639  
FXUS61 KLWX 230038  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
838 PM EDT WED MAR 22 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL BUILD ACROSS THE AREA TONIGHT, AND MOVE  
OFFSHORE THURSDAY NIGHT. A WARM FRONT WILL CROSS THE REGION  
FRIDAY. LOW PRESSURE MAY AFFECT THE AREA SUNDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
 
 
HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT. MAINLY CLEAR  
SKIES...LIGHT WINDS AND DRY AIR WILL PROVIDE A GREAT SETUP FOR  
RADIATIONAL COOLING. THEREFORE...LEANED TOWARD COLDER GUIDANCE  
FOR RURAL AREAS OVERNIGHT. MIN TEMPS WILL RANGE FROM THE TEENS  
IN THE COLDER VALLEYS AND RURAL AREAS TO THE MID AND UPPER 20S  
IN DOWNTOWN WASHINGTON AND BALTIMORE.  
 

 
   
SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/
 
 
WARM ADVECTION WILL COMMENCE BY THURSDAY AFTERNOON, AND THE AXIS  
OF THE HIGH WILL MOVE OFFSHORE BY THURSDAY NIGHT. IT IS LESS  
CERTAIN WHETHER THE WARMING WILL BE REALIZED AT GROUND LEVEL  
DURING THE DAY. THEREFORE, FORECAST HIGHS WILL BE SIMILAR TO  
TODAY. THE WARMING WILL BEGIN TO MIX TO THE SURFACE THURSDAY  
NIGHT. THE ECMWF HAS BEEN (AND CONTINUES TO BE) MUCH WETTER THAN  
OTHER GUIDANCE LATE THURSDAY NIGHT INTO EARLY FRIDAY MORNING NEAR  
A WARM FRONT. GIVEN WARMING ALOFT, THAT SUGGESTS A FREEZING  
RAIN THREAT. THE ECMWF IS ALONE IN THIS SOLUTION; OTHER GUIDANCE  
IS ALL DRY. HAVE REDUCED POPS A PINCH (HAVE 20-30% IN DATABASE).  
AM RELUCTANT TO REMOVE POPS OUTRIGHT, BUT AT THE SAME TIME AM  
SKEPTICAL WHETHER THIS WILL POSE AN IMPACT.  
 
FORECAST AREA WILL BE ON THE WARM SIDE OF THE UPPER RIDGE ON  
FRIDAY. HIGHS NEAR 60; LOWS 45-50.  
 

 
   
LONG TERM /SATURDAY THROUGH WEDNESDAY/
 
 
WARM SOUTHERLY FLOW OVER OUR AREA AS A HIGH PRESSURE SITS  
OFFSHORE- WILL ALLOW FOR WELL ABOVE NORMAL TEMPERATURES ON  
SATURDAY... REACHING THE 70S FOR MOST LOCATIONS... 60S  
OTHERWISE.  
 
BACKDOOR COLD FRONT PUSHES SOUTH SATURDAY NIGHT INTO SUNDAY AND  
STALLS NEAR OR ABOVE OUR CWA INTO MONDAY AS LOW PRESSURE APPROACHES  
THE SOUTHERN GREAT LAKES. POPS WILL BE INCREASING AS THIS LOW  
CONTINUES TO MOVE ENE THROUGH THE FRONT SUNDAY INTO MONDAY.  
 
THERE SEEMS TO BE A DRIER PERIOD SOMETIME MONDAY NIGHT INTO EARLY  
TUESDAY BEFORE A COLD FRONT PUSHES THROUGH THE AREA TUESDAY INTO  
TUESDAY NIGHT AS POPS INCREASES. DRY CONDITIONS RETURN ON WEDNESDAY.  
HIGH TEMPERATURES SUNDAY INTO TUESDAY WILL BE IN THE 50S AND 60S,  
AND IN THE 40S ON WEDNESDAY BEHIND THE FRONT.  
 

 
   
AVIATION /01Z THURSDAY THROUGH MONDAY/
 
 
VFR FLIGHT CONDITIONS WILL PREVAIL THROUGH THE VALID TAF PERIOD.  
WINDS WILL CONTINUE TO DIMINISH OVERNIGHT WITH SPEEDS LESS THAN  
10 KNOTS EXPECTED. A THIN DECK OF HIGH CLOUDS WILL OVERSPREAD  
THE TERMINALS THURSDAY.  
 
SOUTH/SOUTHWESTERLY FLOW THURSDAY NIGHT INTO FRIDAY. CLOUDS WILL  
OVERSPREAD DURING THIS PERIOD. DO NOT ANTICIPATE FLIGHT  
RESTRICTIONS DURING THIS PERIOD. PRECIPITATION SHOULD REMAIN  
NORTH OF THE TERMINALS. THERE IS A SLIGHT CHANCE THAT PRECIP  
COULD MOVE IN BEFORE ALL COLD AIR DEPARTS-- THIS WOULD AFFECT  
ONLY MRB. HAVE LOW CONFIDENCE THAT THIS WOULD OCCUR.  
 
DRY/VFR AND WARM CONDITIONS EXPECTED ON SATURDAY. A FRONT  
PUSHES SOUTH AND STALLS OVER OUR AREA SUNDAY AND INCREASES  
PROBABILITY OF PRECIP OVER OUR REGION INTO MONDAY WITH POSSIBLE  
SUB-VFR PERIODS.  
 

 
   
MARINE
 
 
WINDS WILL CONTINUE TO GRADUALLY DIMINISH OVER THE WATERS  
TONIGHT. A SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL EARLY  
THURSDAY MORNING FOR THE MIDDLE PORTION OF THE BAY AND THE LOWER  
TIDAL POTOMAC RIVER. WINDS WILL BE LIGHT THURSDAY AND THURSDAY  
NIGHT. SOUTHERLY FLOW WILL INCREASE AGAIN FRIDAY.  
 
DRY AND WARM CONDITIONS EXPECTED ON SATURDAY. A FRONT PUSHES  
SOUTH AND STALLS OVER OUR AREA SUNDAY AND INCREASES PROBABILITY  
OF PRECIP OVER OUR REGION INTO MONDAY WITH POSSIBLE. WINDS ARE  
EXPECTED TO REMAIN BELOW THE SCA THRESHOLD TROUGH THIS PERIOD.  
 

 
   
LWX WATCHES/WARNINGS/ADVISORIES
 
 
DC...NONE.  
MD...NONE.  
VA...NONE.  
WV...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT THURSDAY FOR ANZ532>534-  
537-541>543.  
 

 
 

 
SYNOPSIS...HTS  
NEAR TERM...BJL/HTS  
SHORT TERM...HTS  
LONG TERM...IMR  
AVIATION...BJL/IMR/HTS  
MARINE...BJL/IMR/HTS  
 
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