383  
FXUS62 KRAH 291954  
AFDRAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RALEIGH NC  
350 PM EDT THU SEP 29 2016  
   
SYNOPSIS
 
 
A LARGE UPPER LEVEL LOW WILL HOLD OVER KENTUCKY AND SOUTHERN INDIANA  
THROUGH FRIDAY, AS A SURFACE FRONT HOLDS ALONG THE NORTH CAROLINA  
FOOTHILLS. THE UPPER LOW WILL WEAKEN AND DRIFT NORTH AND  
NORTHEASTWARD OVER LOWER MICHIGAN THROUGH THE WEEKEND, AS THE  
SURFACE FRONT PUSHES SLOWLY EASTWARD ACROSS CENTRAL NORTH CAROLINA.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 250 PM THURSDAY...  
 
FLASH FLOOD WATCH FOR THE FAR EASTERN AND SOUTHEAST SECTIONS OF THE  
FORECAST AREA WILL CONTINUE FOR NOW, AND MAY NEED TO BE EXTENDED IN  
AREA BASED ON FURTHER ASSESSMENT OF DEVELOPING CONVECTION. THIS  
MORNING'S BAND OF HEAVY RAIN AND STORMS WHICH INSTIGATED COUNTLESS  
FLOODING REPORTS THIS MORNING WAS ORIENTED ALONG A BAND OF STRONG  
LOW LEVEL MOISTURE TRANSPORT, STRONG UPPER DIVERGENCE, AND FOCUSED  
DEEP IVT, ALL OF WHICH HAVE WEAKENED AND SHIFTED EASTWARD, ALONG  
WITH THE GREATEST COVERAGE OF MODERATE TO HEAVY RAIN. BANDS OF  
SHOWERS AND STORMS ARE DEVELOPING ONCE AGAIN OVER NC THIS AFTERNOON,  
PIVOTING AROUND THE KY UPPER LEVEL LOW, AND WHILE THE STRONGEST  
STORMS ARE EXPECTED TO BE IN THE TRIAD REGION TO THE NORTH AND NW  
(WHERE DEEP LAYER BULK AND EFFECTIVE SHEAR IS QUITE STRONG AND WHERE  
LOW LEVEL LAPSE RATES ARE APPROACHING OR EXCEEDING 7 C/KM) OVER THE  
NEXT 6-8 HRS, A FEW STRONG STORMS ARE POSSIBLE THIS AFTERNOON INTO  
EARLY EVENING OVER THE REMAINDER OF CENTRAL NC WITH SURFACE  
DEWPOINTS SOLIDLY IN THE UPPER 60S TO LOWER 70S. INSTABILITY SO FAR  
HAS BEEN MARGINAL DESPITE SOME INSOLATION, BUT WILL CONTINUE TO  
MONITOR. OTHERWISE, STILL EXPECT TRAINING CELLS GIVEN THE BAND-  
PARALLEL CELL MOTION, WHICH COULD PUSH LOCAL RAIN TOTALS UP TO 2-3"  
IN SPOTS, WHILE MANY AREAS OUTSIDE OF SUCH BANDS MAY SEE LESS THAN A  
HALF INCH. LOCATIONS WHICH HAVE SEEN CONSIDERABLE RAINFALL IN THE  
LAST 24 HOURS CANNOT HANDLE MUCH MORE WATER AND MAY SEE A REBOUNDING  
OF FLOODING WITH EVEN MINOR AMOUNTS OF ADDITIONAL RAINFALL. SHOWERS  
AND ISOLATED STORMS WILL SLOWLY DECREASE IN INTENSITY AND COVERAGE  
LATER THIS EVENING AND INTO THE OVERNIGHT HOURS WITH AN EXPECTED  
DECREASE IN LOW LEVEL MOISTURE TRANSPORT, ALTHOUGH THE PERSISTENCE  
OF UPPER DIVERGENCE ESPECIALLY ACROSS THE NE AND FAR N CWA WILL  
NECESSITATE RETAINING A LOW CHANCE THERE THROUGH THE NIGHT. AREAS OF  
FOG AND STRATUS SHOULD RETURN LATE TONIGHT. LOWS FROM THE LOW 60S  
WEST TO UPPER 60S EAST. -GIH  
 

 
   
SHORT TERM /FRIDAY AND FRIDAY NIGHT/
 
 
AS OF 325 PM THURSDAY...  
 
THE LARGE UPPER LOW WILL WOBBLE AND DRIFT SLOWLY NORTHWARD OVER IN  
DURING THIS PERIOD, WHILE WEAK SURFACE LOW PRESSURE HOLDS OVER THE  
FAR WESTERN PIEDMONT ALONG THE INCREASINGLY DIFFUSE NORTH-SOUTH  
ORIENTED SURFACE FRONT. THIS FRONT WILL WEAKEN FURTHER AS IT EASES  
JUST A BIT EASTWARD INTO CENTRAL NC THROUGH THE DAY, WITH THE  
GREATEST PW OVER THE EASTERN FRINGE OF THE CWA AND OVER COASTAL  
SECTIONS. THE BULK OF THE DPVA PIVOTING AROUND THE MID LEVEL LOW  
APPEARS TO HOLD JUST TO OUR WEST, WHILE THE BETTER UPPER DIVERGENCE  
SHIFTS JUST TO OUR NORTH AND NW, SO WE SHOULD SEE A LESSENING OF  
BOTH DEEP MOISTURE AND OF LARGE SCALE FORCING FOR ASCENT. WILL  
MAINTAIN HIGH CHANCE POPS ACROSS THE FAR N AND NE TRENDING TO SLIGHT  
CHANCE POPS OVER THE SW, DECREASING AFTER NIGHTFALL. EXPECT HIGHS  
FROM THE UPPER 70S TO LOWER 80S, FOLLOWED BY LOWS IN THE MID 50S  
WEST TO MID 60S EAST. -GIH  
 

 
   
LONG TERM /SATURDAY THROUGH THURSDAY/
 
 
AS OF 350 PM THURSDAY...  
 
