Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 300703 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 305 AM EDT SAT MAY 30 2015 .SYNOPSIS...HIGH PRESSURE CENTERED OVER THE WESTERN ATLANTIC WILL EXTEND INTO THE REGION THROUGH SUNDAY MORNING. A COLD FRONT WILL DROP INTO THE MID ATLANTIC AND SOUTHERN APPALACHIANS ON SUNDAY AND MOVE INTO THE CAROLINAS ON MONDAY AND TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 AM SATURDAY... SURFACE HIGH PRESSURE WILL CONTINUE TO EXTEND INTO THE AREA FROM THE WESTERN ATLANTIC TODAY... WHILE A MID/UPPER LEVEL RIDGE REMAINS OVER THE AREA. THIS WILL AGAIN LARGELY SUPPRESS CONVECTION TODAY... WITH NEAR TERM GUIDANCES SHOWING EVEN LESS INSTABILITY THAN YESTERDAY. THIS SHOULD GENERALLY YIELD A DRY DAY ACROSS THE AREA... WITH THE BEST CHANCES OF SEEING ANY ISOLATED SHOWERS/STORMS IN THE FAR NORTHWEST PIEDMONT. OTHERWISE... EXPECT WE COULD SEE SOME PATCHY FOG AND LOW STRATUS ACROSS THE AREA... LIFTING BY MID MORNING... WITH PARTLY TO EVEN MOSTLY SUNNY SKIES EXPECTED TODAY. LOW LEVEL THICKNESS VALUES WILL AGAIN BE SIMILAR TO YESTERDAY. THUS... WOULD EXPECT TEMPS TO RANGE FROM THE MID 80S NW TO THE UPPER 80S/NEAR 90 ELSEWHERE... SIMILAR TO FRIDAY`S HIGHS. MORE OF THE SAME IS EXPECTED TONIGHT... WITH AGAIN THE POTENTIAL FOR SOME PATCHY PRE-DAWN/EARLY MORNING FOG/STRATUS AND LOW TEMPS GENERALLY IN THE MID TO UPPER 60S. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 250 AM SATURDAY... A WEAK SLOW MOVING MID LEVEL TROUGH WILL SLOWLY SHIFT EASTWARD ON SUNDAY ACROSS THE MIDWEST AND DEEP SOUTH. THIS WILL ALLOW/CAUSE THE MID LEVEL RIDGE TO SHIFT EASTWARD... WITH INCREASING SOUTHWESTERLY FLOW ALOFT OVER CENTRAL NC. THIS SHOULD LEAD TO A BETTER CHANCE OF SEEING SOME CONVECTION ON SUNDAY... MAINLY IN THE LATE AFTERNOON/EVENING TIME FRAME... WITH THE HIGHEST PROBABILITIES ACROSS THE NORTHWEST PIEDMONT. IN FACT FURTHER EASTWARD ACROSS THE CENTRAL AND SOUTHERN COASTAL PLAIN WE MAY SEE DRY CONDITIONS CONTINUE TO PREVAIL. HIGHS TEMPS WILL AGAIN BE SIMILAR TO TODAY... MAYBE A FEW DEGREES COOLER IN THE NORTHWEST PIEDMONT. STILL THINK WE SHOULD SEE HIGHS RANGING FROM THE MID TO UPPER 80S THOUGH. GIVEN THE SOUTHWESTERLY MID LEVEL FLOW AND POTENTIAL FOR WEAK PERTURBATIONS TO MOVE ACROSS THE AREA AND ALONG WITH THE MOIST AIRMASS IN PLACE ON SUNDAY NIGHT WE MAY SEE AFTERNOON CONVECTION LINGER A BIT LONGER... ALONG WITH THE POTENTIAL FOR AT LEAST ISOLATED CONVECTION POSSIBLE ACROSS THE WESTERN AND NORTHERN PIEDMONT ALL NIGHT LONG... DEPENDING ON ANY WEAK DISTURBANCES ALOFT IN THE SOUTHWESTERLY FLOW. WRT TO ANY SEVERE POTENTIAL... MIXED LAYER CAPE STILL APPEARS TO BE WEAK TO MODEST AT BEST... WITH GENERALLY ONLY 500 TO 1300 J/KG OF MLCAPE. GIVEN THIS AND STILL WEAK DEEP LAYER SHEAR... THINK SVR THREAT WILL BE QUITE MINIMAL TO NIL FOR SUNDAY AFTERNOON INTO SUNDAY NIGHT. LOWS BY MONDAY MORNING ARE EXPECTED TO BE IN THE MID TO UPPER 60S AGAIN. && .LONG TERM /MONDAY THROUGH FRIDAY/...
