407  
FXUS62 KRAH 310131  
AFDRAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RALEIGH NC  
930 PM EDT SAT JUL 30 2016  
   
SYNOPSIS
 
 
AN UPPER LEVEL TROUGH WILL CROSS THE NORTHEAST AND MID-ATLANTIC  
STATES THROUGH MONDAY, AND THEN WILL SLOWLY DRIFTING OFFSHORE BY  
WEDNESDAY. A COLD FRONT WILL GRADUALLY APPROACH OUR AREA FROM  
THE NORTHWEST BEFORE STALLING OVER THE REGION EARLY IN THE WORK WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 930 PM SATURDAY...  
 
A COUPLE OF INTENSE SUPERCELLS AFFECTED THE NORTHERN CWA EARLIER  
THIS EVENING, INCLUDING ONE DEEP CELL WITH TORNADIC SIGNATURES.  
WHILE THOSE STORMS LOST STRENGTH QUICKLY WITHIN POOR MID LEVEL LAPSE  
RATES AND OTHER CELLS STAYED RATHER WEAK, THE ENVIRONMENT OVER THE  
NORTHEAST CWA AND ALL OF EASTERN NC REMAINS SUPPORTIVE OF STRONG  
CONVECTION FOR A COUPLE MORE HOURS. FAVORABLE FACTORS INCLUDE  
LINGERING ELEVATED INSTABILITY WITH MUCAPE OF 1500-2000 J/KG  
(ALTHOUGH CINH HAS GROWN SINCE SUNSET) AND GOOD LOW LEVEL SHEAR (20+  
KT 0-1 KM), WHICH HAVE HELPED PUSH THE SCP VALUES TO 1-2. UPPER  
DIVERGENCE, ALBEIT WEAK, IS ALSO PROVIDING LARGER SCALE SUPPORT FOR  
LIFT, AND DEEP LAYER EFFECTIVE SHEAR IS DECENT AT 25-30 KTS. DESPITE  
THE STABILIZING COLUMN, WE SHOULD MAINTAIN SMALL ELEVATED  
INSTABILITY THROUGH THE NIGHT, WITHIN HIGH PW WELL OVER 2.0". WILL  
HOLD ONTO SCATTERED POPS EAST / ISOLATED WEST FOR STORMS FOR ANOTHER  
COUPLE OF HOURS BEFORE TRENDING DOWN TO JUST ISOLATED SHOWERS  
AREAWIDE OVERNIGHT, A TREND INDICATED BY THE LATEST CAM RUNS. HAVE  
NUDGED LOWS UPWARD SLIGHTLY BASED ON TRENDS AND HIGH-RES GUIDANCE TO  
72-77. -GIH  
 
EARLIER DISCUSSION AS OF 250 PM SATURDAY: SCATTERED SHOWERS AND  
TSTMS HAVE DEVELOPED AS EXPECTED ACROSS CENTRAL NC, INVOF OF THE  
PIEDMONT TROUGH, AND TO OUR WEST OVER AND JUST EAST OF THE  
MOUNTAINS. ALOFT, SW FLOW PERSISTS ACROSS OUR AREA ON THE EAST SIDE  
OF A BROAD TROUGH CENTERED OVER THE OHIO AND MISSISSIPPI VALLEYS.  
FOR THE REST OF THIS AFTERNOON INTO THIS EVENING, THE AFOREMENTIONED  
SHOWERS AND TSTMS WILL MOVE EAST ACROSS OUR CWA, BUT GIVEN THE  
SCATTERED NATURE, NOT ALL LOCATIONS WILL SEE RAIN, SO FOR NOW WILL  
KEEP POPS CAPPED AT 50%, IMPLYING THE SCATTERED COVERAGE. AS FOR  
STORM INTENSITY, LATEST MESOANALYSIS SHOWS PLENTY OF INSTABILITY, ESP  
FROM THE US-1 CORRIDOR EASTWARD, BUT SHEAR IS PRETTY WEAK, SO LOOK  
FOR MOSTLY PULSE STORMS, WITH PERHAPS SOME MODEST CLUSTERING NORTH  
AND NORTHEAST OF RALEIGH WHERE THE EFFECTIVE SHEAR IS THE HIGHEST IN  
OUR CWA. GIVEN THE INSTABILITY, AN ISOLATED SEVERE CELL (WIND OR  
HAIL THE MAIN THREATS) CAN'T BE RULED OUT, BUT GIVEN THE WEAK SHEAR,  
ANY SEVERE CELLS WON'T REMAIN SEVERE VERY LONG. AGAIN, THE BEST  
CHANCE FOR A STRONG OR SEVERE CELLS WILL BE NORTH AND NORTHEAST OF  
RALEIGH CLOSER TO THE BETTER SHEAR.  
 
LOOK FOR SHOWER/STORM ACTIVITY TO WIND DOWN AROUND MIDNIGHT, WITH THE  
REMAINDER OF THE NIGHT PARTLY CLOUDY. WITH LITTLE OR NO PATTERN OR  
AIRMASS CHANGE, WILL LEAN TOWARD PERSISTENCE FOR TEMPS. LOW'S  
TONIGHT IN THE MID 70S.  
 

 
   
SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/
 
 
AS OF 250 PM SATURDAY...  
 
