652  
FXUS62 KRAH 091811  
AFDRAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RALEIGH NC  
111 PM EST FRI DEC 9 2022  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL EXTEND ACROSS THE MID ATLANTIC AND SOUTHERN  
APPALACHIANS, WHILE BEING OVERSPREAD BY WEAKLY-PERTURBED FLOW ALOFT,  
THROUGH THE WEEKEND.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 1000 AM FRIDAY...  
 
THE MORNING FORECAST UPDATE WAS SENT WITH MINIMAL CHANGE FROM THE  
PREVIOUS FORECAST. UPSLOPE STRATUS, BASED AS LOW AS 200-400 FT AGL  
AT INT AND GSO, AND LIGHT RAIN AND DRIZZLE, MAY PERSIST INTO THE  
EARLY AFTERNOON OVER THE NW PIEDMONT. THE DAYLIGHT HOURS WILL BE DRY  
OTHERWISE AND ELSEWHERE, AS DRIER AIR WILL CONTINUE TO ADVECT IN  
NELY FLOW INTO CNTL NC, AROUND HIGH PRESSURE OVER THE MID ATLANTIC.  
GIVEN THE COMBINATION OF CONTINUED COOL, DRY ADVECTION, AND ALSO  
CLOUDY OR MOSTLY SO CONDITIONS THROUGHOUT THE DAY, TEMPERATURES ARE  
ONLY EXPECTED TO RISE A CATEGORY OR TWO FROM MID-MORNING READINGS  
MOSTLY IN THE UPR 40S TO AROUND 50.  
   
PREV DISCUSSION
 
/ISSUED 318 AM EST FRI DEC 09 2022/  
 
LIGHT RAIN HAS BLOSSOMED IN THE LAST FEW HOURS, ESPECIALLY OVER THE  
SOUTHERN PIEDMONT AND SANDHILLS, OWING TO LOW-LEVEL FRONTOGENESIS  
AND ISENTROPIC ASCENT ATOP THE SURFACE BOUNDARY. THE BOUNDARY IS  
CURRENTLY LOCATED NEAR THE NC/SC BORDER, BUT WITH TIME IT WILL SAG  
SOUTH INTO SOUTHERN SC THIS MORNING AND SOUTHERN GA BY EARLY SAT.  
THE FRONTOGENETICAL FORCING AND ISENTROPIC ASCENT WILL SLOWLY WANE  
BY SUNRISE AS SURFACE HIGH PRESSURE OVER CANADA CONTINUES TO FURTHER  
EXTEND INTO THE CAROLINAS. AS SUCH, A DRY DAY WILL TAKE OVER OVER  
MOST OF CENTRAL NC. THE BUILDING HIGH WILL REINFORCE A CAD WEDGE OF  
COOL/MOIST ENE FLOW, RESULTING IN PERIODS OF STRATOCUMULUS, MOST  
DENSE OVER THE WESTERN PIEDMONT WITH WEAK SURFACE UPSLOPE FLOW. THIS  
WEAK UPSLOPE FLOW FOR THE MORNING HOURS WILL ALSO FAVOR A FEW HOURS  
OF LIGHT DRIZZLE OVER THE TRIAD AND WESTERN/SOUTHERN PIEDMONT THIS  
MORNING. WHILE SOME BREAKS MAY OCCUR IN THE CLOUDS OVER THE  
NORTHEAST PIEDMONT AND COASTAL PLAIN, CONSIDERABLE CLOUDS WILL FAVOR  
A SMALL DIURNAL TREND WITH HIGHS BELOW NORMAL IN THE LOW TO MIDDLE  
50S, COOLEST IN THE NORTH AND WEST.  
 
ALOFT, A MID-LEVEL SHORTWAVE CURRENTLY OVER IA WILL BECOME SHEARED  
OUT AS IT MOVES INTO THE OHIO VALLEY AND LOWER GREAT LAKES. A RIDGE  
OVER THE CENTRAL PLAINS WILL BUILD INTO THE OHIO VALLEY BY EARLY  
SAT. SOME ENERGY TIED TO THE AFOREMENTIONED SHORTWAVE CURRENTLY OVER  
AR WILL DRIFT ESE INTO GA/SC THIS AFTERNOON AND TONIGHT, LARGELY  
MISSING CENTRAL NC. HOWEVER, LOW-LEVEL WAA/UPGLIDE CONFINED NEAR THE  
850MB LAYER, LIFTING ATOP THE LOW-LEVEL FRONTAL ZONE, WILL DEVELOP  
LATE TODAY AND MAINLY TONIGHT OVER WESTERN NC, WANING AFTER  
MIDNIGHT. THIS WILL FAVOR LOW-END CHANCES OF LIGHT RAIN/DRIZZLE OVER  
THE WESTERN PIEDMONT, LARGELY WEST OF US-1. AMOUNTS WOULD BE VERY  
LIGHT, AS EVIDENCE FROM THE LATEST HRRR/NAM-NEST AND HREF.  
 