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AS OF 305 AM SATURDAY... THE APPROACH OF A MINOR S/W AND ATTENDANT COLD FRONT WILL INCREASE THE THREAT FOR SHOWERS AND THUNDERSTORMS MONDAY INTO TUESDAY AS IT INTERACTS WITH THE MOIST AND SLIGHTLY UNSTABLE AIR MASS OVER CENTRAL NC. BASED ON MODEL TIMING (AND DECENT CONSENSUS)...APPEARS BULK OF LIFT TO INITIATE/SUSTAIN CONVECTION WILL OCCUR IN THE WESTERN PIEDMONT LATE MONDAY...AND OVER THE REMAINDER OF CENTRAL NC MONDAY NIGHT. FORCING PRETTY MUCH DEPENDENT ON UPPER DIVERGENCE ALOFT ATTRIBUTED TO AN UPPER JET LIFTING NE ACROSS THE NORTHERN MID ATLANTIC AND A WEAKENING SHEAR AXIS. FORCING ALONG THE 850MB AND 700MB FAIRLY ANEMIC. BASED ON THIS...WILL LIMIT POP CHANCE TO HIGH END CHANCE/LOW END LIKELY. LOOKING AT SEVERE PARAMETERS...WIND SHEAR WEAK WHILE AVAILABLE INSTABILITY ADEQUATE FOR SOME DEEP CONVECTION. OVERALL SEVERE WEATHER THREAT MARGINAL AT BEST AS STORM TYPE WILL BE MULTI- CELLULAR/PULSE TYPE. SFC COLD FRONT WILL GLIDE INTO THE NORTHERN-WESTERN PIEDMONT LATE MONDAY NIGHT...THEN DRIFT SEWD TUESDAY. THIS FEATURE WILL AID TO FOCUS MOST OF THE CONVECTIVE ACTIVITY OVER THE SANDHILLS AND COASTAL PLAIN...ESPECIALLY TUESDAY AFTERNOON. MID LEVEL FLOW VEERS TO A MORE WLY FLOW BY TUESDAY. THIS TYPE OF FLOW PATTERN USUALLY LIMITS CONVECTIVE COVERAGE. WILL ALIGN POPS FROM CHANCE NW TO LOW END LIKELY IN THE EAST AND FAR SOUTH...MAINLY IN THE AFTERNOON-EVENING HOURS. HIGH TEMPS MONDAY AND TUESDAY DEPENDENT UPON THE AMOUNT OF CLOUD COVER AND INITIATION TIME OF CONVECTION. CURRENTLY HAVE MAX TEMPS MONDAY MID-UPPER 80S...AND AROUND 80 NORTH TO THE MID 80S FAR SOUTH TUESDAY. IF CONVECTION ON MONDAY DOES NOT INITIATE IN THE WEST UNTIL LATE IN THE DAY...MAX TEMPS MAY END UP BEING 2-4 DEGREES WARMER. SIMILARLY...IF OVERCAST SKIES PERSIST ACROSS THE NORTHERN PIEDMONT MOST OF THE DAY...HIGH TEMPS MAY FAIL TO REACH 80. WEDNESDAY THROUGH FRIDAY...S/W IN THE NORTHERN STREAM EXITS OFF THE NEW ENGLAND COAST EARLY WEDNESDAY. THIS WILL ALLOW HIGH PRESSURE TO BUILD INTO THE UPPER OH VALLEY AND NOSE SWD TOWARD CENTRAL NC. SOME OF THE DRIER/MORE STABLE AIR WILL BLEED SWD INTO THE NORTHERN PIEDMONT. FORMER FRONTAL BOUNDARY WILL LIE IN VICINITY OF THE NC/SC BORDER AND GRADUALLY FIZZLE OUT. REMNANTS OF THIS BOUNDARY WILL STILL SERVE AS A FOCUS FOR MOISTURE POOLING AND PROBABLY TRIGGER ISOLATED TO SCATTERED CONVECTION OVER OUR FAR SOUTHERN-SE COUNTIES WEDNESDAY INTO THURSDAY. 