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Area Forecast Discussion

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FXUS61 KLWX 201857
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
257 PM EDT SUN APR 20 2014

.SYNOPSIS...
HIGH PRESSURE OVER QUEBEC WILL BUILD INTO THE AREA TONIGHT AND 
MONDAY. A COLD FRONT WILL MOVE THROUGH THE AREA TUESDAY AND
TUESDAY EVENING. HIGH PRESSURE BUILDS BACK IN FOR THE SECOND HALF OF
THE WORK WEEK.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
SURFACE HI HAS MOVED SOUTH OF LONG ISLAND AND WILL WEAKEN AND PUSH 
INTO THE MID ATLANTIC OVERNIGHT. ABUNDANT SUNSHINE IN PLACE WITH 
TEMPERATURES IN THE 50/S HIGHLANDS TO THE 60/S METRO AREAS. EAST TO 
NORTHEAST PRESSURE GRADIENT WINDS AND DEW POINTS IN THE 30/S MAKE 
FOR A CHILLY BREEZE ESPECIALLY ONCE THE SUN SETS. WINDS WILL 
DECOUPLE OVERNIGHT AND GOOD RADIATIONAL COOLING IS EXPECTED. GIVEN 
WHERE CURRENT DEW POINTS AND GOOD MIXING UNTIL LATER TONIGHT...WE 
DO NOT EXPECT A WIDESPREAD FROST TONIGHT AS MANY AREAS WILL REMAIN 
IN THE LOWER TO MID 30/S.  SHELTERED AREAS COULD HAVE SOME FROST 
OVERNIGHT.  

BY MONDAY AFTERNOON AND NIGHT SURFACE LOW PRESSURE MOVES INTO THE
GREAT LAKE STATES AND A COLD FRONT BEGINS TO APPROACH THE AREA.
MODELS KEEP SUNSHINE IN PLACE FOR MOST OF TOMORROW BEFORE HI
CLOUDS INCREASE LATE IN THE DAY AND NIGHT. LIGHT SOUTHERLY WINDS
DEVELOP BUT DRY AIR REMAINS IN PLACE FOR MUCH OF THE DAY. WOULD
EXPECT TEMPERATURES TO BE A BIT WARMER WITH HIGHS IN THE UPPER
50/S TO UPPER 60/S...AND IT WILL FEEL MILDER WITH LESS WIND. MIN
TEMPS MON NGT IN THE MID 40S TO LOWER 50S.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
SUB-1000 MB SFC LOW TRACKS EWD ACROSS UPSTATE NY AND NRN NEW ENGLAND 
ON TUE. ATTENDANT COLD FRONT OVER THE OH VLY IS EXPECTED TO CROSS 
THE APPALACHIANS BY ABOUT 18Z TUE BEFORE MOVING EWD THRU THE CWA 
BETWEEN APPROX 18Z TUE AND 00Z WED. THE BEST FORCING LOOKS TO STAY 
NORTH OF CWA AND CLOSER TO TO SFC LOW AND UPPER SHORTWAVE TROUGH. 
PREVIOUS FCST HAD LIKELY POPS WITH FROPA. DID NOT WANT TO INCREASE 
POPS FURTHER DUE TO THE LIMITED FORCING AND PROGRESSIVE NATURE WITH 
THIS SYSTEM. THUNDER A POSSIBILITY WITH TIMING OF FROPA COINCIDENT 
WITH PEAK HEATING. WEAK MID-LVL LAPSE RATES AND INCREASING CLOUD 
COVER AHEAD OF THE FRONT DURING THE MRNG SHOULD LIMIT DEGREE OF 
DESTABILIZATION. FCST MEAN MLCAPE VALUES FROM THE 09Z SREF ARE UNDER 
500 J/KG FOR THE ENTIRE CWA AND MLCAPE PROBABILITIES AOA 500 J/KG 
ARE LOW...JUST TWO INDICATIONS OF A VERY LIMITED TSTM POTENTIAL. 
EVEN WITH CLOUD COVER...MAX TEMPS IN THE 70S AHEAD OF THE FRONT. 

