[top]
000
FXUS61 KLWX 240108
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
908 PM EDT THU MAY 23 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE MID-ATLANTIC REGION TONIGHT. AN UPPER
LEVEL LOW WILL RESIDE OVER THE AREA ON FRIDAY...THEN CANADIAN HIGH
PRESSURE WILL BUILD OVERHEAD FOR THE MEMORIAL DAY WEEKEND. A WARM
FRONT WILL PASS THROUGH THE AREA DURING THE EARLY TO MIDDLE
PORTION OF NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
CDFNT IN/NEAR THE SHEN VLY ATTM. AFTER AN AFTN WHERE STORMS WERE
SCTD AND LACKED ORGANIZATION...FINALLY HV A CONCENTRATED STRUCTURE
TO WORK OFF OF. HWVR...W/ LOSS OF DIURNAL HEATING WE/RE LOSING
WHAT SEVERITY WE HAD. CENTRAL VA HAS BEEN LARGELY UNTAPPED...AND
XPCT TSRA TO HV MORE LIFE THERE. ELSW...THE HVY RAFL WL BE THE
BIGGER IMPACT. LWX RAOB DEMONSTRATES THIS PREMISE...W/ MORE CINH
THAN CAPE AND 1.33 INCH PWAT. WL KEEP POPS HIGH TIL FROPA...THEN
SCALE BACK. WIND SHIFT TO THE NORTHWEST OCCURS BEHIND THE FRONT
OVERNIGHT...AND DEWPOINTS WILL BEGIN TO DECREASE WITH COOLER AIR
MOVING IN FOR FRIDAY.
FRIDAY WILL CERTAINLY FEEL LIKE A DIFFERENT DAY WITH MAXIMA
RELUCTANT TO RISE MUCH DURING THE DAY WITH LOW LEVEL COLD
ADVECTION AT PLAY AND AN UPPER LOW OVERHEAD. MAXIMA IN THE LOWER
TO MID 60S CAN BE EXPECTED. DECENT GRADIENT WITH COLD ADVECTION
WILL BRING A WINDY DAY...WITH GUSTS POSSIBLY OVER 35 MPH AT TIMES.
WITH THE UPPER LOW OVERHEAD EXPECT PLENTY OF CLOUDS AND ALSO
SCATTERED SHOWERS PARTICULARLY ACROSS THE NORTHERN PORTION OF THE
CWA. SHOWERS MAY PRODUCE STRONGER WIND GUSTS AND ALSO CAN/T RULE
OUT SOME SMALL HAIL DUE TO COLD AIR ALOFT.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
UPPER LOW DRIFTS TO THE NORTHEAST ON SATURDAY...AS HIGH PRESSURE
BUILDS IN FOR THE REST OF THE WEEKEND. IT LOOKS LIKE WINDS STAY UP
FRIDAY NIGHT...SO NO FROST IS EXPECTED. BUT TEMPERATURES COULD
DROP CLOSE TO FREEZING OVER THE HIGHLANDS LATE FRIDAY NIGHT.
ANOTHER WINDY AND COOL DAY IS EXPECTED ON SATURDAY ALTHOUGH SOME
SUNSHINE SHOULD MAKE A RETURN. MODERATING TEMPERATURES AND
SUNSHINE ARE EXPECTED SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
H5 RISES THROUGH ENTIRE LONG TERM AS BERMUDA HIGH STARTS SETTING UP
AT THE BEGINNING OF THE PERIOD WITH WARM FRONT PASSAGE LIKELY ON
TUESDAY PER 12Z GFS. MONDAY APPEARS STABLE WITH LITTLE OR NO MODEL
CAPE. ON TUESDAY...INSTABILITY STARTS TO WORK INTO THE SHEN VALLEY
WITH WEDNESDAY AND THURSDAY HAVING MODERATE INSTABILITY ACROSS
ENTIRE CWA.
