446  
FXUS62 KRAH 191958  
AFDRAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RALEIGH NC  
258 PM EST TUE NOV 19 2019  
   
SYNOPSIS
 
 
A SERIES OF STRONG UPPER LEVEL DISTURBANCES WILL CROSS THE REGION  
THROUGH TONIGHT. HIGH PRESSURE WILL BUILD OVER THE AREA WEDNESDAY  
AND THURSDAY. THIS HIGH PRESSURE AREA WILL THEN PUSH TO OUR SOUTH ON  
FRIDAY, AS A COLD FRONT APPROACHES FROM THE NORTH.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 155 PM TUESDAY...  
 
THE MEAN MID LEVEL TROUGH SITTING OVER EASTERN NOAM FEATURES TWO  
SUBTLE BUT DISTINCT WAVES IN CLOSE PROXIMITY: ONE NOW SHIFTING ENE  
WITH A NEGATIVE TILT THROUGH THE CENTRAL CAROLINAS, AND THE SECOND  
CLOSE ON ITS HEELS, DIVING SOUTHEASTWARD INTO THE S APPALACHIANS.  
THIS MORNING'S LOW CLOUDS HAVE FINALLY LIFTED AND MIXED OUT OVER NW  
AND FAR N SECTIONS, LESS SO OVER THE COASTAL PLAIN/SANDHILLS,  
ALTHOUGH THESE TOO SHOULD START TO MIX OUT IN EARNEST AS THE LEAD  
VORTICITY CENTER NOW MOVING OFF THE SC COAST PUSHES THE TROUGH AXIS  
OFFSHORE. BUT CLOUDS WILL RETURN THIS EVENING AS THE SHEARED,  
ELONGATED VORTICITY LOBE SWINGS SE THROUGH THE CAROLINAS, BRINGING  
STRATOCU/ALTOCU MAINLY TO N SECTIONS OF CENTRAL NC, ACCOMPANIED BY  
PASSAGE OF WEAK SURFACE LOW PRESSURE. WHILE A FEW SPRINKLES ARE  
POSSIBLE GIVEN THIS POTENT LARGE SCALE LIFT, WIDESPREAD MEASURABLE  
PRECIP APPEARS UNLIKELY BASED ON UPSTREAM AND MODEL-PROJECTED  
MOISTURE PROFILES, SO WILL MAINTAIN SUB-15% POPS. THIS FORCING FOR  
ASCENT WILL TRACK TO OUR EAST AND OFF THE COAST VERY LATE TONIGHT  
INTO WED MORNING, AND AS SURFACE WINDS BECOME UNIFORM NORTHWESTERLY  
AND STRENGTHEN, THE RESULTING DOWNSLOPE FLOW ALONG WITH DCVA AND  
RISING HEIGHTS ALOFT WILL PROMPT A CLEARING TREND STARTING VERY LATE  
TONIGHT. WITH THE DELAY IN LOWER DEWPOINTS AND CONTINUED LIGHT  
SURFACE WINDS IN OUR SE SECTIONS, HOWEVER, THERE MAY STILL BE  
PATCHES OF SHALLOW GROUND FOG THERE LATE TONIGHT. EXPECT LOWS IN THE  
MID 30S TO AROUND 40. -GIH  
 

 
   
SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/
 
 
AS OF 230 PM TUESDAY...  
 
THE MEAN TROUGH AXIS WILL CONTINUE TO DEEPEN AS IT HEADS E OFF THE  
MID ATLANTIC AND NORTHEAST COAST WED MORNING, LEAVING RISING HEIGHTS  
AND DECELERATING NW MID LEVEL FLOW IN ITS WAKE OVER NC. APART FROM  
SOME LINGERING EARLY-MORNING CLOUDS IN THE SE, SKIES SHOULD BE  
GENERALLY CLEAR WED, WITH LITTLE MORE THAN SOME FLAT HIGH-BASED CU  
AS THE COLUMN DRIES AND STABILIZES. SURFACE HIGH PRESSURE EXTENDING  
FROM THE NORTH CENTRAL GULF UP ALONG THE SOUTHERN AND MID MISS  
VALLEY THIS AFTERNOON WILL DRIFT NE OVER THE OHIO VALLEY AND INTO  
THE INTERIOR MID ATLANTIC REGION THROUGH WED NIGHT, RESULTING IN A  
PERSISTENT LOW LEVEL THERMAL TROUGH EXTENDING THROUGH CENTRAL NC  
WITH THICKNESSES REMAINING SLIGHTLY BELOW NORMAL. BUT WITH AMPLE  
SUNSHINE TO SOMEWHAT OFFSET THE CAA, TEMPS SHOULD STILL PEAK WITHIN  
A COUPLE OF DEGREES OF NORMAL, IN THE UPPER 50S TO LOWER 60S. LOWS  
WED NIGHT IN THE LOW-MID 30S WITH GOOD RADIATIONAL COOLING EXPECTED,  
ALTHOUGH WE SHOULD SEE SOME HIGH THIN CLOUDINESS SPREADING IN LATE  
AHEAD OF A DAMPENING WAVE (THE REMNANTS OF THE CLOSED LOW CURRENTLY  
OFF BAJA) MOVING NE THROUGH THE MIDWEST. -GIH  
 

 
   
LONG TERM /THURSDAY THROUGH TUESDAY/
 
 
AS OF 255 PM TUESDAY...  
 
