884  
FXUS61 KLWX 202014  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
314 PM EST WED FEB 20 2019  
   
SYNOPSIS
 
 
PRIMARY LOW PRESSURE OVER THE GREAT LAKES WILL TRACK INTO  
SOUTHERN CANADA TONIGHT WHILE SECONDARY LOW PRESSURE WILL MOVE  
UP THE ATLANTIC COAST. HIGH PRESSURE RETURNS BRIEFLY ON  
THURSDAY. A COLD FRONT WILL CROSS THE REGION THURSDAY EVENING  
AND STALL TO THE SOUTH ON FRIDAY. ANOTHER LARGE AND COMPLEX LOW  
PRESSURE SYSTEM WILL MOVE NORTHEAST ACROSS THE REGION SATURDAY  
INTO SUNDAY.  
 

 
   
NEAR TERM /THROUGH THURSDAY/
 
 
WARM AIR HAS SPEAD CROSS THE REGION TODAY ALOFT, WITH MOST  
PRECIPITATION NOW MAINLY IN THE FORM OF SLEET, FREEZING RAIN AND  
PLAIN RAIN WHERE TEMPS HAVE RISEN ABOVE FREEZING. THERE ARE  
STILL SIGNIFICANT POCKETS OF SUB-FREEZING AIR ACROSS THE I-95  
CORRIDOR, BUT THESE ARE LIKELY TO DWINDLE OVER THE NEXT SEVERAL  
HOURS, SO FREEZING RAIN IS LIKELY TO CHANGE TO RAIN AS THE  
EVENING PROGRESSES. TEMPS WILL STRUGGLE FURTHER NORTHWEST IN THE  
I-81 CORRIDOR, SO WARNINGS REMAIN IN EFFECT UNTIL AFTER MIDNIGHT  
IN THESE AREAS.  
 
PRECIP SHOULD CLEAR THE REGION LATE TONIGHT, BUT LOW CLOUDS MAY  
LINGER INTO THE MORNING HOURS. AFTER WESTERLY WINDS KICK IN,  
TEMPS SHOULD SURGE AS CLOUDS BREAK, WITH MANY AREAS LIKELY TO  
TOUCH 50. WILL HAVE TO WATCH OUT FOR POTENTIAL FOR THE LOW  
CLOUDS TO LINGER LONGER THAN EXPECTED, BUT OTHERWISE, THURSDAY  
SHOULD BE MUCH NICER THAN TODAY.  
 

 
   
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/
 
 
WEAK FRONT CROSSES THE REGION LATE THURSDAY AFTERNOON/EVENING,  
PERHAPS WITH SOME SHOWERS OR A LITTLE RAIN, ESPECIALLY IN  
CENTRAL VA. COOLER AIR WILL MOVE IN FOR FRIDAY BEHIND THIS  
FRONT, WITH TEMPS CLOSER TO SEASONABLE NORMS (40S). WITH THE  
FRONT STALLING JUST TO THE SOUTH, SOME RAIN MAY LINGER IN  
CENTRAL VA. COMPLEX LOW PRESSURE WILL THEN START TO ORGANIZE TO  
THE SOUTHWEST, SENDING WARM ADVECTION OUR WAY FRIDAY NIGHT. WILL  
NEED TO WATCH TEMPS CLOSELY FRIDAY NIGHT AS THE RAIN OVERSPRADS  
THE REGION AGAIN, AS NORTHERN AREAS COULD SLIP BELOW FREEZING  
OVERNIGHT AND RESULT IN SOME FREEZING RAIN. TEMPS WILL  
GENERALLY BE IN THE 30S FRIDAY NIGHT.  
 

 
   
LONG TERM /SATURDAY THROUGH WEDNESDAY/
 
 
A WARM FRONT WILL APPROACH THE REGION FROM THE SOUTH ON  
SATURDAY. OVERRUNNING PRECIPITATION AHEAD OF THE WARM FRONT IS  
FORECAST TO START AFFECTING OUR REGION AS EARLY AS FRIDAY  
EVENING.WINDS WILL BE MAINLY OUT OF THE SOUTH BEHIND THE WARM  
FRONT LEADING TO ADVECTION OF WARM AND MOIST AIR INTO OUR  
REGION. AS THE WARM FRONT SHIFTS NORTHWARD AND MOVES OUR OUR  
REGION, THE MODELS ARE TRYING TO TRANSFER ENERGY FROM THE  
SURFACE LOW TOO FORM A SECONDARY LOW ALONG THE WARM FRONT THAT  
SHIFTS EASTWARD TO THE EASTERN SEABOARD NEAR THE MID-ATLANTIC  
COAST. THIS WOULD LEAD TO INCREASED PRECIPITATION FOCUSED OVER  
OUR REGION. MODELS INDICATE THE POTENTIAL FOR OVER A INCH OF  
LIQUID DURING THE WARM FRONT TRANSITION NORTHWARD. THE WARM  
FRONT IS FORECAST TO SHIFT TO OUR NORTH AS THE COLD FRONT  
APPROACHES FROM THE WEST EARLY ON SUNDAY. THE COLD FRONT IS  
EXPECTED TO MOVE THROUGH OUR REGION SATURDAY AFTERNOON. WINDS  
WILL BECOME WESTERLY BEHIND THE FRONTAL PASSAGE. TEMPERATURES  
HAVE THE POTENTIAL TO REACH INTO THE 60S ON SUNDAY AHEAD OF THE  
FRONTAL PASSAGE.  
 