MAX TEMPS MONDAY AND TUESDAY ARE AROUND CLIMO...THEN INCREASING UP
TO 10 DEG ABV CLIMO WITH MAX TEMPS APPROACHING 90 WEDNESDAY AND
THURSDAY.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
SHRA/TSRA IN METRO BALT AND DOWN THE SHEN VLY. FLGT RESTRICTIONS
ATTM GNLY MVFR...ALTHO CUD HV LCL IFR W/IN SHRA/TSRA. THERE MAY BE
A FEW SHRA THEREAFTER...AS WELL AS OCNL MVFR CIGS. CUD BE
CONTENDING W/ A LTL FOG AS WELL TIL FROPA.
A COLD FRONT MOVES THROUGH THE AREA OVERNIGHT WITH A WIND SHIFT.
COOLER/DRIER AIR WL TAKE CARE OF ANY RESIDUAL FOG. EXPECT GUSTY
NORTHWEST WINDS ON FRIDAY...WITH SCATTERED SHOWERS THAT MAY
PRODUCE GUSTIER WINDS.
STRONG NWLY FLOW CONTINUES THROUGH SATURDAY AS THE UPR LOW
REMAINS IN THE REGION AND SFC HIGH PRESSURE BUILDS. VFR EARLY NEXT
WEEK IN A CANADIAN AIRMASS BEFORE A MIDWEEK WARM FRONT.
&&
.MARINE...
ASIDE FM DRUM PT-SMITH PT AND ADJACENT TANGIER SOUND...WINDS HVNT
REALLY BEEN REACHING SCA CRIT. EVEN IN THE MID BAY...SPDS STARTING
TO SUBSIDE. WL ALLOW SCA TO EXPIRE AT 10 PM. THAT/S NOT TO SAY
THERE WONT BE GUSTY WINDS...BUT THEY WL BE ASSOCD W/ SHRA AND TSRA
CROSSING ALONG AND AHEAD OF CDFNT. ANTICIPATE SPECIAL MARINE
WARNINGS WL BE REQD OVNGT.
COLD FRONT MOVES THROUGH OVERNIGHT WITH WINDS SHIFTING
TO THE NORTHWEST. THESE WINDS WILL BE GUSTY ON FRIDAY...FOR A
SOLID SMALL CRAFT ADVISORY. MAY EVEN FLIRT WITH GALES DUE TO
GRADIENT EFFECTS ALONE. IN ADDITION...SCATTERED SHOWERS MAY
PRODUCE STRONGER WIND GUSTS.
NWLY FLOW WITH GUSTS 25 TO 30 KT THROUGH SATURDAY AS AN UPR LOW
PERSIST OVER THE REGION AND SFC HIGH PRESSURE BUILDS. MORE
TRANQUIL WEATHER EARLY NEXT WEEK UNDER A CANADIAN AIRMASS.
&&
.TIDES/COASTAL FLOODING...
ANOMALIES RUNNING 1/2 FT ABOVE NORMAL TNGT. NO COASTAL FLOOD
ADVISORY IS EXPECTED. WINDS WILL SHIFT TO THE NORTHWEST OVERNIGHT
INTO FRIDAY BEHIND A COLD FRONT...BRINGING A RETURN TO NORMAL AT A
MINIMUM...AND MORE LIKELY BLOW OUT CONDS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
ANZ531>534-537>543.
SMALL CRAFT ADVISORY FROM 6 AM FRIDAY TO 6 AM EDT SATURDAY FOR
ANZ530>543.
&&
$$
SYNOPSIS...BPP
NEAR TERM...HTS/BPP
SHORT TERM...BPP
LONG TERM...LEE
AVIATION...HTS/BPP/BAJ
MARINE...HTS/BPP/BAJ
TIDES/COASTAL FLOODING...HTS
000
FXUS61 KLWX 231847
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
247 PM EDT THU MAY 23 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON...MOVING
THROUGH THE MID-ATLANTIC REGION TONIGHT. AN UPPER LEVEL LOW WILL
RESIDE OVER THE AREA ON FRIDAY...THEN CANADIAN HIGH PRESSURE WILL
BUILD OVERHEAD FOR THE MEMORIAL DAY WEEKEND. A WARM FRONT WILL
PASS THROUGH THE AREA DURING THE EARLY TO MIDDLE PORTION OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
CONSIDERABLE CLOUDINESS REMAINS ACROSS THE CWA EARLY THIS
AFTERNOON...BUT VISIBLE SATELLITE IMAGERY INDICATES SOME BREAKS
DEVELOPING WHICH WILL ENHANCE HEATING/INSTABILITY DURING THE MID-
LATE AFTERNOON.
