST. THE GFS DOES SHOW THIS OVERALL PATTERN (SHORT WAVE(S)/SURFACE FRONT)...BUT JUST IS NOT AS DEEP/ORGANIZED WITH THE SYSTEM...THUS THE PRECIP IS MORE SCATTERED IN NATURE. BY THE WEEKEND...BOTH MODELS ARE THEN IN FAIRLY GOOD AGREEMENT WITH THE FRONT BEING PUSHED TO OUR EAST...AND BECOMING NEARLY STATIONARY THERE. THIS SHOULD RESULT IN A MOSTLY DRY FORECAST...WITH ONLY SOME ISOLATED DIURNAL TYPE ACTIVITY...MOSTLY ACROSS THE EAST IN CLOSER PROXIMITY TO THE BOUNDARY. TEMPS WILL BE RATHER WARM TO START THE PERIOD (HIGHS IN THE MID/UPPER 90S...LOWS IN THE LOW/MID 70S)...BUT BY THE WEEKEND THEY SHOULD FALL SOME BEHIND THE FRONT (HIGHS IN THE MID/UPPER 80S...LOWS IN THE MID/UPPER 60S). && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 145 PM MONDAY... VFR CONDITIONS LIKELY TO DOMINATE AT LEAST THROUGH THIS EVENING. THIS MORNING`S PATCHY SUB-VFR CIGS LIFTED AND MIXED OUT BY 15Z... NOW REPLACED BY MOSTLY SCATTERED VFR CUMULUS. ISOLATED SHOWERS/STORMS HAVE PERSISTED WELL SE OF FAY... WHILE IN THE LAST FEW HOURS... SCATTERED SHOWERS HAVE DEVELOPED NEAR THE VA/NC STATE LINE WELL NORTH OF RDU. THIS LOOSELY-ORGANIZED BAND OF SHOWERS MAY LENGTHEN AND EXPAND SOUTHWESTWARD TO AFFECT GSO AND/OR RDU WITH BRIEF MVFR VSBYS/CIGS FOR A PERIOD OF LESS THAN AN HOUR THIS AFTERNOON 18Z-22Z... AS IT DRIFTS TOWARD THE ESE. SIMILARLY... THE SHOWERS AND STORMS NOW OVER THE COASTAL CAROLINAS ARE EXPECTED TO EXPAND TO THE NW THROUGH EARLY EVENING... POTENTIALLY BRINGING BRIEF MVFR CONDITIONS TO FAY. BUT IN ALL CASES... VFR CONDITIONS WILL BE THE RULE FOR MUCH OF THE NEXT 9 HOURS... WITH ANY SHOWERS/STORMS LIKELY TO BE CIRCUMNAVIGABLE. LATER THIS EVENING INTO THE OVERNIGHT... SHOWER/STORM CHANCES WILL DIMINISH (ALTHOUGH AN ISOLATED SHOWER MAY LINGER OVERNIGHT NEAR FAY)... BUT PATCHES OF SUB- VFR CIGS/VSBYS ARE PROBABLE AT FAY AND RWI... WITH A LOWER CHANCE AT RDU... AND ARE UNLIKELY AT INT/GSO. THE MOST LIKELY TIME FOR IFR/LIFR CIGS/VSBYS WITH FOG/STRATUS WILL BE 07Z-12Z... WITH IMPROVEMENT TO VFR LIKELY TO OCCUR 12Z-14Z. LOOKING BEYOND 18Z TUE... VFR CONDITIONS LIKELY INTO TUE EVENING AT ALL SITES... ALTHOUGH LATE DAY SHOWER/STORM CHANCES WILL BE HIGHER AT FAY/RWI AND PERHAPS RDU FROM 19Z TO 02Z. THERE IS A GOOD CHANCE OF ANOTHER ROUND OF IFR VSBYS/CIGS AT ALL SITES BUT MAINLY RDU/RWI/FAY LATE TUE NIGHT INTO WED MORNING. CONFIDENCE IN THE FORECAST DETAILS DROPS TO LOWER THAN USUAL FROM TUE NIGHT ONWARD... AS A COLD FRONT DROPS INTO THE REGION FROM THE NW AND STAYS STALLED ACROSS VA AND NC THROUGH LATE WEEK... WAVERING NORTH AND SOUTH AS WEAK DISTURBANCES ALOFT TRACK ACROSS THE REGION. A STRONGER WAVE APPROACHING FROM THE WNW WED NIGHT MAY BRING THE BEST COVERAGE OF SUB-VFR SHOWERS/STORMS THU INTO EARLY FRI. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...26 LONG TERM...KRD AVIATION...HARTFIELD

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