Area Forecast Discussion
Issued by NWS Sterling, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
000
FXUS61 KLWX 191917
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
317 PM EDT SAT APR 19 2014

.SYNOPSIS...

HIGH CLOUDS WILL ERODE THROUGH THE EVENING TODAY AS HIGH PRESSURE
BUILDS INTO THE AREA. THIS HIGH WILL REMAIN IN CONTROL OF THE
REGION`S WEATHER THROUGH MONDAY. A COLD FRONT WILL BRING SHOWERS
TO THE AREA TUESDAY INTO TUESDAY EVENING BEFORE HIGH PRESSURE
BUILDS BACK IN FOR THE SECOND HALF OF THE WORKWEEK. NEXT UP IS
ANOTHER COLD FRONT LATER FRIDAY OR SATURDAY.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...

HIGH CLOUDS HUNG ON LONGER THAN ANTICIPATED THIS AFTERNOON AS
TAIL END OF UPPER JET EXITING NEW ENGLAND COMBINED WITH LOW
PRESSURE OVER SE US TO GIVE AGEOSTROPHIC LIFT IN UPPER LEVELS.
THIS CIRRIUS BKN-OVC SKY COVER WILL CONTINUE THROUGH TONIGHT. NE
WIND FLOW 5-10 KTS WILL CONTINUE TONIGHT...BUT WILL LOSE THE
GUSTINESS IN IN THE UPPER TEENS AS WE`VE SEEN ON INLAND LOCATIONS
THIS AFTERNOON. TEMPERATURES ARE COUPLED AND WENT WITH A BLEND OF
SREF AND NAM FOR OVERNIGHT MINS.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...

EXPECTING HIGH CLOUDS TO START EASTER SUNDAY BUT DIMINISH THROUGH
THE DAY.  SLIGHTLY LOWER MAX TEMPERATURES AS HIGH PRESSURE GETS
ESTABLISHED OVER SOUTHERN NEW ENGLAND AND OUR AREA RECEIVES A DEEP
LLVL MARINE/NE INFLOW ORIGINATING FROM THE GULF OF MAINE.  TEMPS WILL
REACH THE LOWER 60S IN MOST AREAS EXCEPT DIRECTLY ON THE WESTERN
SHORE OF THE CHESAPEAKE WHERE THEY`LL BE IN THE UPPER 50S TO NEAR 60.

NOTHING MUCH OF A CHANGE FOR SUN NIGHT AS MARINE FLOW CONTINUES.
NIGHTTIME MINS ON SUN NIGHT WILL BE FLIRTING ONCE AGAIN WITH FROST
ADVISORIES AS DRYER AIR WORKS IN AND CALMER WINDS.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...

MONDAY THROUGH TUESDAY...
NORTHERN JET STREAM GETS A BIT MORE AMPLIFIED BETWEEN MON AND TUE.
WE START WITH AN AXIS OF SURFACE HIGH PRESSURE OVER THE EAST MONDAY
MORNING. BUT A NORTHERN STREAM 500MB TROUGH WILL DIP DOWN INTO THE
NE AND BRING A COLD FRONT IN FROM THE WEST. THERE IS SOME
DISAGREEMENT BETWEEN THE VARIOUS MODELS AS TO TIMING AND HOW QUICKLY
IT WILL PASS THRU. WENT WITH THE SREF ENSEMBLE FOR POPS AND CLOUDS
TO ACCOUNT FOR THE POSSIBLE DIFFS. IN ANY CASE...EXPECT THE COLD
FRONT TO CROSS THE APPALACHIANS TUESDAY MORNING AND MOVE THRU THE
FORECAST AREA DURING THE DAY TUESDAY. HOW QUICKLY IT WILL CLEAR IS
IN QUESTION...PARTIALLY DUE TO ITS INTERACTION WITH THE LIFTING AREA
OF LOW PRESSURE MOVING SLOWLY NE OFFSHORE. FOR TEMPS RELIED ON THE
BIAS CORRECTED SREF AND BIAS CORRECTED ADJUSTED NAM MOS...BOTH OF
WHICH HAVE BEEN DOING WELL RECENTLY.

SHOWERS WITH THE COLD FRONT ARE NOT EXPECTED TO LEAVE A LOT OF
RAIN...FORECAST IS FOR 0.15 TO A QUARTER OF AN INCH. HOWEVER LOOKING
AT A SMALL AMOUNT OF FORECAST ATMOSPHERIC INSTABILITY...THERE IS A
CHANCE FOR A THUNDERSTORM EMBEDDED WITH THE SHOWERS IN OUR SOUTHERN
HALF WHICH COULD BOOST RAINFALL IN TARGETED AREAS IF IT COMES TO
PASS.