SUNDAY WILL START OFF MUCH LIKE TODAY, WITH PC SKIES AND ISOLATED  
SHOWERS OR SPRINKLES PERHAPS LINGERING ON OLD OUTFLOW BOUNDARIES.  
LIKE TODAY, ISOLATED-TO-SCATTERED SHOWERS AND TSTMS ARE EXPECTED TO  
DEVELOP INVOF OF THE PIEDMONT TROUGH DURING THE EARLY-TO-MID  
AFTERNOON. THEN DURING THE EARLY EVENING, GUIDANCE IS SUGGESTING  
THAT A BROKEN BAND OF THUNDERSTORMS, FIRST HAVING FORMED OVER THE  
MOUNTAINS, WILL MOVE EAST ACROSS OUR CWA. THIS BAND OF TSTMS MAY  
HAVE A LITTLE BETTER COVERAGE SINCE IT WILL BE SUPPORTED BY A  
SHORTWAVE EMBEDDED IN THE SW FLOW. THAT SHORTWAVE IS CURRENTLY  
MOVING ACROSS THE CENTRAL PLAINS. DESPITE THIS UPPER SUPPORT, 0-6KM  
SHEAR IS STILL PROGGED TO BE AOB 25 KT. SO ONCE AGAIN, MOST STORMS  
SHOULD REMAIN BELOW SEVERE LIMITS, BUT AN ISOLATED SEVERE CELL  
OR TWO STILL CAN'T BE RULED OUT GIVEN THE INSTABILITY.  
 
SPEAKING OF INSTABILITY, TEMPS AND DEW POINTS ON SUNDAY WILL BE  
SIMILAR TO TODAY, GIVEN THAT THE AIRMASS WILL HAVE CHANGED LITTLE.  
HOWEVER, WITH SLIGHTLY INCREASED SHOWER/STORM COVERAGE, OUR  
CONFIDENCE OF HITTING HEAT ADVISORY CRITERIA IN OUR EASTERN COUNTIES  
IS NOT PARTICULARLY HIGH. FOR NOW, WILL FORECAST HIGHS IN THE LOWER  
90S AND HEAT INDICES AROUND 100. NEVERTHELESS, IT WILL STILL BE  
UNCOMFORTABLY HOT, SO FOLKS NEED TO CONTINUE EXERCISING THE HEAT  
PRECAUTIONS THAT WE'VE BEEN ADVERTISING.  
 

 
   
LONG TERM /MONDAY THROUGH SATURDAY/
 
 
AS OF 245 PM SATURDAY...  
 
RELATIVELY FLAT UPPER LEVEL TROUGH WILL EXTEND FROM NEW ENGLAND INTO  
THE CAROLINAS AT THE BEGINNING OF THE WEEK. PERTURBATIONS ROUNDING  
THE BASE OF THIS TROUGH WILL INTERACT WITH AVAILABLE MOISTURE  
(PRECIP WATER VALUES HOVERING AROUND 2 INCHES MON AND TUES) AND  
INSTABILITY TO TRIGGER SCATTERED CONVECTION. THE BULK OF THE  
CONVECTION WILL OCCUR DURING THE AFTERNOON-EARLY EVENING HOURS AND  
CONCENTRATED ALONG A SW-NE ORIENTATED SURFACE TROUGH BISECTING OUR  
REGION.  
 
AN UPPER LEVEL RIDGE CENTERED OVER THE LOWER MS VALLEY/SOUTHERN  
PLAINS IS PROJECTED TO AMPLIFY NORTHWARD IN RESPONSE TO AN UPPER  
LEVEL LOW CROSSING THE PACIFIC NW. THIS SHOULD LEAD TO BUILDING  
HEIGHTS OVER CENTRAL NC THE LATER HALF OF THE WORK WEEK, LEADING TO  
A DECREASING CHANCE FOR AFTERNOON/EVENING CONVECTION.  
 
HIGH TEMPERATURES EARLY IN THE WEEK WILL AVERAGE CLOSE TO NORMAL DUE  
TO ANTICIPATED CLOUD AND CONVECTION COVERAGE. HIGH TEMPERATURES WILL  
LIKELY RETURN TO ABOVE NORMAL LEVELS LATER IN THE WEEK AS THE UPPER  
LEVEL RIDGE EXERTS ITS INFLUENCE ON OUR WEATHER.  
 
 

 
   
AVIATION /00Z SUNDAY THROUGH THURSDAY/
 
 
AS OF 730 PM SATURDAY...  
 
24-HOUR TAF PERIOD: SCATTERED SHOWERS AND THUNDERSTORMS WILL LOCALLY  
REDUCE CIGS AND VSBYS TO MVFR OR IFR CATEGORY. OTHERWISE, EXPECT VFR  
CONDITIONS AND LIGHT AND VARIABLE WINDS FOR THE REST OF THE EVENING  
AND OVERNIGHT. EXPECT VARIABLE GUSTS AROUND 20 KTS NEAR STORMS  
AND/OR THUNDERSTORM OUTFLOWS. STORMS SHOULD DISSIPATE AFTER SUNSET.  
SIMILAR CONDITIONS WILL PREVAIL SUNDAY, WITH SLIGHTLY HIGHER CHANCES  
FOR SHOWERS/STORMS RESULTING IN GUSTY WINDS AND LOCALLY REDUCED CIGS  
AND VISBYS.  
 
LOOKING AHEAD: SIMILAR CONDITIONS THROUGH TUESDAY WITH SCATTERED  
AFTERNOON/EVENING TSTMS AND ASSOCIATED REDUCED FLIGHT CONDITIONS.  
PATCHY MORNING FOG POSSIBLE AS WELL. DURING THE MID-WEEK PERIOD, WE  
MAY SEE DECREASED DAILY SHOWER/STORM CHANCES AS SLIGHTLY DRIER AIR  
MOVES IN THE FROM THE NORTH. -NP  
 

 
   
RAH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
 
SYNOPSIS...HARTFIELD  
NEAR TERM...HARTFIELD/NP  
SHORT TERM...NP  
LONG TERM...WSS  
AVIATION...KC/NP  
 
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