THROUGH THURSDAY: THE SURFACE HIGH WILL SHIFT SLOWLY SOUTHEASTWARD  
THROUGH THURSDAY NIGHT WHILE THE RIDGE ALOFT DAMPENS OVER THE  
REGION. CLOUDS WILL START TO CREEP IN FROM THE WEST THURSDAY NIGHT  
AS THE NEXT COLD FRONT APPROACHES. WINDS BOTH ALOFT AND AT THE  
SURFACE WILL BACK TO MORE WEST/SOUTHWESTERLY BY FRIDAY MORNING.  
TEMPERATURES SHOULD BE NEAR TO SLIGHTLY BELOW NORMAL WITH HIGHS IN  
THE MID 50S TO LOW 60S. AS A RESULT OF THE INCREASING CLOUDS AND  
SOUTHWESTERLY FLOW THURSDAY NIGHT, LOWS WILL BE QUITE A BIT HIGHER  
THAN THE PREVIOUS NIGHT, GENERALLY IN THE MID 40S.  
 
FRIDAY THROUGH SUNDAY: VARIOUS INTERACTIONS BETWEEN NORTHERN AND  
SOUTHERN STREAM FEATURES WILL SHAPE THE WEATHER FOR CENTRAL NC OVER  
THE WEEKEND. THERE ARE SEVERAL FEATURES AT PLAY HERE. FIRST, THERE  
IS A TROPICAL SYSTEM OVER THE PACIFIC THAT WILL MOVE NORTHEASTWARD  
OVER THE BAJA AND INTO THE SOUTHWEST US TONIGHT. MEANWHILE, A  
NORTHERN STREAM TROUGH OVER THE PACIFIC NORTHWEST WILL AMPLIFY AS A  
S/W LOW SWINGS AROUND THE BASE OF THE TROUGH. THE S/W LOW WILL BREAK  
OFF FROM THE PARENT TROUGH, CLOSING OFF OVER OR/CA/NV THIS EVENING.  
THESE TWO UPPER LOWS WILL INTERACT AS THE NORTHERN STREAM LOW  
ABSORBS SOME OF THE ENERGY FROM THE TROPICAL SYSTEM, DEEPENING  
ITSELF IN THE PROCESS OVER THE SOUTHWEST US TONIGHT/EARLY WED. AS  
THE NORTHERN STREAM LOW BECOMES DOMINANT AND NEARLY STATIONARY OVER  
THE INTERMOUNTAIN WEST, THE REMNANTS OF THE TROPICAL/SOUTHERN STREAM  
LOW WILL LIFT EAST-NORTHEAST AS A SHORTWAVE. A SURFACE LOW WILL  
DEVELOP IN RESPONSE TO THE S/W ALOFT WITH FRONTOGENESIS OVER THE  
PLAINS/MIDWEST WED NIGHT/THU. THE FRONT WILL PROGRESS EASTWARD  
THROUGH THE MIDWEST AS THE SURFACE LOW LIFTS/MOVES EAST-NORTHEAST  
TOWARD AND THROUGH THE GREAT LAKES. THE EASTWARD PROGRESSION OF THE  
FRONT WILL SLOW/STALL AS THE BEST ENERGY LIFTS FURTHER AWAY FROM THE  
AREA AND HIGH PRESSURE LINGERS OVER THE SOUTHEAST US. THE COLD  
CANADIAN HIGH WILL SETTLE SOUTH OVER THE NORTHERN PLAINS/WESTERN  
GREAT LAKES THURSDAY NIGHT. IT STILL APPEARS THE NORTHERN STREAM  
TROUGH WILL REMAIN ANCHORED WITH THE CLOSED LOW OVER THE IM WEST  
UNTIL IT MOVES EASTWARD OVER THE ROCKIES THU NIGHT. AS THE LOW WILL  
SHIFTS EASTWARD OVER INTO THE PLAINS/MIDWEST FRIDAY THE NORTHERN  
STREAM TROUGH WILL DETACH FROM IT AND SWING THROUGH THE GREAT LAKES  
AND INTO NEW ENGLAND. SUBSEQUENTLY, THE LOW WILL OPEN INTO A TROUGH  
OVER THE MIDWEST, ONCE AGAIN STRENGTHENING FRONTOGENESIS, WITH A  
SURFACE LOW DEVELOPING ALONG THE FRONT IN THE VICINITY OF LA/MS/THE  
SOUTHERN APPALACHIANS FRIDAY NIGHT. ALTHOUGH THERE ARE STILL SOME  
SUBTLE DIFFERENCES BETWEEN THE MEDIUM-RANGE MODELS WITH THE  
PROGRESSION OF THE SURFACE LOW AND COLD FRONT, THEY ARE IN  
SURPRISINGLY GOOD AGREEMENT. THE AFOREMENTIONED SURFACE LOW IS  
EXPECTED TO TREK NORTHEAST ALONG THE SPINE OF THE MTNS AS A  
SECONDARY LOW DEVELOPS OVER THE CAROLINAS, ENHANCING LIFT AND THUS  
PRECIPITATION CHANCES/AMOUNTS OVER THE AREA. BEST CHANCES FOR RAIN  
WILL BE BETWEEN MIDNIGHT SATURDAY AND MIDNIGHT SUNDAY. THE FRONT AND  
ASSOCIATED RAINFALL SHOULD EXIT THE AREA SUNDAY, WITH A RETURN TO  
DRY WEATHER. FRIDAY WILL LIKELY BE THE WARMEST DAY OF THE PERIOD,  
ALBEIT CLOUDY. WEEKEND TEMPERATURES WILL BE HIGHLY DEPENDENT ON THE  
FRONT AND ASSOCIATED RAINFALL.  
 
