789  
FXUS62 KRAH 040450  
AFDRAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RALEIGH NC  
1250 AM EDT SAT JUL 4 2020  
   
SYNOPSIS
 
 
A WEAK BACKDOOR FRONT WILL MOVE SOUTHWARD THROUGH THE REGION TODAY,  
BRINGING SCATTERED LATE DAY SHOWERS AND STORMS. BEHIND THIS FRONT,  
HIGH PRESSURE WILL EXTEND INTO THE AREA FROM THE NORTH TONIGHT  
THROUGH SUNDAY BEFORE MOVING OFFSHORE. LOW PRESSURE WILL DEVELOP  
OVER THE LOWER MISSISSIPPI VALLEY AND GULF COAST STATES MONDAY,  
ALLOWING MOISTURE TO RETURN TO THE CAROLINAS WITH INCREASING RAIN  
CHANCES EARLY TO MID WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 837 PM FRIDAY...  
 
QUIET WEATHER REMAINS IN PLACE THIS EVENING AS THE AREA SITS UNDER  
THE INFLUENCE OF A DRY SUBSIDENT AIRMASS. LINGERING CU FROM LATE  
AFTERNOON HAS DISSIPATED, LEAVING BEHIND CLEAR/MOSTLY CLEAR SKIES.  
SOME HIGHER CLOUDS ARE STILL MAKING THEIR WAY OVER THE APPALACHIAN  
MTNS AND THEY WILL EVENTUALLY MAKE IT INTO NC BEFORE DAYBREAK, BUT  
SHOULD BE OF LITTLE CONSEQUENCE TO THE FORECAST.  
 
QUICK LOOK AT INCOMING MODEL DATA YIELDS VERY LITTLE CHANGE FROM THE  
INHERITED FORECAST OR PREVIOUS FORECAST THINKING. OVERNIGHT LOWS IN  
THE LOWER 70S IS A SOLID BET WITH PRECIP-FREE SKIES. I ONLY MADE  
SOME MINOR CHANGES TO TEMPS/DEWPOINTS BASED ON OBSERVATIONAL TRENDS,  
OTHERWISE THINGS ARE IN GOOD SHAPE.  
 

 
   
SHORT TERM /SATURDAY AND SATURDAY NIGHT/
 
 
AS OF 400 PM FRIDAY...  
 
A COUPLE OF MINOR SHORTWAVE TROUGHS OVER SWRN QC AND NRN MI THIS  
AFTERNOON WILL SETTLE SEWD ACROSS AND OFFSHORE THE MIDDLE ATLANTIC  
ON SAT, WITH GENERALLY NEUTRAL MID LEVEL HEIGHT TENDENCY AND FORCING  
FOR VERTICAL MOTION OVER CNTL NC THROUGH SAT NIGHT.  
 
AT THE SURFACE, A COLD FRONT ANALYZED FROM CT NWWD ACROSS CNTL NY  
WILL SAG SWD ACROSS SRN/SERN VA AND NRN/NERN NC ON SAT, IMMEDIATELY  
PRECEDED BY A PRE-FRONTAL TROUGH.  
 
CONVERGENCE AND LOW LEVEL MOISTURE POOLING ALONG AND IMMEDIATELY  
BEHIND THOSE BOUNDARIES WILL CONTRIBUTE TO THE DEVELOPMENT OF  
MODERATE INSTABILITY AND PROBABLE DEVELOPMENT OF SCATTERED SHOWERS  
AND STORMS ACROSS MAINLY THE NRN/NERN HALF OF CNTL NC SAT AFTERNOON-  
EVENING. OTHERWISE, THE WARM SECTOR OVER THE CAROLINAS WILL BE A HOT  
AND DEEPLY MIXED ONE WITH SURFACE DEWPOINTS LIKELY TO MIX OUT INTO  
THE LWR-MID 60S AHEAD OF THE TROUGH/FRONT. HIGH TEMPERATURES WILL BE  
NEAR TO PERHAPS A DEGREE OR TWO HOTTER THAN THOSE OF FRI, GIVEN  
FORECAST 850 MB TEMPERATURES NEAR 19-20 C. GIVEN THE MIXING OUT OF  
SURFACE MOISTURE IN THE WARM SECTOR, HEAT INDEX VALUES ARE EXPECTED  
TO TOP OUT BETWEEN 93 AND 98 DEGREES - MARGINALLY HAZARDOUS.  
 
THE COMBINATION OF POST-FRONTAL ELY FLOW AND RAIN-COOLED AIR/OUTFLOW  
AND LOCALLY MAXIMIZED RELATIVE HUMIDITY VALUES SAT NIGHT WILL FAVOR  
THE DEVELOPMENT OF AREAS OF STRATUS AND/OR FOG ACROSS THE NE  
PIEDMONT AND NRN-CNTL COASTAL PLAIN THROUGH SUN MORNING, WITH LOW  
TEMPERATURES GENERALLY AROUND 70 DEGREES.  
 

