369  
FXUS62 KRAH 270747  
AFDRAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RALEIGH NC  
345 AM EDT MON JUN 27 2016  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL WEAKEN OVER THE AREA TODAY AS A COLD FRONT  
APPROACHES FROM THE WEST EARLY TONIGHT THROUGH TUESDAY.  
 

 
   
NEAR TERM /TODAY AND TONIGHT/
 
 
AS OF 345 AM MONDAY...  
 
SURFACE AND LOW AMPLITUDE MID LEVEL RIDGING WEAKENS TODAY, SETTING  
UP A SOUTHERLY RETURN FLOW REGIME FEATURING WARM AIR AND MOISTURE  
ADVECTION AHEAD OF A COLD FRONT SAGGING SOUTHEAST OUT OF THE OHIO  
VALLEY THIS EVENING. WITH THE LATE ARRIVAL OF THE FRONTAL ZONE,  
PARTLY TO MOSTLY SUNNY SKIES ARE ON TAP WHICH WILL ALLOW HIGHS TO  
INCH UP A BIT FROM SUNDAY'S MID AND UPPER 80S, WITH UPPER 80S NORTH  
TO WIDESPREAD 90 TO 92 DEGREES ACROSS THE SOUTHERN HALF OF THE AREA.  
 
STRENGTHENING OF THE LOW LEVEL FLOW IMMEDIATELY AHEAD OF THE SLOW  
MOVING FRONT WILL BOOST PRECIPITABLE WATER IN THE WEST BY SUNSET,  
WITH THE SUBSEQUENT 1.5 TO 2 INCH PLUME SETTLING SLOWLY ACROSS THE  
AREA OVERNIGHT. INITIAL INSTABILITY IN THE WEST MAY BE SUFFICIENT  
FOR THUNDERSTORMS IN THE NORTHWEST PIEDMONT EARLY THIS EVENING, BUT  
INSTABILITY WILL BE WANING WITH UNFAVORABLE DIURNAL TIMING  
CONCURRENT WITH THE ARRIVAL OF STRONGER LOW LEVEL CONVERGENCE  
ASSOCIATED WITH THE H85 TROF. IN ADDITION, MID LEVEL SUPPORT LAGS  
THE EASTWARD PROGRESSION OF THE LOW LEVEL FORCING SO EXPECT ONLY  
ISOLATED STORMS, BUT SCATTERED TO NUMEROUS SHOWERS OVERNIGHT,  
FOCUSED IN THE WEST EARLY TO CENTRAL AND EAST AFTER MIDNIGHT.  
 

 
   
SHORT TERM /TUESDAY AND TUESDAY NIGHT/
 
 
AS OF 345 AM MONDAY...  
 
UPPER TROF AXIS ROTATING ACROSS THE APPALACHIANS ON TUESDAY WILL  
PROVIDE SOME MISSING KINEMATIC INGREDIENTS NEEDED FOR STORM  
INITIATION AND ORGANIZATION. WHILE SHEAR AND INSTABILITY WILL BE  
RATHER UNIMPRESSIVE (CAPE OF ~1.2K JOULES) DUE TO CLOUD COVERAGE AND  
MID LEVEL LAPSE RATES OF LESS THAN 5.5C/KM, THESE WILL BE OFFSET BY  
FAVORABLE ALIGNMENT OF MODEST UPPER DIFFLUENCE AHEAD OF THE TROF  
AXIS AND MID LEVEL DPA. AS SUCH, THERE IS STRONG CONSENSUS IN JUST  
ABOUT EVERY MESO-MODEL AVAILABLE ON THE DEVELOPMENT OF A SQUALL LINE  
IN THE EARLY AFTERNOON ACROSS THE NORTHWEST PIEDMONT WITH SUBSEQUENT  
MOVEMENT EAST ACROSS THE AREA DURING THE AFTERNOON AND EARLY  
EVENING. THE CONVECTIVE LINE MOVES EAST OF THE AREA AROUND SUNSET,  
WITH SUBSEQUENT DRYING OVERNIGHT. HIGHS TUESDAY WILL BE HAMPERED BY  
THE CLOUD COVERAGE AND WEAK COOL AIR ADVECTION BEHIND THE FRONT,  
WITH MOST AREAS TOPPING OUT IN THE MID 80S. LOWS TUESDAY NIGHT WILL  
BE MOSTLY MID 60S.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SUNDAY/
 
 
AS OF 317 AM MONDAY...  
 