TONIGHT, CLOUDS WILL REMAIN SOCKED IN, THOUGH SOME BREAKS IN THE  
CLOUDS IN THE NORTHEAST ARE POSSIBLE AS DRY ADVECTION CONTINUES TO  
FILTER IN, WITH DEWPOINTS LOWERING TO THE MID 30S TO AROUND 40 BY  
EARLY SAT. CAA WILL FAVOR COLDER OVERNIGHT LOWS BUT ABOVE NORMAL.  
CLOUDS WILL TEMPER THE RADIATIONAL COOLING WITH LOWS IN THE UPPER  
30S IN THE NE TO THE LOWER 40S IN THE SW.  
 

 
   
SHORT TERM /SATURDAY AND SATURDAY NIGHT/
 
 
AS OF 318 AM FRIDAY...  
 
HIGH PRESSURE OVER SE CANADA WILL CONTINUE TO EXTEND INTO THE MID-  
ATLANTIC AND CENTRAL NC SAT AND SAT NIGHT, KEEPING THE CAD WEDGE IN  
PLACE. AT MID-LEVELS, A RIDGE OVER THE OHIO VALLEY WILL MOVE EAST  
INTO OUR AREA DURING THE AFTERNOON/EVENING. CAA WILL RESULT IN LOW-  
LEVEL THICKNESSES ABOUT 10M LOWER THAN FRI, RESULTING IN ANOTHER  
COOL AND BELOW NORMAL DAY WITH HIGHS IN THE UPPER 40S IN THE NORTH  
TO THE LOW/MID 50S IN THE SOUTH. MOST OF SAT WILL BE DRY WITH PW'S  
DECREASING TO 90-PERCENT OF NORMAL, BUT WITH EXTENSIVE CLOUD COVER -  
THOUGH CANNOT RULE OUT SOME PARTIAL SUNSHINE ACROSS THE COASTAL  
PLAIN WITH LOW-LEVEL MOISTURE DECREASING IN THE NE FLOW.  
 
BY SAT NIGHT INTO EARLY SUN, OUR NEXT MID-LEVEL SHORTWAVE OVER THE  
UPPER MISSISSIPPI VALLEY AND GREAT LAKES REGION WILL TRACK INTO THE  
LOWER GREAT LAKES AND WESTERN NY, SENDING SHORTWAVE ENERGY INTO  
VA/NC. PW'S INCREASE ABOVE NORMAL TO ABOUT 0.9 INCHES. ISENTROPIC  
ASCENT/FRONTOGENETICAL FORCING WILL DEVELOP TOWARD EARLY SUN AS A  
SURFACE WAVE TRACKS ALONG THE TN VALLEY, WITH THE FRONTAL ZONE  
SLOWLY EDGING NORTH AS A WARM FRONT OVER CENTRAL GA. THIS WILL FAVOR  
DEVELOPMENT OF LIGHT RAIN COME EARLY SUN, BUT MOST FAVORED OVER THE  
WESTERN PIEDMONT. MODEL GUIDANCE HAS SLOWED THE START TIME OF THE  
PRECIPITATION SHIELD, WITH MOST ENERGY NOW COMING IN SUN MORNING  
INTO THE EVENING. THIS COUPLED WITH DRY AIR IN PLACE EVIDENT IN  
FORECAST SOUNDINGS SHOULD KEEP ANY PRECIPITATION AMOUNTS RATHER  
LIGHT BY EARLY SUN. OVERNIGHT LOWS WILL BE SIMILAR TO FRI NIGHT WITH  
CLOUD COVER IN PLACE, UPPER 30S TO LOWER 40S, LOWEST IN THE NORTH.  
 

 
   
LONG TERM /SUNDAY THROUGH THURSDAY/
 
 
AS OF 300 AM FRIDAY...  
 
SUNDAY: A SOUTHERN STREAM WAVE INVOF ARKLATEX REGION EARLY SUNDAY  
WILL CONTINUE TO EJECT ESEWD THROUGH THE DEEP SOUTH THROUGH EARLY  
MONDAY. ASSOCIATED ISENTROPIC LIFT AND WAA OVER THE SE US WILL  
RESULT IN ANOTHER WET AND GRAY DAY OVER CENTRAL NC, WITH LATEST  
ROUND OF MODEL GUIDANCE KEEPING THE BULK OF THE PRECIPITATION ALONG  
AND SOUTH OF US 1, IN PROXIMITY TO THE QUASI-STATIONARY FRONTAL ZONE  
DRAPED OVER AL, GA AND SOUTHERN PARTS OF SC. RAINFALL AMOUNTS ARE  
EXPECTED TO BE LIGHT. RAIN SHOULD GRADUALLY TAPER OFF FROM NORTH TO  
SOUTH DURING THE LATE AFTERNOON AND EVENING WITH THE EVENTUAL  
EROSION OF THE CAD AIRMASS SUNDAY NIGHT/EARLY MONDAY VIA POST-  
FRONTAL DRY, COLD AIR ADVECTION,  
 
THE CAD REGIME IN PLACE WILL BE MAINTAINED AND THUS WILL FEATURE  
ANOTHER COOL/CHILLY DAY. HIGHS RANGING FROM MID/UPPER 40S NORTH TO  
LOWER 50S SOUTH. LOWS SUNDAY NIGHT IN THE LOWER/MID 30S NORTH TO  
UPPER 30S/LOWER 40S SOUTH.  
 