HIGH PRESSURE WILL BUILD INTO OUR REGION BEHIND THE COLD  
FRONTAL PASSAGE THROUGH MIDWAY NEXT WEEK. WINDS WILL START OUT  
OF THE WEST BUT AS THE HIGH MOVES OVER OUR REGION, WINDS WILL  
BECOME MORE NORTHERLY. TEMPERATURES WILL BE MILD TO SLIGHTLY  
BELOW AVERAGE THROUGH EARLY NEXT WEEK.  
 

 
   
AVIATION /20Z WEDNESDAY THROUGH MONDAY/
 
 
MVFR/IFR CIGS AND VIS WITH LINGERING RAIN, WITH FREEZING RAIN  
AND SLEET AT THE COLDER TERMINALS. PRECIP ENDS AFTER MIDNIGHT  
AND CIGS/VIS IMPROVE LATE TONIGHT/EARLY THURSDAY. VFR SHOULD  
PREDOMINATE AFTER THAT UNTIL LATER FRIDAY NIGHT, WHEN THE NEXT  
SYSTEM BRINGS RAIN BACK TO THE REGION.  
 
RAIN WILL MOVE INTO OUR REGION WITH WINDS BECOMING SOUTHERLY ON  
SATURDAY. SUBVFR CONDITIONS ARE LIKELY.  
 
ON SUNDAY, RAIN WILL MOVE THROUGH THE AREA BY THE AFTERNOON.  
WINDS WILL BE STRONG ALOFT WITH THE POTENTIAL FOR GUSTS OVER 30  
KNOTS. SUBVFR CONDITIONS ARE POSSIBLE.  
 

 
   
MARINE
 
 
MARGINAL SCA WILL EBB TONIGHT AS LOW PRESSURE DEVELOPING ALONG  
THE COAST PULLS AWAY TO THE NORTHEAST. AS ANOTHER WEAK FRONT  
CROSSES THE REGION LATER THURSDAY INTO THURSDAY EVENING, SCA MAY  
BE NEEDED ESPECIALLY OVER NORTHERN WATERS, LESS LIKELY TO THE  
SOUTH. LIGHT WINDS ARE LIKELY FRIDAY AND FRIDAY NIGHT AS HIGH  
PRESSURE SETTLES TO THE NORTH, FOLLOWED BY THE APPROACH OF THE  
NEXT SYSTEM FROM THE SOUTHWEST.  
 
ON SATURDAY, RAIN WILL MOVE THROUGH THE WATERS. WINDS ALOFT  
WILL HOVER NEAR THE 10 TO 15 KNOT RANGE. SMALL CRAFT LIKELY WONT  
BE NEEDED AT THIS TIME.  
 
SUNDAY, SHOWERS WILL MOVE THROUGH THE WATER SUNDAY AFTERNOON.  
WINDS ALOFT WILL BE STRONG ABOVE 35 KNOTS WITH THE POTENTIAL TO  
REACH UP TO 40 KNOTS. THIS INDICATES THAT AT LEAST A SMALL CRAFT  
ADVISORY WILL BE NEEDED WITH THE POTENTIAL FOR A GALE WARNING  
ON SUNDAY.  
 

 
   
HYDROLOGY
 
 
ULTIMATELY, OUR UPCOMING FLOOD POTENTIAL WILL BE DETERMINED  
AFTER WE SEE EXACTLY HOW MUCH SNOW FELL ON WEDNESDAY AND HOW  
MUCH LIQUID IS IN THAT SNOW. A GOOD MELT IS AHEAD FOR THURSDAY  
AND FRIDAY WITH TEMPERATURES ABOVE FREEZING AND A DECENT AMOUNT  
OF SUNSHINE. THAT WILL ELEVATE STREAMS AND KEEP THEM ELEVATED,  
AHEAD OF THE NEXT SYSTEM WHICH AFFECTS US OVER THE WEEKEND. THAT  
EVENT LOOKS LIKE ALL RAIN. CURRENT INDICATIONS ARE FOR BETWEEN  
0.5 INCH (LOW-END) AND 2.0 INCHES (HIGH-END) OF RAIN OVER THE  
WEEKEND, ON TOP OF REMAINING SNOWMELT. IF THERE'S STILL SNOW ON  
THE GROUND AND IF THE HIGHER RAINFALL AMOUNTS ARE REALIZED, THIS  
COMBINATION WOULD PRODUCE FLOODING BOTH ON SMALL AND LARGER  
STREAMS STARTING LATE SATURDAY THROUGH POSSIBLY EARLY NEXT WEEK.  
WE WILL CONTINUE TO MONITOR THE POTENTIAL IN THE COMING DAYS.  
 

 
   
LWX WATCHES/WARNINGS/ADVISORIES
 
 
DC...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR DCZ001.  
MD...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR MDZ005-  
006-503>507.  
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MDZ011-  
013-014-508.  
WINTER STORM WARNING UNTIL 1 AM EST THURSDAY FOR MDZ003-004-  
501-502.  
WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR  
MDZ016>018.  
VA...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR VAZ025-  
026-503-504-506>508.  
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR VAZ054.  
WINTER STORM WARNING UNTIL 1 AM EST THURSDAY FOR VAZ027>031-  
040-501-505.  
WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR  
VAZ036>039-050>053-502.  
WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR  
VAZ055>057.  
WV...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR WVZ505-  
506.  
WINTER STORM WARNING UNTIL 1 AM EST THURSDAY FOR WVZ050>053-  
055-501>504.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ532-  
533-540-541.  
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ534-  
537-543.  
 

 
 

 
SYNOPSIS...RCM  
NEAR TERM...RCM  
SHORT TERM...RCM  
LONG TERM...JMG  
AVIATION...RCM/JMG  
MARINE...RCM/JMG  
HYDROLOGY...JE  
 
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