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 300654 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 253 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/...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& .SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 325 PM FRIDAY... A LARGE SCALE PATTERN CHANGE IS AFOOT...WHEREIN THE WRN ATLANTIC RIDGE WILL FINALLY GIVE WAY TO A SOUTHWARD DIP IN THE WESTERLIES OVER THE CONUS. THIS WILL BRING IMPROVING CHANCES FOR MUCH-NEEDED RAINFALL BEGINNING EARLY IN THE WORK WEEK. THE VAST MAJORITY OF CENTRAL NC HAS SEEN VERY LITTLE RAIN IN THE LAST COUPLE OF WEEKS... BETWEEN 1 AND 2 INCHES BELOW NORMAL IN THE LAST 14 DAYS ACCORDING TO WATER.WEATHER.GOV/PRECIP/. SUNDAY SHOULD BE OUR LAST STEAMY BUT MOSTLY DRY DAY. THE APPROACHING COLD FRONT IS EXPECTED TO STRETCH ACROSS THE MASON DIXON LINE DOWN THROUGH ERN KY LATE SUN... WITH ITS ASSOCIATED MID LEVEL TROUGH EXTENDING FROM THE GREAT LAKES TO THE LOWER MISS VALLEY AS THE WRN ATLANTIC RIDGE HOLDS ON FOR ONE MORE DAY. LATEST MODEL OUTPUT SHOWS SCATTERED TO NUMEROUS SHOWERS/STORMS POPPING UP BY AFTERNOON OVER THE HIGHER TERRAIN TRACKING TO THE NE WITHIN THE WEAK MEAN STEERING FLOW AROUND THE RIDGE. THIS CONVECTION IS EXPECTED TO WEAKEN DURING THE EVENING BUT EASE EASTWARD INTO THE NORTHWEST CWA SUN NIGHT... FOLLOWING THE PROGRESSION OF THE NRN PORTION OF THE MID LEVEL TROUGH INTO THE NORTHEAST STATES THROUGH MON. THE REST OF THE CWA SHOULD REMAIN MOSTLY DRY (ALTHOUGH AN ISOLATED SLOW-MOVING CELL OR TWO IS CERTAINLY POSSIBLE) GIVEN THE SOMEWHAT DRY LOW LEVELS (LIMITING CAPE) AND DRY AIR THROUGH THE COLUMN (BELOW NORMAL PW OVER ERN HALF OF CWA). HIGHS SUN 85-90. LOWS SUN NIGHT MAINLY IN THE UPPER 60S WITH CONVECTIVE DEBRIS CLOUDS AND A SMALL CHANCE OF SHOWERS OVER THE NRN/WRN CWA OVERNIGHT. WHILE WE SHOULD SEE A PIEDMONT TROUGH FORMING (OR BECOMING BETTER DEFINED) OVER THE CWA MON... MODELS ARE KEEPING A THERMAL RIDGE ACROSS OUR AREA WITH THE FRONTAL ZONE HOLDING TO OUR NW THROUGH THE DAY... A FUNCTION OF THE SLOW SPEED AND LOW AMPLITUDE OF THE MID LEVEL TROUGH TO OUR WEST. WE`LL NEED TO WAIT FOR ADDITIONAL ENERGY TO DROP FROM SW ONTARIO DOWN THROUGH THE GREAT LAKES STARTING MON IN ORDER FOR THE TROUGH TO MAKE ANY MEANINGFUL EASTWARD PROGRESS. ALL OF THIS WILL SERVE TO DELAY COOLING INTO NC UNTIL THE SURFACE FRONT DROPS INTO NC TUE NIGHT OR EARLY WED. BOTH MOISTURE AND FORCING FOR ASCENT WILL DEEPEN AND INCREASE AHEAD OF THE FRONT... AND BY LATE MON AFTERNOON WE SHOULD SEE GOOD COVERAGE OF SHOWERS AND STORMS PARTICULARLY OVER THE WRN AND SW CWA WHERE LOW LEVEL MOISTURE POOLING SHOULD BE GREATEST. COVERAGE AND INTENSITY WILL WANE MON NIGHT WITH LOSS OF HEATING... BUT NOT GO AWAY ENTIRELY GIVEN THE PERSISTENCE OF ELEVATED INSTABILITY OVERNIGHT AND ABOVE-NORMAL PW. MODERATE INSTABILITY AND HIGH MOISTURE SHOULD PERSIST AREAWIDE TUE... SUPPORTING ABOVE NORMAL CHANCES FOR SHOWERS AND STORMS (50- 60%). EXPECT HIGH COVERAGE AGAIN WED ACROSS ALL BUT THE NW AS THE FRONT SETTLES INTO THE NRN/WRN CWA. THE GFS/ECMWF SOLUTIONS DIVERGE WITH THE LATTER SHOWING A DEEPER TROUGH JUST TO OUR IMMEDIATE WEST TUE AND SHIFTING OVER THE ERN STATES WED... WHILE THE GFS KEEPS THE STREAMS UNPHASED WITH A CUTOFF MID LEVEL LOW OVER THE LOWER MISS VALLEY. PREFER THE WEAKER-FLOW GFS WITH THE FRONT LOITERING ACROSS ERN AND SRN NC THROUGH THU/FRI... AS THE ONCE-COOL SURFACE HIGH CENTERED OVER THE ERN GREAT LAKES EARLY WED MODIFIES AND STARTS TO DRIFT OFF THE NORTHEAST COAST BY FRI. THE FRONT SHOULD BE MOSTLY WASHED OUT AND BE OVERTAKEN BY COASTAL INVERTED TROUGHING OVER THE SOUTHEAST COAST. WILL TREND POPS TOWARD MORE CLIMATOLOGICALLY NORMAL VALUES THU/FRI -- 25-35% CHANCES MAINLY IN THE EAST AND SOUTH -- GIVEN THE DECREASING DEEP LAYER SHEAR AND WEAKENING FORCING FEATURES. DESPITE WHAT SHOULD BE A PERIOD OF MOSTLY CLOUDY SKIES FROM CONVECTIVE DEBRIS AND LIFTING MORNING STRATUS ON MON... WE SHOULD SEE ENOUGH HEATING WITHIN THE WARM SECTOR TO PUSH TEMPS UP TO HIGHS FROM THE MID 80S TO AROUND 90 (COOLEST NW AND FAR NORTH). HIGH TEMPS SHOULD SLIP BACK CLOSER TO NORMAL TUE GIVEN THE EXPECTED CONSIDERABLE CLOUDINESS... WITH THESE CLOUDS EQUATING TO MILD/HUMID OVERNIGHT LOWS THROUGH TUE NIGHT. SLIGHTLY BELOW NORMAL TEMPS WED... THEN TRENDING BACK TOWARD NEAR OR SLIGHTLY ABOVE NORMAL THU/FRI AS THE FRONT WASHES OUT AND THE RESIDENT AIR MASS MODIFIES. -GIH && .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...HARTFIELD AVIATION...BSD/VINCENT

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