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Area Forecast Discussion

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FXUS61 KLWX 221433
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1033 AM EDT TUE APR 22 2014

.SYNOPSIS...
A COLD FRONT WILL PASS THROUGH THE AREA THIS AFTERNOON AND EVENING. 
HIGH PRESSURE RETURNS FOR WEDNESDAY AND THURSDAY BEFORE MOVING OFF 
THE COAST FRIDAY. A COLD FRONT IS EXPECTED TO PASS THROUGH THE AREA 
SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
SFC COLD FRONT WAS ANALYZED OVER THE ERN GREAT LAKES AND OH VLY AT 
13Z. THIS FRONT IS ASSOCIATED WITH A 1000 MB SFC LOW NEAR THE SRN 
ONTARIO-QUEBEC BORDER. PRE-FRONTAL CLOUDS AND SHOWERS ARE CURRENTLY 
MOVING INTO THE MTS THIS MRNG IN ASSOCIATION WITH A LEADING MID-LVL 
SHORTWAVE TROUGH. UPSTREAM RADAR AND THE LATEST HI-RES MODEL 
GUIDANCE  SUPPORT DECREASING POPS WITH THE FCST FOR TDA WITH 
COVERAGE OF SHOWERS NOT EXPECTED TO BE WIDESPREAD. THIS WOULD MAKE 
SENSE GIVEN THE BEST FORCING ASSOCIATED WITH THE UPPER SHORTWAVE 
TROUGH/JET STREAK AND SFC LOW REMAINING TO OUR NORTH.

12Z IAD RAOB REVEALED AN IMPRESSIVE LLVL INVERSION WITH THE WARM 
NOSE OF 19C AT 950 MB. IT WILL NOT TAKE MUCH TO MIX DOWN THIS WARMER 
AIR. THEREFORE INCREASED MAX TEMPS FOR TDA ACROSS THE ENTIRE AREA 
EVEN WITH THE CLOUD COVER TO CONTEND WITH. TEMPS THIS AFTN COULD 
REACH THE LOWER 80S ALONG AND EAST OF I-95 WHERE STRONG HEATING THIS 
MRNG WILL PRECEDE ARRIVAL OF DENSER CLOUDS THIS AFTN. 

LLVL WINDS ARE FCST TO VEER MORE OUT OF THE WEST THIS AFTN BEHIND A 
PRE-FRONTAL TROUGH. EXPECT LOWER DEWPOINTS EAST OF THE MTS THAN WHAT 
MODELS ARE INDICATING JUST PRIOR TO FROPA DUE TO DOWNSLOPING FLOW. 
RAOB SOUNDINGS MODIFIED FOR A SFC TEMP NEAR 80F AND DEWPOINT NEAR 
50F REVEAL MARGINAL INSTABILITY (SBCAPE AOB 500 J/KG) OWING TO THIS 
LIMITED MOISTURE RETURN AND WEAK MID-LVL LAPSE RATES AHEAD OF THE 
FRONT. THIS WILL FAVOR COVERAGE OF TSTMS ISOLATED AND TSTM INTENSITY 
WEAK. THE OPPORTUNITY FOR TSTMS APPEAR TO BE LIMITED TO ALONG OR
JUST AHEAD OF THE FRONT FOR A 2-4 HR WIND THIS AFTN IN THE MTS
AND DURING THE LATE AFTN/ERY EVE TOWARD THE I-95 AND THE CHSPK
BAY.

AS THE VORT MAX FROM THE GREAT LAKES REGION NEARS THE AREA LATE 
TONIGHT...SOME OF THE GUSTIER PARTS OF THE LOW LEVEL JET WILL GET 
MIXED DOWN TO THE SFC AND NW WINDS WILL SWEEP ACROSS THE AREA W/ 
GUSTS IN THE 20-30MPH RANGE FOR MUCH OF THE NIGHTTIME HRS. DEWPOINTS 
WILL DROP BACK DOWN INTO THE 30S AND TEMPS WILL DROP BACK INTO THE 
40S FOR OVERNIGHT LOWS...W/ LOWER WIND CHILLS FROM THE GUSTY AND DRY 
NW WINDS.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
LOW PRESSURE WILL INTENSIFY OFF THE NEW ENGLAND COAST 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. MAX TEMPS WILL RANGE 
FROM THE 40S ALONG THE ALLEGHENY HIGHLANDS...TO THE LOWER AND MIDDLE 
60S NEAR WASHINGTON AND BALTIMORE...TO THE UPPER 60S IN THE VIRGINIA 
PIEDMONT. A DEEP MIXING LAYER AND STRONG PRESSURE GRADIENT WILL 
CAUSE NORTHWEST WINDS TO GUST FREQUENTLY BETWEEN 30 AND 40 MPH. 