THE COLD FRONT MOVES OFF THE DELMARVA COAST TUE NGT WHILE HIPRES 
BUILDS IN FROM CENTRAL CANADA. A STRONG PRESSURE GRADIENT BETWEEN 
THESE TWO SYSTEMS WILL PRODUCE BREEZY NW WINDS TUE NGT AND 
CONTINUING INTO WED. 12Z NAM/GFS BUFKIT PROFILES SHOW A POTENTIAL 
FOR WIND GUSTS OF 30-35 MPH TO MIX DOWN THE SFC ON WED. MAX TEMPS A 
FEW DEGREES BELOW NORMAL ON WED OWING TO THE CAA IN WAKE OF FROPA.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
SURFACE HIGH BUILDING ACROSS AREA WEDNESDAY NIGHT. TEMPERATURES MAY 
DROP 5 DEGREES BELOW NORMAL BEFORE REBOUNDING THROUGH THURSDAY
NIGHT. 

HIGH PRESSURE MOVING OFFSHORE FRIDAY EVENING AND NIGHT AS COLD
FRONT FROM CENTRAL PLAINS TRACK EAST ACROSS GREAT LAKES/OHIO
VALLEY. MARGINALLY SUPPORT FOR PRECIPITATION WITH THE FRONT AS
MAIN AREA PVA IS NORTH OF AREA. INCREASED CHANCES OF PRECIPITATION
SATURDAY MORNING WHEN A SECOND FRONT SUPPORTED BY STRONG PVA
ENTERS THE AREA FROM THE NORTH.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
VFR SKC-SCT/BKN250 THRU MONDAY AFTERNOON AT THE TERMINALS. EAST 
SURFACE WINDS 10-15KT WILL SUBSIDE AT SUNSET THIS EVENING THEN SHIFT 
TO THE SOUTH BUT LESS THAN 10KT MONDAY. INCREASING HI CLOUDS LATE 
MONDAY. 

A COLD FRONT IS ANTICIPATED TO MOVE THRU THE TERMINALS FROM WEST TO 
EAST BETWEEN 18Z TUE AND 00Z WED. SHRA LIKELY AND ISO TSRA DURING 
THE AFTN WITH FROPA. BRIEF/LOCAL RESTRICTIONS POSSIBLE WITH HEAVIER 
SHRA OR TSRA. SLY WINDS AROUND 10 KT AHEAD OF THE FRONT WILL BECOME 
NWLY 10-15 KT FOLLOWING FROPA. WIND GUSTS UP TO 30 KT POSSIBLE ON 
WED AS HIPRES BUILDS IN FROM THE NW.

VFR WITH HIPRES OVERHEAD WED NGT THRU FRI.

&&

.MARINE...
SCA CONDITIONS IN PLACE FROM MIDDLE AND LOWER TIDAL POTOMAC TO 
PORTIONS OF THE BAY AS HIGH PRESSURE BUILDS OVER THE WATERS. WINDS 
WILL DECREASE TONIGHT THOUGH NE GUSTS TO 15 KT POSSIBLE SOUTHERN 
WATERS UNTIL MIDNIGHT OR SO. WINDS WILL BE LIGHTER FROM THE SOUTH 
DURING THE DAY MONDAY. 

SLY FLOW AHEAD OF A COLD FRONT GENERALLY 10 KT ON TUE. THERE IS A 
LIMITED POTENTIAL HOWEVER FOR WINDS TO REACH SCA CRITERIA IN THE 
MAIN STEM OF THE CHSPK BAY DUE TO SLY CHANNELING. CAPPED WINDS AT 15 
KT IN THESE ZONES FOR NOW WITH SUCH A MARGINAL WIND FIELD. SHRA AND 
POSSIBLY AN ISO TSTMS WITH THE FROPA LATE TUE AFTN AND EVE. NW WINDS 
BEHIND THE FRONT WILL BECOME GUSTY AS HIPRES BUILDS IN FROM THE NW. 
SCA LIKELY TUE NGT AND WED.

WINDS BELOW SCA LVLS BY WED NGT AS HIPRES BUILDS OVERHEAD.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR 
     ANZ531>534-536-537-541>543.

&&

$$
SYNOPSIS...JRK/SDG
NEAR TERM...SDG
SHORT TERM...JRK
LONG TERM...CEM
AVIATION...SDG/JRK/CEM
MARINE...SDG/JRK/CEM







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