MONDAY AND TUESDAY: PRIMARILY DRY WEATHER EXPECTED THROUGH TUESDAY  
AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE  
FRONT. ANOTHER FRONTAL SYSTEM WILL DEVELOP OVER THE PLAINS AND  
PROGRESS EASTWARD THROUGH MID-WEEK.  
 

 
   
AVIATION /18Z TUESDAY THROUGH SUNDAY/
 
 
AS OF 123P PM TUESDAY...  
 
IFR TO MVFR CONDITIONS HELD ON FOR MUCH OF THE MORNING BUT HAVE  
BEGUN TO BREAK UP IN THE LAST FEW HOURS AS DRIER AIR ALOFT HAS  
STARTED TO MIX GROUNDWARD WITH DECREASING SURFACE-BASED STABILITY.  
INT/GSO HAVE ALREADY BECOME SCATTERED WITH THEIR LOW CLOUDS, AND THE  
BROKEN IFR/MVFR CIGS AT RDU/RWI/FAY SHOULD CONTINUE TO SLOWLY LIFT  
WITH PERIODIC BREAKS THROUGH 22Z. AFTER THIS TIME, SCATTERED TO  
BROKEN STRATOCU (VFR) TOPPED WITH MID CLOUDS WILL SPREAD IN FROM THE  
NW AS MID LEVEL ENERGY DIVES INTO THE TROUGH BASE AND OVER NC THIS  
EVENING INTO THE OVERNIGHT HOURS. THERE IS A CHANCE FOR SHALLOW  
GROUND FOG LATE TONIGHT AT RDU/FAY/RWI WITH LINGERING NEAR-SURFACE  
MOISTURE, BUT UNCERTAINTY IS HIGH AND COVERAGE SHOULD BE LOW.  
OTHERWISE, CLEARING IS EXPECTED FROM THE W TOWARD DAYBREAK WED, AS  
THE TROUGH AXIS SHIFTS TO OUR E WITH RISING HEIGHTS ALOFT AND LOW  
LEVEL DRYING AS A STEADY DOWNSLOPE NW FLOW DEVELOPS. VFR CONDITIONS  
ARE LIKELY FROM MID MORNING ON.  
 
LOOKING BEYOND 18Z WED, VFR CONDITIONS ARE EXPECTED TO HOLD THROUGH  
AT LEAST THE FIRST PART OF FRI AS HIGH PRESSURE BUILDS OVER THE  
AREA, ALTHOUGH THERE IS A RISK FOR LLWS EARLY FRI MORNING. AN  
APPROACHING UPPER TROUGH AND SURFACE LOW WILL BRING INCREASING  
CHANCES FOR SUB-VFR CONDITIONS AND RAIN STARTING LATE FRI AND  
CONTINUING THROUGH SAT NIGHT, WITH STRONG/GUSTY/SHIFTING WINDS. VFR  
CONDITIONS ARE EXPECTED SUN AS HIGH PRESSURE RETURNS. -GIH  
 

 
   
RAH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

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