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 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KLWX 280120
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
920 PM EDT WED AUG 27 2014

.SYNOPSIS...
A WEAK COLD FRONT OVER SOUTHERN PENNSYLVANIA WILL MOVE INTO THE AREA
TONIGHT. HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN MID-ATLANTIC
THURSDAY NIGHT...LINGERING OFF THE COAST INTO THE WEEKEND. THE
NEXT COLD FRONT WILL APPROACH THE MID-ATLANTIC EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...

WK CD FNT NOW ACROSS SRN PA WL CONT TO SINK THRU THE CWA OVRNGT.
IT IS APPEARING LK ONLY THE FAR WRN SXN OF THE CWA WL XPRNC ANY
PCPN W/ THIS.

NW FLOW AND DRIER AIR WILL MOVE IN BEHIND THE FRONT. THE FRONT
SHOULD BE IN SRN VA BY THURSDAY MORNING AND CLOUDS WILL CLEAR FROM
NORTH TO SOUTH EARLY THURSDAY MORNING.

THURSDAY...NW FLOW WILL DROP DEWPTS INTO THE 50S. FCST MAX TEMPS ARE
IN THE LOW 80S NEAR THE MASON DIXON LINE TO THE MID 80S IN CENTRAL
VA...WITH MID TO UPPER 80S IN DC/BALTIMORE.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...

NLY FLOW FROM HIGH PRESSURE MOVING EAST ACROSS THE NRN MID-
ATLANTIC SHOULD LIMIT FOG THURSDAY NIGHT. MIN TEMPS MID 50S NW TO
LOW 60S SE (MID 60S URBAN).

FRIDAY...MID LEVEL RIDGE AXIS LIFT OVER THE AREA WITH A RETURN OF
MOISTURE BY THAT EVENING. ISO WORDING FOR THUNDERSTORMS IN
MOUNTAINS OF THE SOUTHWEST ZONES. MAX TEMPS GENERALLY MID 80S IN
SELY ONSHORE SFC FLOW.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
SURFACE HIGH PRESSURE WILL MOVE OFF OF THE NEW ENGLAND COAST OVER
THE COURSE OF THE WEEKEND. GRADUALLY INCREASING WARM AND MOIST
SOUTHERLY FLOW COMBINED WITH HEIGHT FALLS ALOFT WILL LEAD TO
INCREASED INSTABILITY DURING THIS TIME. THUNDERSTORM ACTIVITY SATURDAY
SHOULD BE LIMITED TO THE HIGH TERRAIN ALONG THE POTOMAC HIGHLANDS
AND WESTERN MD WHERE UPSLOPE FLOW WILL PROVIDE THE BEST TRIGGER FOR
CONVECTION. LITTLE STEERING FLOW SHOULD ENSURE THAT THESE STORMS
REMAIN WEST OF THE METRO AREAS UNTIL THEY DIE OUT SHORTLY AFTER
SUNSET SATURDAY NIGHT.

HIGH PRESSURE OFF THE COAST WILL SETTLE INTO A MORE TYPICAL
BERMUDA HIGH LOCATION BY SUNDAY EVENING...ALLOW LEE TROUGHING TO SET
UP LOCALLY AHEAD OF AN APPROACHING WEAK COLD FRONT SUNDAY. THIS
LIFTING MECHANISM WILL LEAD TO AN INCREASE IN SHOWERS AND
THUNDERSTORM COVERAGE AHEAD OF THE FRONT BY SUNDAY AFTERNOON.
INSTABILITY LESS THAN 1000 J AND RELATIVELY WEAK SHEAR SUNDAY SHOULD
LIMIT THE SEVERE POTENTIAL OF THUNDERSTORMS THAT DO FORM. THE
FRONTAL BOUNDARY WILL ESSENTIALLY STALL AND DETERIORATE OVER THE
AREA THROUGH MONDAY...SO CHANCE POPS AND THUNDERSTORMS WILL REMAIN
IN THE FORECAST FOR MONDAY WITH SLIGHTLY MORE INSTABILITY
THAN ON SUNDAY.

MONDAY NIGHT SHOULD BE DRY AS LITTLE DYNAMIC ENHANCEMENT WILL REMAIN
OVER THE AREA AS THE FRONT WILL HAVE MOSTLY DETERIORATED. SOUTHERLY
FLOW AROUND THE BERMUDA HIGH AND THE RESULTING LEE TROUGH WILL
RESUME TUESDAY AND AFTERNOON THUNDERSTORMS WILL BE POSSIBLE ONCE
AGAIN. A REINFORCING COLD FRONT SHOULD MOVE THROUGH
WEDNESDAY...BRINGING SHOWERS AND THUNDERSTORMS FOR THE MIDDLE OF THE
WORKWEEK.

HIGH TEMPS WILL BE NEAR 90 SATURDAY...SUNDAY AND TUESDAY...AS
PREFRONTAL SOUTHERLY FLOW AND LEE TROUGHING SET UP LOCALLY. HIGHS ON
MONDAY AND WEDNESDAY WILL BE IN THE MID TO UPPER 80S AS FRONTS
APPROACH AND CROSS THE AREA.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
VFR TONIGHT FOR MOST TERMINALS. DC METROS SHOULD BE DRY TONIGHT
IN SPITE OF A COLD FRONTAL PASSAGE. NWLY FLOW AROUND 10 KT BEHIND
THE FRONT LATE TONIGHT. HIGH PRESSURE THROUGH THURSDAY NIGHT WITH
VFR CONDS THROUGH FRIDAY.

CONFIDENCE IS LOW IN THE OCCURRENCE OF ANY HAZARDS TO AVIATION IN
THE LONG TERM.

&&

.MARINE...
NWLY WINDS TONIGHT BEHIND A DRY COLD FRONT. 10 TO 15 KT NWLY FLOW
THURSDAY AS HIGH PRESSURE BUILDS FROM THE GREAT LAKES. LIGHTER NLY
FLOW THURSDAY NIGHT...BECOMING ONSHORE FOR FRIDAY.

A SMALL CRAFT ADVISORY MAY BE NECESSARY SUNDAY IN BREEZY PREFRONTAL
SOUTHERLY FLOW.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

$$
UPDATE...WOODY!
PRVS...BAJ/CEB






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