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Area Forecast Discussion

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FXUS61 KLWX 210752
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
352 AM EDT MON APR 21 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH TODAY. HIGH PRESSURE 
WILL SLOWLY SLIDE EAST TONIGHT AND A COLD FRONT WILL PASS THROUGH 
THE AREA TUESDAY AFTERNOON AND EVENING. HIGH PRESSURE WILL RETURN 
FOR WEDNESDAY AND THURSDAY BEFORE MOVING OFF THE COAST FRIDAY. A 
COLD FRONT WILL PASS THROUGH THE AREA SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
A CLEAR AND NEARLY CALM NIGHT ACROSS THE MID ATLC REGION. THE UPPER 
LOW THAT HAS BEEN HANGING OUT OVER THE SRN ATLC STATES IS STILL 
THERE ATTM...BUT WILL SLOWLY BE PUSHED OUT TO SEA OVER THE COURSE OF 
THE DAY. BETWEEN THIS FEATURE AND AN AREA OF HIGH PRESSURE NOW 
MOVING OFF THE NEW ENGLAND COASTLINE...A THIN CORRIDOR OF TIGHTER 
PRES GRADIENT EXISTS AND TAPERS OFF OVER DELMARVA. WINDS ALONG THIS 
CORRIDOR WERE STRONGER EARLIER AND CONTINUE TO BE DOWN ACROSS THE VA 
TIDEWATER AND NC COAST...BUT HAVE LARGELY SUBSIDED UP ACROSS OUR 
CWA. TEMPS ACROSS THE AREA HAVE DROPPED INTO THE U30S...W/ ROOM FOR 
A FEW MORE DEGREES BY SUNRISE AS DEWPOINTS HOVER IN THE L-M30S. 

PATCHY FROST DEVELOPMENT EXPECTED ACROSS MUCH OF THE VA/MD PIEDMONT 
AND THE PORTIONS OF THE METRO AREAS SURROUNDING DC/BALT. THE FROST 
ADVISORY HAS BEEN EXPANDED FROM NERN MD DOWN ACROSS MUCH OF THE AREA 
E OF THE BLUE RIDGE THRU 8AM. 

AFTER THE RELATIVELY COLD START TO THE DAY...TEMPS WILL AGAIN RISE 
QUICKLY BACK INTO THE 60S OVER THE COURSE OF THE MRNG AND INTO THE 
EARLY AFTN. CLEAR SKIES WILL LAST THROUGH MUCH OF THE DAY...AS THE 
SRN ATLC LOW SLOWLY MOVES OUT TO SEA AND THE NEXT WX-MAKER SLIDES 
TOWARD THE AREA FROM THE WEST. SOME OF THE CIRRUS DEBRIS FROM THIS 
INCOMING SHORTWAVE WILL ARRIVE LATE THIS AFTN AS TEMPS REACH THE 
U60S/L70S. WINDS TODAY WILL BE LIGHT AS A WEAK IN-SITU SFC HIGH 
BUILDS OVER THE AREA IN BETWEEN THE TWO SURROUNDING SYSTEMS...
TURNING SLY OVERNIGHT AS THE HIGH IS PUSHED OFF THE COAST. THE 
INCREASE IN CLOUD COVER TONIGHT AND LOW LEVEL MOISTURE WILL MODERATE 
TEMPS TO ONLY DROP INTO THE U40S/L50S - A GOOD 10-15F DEG WARMER 
THAN TONIGHT'S LOW TEMPS.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
WEAK HIGH PRESSURE WILL CONTINUE TO MOVE OFF THE COAST TUESDAY WHILE 
A COLD FRONT OVER THE OHIO VALLEY TUESDAY MORNING PASSES THROUGH OUR 
AREA TUESDAY AFTERNOON AND EVENING. A SOUTHERLY FLOW AHEAD OF THE 
FRONT WILL ALLOW FOR WARMER CONDITIONS...DESPITE CLOUD COVER 
ASSOCIATED WITH THE FRONTAL PASSAGE. MAX TEMPS WILL RANGE FROM THE 
LOWER 60S IN THE MOUNTAINS TO NEAR 80 IN THE VIRGINIA PIEDMONT. 

THE COMBINATION OF WARMER AIR AND INCREASING DEWPOINTS FROM THE 
SOUTHERLY FLOW WILL BE ENOUGH TO CAUSE AN UNSTABLE ATMOSPHERE. 
HOWEVER...INSTABILITY WILL BE LIMITED WITH DEEP MOISTURE
REMAINING OFF TO OUR SOUTH. MOST OF THE DYNAMICS WITH THIS SYSTEM
WILL BE TO OUR NORTH...BUT THERE SHOULD BE ENOUGH FORCING WITH
THE FRONT TO COMBINE WITH THE INSTABILITY...CAUSING SOME SHOWERS
ALONG AND AHEAD OF THE FRONT. A FEW THUNDERSTORMS CANNOT BE RULED
OUT AS WELL. HOWEVER...ANY SEVERE THREAT WILL BE EXTREMELY LIMITED
DUE TO THE LOW INSTABILITY. THE BEST CHANCE FOR SHOWERS AND
THUNDERSTORMS WILL BE FROM MID-MORNING THROUGH EARLY AFTERNOON
WEST OF THE BLUE RIDGE MOUNTAINS...AND DURING THE AFTERNOON HOURS
EAST OF THE BLUE RIDGE MOUNTAINS.

