878  
FXUS62 KCAE 271031  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
631 AM EDT TUE JUN 27 2017  
   
SYNOPSIS
 
 
A FRONT LINGERING NEAR THE COAST WILL SHIFT FARTHER OFFSHORE  
TONIGHT. A PRESSURE RIDGE EXTENDING THROUGH THE OHIO RIVER  
VALLEY TODAY WILL BE IN THE MID-ATLANTIC REGION WEDNESDAY AND  
OFF THE EAST COAST THURSDAY. DIMINISHED RELATIVE HUMIDITY  
WILL BE ASSOCIATED WITH THIS PATTERN THROUGH WEDNESDAY BUT  
MOISTURE WILL BE ON THE INCREASE LATE IN THE WEEK AS THE  
OFFSHORE RIDGE DIRECTS AN ONSHORE FLOW INTO THE FORECAST AREA.  
THIS TREND WILL LEAD TO INCREASING CHANCES OF THUNDERSTORMS.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
DRYING HAS OCCURRED BEHIND THE COLD FRONT. HOWEVER, THERE MAY BE  
ENOUGH RECOVERY OF MOISTURE AND INSTABILITY ASSOCIATED WITH A  
MID-LEVEL SHORTWAVE TROUGH TO SUPPORT A FEW SHOWERS OR  
THUNDERSTORMS THIS AFTERNOON INTO THE EVENING MAINLY IN THE  
NORTH AND EAST SECTIONS CLOSER TO GREATER UPPER LIFT OR DEEPER  
MOISTURE. THE HRRR SUGGESTED ISOLATED COVERAGE IN NORTH AND EAST  
SECTIONS THIS AFTERNOON. THE NAM AND GFS DEPICTED THE GREATEST  
INSTABILITY IN THE EASTERN MIDLANDS WITH SURFACE-BASED LI  
VALUES -4 TO -6. THE GFS HAD THE GREATER INSTABILITY. FORECAST  
SOUNDINGS INDICATED A GENERALLY DRY ATMOSPHERIC COLUMN AND AN  
INVERTED-V SIGNATURE. IF THUNDERSTORMS DO DEVELOP WITH THE  
LIMITED MOISTURE THEN STRONG GUSTY WINDS MAY OCCUR. THE  
THUNDERSTORM CHANCE SHOULD FURTHER DIMINISH OVERNIGHT WITH THE  
LOSS OF HEATING AND DRYING BEHIND THE MID-LEVEL SHORTWAVE  
TROUGH.  
 
FOLLOWED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.  
 

 
   
SHORT TERM /WEDNESDAY THROUGH THURSDAY/
 
 
THE MODELS HAVE BEEN CONSISTENT WITH DRY HIGH PRESSURE  
DOMINATING WEDNESDAY AND WEDNESDAY NIGHT. MOISTURE SHOULD BE ON  
THE INCREASE THURSDAY ESPECIALLY IN THE SOUTH PART OF THE  
FORECAST AREA IN AN ONSHORE FLOW ASSOCIATED WITH THE RIDGE OFF  
THE EAST COAST AND A MID-LEVEL SHORTWAVE TROUGH MOVING INTO THE  
REGION. FOLLOWED THE GUIDANCE CONSENSUS AND FORECASTED CHANCE  
POPS. ALSO USED THE CONSENSUS FOR THE TEMPERATURE FORECAST.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
 
 
THE GFS AND ECWMF DISPLAY MOISTURE IN A SOUTHERLY FLOW  
ASSOCIATED WITH OFFSHORE HIGH PRESSURE AND BROAD UPPER  
TROUGHING DURING MUCH OF THE MEDIUM-RANGE PERIOD. THE PATTERN  
SUPPORTS SCATTERED MAINLY DIURNAL THUNDERSTORMS. THE GFS AND  
ECWMF MOS PLUS GFS ENSEMBLE MEAN INDICATE CHANCE POPS WITH  
TEMPERATURES NEAR CLIMATOLOGY.  
 

 
   
AVIATION /12Z TUESDAY THROUGH SATURDAY/
 
 
A DRY ATMOSPHERE IS EXPECTED TO ENSURE VFR CONDITIONS THROUGH  
THE MORNING. SOME MID-LEVEL CLOUDINESS MAY STREAM ACROSS THE  
REGION. UPPER ENERGY AND A SURFACE TROUGH IS EXPECTED TO  
TRAVERSE THE REGION IN THE AFTERNOON. MOISTURE WILL BE LIMITED.  
HOWEVER, SOME GUIDANCE IS INDICATING A FEW SHOWERS AND ISOLATED  
THUNDERSTORMS POSSIBLE WITH THESE FEATURES IN THE AFTERNOON,  
MAINLY EAST OF CAE. HOWEVER, CONFIDENCE IS TOO LOW TO MENTION AT  
ANY OF THE TAF SITES. VFR CIGS POSSIBLE LATER THIS AFTERNOON BUT  
SKIES SHOULD BECOME MORE SCATTERED LATER THIS EVENING AFTER THE  
PASSAGE OF THE UPPER LEVEL ENERGY MOVES EAST OF THE AREA.  
 
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION  
EXPECTED THROUGH WEDNESDAY. A RETURN FLOW AND INCREASING LOW-LEVEL  
MOISTURE MAY PROVIDE A LATE NIGHT/EARLY MORNING STRATUS THREAT  
THU/FRI. SCATTERED THUNDERSTORMS EXPECTED FRI/SAT.  
 

 
   
CAE WATCHES/WARNINGS/ADVISORIES
 
 
GA...NONE.  
SC...NONE.  
 

 
 

 
SYNOPSIS...99  
NEAR TERM...99  
SHORT TERM...99  
LONG TERM...99  
AVIATION...99  
 
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