ALREADY HAVE CONVECTION BEGINNING TO DEVELOP WITH CONVECTIVE
TEMPERATURES BEING REACHED. LARGE SCALE LIFT IS STARTING TO
INCREASE AHEAD OF THE OHIO VALLEY TROUGH...AND THERE/S ALSO A LEE
TROUGH IN PLACE. THESE WILL SERVE AS INITIAL TRIGGERS AND THERE IS
ALSO THE COLD FRONT TO CONSIDER WHICH WILL ALSO SUPPORT CONVECTION
INTO THE EVENING.
WHILE INITIAL CONVECTION MAY LACK ORGANIZATION...AS WIND FIELDS
IMPROVE THROUGH THE LATE AFTERNOON/EVENING SHEAR WILL INCREASE AND
THIS COMBINED WITH EXISTING INSTABILITY SHOULD HELP TO FAVOR
BETTER ORGANIZATION /MULTICELL CLUSTERS/ OF STORMS. SOME OF THESE
STORMS WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS AND
POSSIBLY LARGE HAIL.
ANOTHER CONCERN WILL BE FOR HEAVY RAINFALL IN VULNERABLE PLACES OF
THE SHENANDOAH VALLEY/POTOMAC HIGHLANDS WHERE 1 HR FLASH FLOOD
GUIDANCE MAY ONLY BE AROUND 1/2 INCH. STORMS MAY CAUSE LOCALIZED
FLASH FLOODING IN THESE LOCATIONS INTO EARLY EVENING.
SEVERITY OF STORMS SHOULD WANE AFTER SUNSET...BUT THE FRONTAL
BOUNDARY ITSELF WILL LIKELY KEEP AT LEAST SCATTERED CONVECTION
GOING WELL INTO THE EVENING.
WIND SHIFT TO THE NORTHWEST OCCURS BEHIND THE FRONT
OVERNIGHT...AND DEWPOINTS WILL BEGIN TO DECREASE WITH COOLER AIR
MOVING IN FOR FRIDAY.
FRIDAY WILL CERTAINLY FEEL LIKE A DIFFERENT DAY WITH MAXIMA
RELUCTANT TO RISE MUCH DURING THE DAY WITH LOW LEVEL COLD
ADVECTION AT PLAY AND AN UPPER LOW OVERHEAD. MAXIMA IN THE LOWER
TO MID 60S CAN BE EXPECTED. DECENT GRADIENT WITH COLD ADVECTION
WILL BRING A WINDY DAY...WITH GUSTS POSSIBLY OVER 35 MPH AT TIMES.
WITH THE UPPER LOW OVERHEAD EXPECT PLENTY OF CLOUDS AND ALSO
SCATTERED SHOWERS PARTICULARLY ACROSS THE NORTHERN PORTION OF THE
CWA. SHOWERS MAY PRODUCE STRONGER WIND GUSTS AND ALSO CAN/T RULE
OUT SOME SMALL HAIL DUE TO COLD AIR ALOFT.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
UPPER LOW DRIFTS TO THE NORTHEAST ON SATURDAY...AS HIGH PRESSURE
BUILDS IN FOR THE REST OF THE WEEKEND. IT LOOKS LIKE WINDS STAY UP
FRIDAY NIGHT...SO NO FROST IS EXPECTED. BUT TEMPERATURES COULD
DROP CLOSE TO FREEZING OVER THE HIGHLANDS LATE FRIDAY NIGHT.