HIGH PRESSURE WILL BUILD OVERHEAD WEDNESDAY NIGHT...CAUSING DRY AND 
CHILLY CONDITIONS. WINDS WILL DIMINISH AROUND SUNSET. MIN TEMPS 
WEDNESDAY NIGHT WILL RANGE FROM NEAR 30 IN THE POTOMAC HIGHLANDS TO 
THE LOWER AND MIDDLE 40S IN DOWNTOWN WASHINGTON AND BALTIMORE.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
HIGH PRESSURE WILL REMAIN OVER THE REGION THURSDAY...BRINGING DRY 
CONDITIONS ALONG WITH SUNSHINE. THE HIGH WILL MOVE OFF THE COAST 
THURSDAY NIGHT AHEAD OF AN APPROACHING COLD FRONT FROM THE WEST. THE 
COLD FRONT WILL PASS THROUGH THE AREA FRIDAY...BRINGING MORE CLOUDS 
ALONG WITH THE LIKELIHOOD FOR SHOWERS.  

ANOTHER COLD FRONT WILL APPROACH THE AREA SATURDAY BEFORE PASSING 
THROUGH SATURDAY NIGHT. A WESTERLY DOWNSLOPING FLOW AHEAD OF THE 
COLD FRONT SHOULD ALLOW FOR MILD CONDITIONS SATURDAY. A COUPLE 
SHOWERS CANNOT BE RULED OUT AHEAD OF THE FRONT FOR LOCATIONS NEAR 
THE MASON-DIXON LINE...BUT MOST OF THE TIME WILL TURN OUT DRY SINCE  
LITTLE MOISTURE WILL BE ASSOCIATED WITH THE BOUNDARY. 

THE BOUNDARY WILL STALL TO OUR SOUTH SUNDAY AND MONDAY. WAVES OF LOW 
PRESSURE WILL DEVELOP ALONG THE BOUNDARY...POSSIBLY BRINGING 
UNSETTLED CONDITIONS TO THE AREA NEXT WEEK.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
MID AND HI CLOUDS HAVE BEEN STREAMING IN FROM THE WEST THIS MRNG
AHEAD OF A COLD FRONT. BRIEF PERIOD OF SHRA BEFORE 16Z AT MRB/CHO
AND BETWEEN 16-18Z FARTHER EAST. NO FLIGHT RESTRICTIONS EXPECTED
WITH THESE LEADING SHRA. ANOTHER AREA OF SHRA AND ISO TSRA
POSSIBLE BETWEEN 18-21Z IN THE WRN TERMINALS AND 21-00Z FROM IAD
EWD. BRIEF/LOCAL FLIGHT RESTRICTIONS POSSIBLE WITH THIS ACTIVITY.
WINDS WILL STAY OUT OF THE SOUTH UNTIL LATER THIS AFTN WHEN A
COLD FRONT SLIDES THRU AND TURNS WINDS BACK TO THE NW AND HIGHER
GUSTS IN THE 20-30KT RANGE APPEAR FOR THE LATE EVE/OVERNIGHT HRS.
CONDITIONS WILL DRY OUT TONIGHT BUT WINDS WILL STAY BREEZY INTO
WED MRNG.

GUSTY NORTHWEST WINDS AROUND 30 TO 35 KNOTS ARE EXPECTED WEDNESDAY 
BEHIND A COLD FRONT. HIGH PRESSURE WILL BUILD OVER THE TERMINALS 
WEDNESDAY NIGHT AND THURSDAY. WINDS WILL DIMINISH AROUND SUNSET 
WEDNESDAY EVENING. 

A COLD FRONT WILL PASS THROUGH THE TERMINALS FRIDAY...LIKELY 
TRIGGERING A FEW SHOWERS. CIGS/VSBYS MAY APPROACH MVFR LEVELS DURING 
THIS TIME. ANOTHER COLD FRONT WILL APPROACH THE TERMINALS 
SATURDAY...BUT MOST PLACES WILL END UP DRY WITH VFR CONDITIONS.

