Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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 260632 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 232 AM EDT TUE APR 26 2016 .SYNOPSIS... A WEAKENING FRONTAL ZONE WILL APPROACH THE AREA FROM THE NORTH TONIGHT...THEN STALL OVER PORTIONS OF THE CAROLINAS ON WEDNESDAY AND THURSDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 130 AM TUESDAY... CONTINUED AIRMASS MODIFICATION /WARM ADVECTION/ WILL ALLOW HIGHS TO REACH THE MID 80S THIS AFTERNOON. LOW-LEVEL MOISTURE RECOVERY ATTENDANT PERSISTENT SOUTHERLY RETURN FLOW IN ADDITION TO STEEPER MID-LEVEL LAPSE RATES ADVECTING INTO THE STATE FROM THE WEST WILL RESULT IN THERMODYNAMIC PROFILES INCREASINGLY SUPPORTIVE OF ISOLD DIURNAL CONVECTION LATE THIS AFTERNOON AND EARLY EVENING...THOUGH ALMOST EXCLUSIVELY IN THE NW PIEDMONT. WEAK/BROAD FORCING ATTENDANT WARM ADVECTION WILL BE PRESENT THIS AFTERNOON...THOUGH THIS IS UNLIKELY IN OF ITSELF TO INITIATE CONVECTION IN THE CONTEXT OF A MARGINAL (WEST) OR UNFAVORABLE (EAST) THERMODYNAMIC ENVIRONMENT. UPPER LEVEL FORCING...IN THE FORM OF DPVA ATTENDANT SMALL AMPLITUDE WAVES IN WNW FLOW ALOFT...WILL MOST LIKELY DICTATE WHETHER OR NOT CONVECTION DEVELOPS IN THE NW PIEDMONT THIS AFT/EVE. THE LATEST MODEL GUIDANCE IS IN BETTER AGREEMENT WITH REGARD TO SHOWING ~1000 J/KG OF MLCAPE IN THE NW PIEDMONT DURING PEAK HEATING...THOUGH UNCERTAINTY PERSISTS WITH REGARD TO WHETHER OR NOT SMALL AMPLITUDE SHORTWAVE ENERGY WILL BE PRESENT IN VICINITY OF PEAK HEATING. INCREASED DEEP LAYER SHEAR ASSOC/W STRENGTHENING MID- LEVEL FLOW IN ADVANCE OF ANY SMALL AMPLITUDE WAVE COULD AUGMENT CONVECTIVE ORGANIZATION POTENTIAL FROM MULTICELL TO LOW-END SUPERCELL. NAM/GFS FCST SOUNDINGS IN THE NW PIEDMONT SHOW SCP VALUES INCREASING TO 1-2 BETWEEN 21-00Z...SUGGESTING A CONDITIONAL POTENTIAL FOR AN ISOLD SEVERE STORM WILL EXIST IN THE NW PIEDMONT LATE THIS AFTERNOON. LATER THIS EVE/TONIGHT...A WEAKENING COLD FRONT (ASSOC/W A SFC LOW ATTENDANT MORE POTENT SHORTWAVE ENERGY TRAVERSING THE NORTHERN MID- ATLANTIC) WILL APPROACH CENTRAL NC FROM THE N/NE...APPROACHING THE VA/NC BORDER FROM THE NORTH BY ~12Z WED. DESPITE POOR DIURNAL TIMING...NOCTURNAL DESTABILIZATION (ON THE ORDER OF 1000-1500 J/KG MUCAPE) IS EXPECTED TO OCCUR AS LOW-LEVEL MOISTURE POOLS BENEATH STEEPENING MID-LEVEL LAPSE RATES ALOFT...AND ISOLD TO SCT ELEVATED CONVECTION CANNOT BE RULED...PARTICULARLY IF ADDITIONAL SMALL AMPLITUDE WAVES /DPVA/ TRACK ACROSS THE STALLING LOW-LEVEL TROUGH NEAR THE VA BORDER AFTER MIDNIGHT. EXPECT LOWS IN THE LOWER TO MID 60S. -VINCENT && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 200 AM TUESDAY... THE AFOREMENTIONED FRONTAL ZONE IS PROGGED TO STALL DIRECTLY OVER PORTIONS OF CENTRAL NC ON WEDNESDAY...AND SHOULD SERVE AS A SUFFICIENT FOCUS FOR ISOLD/SCT CONVECTIVE DEVELOPMENT DURING PEAK HEATING /DIURNAL DESTABILIZATION/. THE PRECISE LOCATION OF THE MODIFIED FRONTAL ZONE WILL BE DIFFICULT TO PIN DOWN BY WED EVENING (ASSUMING CONVECTION DEVELOPS DURING THE AFTERNOON)...AS CONVECTIVE OUTFLOW AND DIFFERENTIAL HEATING WILL LIKELY AFFECT IT`S POSITION IN A MANNER THAT MODEL GUIDANCE MAY HAVE DIFFICULTY IN ACCURATELY CAPTURING. EXPECT HIGHS IN THE MID 80S...EXCEPT UPPER 70S TO LOWER80S IN THE FAR NE COASTAL PLAIN. ONCE AGAIN...NOCTURNAL DESTABILIZATION ATTENDANT LOW-LEVEL MOISTURE POOLING BENEATH RELATIVELY STEEP MID-LEVEL LAPSE RATES ALOFT WILL PROVIDE SUFFICIENT ENERGY FOR ADDITIONAL CONVECTIVE DEVELOPMENT WED EVE/NIGHT...ESP WITH A LOW-LEVEL TROUGH STALLED OVER PORTIONS OF THE REGION AND AN INCREASING POTENTIAL FOR SMALL AMPLITUDE WAVES IN W/WSW FLOW ALOFT. NO CLEAR INDICATION FOR SEVERE WEATHER IS PRESENT GIVEN DECREASED DEEP-LAYER SHEAR WED AFT/EVE UNDERNEATH A SHORTWAVE RIDGE ALOFT PROGRESSING ACROSS THE CAROLINAS/MID-ATLANTIC. EXPECT LOWS WED NIGHT IN THE MID 60S SOUTH TO LOWER 60S NORTH...PERHAPS UPPER 50S IN THE FAR NE COASTAL PLAIN. -VINCENT && .LONG TERM /THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