00Z GFS HAS INTENSIFIED AN AREA OF LOW PRESSURE IN THE NW CARIBBEAN AND LIFTS IT NWD THROUGH THE FL PENINSULA THURSDAY. THIS IS A BIG DEPARTURE FROM ITS PREVIOUS RUNS. 00Z ECMWF FAIRLY CONSISTENT WITH ITSELF...DEPICTING AN INVERTED TROUGH IN THIS REGION. WILL LEAN TOWARD THE ECMWF FOR NOW WHICH HAS A PIECE OF AN UPPER LEVEL RIDGE LEANING EWD ACROSS OUR REGION. IF THIS VERIFIES...EXPECT POPS CHANCES TO DWINDLE THURSDAY INTO FRIDAY WITH HIGH TEMPS CLOSE TO OR SLIGHTLY ABOVE NORMAL.
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&& .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 1250 AM SATURDAY... 24-HR TAF PERIOD: VFR CONDITIONS ARE GENERALLY EXPECTED TO CONTINUE THROUGH THE 24 HOUR TAF PERIOD... ASIDE FROM THE POTENTIAL FOR SOME PATCHY SUB-VFR CIGS AND/OR FOG DURING THE PRE-DAWN/EARLY MORNING HOURS THIS MORNING (08-14Z). GIVEN THE RATHER PATCHY NATURE OF THE SUB-VFR CONDITIONS YESTERDAY MORNING... WILL KEEP MENTION OF MAINLY SUB-VFR CIGS IN A TEMPO GROUP FOR NOW. OTHERWISE... VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE TAF PERIOD IN ASSOC/W A PERSISTENT UPPER LEVEL RIDGE ALONG THE EASTERN SEABOARD... WHICH SHOULD HELP TO LIMIT AFTERNOON/EVENING SHOWERS AND STORMS. THE BEST CHANCES OF SEEING ANY AFTERNOON/EVENING SHOWERS AND/OR STORMS WILL AGAIN BE IN THE TRIAD (KGSO/KINT)... THOUGH EVEN LOWER PROBABILITIES THAN YESTERDAY. THUS... WILL NOT INCLUDE ANY MENTION OF CONVECTION IN THE TAFS AT THIS TIME. -BSD LOOKING AHEAD: ASIDE FROM A POTENTIAL FOR SUB-VFR CEILINGS/FOG DURING THE EARLY MORNING (08-13Z) AND CONVECTION DURING THE LATE AFT/EVE (20-01Z)...PRIMARILY AT THE INT/GSO TERMINALS...EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE WEEKEND. CHANCES FOR EARLY MORNING STRATUS/FOG AND AFT/EVE CONVECTION WILL INCREASE AT ALL TERMINALS (PARTICULARLY INT/GSO) MONDAY INTO TUESDAY AS THE UPPER LEVEL RIDGE WEAKENS AND A SLOW-MOVING UPPER LEVEL TROUGH APPROACHES THE CAROLINAS/MID-ATLANTIC FROM THE WEST. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD/BLAES NEAR TERM...BSD SHORT TERM...BSD LONG TERM...WSS AVIATION...BSD/VINCENT

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