ANOTHER WINDY AND COOL DAY IS EXPECTED ON SATURDAY ALTHOUGH SOME
SUNSHINE SHOULD MAKE A RETURN. MODERATING TEMPERATURES AND
SUNSHINE ARE EXPECTED SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
H5 RISES THROUGH ENTIRE LONG TERM AS BERMUDA HIGH STARTS SETTING UP
AT THE BEGINNING OF THE PERIOD WITH WARM FRONT PASSAGE LIKELY ON
TUESDAY PER 12Z GFS. MONDAY APPEARS STABLE WITH LITTLE OR NO MODEL
CAPE. ON TUESDAY...INSTABILITY STARTS TO WORK INTO THE SHEN VALLEY
WITH WEDNESDAY AND THURSDAY HAVING MODERATE INSTABILITY ACROSS
ENTIRE CWA.
MAX TEMPS MONDAY AND TUESDAY ARE AROUND CLIMO...THEN INCREASING UP
TO 10 DEG ABV CLIMO WITH MAX TEMPS APPROACHING 90 WEDNESDAY AND
THURSDAY.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
MVFR CIGS HAVE IMPROVED TO VFR EARLY THIS AFTERNOON...BUT
CONVECTION WILL INCREASE AS THE AFTERNOON PROGRESSES AS CONVECTIVE
TEMPERATURES ARE REACHED AND A SURFACE TROUGH INTERACTS WITH
MOISTURE/INSTABILITY. STARTED THE TAFS WITH VCTS...BUT WITH POPS
RAMPING UP TO LIKELY MID-LATE AFTERNOON PREVAILING TSRA WITH MVFR
VSBYS ARE IN THE TAFS. AMENDMENTS MAY BE NECESSARY TO ADD MORE
DETAIL TO TIMING/IMPACT AT EACH TERMINAL. EXPECT AT LEAST SHOWERS
TO CONTINUE WELL INTO THE EVENING UNTIL A COLD FRONT MOVES THROUGH
THE AREA OVERNIGHT WITH A WIND SHIFT. EXPECT GUSTY NORTHWEST WINDS
ON FRIDAY...WITH SCATTERED SHOWERS THAT MAY PRODUCE GUSTIER WINDS.
STRONG NWLY FLOW CONTINUES THROUGH SATURDAY AS THE UPR LOW
REMAINS IN THE REGION AND SFC HIGH PRESSURE BUILDS. VFR EARLY NEXT
WEEK IN A CANADIAN AIRMASS BEFORE A MIDWEEK WARM FRONT.
&&
.MARINE...
MARGINAL SCA IN EFFECT THIS AFTERNOON DUE TO SOUTHERLY FLOW.
BIGGER CONCERN IS FROM CONVECTION LATER THIS AFTERNOON WHICH CAN
PRODUCE STRONG GUSTY WINDS WHICH COULD REQUIRE SPECIAL MARINE
WARNINGS. COLD FRONT MOVES THROUGH OVERNIGHT WITH WINDS SHIFTING
TO THE NORTHWEST. THESE WINDS WILL BE GUSTY ON FRIDAY...FOR A
SOLID SMALL CRAFT ADVISORY. MAY EVEN FLIRT WITH GALES DUE TO
GRADIENT EFFECTS ALONE. IN ADDITION...SCATTERED SHOWERS MAY
PRODUCE STRONGER WIND GUSTS.
NWLY FLOW WITH GUSTS 25 TO 30 KT THROUGH SATURDAY AS AN UPR LOW
PERSIST OVER THE REGION AND SFC HIGH PRESSURE BUILDS. MORE
TRANQUIL WEATHER EARLY NEXT WEEK UNDER A CANADIAN AIRMASS.
&&
.TIDES/COASTAL FLOODING...
ANOMALIES WERE RUNNING 1/4 TO 1/2 FT THIS AFTERNOON...AND WITH
SOUTHERLY FLOW WILL LIKELY INCREASE MORE THROUGH THIS EVENING.
HOWEVER...THE UPCOMING TIDE IS THE LOWER OF THE NEXT TWO AND
ANOMALIES EVEN UP TO 1 FT WOULD NOT LIKELY RESULT IN MINOR TIDAL
FLOODING. THEREFORE...NO COASTAL FLOOD ADVISORY IS EXPECTED. WINDS
WILL SHIFT TO THE NORTHWEST OVERNIGHT INTO FRIDAY BEHIND A COLD
FRONT.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
ANZ531>534-537>543.