AS OF 232 AM TUESDAY... ...CONTINUED WARM AND UNSETTLED INTO LATE WEEK... THEN TURNING STORMY AGAIN SUNDAY AND MONDAY... ANOTHER WAVE WILL TRACK FROM THE OHIO VALLEY TOWARDS THE MID ATLANTIC AND WILL PULL A COLD FRONT TOWARD INTO THE REGION LATE THURSDAY NIGHT AND FRIDAY. MODELS ARE SHOWING THE FRONT WILL BECOME MORE DIFFUSE WITH TIME FRIDAY. SHOWERS AND THUNDERSTORMS ARE LIKELY THURSDAY AFTERNOON AND EVENING WITH THE APPROACH OF THIS NEXT WAVE. THE HIGHEST POP WILL OCCUR WITH HEATING ON THURSDAY AFTERNOON... THEN LINGER INTO THE EVENING. IT APPEARS THAT BOTH SHEAR AND INSTABILITY WILL FALL A BIT SHORT OF PLACING THE REGION IN A MARGINAL RISK OF ORGANIZED SEVERE DEVELOPMENT. HOWEVER... SOME OF THE THUNDERSTORMS SHOULD BECOME ROBUST DURING THE AFTERNOON AND EVENING HOURS. QPF IN THE GENERAL RANGE OF 0.25 TO 0.50 IS EXPECTED WITH LOCALLY HIGHER TOTALS EXPECTED ESPECIALLY IN THE NORTHERN AND EASTERN PIEDMONT TO THE COAST. HIGHS SHOULD REACH THE UPPER 70S NORTH INTO THE MID 80S SOUTH. LOWS THURSDAY NIGHT GENERALLY 60-65. THE FRONT MAY LINGER FROM NW TO SE ACROSS THE REGION WELL INTO FRIDAY. THIS WILL ALLOW FOR ADDITIONAL, YET SMALLER POP ON FRIDAY. LOW CONFIDENCE IN PLACEMENT OF POP AND QPF ON FRIDAY AS THE LINGERING BOUNDARY ALONG WITH ANOTHER NW FLOW DISTURBANCE ADD TO THE UNCERTAINTY. WE WILL KEEP 30-40 POP AND MAINLY FOR THE AFTERNOON/EVENING FRIDAY. HIGHS WILL BE A BIT COOLER DUE TO THE ADDITIONAL CLOUDINESS AND SHOWER POTENTIAL. EXPECT MOSTLY 75-82. THE FIRST HALF OF THE WEEKEND STILL LOOKS TO BE DRY AND SLIGHTLY COOLER/LESS HUMID SATURDAY. WEAK HIGH PRESSURE OVER THE MID-ATLANTIC WILL EXTEND SOUTH INTO NC/SC SATURDAY. HIGHS GENERALLY IN THE 70S EXPECTED. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL INCREASE DRAMATICALLY SUNDAY AND EARLY NEXT WEEK WITH AN EXPECTED ACTIVE STORM TRACK FROM THE PLAINS EASTWARD TO THE EASTERN SEABOARD. THERE SHOULD BE MULTIPLE ROUNDS OF SIGNIFICANT SHOWERS/STORMS IN THE PERIOD FROM LATE SUNDAY WELL INTO NEXT WEEK.
-- End Changed Discussion --
&& .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 200 AM TUESDAY... 24-HOUR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD IN MOST LOCATIONS. EXPECT SCATTERED VFR CEILINGS AT 4000-5000 FT AGL THIS AFTERNOON AND SSW/SW WINDS AT 10-15 KT PERHAPS GUSTING TO ~20 KT THIS AFTERNOON. A CONDITIONAL POTENTIAL FOR AN ISOLD THUNDERSTORM OR TWO WILL BE PRESENT AT THE INT/GSO TERMINALS DURING THE LATE AFTERNOON (21-00Z)...OTHERWISE...EXPECT DRY CONDITIONS AND VFR CEILINGS. LOOKING AHEAD: A WEAKENING COLD FRONT WILL STALL OVER THE REGION WED/THU...IN THE PRESENCE OF INCREASING MOISTURE VIA PERSISTENT SOUTHERLY RETURN FLOW. AS A RESULT...SUB-VFR CONDITIONS ASSOC/W CONVECTION WILL BE POSSIBLE AT ALL TERMINALS THROUGH MID/LATE WEEK...BOTH DURING THE DAY AND AT NIGHT. PRE-DAWN FOG/STRATUS WILL BE POSSIBLE EACH MORNING...ESP. IN AREAS AFFECTED BY AFT/EVE CONVECTION. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT LONG TERM...BADGETT/KRD AVIATION...VINCENT

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