TUESDAY NIGHT THROUGH SATURDAY...
PRECIP WILL EXIT THE EASTERN EXTENT OF THE CWA OVERNIGHT TUES AS
COOL DRY AIR FILLS IN IN BREEZY NW FLOW BEHIND THE FRONT. SKIES
WILL BE PARTLY TO MOSTLY SUNNY FOR SUNRISE ON WED AND SHOULD
CONTINUE TO CLEAR THROUGH THE MORNING. A WEAK VORT MAX MAY LEAD TO
A SLIGHT INCREASE IN CLOUD COVER NEAR THE MASON DIXON LINE FOR WED
AFTERNOON/EVENING...BUT EVERYWHERE WILL STAY DRY. MODEST COLD AIR
ADVECTION WILL KEEP HIGHS 5 TO 10 DEGREES COOLER THAN TUES...IN
THE UPPER 50S TO MID 60S.

HIGH PRESSURE WILL FILL IN OVER THE AREA BEGINNING OVERNIGHT
WED AND THURS WILL BE A COOL BUT PLEASANT SPRING DAY. LOWS THURSDAY
MORNING WILL BE NEAR 40 WITH HIGHS REACHING INTO THE MID 60S UNDER
MOSTLY SUNNY SKIES.

THE HIGH WILL MOVE OFF THE COAST ON THURS NIGHT AND WE WILL SEE
WARMING IN THE SOUTHERLY RETURN FLOW FOR THE DAY ON FRI AS A COLD
FRONT APPROACHES FROM THE WEST. DETERMINISTIC MODELS DISAGREE ON THE
EXACT TIMING OF THE COLD FRONTAL PASSAGE WITH THE EURO BRINGING RAIN
THROUGH THE DAY FRI AND THE GFS KEEPING US WARM AND DRY DURING
THE DAY BUT WET OVERNIGHT ON FRI. LARGE SPREAD AMONGST ENSEMBLE
MEMBERS JUSTIFIED KEEPING CHANCE POPS IN THE FORECAST THROUGH THE
DAY AND NIGHT ON FRI AND INTO SAT. TIMING OF THE FRONTAL PASSAGE
WILL DETERMINE HIGHS SAT...BUT FAVORING SLOWER PROGRESSION OF FRONT
EXPECT HIGH TEMPS SLIGHT COOLER THAN FRI...MID 70S FRI AND LOWER
70S SAT.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...

VFR CONDITIONS ALL TERMS THROUGH 36 HOURS WITH WIND GENERALLY
03008KT THROUGH THE ENTIRE TAF PERIOD.

VFR CONDS ARE XPCTD FOR MONDAY AND MONDAY NIGHT. LARGELY VFR ON TUE
AS WELL BUT IFR POSSIBLE FOR FEW HOURS AROUND COLD FRONTAL PASSAGE.

IFR CONDITIONS ARE POSSIBLE IN LINGERING LOW CEILINGS AND RAIN
SHOWERS AS A COLD FRONT DEPARTS THE AREA TUESDAY NIGHT.

&&

.MARINE...

THRESHOLD SCA LATE TONIGHT ON BIG WATER OF OUR MARINE ZONES...THEN
EXPECTING THE ENTIRE MARINE AREA TO HAVE SCA CONDITIONS FROM 8 AM
SUNDAY THROUGH EARLY AFTERNOON.  AGAIN BIG WATER WILL CONTINUE SCA
THROUGH EARLY SUNDAY EVENING AS THE SE US SFC LOW MAKES IT WAY
OFFSHORE.

WIND SHIFT ON TUESDAY INTO TUE NIGHT...BUT NO HAZARDS DURING THAT
TIME.

A SMALL CRAFT ADVISORY MAY BE NECESSARY TUESDAY NIGHT THROUGH
THURSDAY MORNING IN BREEZY POST FRONTAL NORTHWEST FLOW.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 2 PM EDT SUNDAY FOR
     ANZ530>532-535-536-538>540.
     SMALL CRAFT ADVISORY FROM 4 AM TO 8 PM EDT SUNDAY FOR ANZ533-
     534-537-541>543.
     SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ534-
     537-543.

&&

$$
SYNOPSIS...CAS
NEAR TERM...LEE
SHORT TERM...LEE
LONG TERM...CAS/CEB
AVIATION...LEE/CAS/CEB
MARINE...LEE/CAS/CEB





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.