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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 171931
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
331 PM EDT FRI MAY 17 2013

.SYNOPSIS...
-- Changed Discussion --
A FRONTAL BOUNDARY OVER THE CENTRAL APPALACHIANS AND SOUTHERN
MID-ATLANTIC WILL REMAIN STALLED THROUGH THE WEEKEND AS AN ONSHORE
FLOW DEVELOPS WITH SURFACE HIGH PRESSURE BUILDING OFF THE NORTHERN
MID-ATLANTIC COAST. HIGH PRESSURE WILL BUILD OVER THE EASTERN STATES
THROUGH THE FIRST HALF OF NEXT WEEK.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH SATURDAY/...
-- Changed Discussion --
COLD FRONT HAS STALLED OVER THE WESTERN PORTION OF THE FORECAST
AREA. NORTH OF THE FRONT THE AIRMASS WILL REMAIN STABLE WITH NOTHING
MORE THAN SOME MID AND HIGH LEVEL CLOUDS EXPECTED FROM TIME TO TIME.
THE AREA FROM WESTERN MARYLAND AND ESPECIALLY THE POTOMAC HIGHLANDS
AND A PORTION OF THE SHENANDOAH VALLEY ARE MORE UNSTABLE. SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS STILL EXPECTED LATER THIS
AFTERNOON AND EVENING. EXPECTING PULSE TYPE STORMS...WEAK SHEAR AND
STEERING FLOW. OVERNIGHT LOWS WILL FALL BACK INTO THE 50S TO LOWER
60S.

MOISTURE WILL INCREASE OVERNIGHT AS EASTERLY FLOW TAKES SHAPE. LOW
CLOUDS WITH INCREASING CHANCES FOR LIGHT RAIN/SHOWERS AND SOME FOG
EXPECTED DURING THE DAY. ISOLATED THUNDER POSSIBLE FURTHER SOUTH BUT
GENERALLY AN OVERCAST DAY WITH COOL TEMPERATURES AND PERIODS OF
LIGHT RAIN. TEMPERATURES WILL STRUGGLE TO REACH 70 IN MANY
LOCATIONS.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
AN UPR TROUGH EJECTING FROM THE NORTHERN INTERMOUNTAIN WEST TO THE
GREAT PLAINS AND AN AMPLIFYING TROUGH OVER THE CANADIAN MARITIMES
WILL AMPLIFY A LONG-WAVE RIDGE OVER THE MIDWEST THIS WEEKEND. AT THE
SFC...HIGH PRESSURE WILL BUILD OFF THE NRN MID-ATLANTIC COAST WITH
THE STALLED BOUNDARY PERSISTING OVER THE SRN MID-ATLANTIC. AS A
RESULT...AN ONSHORE FLOW IS EXPECTED SATURDAY THROUGH SUNDAY NIGHT.
EXPECT WIDESPREAD SHOWERS TO SPREAD NORTHEAST TO THE BALT-WASH METRO
SATURDAY NIGHT AS MOIST SLY LLVL FLOW EXPANDS ACROSS THE CWA. CLOUDS
AND ONSHORE FLOW MAKE FOR A MILD SATURDAY NIGHT WITH MIN TEMPS MID
TO UPR 50S...LOW 60S URBAN/NEAR SHORE. WAA OVERRIDES THE CLOUDS
MAKING FOR MAX TEMPS ONLY ABOUT 5 DEGREES BELOW NORMAL (LOW 70S).
-- End Changed Discussion --

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
A LONG WAVE (WARM) RIDGE WILL PERSIST OVER THE ERN STATES MONDAY
THROUGH MOST OF NEXT WEEK WITH A SLY FLOW AND ABOVE NORMAL
TEMPERATURES. GENERALLY 80S MAX TEMPS THROUGH THE WEEK WITH MID TO
UPR 60 FOR MINS IN THE HUMID AIR. AT LEAST DIURNALLY DRIVEN
CONVECTION IS EXPECTED WITH ANY DISTURBANCE MAKING FOR ALL-DAY
THUNDERSTORM POTENTIAL.
-- End Changed Discussion --

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
VFR EXPECTED AT LEAST THROUGH MIDNIGHT. SCATTERED SHOWERS/ISOLATED
STORMS FOCUSED OVER THE SOUTHWEST. MVFR CIGS/VSBYS EXPECTED AFTER
09Z AS EASTERLY WIND TAKES SHAPE. EXPECT SUB VFR CIGS/VSBYS
EVERYWHERE BY SATURDAY AFTERNOON/EVENING ALONG WITH RAIN/SHOWERS.

MVFR/IFR CIGS SATURDAY NIGHT THROUGH SUNDAY NIGHT AS AN ONSHORE FLOW
BRINGS AMPLE MOISTURE ACROSS THE REGION. PASSING SHOWERS THROUGH
THIS TIME COULD CAUSE IFR VSBYS DURING THE HEAVIEST RAINFALL.
UNSTABLE PATTERN CONTINUES THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
WINDS WILL REMAIN BELOW SCA TODAY BUT INCREASE OUT OF THE EAST
OVERNIGHT. WINDS COULD APPROACH SCA LEVELS DURING SATURDAY BUT
CONFIDENCE NOT HIGH ENOUGH TO ISSUE ATTM. VSBYS OVER THE WATERS WILL
BE REDUCED AT TIMES IN RAIN/SHOWERS.

ONSHORE FLOW 10 TO 15 KT SATURDAY NIGHT THROUGH SUNDAY
NIGHT...BECOMING SLY MONDAY MORNING. PERHAPS AN SCA FOR SLY
CHANNELING MONDAY AFTERNOON/EVENING...OTHERWISE WINDS STAY BELOW 18
KT. SWLY FLOW AROUND 10 KT THEN TUESDAY THROUGH WEDNESDAY.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...BAJ
NEAR TERM...KRW
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...BAJ/KRW
MARINE...BAJ/KRW