SMALL CRAFT ADVISORY FROM 6 AM FRIDAY TO 6 AM EDT SATURDAY FOR
ANZ530>543.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ530-
535-536.
&&
$$
SYNOPSIS...BPP
NEAR TERM...BPP
SHORT TERM...BPP
LONG TERM...LEE
AVIATION...BPP/BAJ
MARINE...BPP/BAJ
TIDES/COASTAL FLOODING...BPP
000
FXUS61 KLWX 231357
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
957 AM EDT THU MAY 23 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH AREA TODAY BEFORE CROSSING TONIGHT. AN
UPPER-LEVEL LOW PERSISTS OVER THE REGION FRIDAY AND SATURDAY.
CANADIAN HIGH PRESSURE WILL BUILD OVERHEAD FOR THE MEMORIAL DAY
WEEKEND. A WARM FRONT WILL PASS THROUGH THE AREA DURING THE
MIDDLE PORTION OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
EXTENSIVE CLOUD COVER REMAINS ACROSS THE MID-ATLANTIC AT 13Z.
HOWEVER...AM ALREADY STARTING TO SEE BREAKS IN THE CLOUDS OVER
PORTIONS OF SOUTHERN AND CENTRAL VIRGINIA...AND ALSO INTO WEST
VIRGINIA AND EXPECT THESE BREAKS TO WORK INTO THE CWA LATER ON
THIS AFTERNOON. THESE BREAKS WILL ALLOW WARMING TO TAKE
PLACE...BOOSTING MAXIMA AOA 80F ESPECIALLY EAST OF THE BLUE RIDGE.
UP TIL NOON...THERE WILL BE SCATTERED SHOWERS OVER THE CWA. BUT
WITH EXPECTED HEATING...EXPECT TO SEE AN UPTICK IN COVERAGE OF
CONVECTION INCLUDING THUNDERSTORMS BETWEEN NOON AND 2 PM.
APPROACHING UPPER SHORTWAVE AND SURFACE TROUGH WILL HELP TO SERVE
AS INITIAL TRIGGERS /FRONTAL BOUNDARY MAY ALSO BE A TRIGGER LATER
ON/. MODIFIED 12Z KIAD RAOB FOR 80/65 INDICATES OVER 1500 J/KG OF
MOST UNSTABLE CAPE...MIXED LAYER IS LESS THAN 1000 BUT SUFFICIENT.
IN ADDITION...WIND FIELDS BECOME MORE FAVORABLE AS THE DAY
PROGRESSES WHICH WILL ENHANCE SHEAR. COMBINATION OF INSTABILITY
AND SHEAR IS EXPECTED TO HELP ORGANIZE STORMS INTO MULTICELL
CLUSTERS...SOME OF WHICH MAY PRODUCE DAMAGING WIND GUSTS AND
PERHAPS SOME LARGE HAIL.
SEVERITY OF STORMS SHOULD WANE AFTER SUNSET...BUT THE FRONTAL
BOUNDARY ITSELF WILL LIKELY KEEP AT LEAST SCATTERED CONVECTION
GOING WELL INTO THE EVENING.
TEMPS BEHIND THE FRONT WILL BE NOTICEABLY COOLER ACROSS WESTERN
PORTIONS OF THE CWA. HOWEVER...THE COOLER AIR MAY NOT ARRIVE UNTIL
FRIDAY FOR LOCATIONS EAST OF THE BLUE RIDGE MOUNTAINS. MIN TEMPS
WILL RANGE FROM THE 40S IN THE ALLEGHENY HIGHLANDS TO THE MID 60S
IN WASHINGTON/BALTIMORE.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
CLOSED UPR LOW NOW PROGGED TO DRIFT EAST OVER THE CENTRAL MID
ATLANTIC FRIDAY BEFORE DRIFTING UP TO NEW ENGLAND THROUGH THE
WEEKEND. CONFIDENCE IS LOW ON EXACT PLACEMENT OF THIS LOW. WILL
PROBABLY UPDATE THE FORECAST WITH THE 00Z ECMWF WHICH IS
FORTHCOMING. THIS COLD CORE WILL BRING INSTABILITY SHOWERS TO THE
AREA FRIDAY INTO (UNCERTAIN HOW FAR INTO) SATURDAY WITH GUSTY NWLY
FLOW (GUSTS AROUND 30 MPH)...CLOUDY SKIES...AND MUCH BELOW NORMAL
TEMPERATURES. SHOULD BE PRETTY SIMILAR TO LAST SATURDAY IT DROPPED
TO AROUND 60F ONCE THE INTERMITTENT SHOWERS GOT GOING.