&&

.MARINE...
SLY FLOW WILL LAST FOR MUCH OF THE DAYTIME HRS...W/ SOME MINOR 
CHANNELING BUT SUB-SCA UNTIL THIS AFTN. SHOWERS WILL CARRY ISOLATED 
HIGHER WIND GUSTS THIS AFTN/EVE...THEN THE PRESSURE GRADIENT WILL 
BRING MORE WIDESPREAD GUSTY WINDS LATER THIS EVE. A FEW HEAVIER 
SHOWERS AND ISOLATED TSTMS POSSIBLE LATER TODAY...SO THE POTENTIAL 
FOR HIGHER LOCALIZED WINDS EXISTS UNTIL A COLD FRONT PUSHES THRU 
LATE TONIGHT...SPREADING MORE WIDESPREAD AND NW WINDS OVER THE 
WATERS FOR MOST OF THE OVERNIGHT HRS...WELL INTO SCA RANGE.

GUSTY NORTHWEST WINDS ARE EXPECTED BEHIND A COLD FRONT WEDNESDAY.
A GALE WARNING IS IN EFFECT FOR THE WATERS. WINDS WILL GRADUALLY
DIMINISH WEDNESDAY NIGHT...BUT A SMALL CRAFT ADVISORY WILL LIKELY
BE NEEDED FOR PORTIONS OF THE WATERS. THE SMALL CRAFT ADVISORY MAY
ALSO BE NEEDED FOR PORTIONS OF THE WATERS ON THURSDAY.

A COLD FRONT WILL PASS THROUGH THE WATERS FRIDAY...LIKELY TRIGGERING 
A FEW SHOWERS. ANOTHER COLD FRONT WILL APPROACH THE WATERS SATURDAY 
BEFORE PASSING THROUGH SATURDAY NIGHT. A SMALL CRAFT ADVISORY MAY BE 
NEEDED FOR PORTIONS OF THE WATERS SATURDAY.

&&

.FIRE WEATHER...
FUEL MOISTURE REMAINS LOW THIS MORNING. THERE WILL BE A FEW SHOWERS 
AROUND TODAY AHEAD OF A COLD FRONT...BUT RAINFALL AMOUNTS SHOULD 
AVERAGE TO BE LESS THAN ONE-QUARTER INCH ACROSS MOST AREAS. 

THE COLD FRONT WILL PASS THROUGH THE AREA TONIGHT AND GUSTY 
NORTHWEST WINDS ARE EXPECTED BEHIND THE COLD FRONT WEDNESDAY. A DEEP 
MIXING LAYER WILL ALLOW FOR DRIER AIR TO MIX DOWN...CAUSING LOW 
RELATIVE HUMIDITY VALUES DURING THE LATE MORNING THROUGH THE 
AFTERNOON. THE COMBINATION OF GUSTY WINDS...LOW FUEL MOISTURE AND 
LOW RELATIVE HUMIDITY WILL ENHANCE THE THREAT FOR THE SPREAD OF 
WILDFIRES WEDNESDAY. DAY SHIFT HAS COORDINATE WITH STATE 
CONTACTS ABOUT FUEL MOISTURE. A FIRE WEATHER WATCH MAY BE
NECESSARY FOR TOMORROW AND WOULD BE ISSUED THIS AFTN.

&&

.TIDES/COASTAL FLOODING...
A SOUTHERLY FLOW HAS CAUSED TIDAL ANOMALIES TO BE AROUND THREE-
QUARTERS OF A FOOT ABOVE THE ASTRONOMICAL NORM. THE TIDAL
ANOMALIES SHOULD NOT CHANGE MUCH THIS AFTN AS THE FLOW GRADUALLY
SHIFTS WEST OF SOUTH. THIS WILL KEEP TIDAL LEVELS BELOW THRESHOLDS
FOR MINOR COASTAL FLOODING.

GUSTY NORTHWEST WINDS WILL DEVELOP TONIGHT AND CONTINUE THROUGH 
WEDNESDAY. BLOWOUT TIDES ARE EXPECTED WEDNESDAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ530>543.
     GALE WARNING FROM 6 AM TO 6 PM EDT WEDNESDAY FOR ANZ530>543.

&&

$$
SYNOPSIS...BJL
NEAR TERM...JRK/GMS
SHORT TERM...BJL
LONG TERM...BJL
AVIATION...JRK/BJL
MARINE...JRK/BJL
FIRE WEATHER...BJL/JRK
TIDES/COASTAL FLOODING...JRK






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