MONDAY THROUGH TUESDAY: STRONG HIGH PRESSURE OVER EASTERN CANADA  
WILL EXTEND SOUTH DOWN THE EASTERN SEABOARD RESULTING IN DRY, SUNNY  
CONDITIONS TO START THE WORK WEEK AS UPPER LEVEL RIDGING BUILDS OVER  
THE EASTERN US, IN ADVANCE OF A SPRAWLING UPPER LOW OVER THE  
NATION'S MID SECTION. TEMPERATURES WILL AVERAGE NEAR TO SLIGHTLY  
BELOW NORMAL  
 
WEDNESDAY THROUGH THURSDAY: THE DEEP, MATURE LOW PRESSURE OVER THE  
CENTRAL US PLAINS IS FORECAST TO MOVE VERY LITTLE ON WEDNESDAY,  
BEFORE FINALLY EJECTING EASTWARD INTO THE OHIO VALLEY BY THURSDAY  
NIGHT. CLOUDS WILL OVERSPREAD THE AREA DURING THE DAY ON WEDNESDAY  
WITH RAIN LIKELY DELAYED UNTIL THE ARRIVAL OF THE OCCLUDED FRONTAL  
ZONE INTO THE TN VALLEY WEDNESDAY EVENING/NIGHT. DRIVEN BY A 50 KT  
LLJ, A POTENTIAL MILLER B STORM SYSTEM WILL BRING A HIGH CHANCE OF A  
SOAKING RAIN EVENT TO MUCH OF THE SE US DURING THE WEDNESDAY NIGHT-  
THURSDAY AFTERNOON/EVENING TIME FRAME. WILL ALSO HAVE TO CLOSELY  
MONITOR THE THREAT FOR SEVERE STORMS, PARTICULARLY THE  
TRACK/LOCATION OF THE SECONDARY SFC LOW/WARM FRONT AND ASSOCIATED  
MARITIME AIR THAT COULD BRIEFLY ADVECT INTO OUR SE COUNTIES. WRT TO  
TEMPERATURES, ANOTHER CAD EVENT LOOKS PROBABLE OVER THE  
WESTERN/CENTRAL PIEDMONT, WHICH WILL SET THE STAGE FOR A SHARP NW TO  
SE TEMPERATURE GRADIENT OVER THE CAROLINAS.  
 

 
   
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
 
 
AS OF 105 PM FRIDAY...  
 
GENTLE LIFT ATOP COOL SURFACE PRESSURE RIDGING SOUTH ACROSS THE MID  
ATLANTIC WILL MAINTAIN GENERALLY BROKEN TO OVERCAST STRATOCUMULUS  
LAYERS (LOW VFR CEILINGS) BASED BETWEEN 3500-5000 FT AGL THROUGH THE  
TAF PERIOD. THE EXCEPTION WILL BE AT INT/GSO, WHERE ELY UPSLOPE FLOW  
TODAY WILL FAVOR CURRENT LIFR-IFR CONDITIONS THAT SHOULD LIFT TO  
MVFR THROUGH EARLY THIS EVENING, AS THE DRIER AIR TO THE EAST AND  
NORTHEAST IS ADVECTED IN THEIR DIRECTION. WHILE A BRIEF SCATTERING  
TO VFR CANNOT BE RULED OUT DURING THAT TIME, THE ARRIVAL OF PATCHY  
LIGHT RAIN OVER THE WRN NC PIEDMONT WILL LIKELY REINFORCE THE MVFR  
MOIST LAYER, OR CAUSE IT TO LOWER INTO IFR RANGE ONCE AGAIN,  
OVERNIGHT. HOWEVER, THE BETTER CHANCE OF THOSE LIFR-IFR CONDITIONS  
WILL REMAIN ENTRENCHED ACROSS THE WRN CAROLINAS, NEAR AND JUST TO  
THE WEST OF INT.  
 
OUTLOOK: PERSISTENT COOL AND MOIST NELY FLOW AROUND SURFACE HIGH  
PRESSURE ACROSS THE MID ATLANTIC WILL FAVOR CONTINUED LOW VFR  
CEILINGS, TO OCCASIONAL SUB-VFR CONDITIONS MAINLY EACH NIGHT-  
MORNING, THROUGH MONDAY. PATCHY LIGHT RAIN WILL ALSO BE POSSIBLE AS  
A DISTURBANCE ALOFT CROSSES THE REGION EARLY SUNDAY.  
 

 
   
RAH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
SYNOPSIS...KREN/MWS  
NEAR TERM...MWS/KREN  
SHORT TERM...KREN  
LONG TERM...CBL  
AVIATION...MWS  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab NC Page Main Text Page