LOW/TROUGH TAKES ON A NEGATIVE TILT SATURDAY WHICH SHOULD SHUNT THE
LOW OFF THE MID-ATLANTIC COAST. NWLY FLOW CONTINUES TO GUST 25 TO 30
MPH. OUR GRIDS DO NOT INDICATE A WIND CHILL...BUT IF IT IS PRETTY
CLOUDY AND THAT WINDY THERE WOULD CERTAINLY BE A CHILL.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
WITH THE UPR LOW MERELY DRIFTING TO NEW ENGLAND THROUGH SUNDAY...THE
SHORTWAVE OVER THE TN VLY LOOKS CONTAINED/AWAY FROM THE CENTRAL
MID-ATLANTIC UNTIL PERHAPS TUESDAY. WITH CANADIAN AIRMASS IN
PLACE...EXPECT A STEADY WARMING TREND DUE TO MODIFICATION BY THE
STRONG LATE MAY SUN.
WARM FRONT LIFTS NORTH ACROSS THE REGION MID NEXT WEEK WITH
THUNDERSTORM CHANCES AND A RETURN OF SEASONABLY WARM CONDITIONS.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
MVFR CIGS NEAR DCA/BWI WILL IMPROVE ABV 3K FT BY 15Z...LEAVING
PREVAILING VFR FOR THE REST OF THE DAY. HOWEVER...FLIGHT
RESTRICTIONS IN SHRA/TSRA CAN BE EXPECTED DURING THE
AFTERNOON/EARLY EVENING. THUNDERSTORMS WILL BE CAPABLE OF
PRODUCING GUSTY WINDS AND HAIL AS WELL. A COLD FRONT WILL PASS
THROUGH THE TERMINALS LATE TONIGHT WITH A WIND SHIFT. GUSTY WINDS
EXPECTED FRIDAY.
NWLY FLOW WITH GUSTS 25 TO POSSIBLY 30 KT WITH PSBL MVFR CIGS AND
OCCASIONAL SHOWERS FRIDAY UNDER AND UPR LOW. STRONG NWLY FLOW
CONTINUES THROUGH SATURDAY AS THE UPR LOW REMAINS IN THE REGION AND
SFC HIGH PRESSURE BUILDS. VFR EARLY NEXT WEEK IN A CANADIAN AIRMASS
BEFORE A MIDWEEK WARM FRONT.
&&
.MARINE...
A SOUTHERLY FLOW WILL CONTINUE AROUND HIGH PRESSURE TODAY. A SMALL
CRAFT ADVISORY IS IN EFFECT FOR THE WATERS. SHOWERS AND
THUNDERSTORMS WILL INCREASE IN COVERAGE THIS AFTERNOON AND
EVENING. SOME THUNDERSTORMS WILL BE CAPABLE OF PRODUCING GUSTY
WINDS AND HAIL. SPECIAL MARINE WARNINGS MAY BE WARRANTED.
A COLD FRONT WILL APPROACH THE WATERS TONIGHT. A LULL IN THE
PRESSURE GRADIENT SUGGESTS THAT WIND SPEEDS MAY BE BELOW SCA
CRITERIA.
NWLY FLOW WITH GUSTS 25 TO 30 KT FRIDAY THROUGH SATURDAY AS AN UPR
LOW PERSIST OVER THE REGION AND SFC HIGH PRESSURE BUILDS. SCA IN
EFFECT FOR FRIDAY...EXPECT IT TO BE EXTENDED INTO SATURDAY NIGHT.