THE FRONT WILL MOVE OFF TO OUR EAST TUESDAY EVENING. ANY LEFTOVER 
SHOWERS ACROSS EXTREME SOUTHERN MARYLAND WILL END DURING THIS TIME. 
A NORTHWEST FLOW WILL USHER IN COOLER AND DRIER CONDITIONS FOR 
TUESDAY NIGHT. MIN TEMPS WILL RANGE FROM THE 20S ALONG THE RIDGE 
TOPS OF THE ALLEGHENY HIGHLANDS TO NEAR 50 IN DOWNTOWN WASHINGTON 
AND BALTIMORE.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
LOW PRESSURE WILL INTENSIFY NEAR NOVA SCOTIA WEDNESDAY WHILE HIGH 
PRESSURE BUILDS TOWARD THE REGION FROM THE GREAT LAKES. THE PRESSURE 
GRADIENT BETWEEN THESE SYSTEMS WILL CAUSE GUSTY NORTHWEST 
WINDS...AND MAX TEMPS WILL BE BELOW CLIMO DUE TO THE COLD ADVECTION 
ASSOCIATED WITH THE NORTHWEST FLOW. HIGH PRESSURE WILL BUILD 
OVERHEAD WEDNESDAY NIGHT...CAUSING DRY AND CHILLY CONDITIONS. 
HIGH PRESSURE WILL CONTINUE TO CONTROL THE WEATHER PATTERN
THURSDAY BEFORE MOVING OF THE COAST FRIDAY.

A RETURN FLOW AROUND THE HIGH WILL CAUSE WARMER CONDITIONS LATE IN 
THE WEEK BEFORE ANOTHER COLD FRONT PASSES THROUGH SATURDAY. CHILLIER 
CONDITIONS ARE EXPECTED BEHIND THIS BOUNDARY EARLY NEXT WEEK.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
VFR CONDS TODAY/TONIGHT. THE OFFSHORE UPPER LOW JUST EAST OF THE 
CAROLINAS WILL FINALLY MOVE OUT TO SEA AFTER BEING STATIONED OVER 
THE SRN ATLC STATES FOR THE PAST FEW DAYS. SOME FROST FORMATION 
POSSIBLE IN THE NEXT FEW HRS...AS WINDS DROP OFF AND SO DO TEMPS - 
HOVERING IN THE MIDDLE 30S THRU DAWN. LIGHT WINDS WILL BE THE MAIN 
STORY TODAY...W/ CLEAR SKIES AS HIGH PRESSURE REMAINS OVERHEAD BUT 
WILL MOVE OFF THE COAST LATE TONIGHT JUST AHEAD OF THE NEXT WAVE OF 
LOW PRESSURE.

VFR CONDITIONS ARE EXPECTED MOST OF THE TIME TUESDAY THROUGH 
FRIDAY. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE TUESDAY AND
CIGS/VSBYS MAY BRIEFLY BE REDUCED IN ANY CONVECTION. NORTHWEST
WINDS WILL INCREASE BEHIND A COLD FRONT TUESDAY NIGHT AND
WEDNESDAY. THE STRONGEST WINDS ARE EXPECTED WEDNESDAY WITH GUSTS
AROUND 30 KNOTS. HIGH PRESSURE WILL BUILD OVERHEAD WEDNESDAY NIGHT
AND THURSDAY...CAUSING WINDS TO DECREASE.

A SOUTHERLY FLOW IS EXPECTED FRIDAY AS THE HIGH MOVES OFF THE 
COAST.

&&

.MARINE...
HIGH PRESSURE WILL SUPPLY LIGHT WINDS FOR THE WATERS TODAY...THOUGH 
STILL SOME 10-15KT BREEZES FROM THE MIDDLE-TO-LOWER PORTION OF THE 
BAY. THESE CONDITIONS WILL GENERALLY CONTINUE THRU THE FIRST-HALF OF 
THE DAY...WHILE AN OFFSHORE UPPER LOW OFF THE CAROLINAS SLOWLY MOVES 
EAST. WINDS WILL THEN DROP OFF LATER TONIGHT AND SWITCH TO A SLY 
FLOW AS THE HIGH PRES MOVES OFF THE MID ATLC COAST. 

A COLD FRONT WILL PASS THROUGH THE WATERS LATE TUESDAY AFTERNOON
AND EVENING. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE AHEAD OF
THE FRONT TUESDAY AFTERNOON AND EARLY EVENING. ANY THUNDERSTORMS
THAT DO DEVELOP WILL BE CAPABLE OF PRODUCING GUSTY WINDS.

NORTHWEST WINDS WILL INCREASE BEHIND THE COLD FRONT TUESDAY NIGHT. 
GUSTY NORTHWEST WINDS WILL CONTINUE INTO WEDNESDAY EVENING BEFORE 
GRADUALLY DECREASING WEDNESDAY NIGHT. A SMALL CRAFT ADVISORY WILL 
LIKELY BE NEEDED FOR THE WATERS TUESDAY NIGHT INTO WEDNESDAY NIGHT. 
THE STRONGEST WINDS ARE EXPECTED WEDNESDAY WITH GUSTS AROUND 30 
KNOTS. HIGH PRESSURE WILL BUILD OVERHEAD LATE WEDNESDAY NIGHT AND
THURSDAY BEFORE MOVING OFF THE COAST FRIDAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR DCZ001.
MD...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MDZ004>007-
     009>011-013-014-016.
VA...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR VAZ042-050>057-
     501-502.
WV...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...BJL
NEAR TERM...GMS
SHORT TERM...BJL
LONG TERM...BJL
AVIATION...BJL/GMS
MARINE...BJL/GMS






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