CYCLONIC FLOW AROUND THE BROAD MID-UPR LONGWAVE TROUGH OVER MUCH OF  
THE EASTERN US WILL BE THE GENERAL PATTERN FOR THE LONG TERM PERIOD.  
THE SURFACE PATTERN OVER THE CAROLINAS WILL FEATURE A PERSISTENT  
PIEDMONT TROUGH THAT IS TYPICAL WITH WESTERLY OR WEST-NORTHWESTERLY  
FLOW. WHILE THE MAIN MOISTURE AXIS IS PROGGED TO REMAIN MOSTLY TO  
OUR EAST THROUGH THE REST OF THE WORK WEEK, IT APPEARS THAT THERE  
WILL BE ENOUGH MOISTURE LINGERING OVER OUR AREA, WHEN COMBINED WITH  
THE SFC TROUGH AND WAVES EMBEDDED IN THE CYCLONIC FLOW ALOFT, THAT  
20-40 PERCENT POPS (HIGHEST EAST) APPEARS WARRANTED...MAINLY DURING  
THE AFTERNOON/EVENING EACH DAY THROUGH THE PERIOD. RAIN CHANCES  
WILL THEN INCREASE NEXT SUNDAY AS THE NEXT SFC FRONT APPROACHES AND  
MOVES THROUGH THE AREA.  
 
WITH LITTLE AIRMASS CHANGE EXPECTED...LOOK FOR TEMPS TO REMAIN A FEW  
DEGREES EITHER SIDE OF CLIMO THROUGH THE PERIOD, WITH THE MAIN  
INFLUENCE BEING CLOUD AND PRECIP COVERAGE.  
 

 
   
AVIATION /06Z MONDAY THROUGH FRIDAY/
 
 
AS OF 245 AM MONDAY...  
 
PATCHY IFR/MVFR VISIBILITIES ARE POSSIBLE IN THE PREDAWN ACROSS THE  
NORTHEAST PIEDMONT AND NORTHERN COASTAL PLAIN (RWI TAF, PRIMARILY)  
AS THE T/TD SPREAD NARROWS UNDER CLEAR AND CALM CONDITIONS. VFR  
CONDITIONS WILL PREVAIL ACROSS THE AREA AFTER 12Z THROUGH LATE DAY  
AS HIGH PRESSURE WEAKENS AHEAD OF A COLD FRONT SAGGING SOUTH OUT OF  
THE OHIO VALLEY EARLY TONIGHT. EXPECT WIDELY SCATTERED SHOWERS AFTER  
00Z IN THE TRIAD (GSO/INT), WITH INCREASING COVERAGE INTO THE EAST  
AFTER 03Z. MVFR CONDITIONS WILL ACCOMPANY STRONGER SHOWERS AND  
ISOLATED THUNDERSTORMS.  
 
BEYOND THE 24 HOUR TAF PERIOD, SHOWERS AND ISOLATED STORMS ARE  
EXPECTED FOR THE REMAINDER OF THE OVERNIGHT AS THE FRONT APPROACHES.  
A LINE OF STRONG THUNDERSTORMS WILL ACCOMPANY THE FRONT ON TUESDAY  
BEGINNING AROUND MIDDAY IN THE WEST (INT/GSO) AND PROGRESSING INTO  
THE EAST (RDU/FAY/RWI) AREAS BETWEEN 21-00Z.  
 
BEYOND TUESDAY, THE FRONT LOOKS TO STALL FAR ENOUGH SOUTHEAST OF THE  
AREA THAT TO PRECLUDE THE THREAT OF ADVERSE AVIATION CONDITIONS  
OUTSIDE OF ISOLATED DIURNAL CONVECTION FROM WEDNESDAY THROUGH THE  
WEEKEND.  
 

 
   
RAH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
 
SYNOPSIS...MLM  
NEAR TERM...MLM  
SHORT TERM...MLM  
LONG TERM...MWS  
AVIATION...MLM  
 
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