MORE TRANQUIL WEATHER EARLY NEXT WEEK UNDER A CANADIAN AIRMASS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
ANZ530>543.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT FRIDAY FOR
ANZ530>543.
&&
$$
SYNOPSIS...BJL
NEAR TERM...BPP/BJL
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...BPP/BJL/BAJ
MARINE...BPP/BJL/BAJ
000
FXUS61 KLWX 230754
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
354 AM EDT THU MAY 23 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH AREA TODAY BEFORE CROSSING TONIGHT. AN
UPPER-LEVEL LOW PERSISTS OVER THE REGION FRIDAY AND SATURDAY.
CANADIAN HIGH PRESSURE WILL BUILD OVERHEAD FOR THE MEMORIAL DAY
WEEKEND. A WARM FRONT WILL PASS THROUGH THE AREA DURING THE
MIDDLE PORTION OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
SURFACE HIGH PRESSURE REMAINS OVER THE ATLANTIC OCEAN EARLY THIS
MORNING WHILE A COLD FRONT TRACKS THROUGH THE GREAT LAKES. AN
UPPER-LEVEL TROUGH ALSO REMAINS OVER THE GREAT LAKES.
A SOUTHERLY FLOW AROUND THE HIGH WILL ALLOW FOR MORE WARM AND
HUMID CONDITIONS TODAY. HOWEVER...TEMPS WILL NOT BE QUITE AS WARM
AS RECENT DAYS DUE TO MORE CLOUD COVER. MAX TEMPS WILL RANGE FROM
THE UPPER 60S IN THE MOUNTAINS TO THE UPPER 70S AND LOWER 80S
ACROSS MOST OTHER LOCATIONS. THE WARM AND HUMID AIRMASS WILL LEAD
TO MODERATE AMOUNTS OF INSTABILITY. THE INSTABILITY WILL COMBINE
WITH FORCING FROM SEVERAL UPPER-LEVEL DISTURBANCES IN THE
SOUTHWEST FLOW ALOFT AND A SURFACE TROUGH TO TRIGGER SHOWERS AND
THUNDERSTORMS. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL
BE DURING THE AFTERNOON AND EVENING HOURS. INCREASED DEEP LAYER
SHEAR ALONG WITH MODERATE INSTABILITY SUGGESTS THAT SOME
THUNDERSTORMS WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS AND
LARGE HAIL.
THE COLD FRONT WILL PASS THROUGH THE AREA LATE TONIGHT. MORE
SHOWERS ARE POSSIBLE...BUT PRECIPITATION WILL NOT BE AS WIDESPREAD
DUE TO THE LOSS OF DAYTIME HEATING. TEMPS BEHIND THE FRONT WILL BE
NOTICEABLY COOLER ACROSS WESTERN PORTIONS OF THE CWA.
HOWEVER...THE COOLER AIR MAY NOT ARRIVE UNTIL FRIDAY FOR LOCATIONS
EAST OF THE BLUE RIDGE MOUNTAINS. MIN TEMPS WILL RANGE FROM THE
40S IN THE ALLEGHENY HIGHLANDS TO THE MID 60S IN
WASHINGTON/BALTIMORE.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
CLOSED UPR LOW NOW PROGGED TO DRIFT EAST OVER THE CENTRAL MID
ATLANTIC FRIDAY BEFORE DRIFTING UP TO NEW ENGLAND THROUGH THE
WEEKEND. CONFIDENCE IS LOW ON EXACT PLACEMENT OF THIS LOW. WILL
PROBABLY UPDATE THE FORECAST WITH THE 00Z ECMWF WHICH IS
FORTHCOMING. THIS COLD CORE WILL BRING INSTABILITY SHOWERS TO THE
AREA FRIDAY INTO (UNCERTAIN HOW FAR INTO) SATURDAY WITH GUSTY NWLY
FLOW (GUSTS AROUND 30 MPH)...CLOUDY SKIES...AND MUCH BELOW NORMAL
TEMPERATURES. SHOULD BE PRETTY SIMILAR TO LAST SATURDAY IT DROPPED
TO AROUND 60F ONCE THE INTERMITTENT SHOWERS GOT GOING.