THE PERSISTENT UPPER LOW OVER THE TENN VALLEY WILL FINALLY LIFT  
NORTH INTO THE GREAT LAKES AND WEAKEN, AS A TROUGH DEEPENS OVER THE  
PACIFIC NORTHWEST. THIS WILL LEAD TO A GENERAL TREND TOWARD HIGHER  
HEIGHTS OVER THE EASTERN U.S, A SURFACE HIGH PRESSURE RIDGE DOWN THE  
EAST COAST AND TEMPS NEAR AT OR JUST SLIGHTLY ABOVE. BEFORE THE LOW  
FULLY DEPARTS THE REGION, SOME DIURNAL CONVECTION IS POSSIBLE ACROSS  
THE FAR SOUTH/EAST SATURDAY AND SUNDAY GIVEN THE CONTINUED PRESENCE  
OF THE FRONT THAT SINKS OVER THE AREA THIS WEEKEND, BUT WITH  
DIMINISHING IN COVERAGE WITH EACH DAY.  
 
MOST OF THE LONG TERM FOCUS IS WITH THE UNCERTAINTY IN THE TRACK OF  
WHAT IS CURRENTLY HURRICANE MATTHEW OVER IN THE CENTRAL CARRIBEAN.  
THE OFFICIAL NHC TRACK BRINGS MATTHEW NORTH ACROSS THE BAHAMAS EARLY  
NEXT WEEK IN RESPONSE TO AN UPPER TROUGH CROSS THE GULF COAST  
REGION. THIS IS STILL RATHER UNCERTAIN AT DAY 7, HOWEVER, AND QUITE  
LIKELY TO CHANGE IN THE COMING BACKS.  
 

 
   
AVIATION /18Z THURSDAY THROUGH TUESDAY/
 
 
AS OF 215 PM THURSDAY...  
 
CONDITIONS HAVE IMPROVED TO VFR OVER ALL BUT FAY, WHERE MVFR CIGS  
LINGERED, AND NEAR GSO WHERE MVFR CIGS RETURNED WITH SHOWERS IN THE  
VICINITY. PERIODS OF SUB-VFR CONDITIONS -- MAINLY MVFR BUT BRIEFLY  
IFR AT TIMES -- IS EXPECTED AT ALL CENTRAL NC TERMINAL SITES THROUGH  
THE REST OF THE AFTERNOON, AS SCATTERED TO NUMEROUS SHOWERS AND  
STORMS FORM OVER THE AREA AND MOVE SWIFTLY TOWARD THE NORTH,  
GENERATING BRIEF HEAVY RAIN, PERIODIC WIND GUSTS, AND POSSIBLE SMALL  
HAIL. THE SHOWER/STORM COVERAGE WILL SLOWLY DECREASE THROUGH THE  
EVENING AND NIGHT FROM SW TO NE, WITH RWI THE LAST TO SEE THE RAIN  
THREAT DIMINISH. WITH A MOIST GROUND AND LIGHT WINDS FROM THE SE,  
WIDESPREAD IFR TO LIFR CIGS AND MVFR TO IFR VSBYS ARE EXPECTED TO  
DEVELOP AT ALL SITES AFTER 07Z TONIGHT, LASTING UNTIL AROUND 13Z  
FRI. VFR CONDITIONS EXPECTED AFTER THAT, THROUGH THE END OF THE TAF  
VALID PERIOD. A FEW SHOWERS MAY LINGER THROUGH THE MORNING IN THE  
EAST NEAR FAY/RWI.  
 
LOOKING BEYOND 18Z FRI, ANOTHER ROUND OF MVFR SHOWERS AND ISOLATED  
STORMS ARE EXPECTED MAINLY AT RDU/FAY/RWI FRI AFTERNOON INTO EARLY  
EVENING AS A SURFACE FRONT SHIFTS SLOWLY EASTWARD INTO CENTRAL NC.  
THIS FRONT WILL WEAKEN AND DISSIPATE HEADING INTO THE WEEKEND,  
ALLOWING THE BETTER RAIN CHANCES TO SHIFT TO OUR EAST. EXCEPT FOR A  
POTENTIAL FOR MVFR OR IFR FOG/STRATUS AT RWI EARLY SAT MORNING, VFR  
CONDITIONS WILL DOMINATE THROUGH TUE WITH LOW RAIN CHANCES. -GIH  
 

 
   
RAH WATCHES/WARNINGS/ADVISORIES
 
 
FLASH FLOOD WATCH UNTIL 10 PM EDT THIS EVENING FOR NCZ028-042-043-  
075>078-084>086-088-089.  
 

 
 

 
 
SYNOPSIS...HARTFIELD  
NEAR TERM...HARTFIELD  
SHORT TERM...HARTFIELD  
LONG TERM...BS  
AVIATION...HARTFIELD  
 
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