 
   
LONG TERM /SUNDAY THROUGH FRIDAY/
 
 
AS OF 320 PM FRIDAY...  
 
THE UPPER LEVEL TROUGH AXIS WILL LARGELY REMAIN SOUTH OF THE AREA  
THROUGH THE WEEKEND, WITH MEDIUM-RANGE MODELS STILL DEVELOPING A LOW  
OVER THE DEEP SOUTH/ARKLATEX BY SUNDAY OR MONDAY. OTHERWISE, THE  
FLOW ALOFT WILL BE SOMEWHAT DIFFUSE, WITH THE AFOREMENTIONED LOW  
SLOWLY DRIFTING EAST-NORTHEAST AND AMPLIFYING A WEAK TROUGH BEFORE  
MOVING EAST THROUGH THE REGION MID- TO LATE-WEEK. AT THE SURFACE,  
SOUTH-SOUTHEASTERLY FLOW INTO THE AREA OFF THE ATLANTIC WILL  
PERSIST, WITH HIGH PRESSURE CENTERED WELL TO THE NORTHEAST OFF THE  
NEW ENGLAND/NORTHEAST US COAST. THERE IS NOT VERY GOOD AGREEMENT  
WITH THE DEVELOPMENT AND SUBSEQUENT PROGRESSION OF A LOW DEVELOPING  
IN RESPONSE TO THE LOW ALOFT, THUS CONFIDENCE WITH EXACTLY IF AND  
WHEN IT WOULD IMPACT CENTRAL NC IS LOW AT THIS TIME. REGARDLESS OF  
THE COVERAGE, STILL EXPECT SHOWER AND THUNDERSTORM ACTIVITY TO BE  
DIURNALLY DRIVEN AND BEST CHANCES TO BE ACROSS THE SOUTHERN PORTIONS  
OF THE AREA. TEMPERATURES SHOULD BE NEAR NORMAL ON SUNDAY, WITH THE  
POTENTIAL FOR SOME BELOW NORMAL HIGHS ON THE DAYS WITH MORE  
EXTENSIVE CLOUD COVER AND CONVECTION. HIGHS WILL GENERALLY BE IN THE  
MID 80S TO LOW 90S AND LOWS IN THE UPPER 60S TO MID 70S.  
 

 
   
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
 
 
AS OF 1250 AM SATURDAY...  
 
VFR CONDITIONS ARE LIKELY TO DOMINATE THROUGH THE NEXT 24 HOURS  
ACROSS CENTRAL NC. FAIRLY DRY AIR IN PLACE NEAR THE GROUND WILL  
LIMIT POTENTIAL FOR FOG/STRATUS, PARTICULARLY WITH A BATCH OF MID  
AND HIGH CLOUDS SPREADING IN FROM THE WEST THIS MORNING TO SLIGHTLY  
LIMIT RADIATIONAL COOLING, BUT ISOLATED PATCHES OF GROUND FOG REMAIN  
POSSIBLE IN THE E AND FAR S 08Z-12Z THIS MORNING. JUST A FEW MID AND  
HIGH CLOUDS AT MOST ARE EXPECTED FOR MUCH OF THE DAY, BUT BROKEN  
HIGH-BASED CU IS EXPECTED WITH HEATING THIS AFTERNOON, AND THERE IS  
A CHANCE FOR STORMS MAINLY IMPACTING (BUT NOT LIMITED TO) RWI/RDU  
18Z TO 00Z, LEADING TO ISOLATED SUB-VFR CONDITIONS AND GUSTY WINDS  
IN/NEAR STORMS. SURFACE WINDS OVERALL WILL REMAIN LIGHT/VARIABLE.  
 
LOOKING BEYOND 06Z SUN, THERE IS A RISK FOR SUB-VFR FOG AND STRATUS  
PARTICULARLY NEAR RDU/RWI/FAY 08Z-12Z SUN MORNING. DAILY AFTERNOON  
AND EVENING SCATTERED STORMS AND THE RESULTANT RISK OF BRIEF SUB-VFR  
CONDITIONS AND GUSTY WINDS WILL RETURN SUN AFTERNOON AND BE THE NORM  
THROUGH MID WEEK, AS WEAK BUT PERSISTENT MID LEVEL LOW PRESSURE SITS  
OVER THE MID MISS VALLEY ACROSS THE MID SOUTH AND CAROLINAS. THERE  
IS A GOOD CHANCE FOR EARLY-MORNING SUB-VFR FOG AND STRATUS AREAWIDE  
BOTH TUE MORNING AND WED MORNING. -GIH  
 

 
   
RAH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
SYNOPSIS...HARTFIELD  
NEAR TERM...LEINS  
SHORT TERM...MWS  
LONG TERM...KC  
AVIATION...HARTFIELD  
 
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