LOW/TROUGH TAKES ON A NEGATIVE TILT SATURDAY WHICH SHOULD SHUNT THE
LOW OFF THE MID-ATLANTIC COAST. NWLY FLOW CONTINUES TO GUST 25 TO 30
MPH. OUR GRIDS DO NOT INDICATE A WIND CHILL...BUT IF IT IS PRETTY
CLOUDY AND THAT WINDY THERE WOULD CERTAINLY BE A CHILL.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
WITH THE UPR LOW MERELY DRIFTING TO NEW ENGLAND THROUGH SUNDAY...THE
SHORTWAVE OVER THE TN VLY LOOKS CONTAINED/AWAY FROM THE CENTRAL
MID-ATLANTIC UNTIL PERHAPS TUESDAY. WITH CANADIAN AIRMASS IN
PLACE...EXPECT A STEADY WARMING TREND DUE TO MODIFICATION BY THE
STRONG LATE MAY SUN.
WARM FRONT LIFTS NORTH ACROSS THE REGION MID NEXT WEEK WITH
THUNDERSTORM CHANCES AND A RETURN OF SEASONABLY WARM CONDITIONS.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
LOW-LEVEL MOISTURE TRAPPED UNDERNEATH THE NOCTURNAL INVERSION MAY
RESULT IN A BRIEF PERIOD OF LOW CLOUDS EARLY THIS MORNING. HAVE
LOW END MVFR CIGS IN THE FORECAST NOW...BUT IFR CONDITIONS ARE
POSSIBLE DURING THIS TIME.
CIGS WILL IMPROVE LATER THIS MORNING...BUT PERHAPS REMAINING AT
MVFR LEVELS. SHOWERS AND THUNDERSTORMS WILL INCREASE IN
COVERAGE...WITH THE BEST CHANCE FOR THUNDERSTORMS EXPECTED THIS
AFTERNOON AND EVENING. THUNDERSTORMS WILL BE CAPABLE OF PRODUCING
GUSTY WINDS AND HAIL. SUBVFR CONDITIONS ARE ALSO EXPECTED IN
HEAVIER SHOWERS AND T-STORMS. A COLD FRONT WILL PASS THROUGH THE
TERMINALS LATE TONIGHT. MORE SHOWERS ARE POSSIBLE ALONG WITH AREAS
OF BR.
NWLY FLOW WITH GUSTS 25 TO POSSIBLY 30 KT WITH PSBL MVFR CIGS AND
OCCASIONAL SHOWERS FRIDAY UNDER AND UPR LOW. STRONG NWLY FLOW
CONTINUES THROUGH SATURDAY AS THE UPR LOW REMAINS IN THE REGION AND
SFC HIGH PRESSURE BUILDS. VFR EARLY NEXT WEEK IN A CANADIAN AIRMASS
BEFORE A MIDWEEK WARM FRONT.
&&
.MARINE...
A SOUTHERLY FLOW WILL CONTINUE AROUND HIGH PRESSURE TODAY. A SMALL
CRAFT ADVISORY IS IN EFFECT FOR THE WATERS. SHOWERS AND
THUNDERSTORMS WILL INCREASE IN COVERAGE THIS AFTERNOON AND
EVENING. SOME THUNDERSTORMS WILL BE CAPABLE OF PRODUCING GUSTY
WINDS AND HAIL. SPECIAL MARINE WARNINGS MAY BE WARRANTED.
A COLD FRONT WILL APPROACH THE WATERS TONIGHT. A LULL IN THE
PRESSURE GRADIENT SUGGESTS THAT WIND SPEEDS MAY BE BELOW SCA
CRITERIA.
NWLY FLOW WITH GUSTS 25 TO 30 KT FRIDAY THROUGH SATURDAY AS AN UPR
LOW PERSIST OVER THE REGION AND SFC HIGH PRESSURE BUILDS. SCA IN
EFFECT FOR FRIDAY...EXPECT IT TO BE EXTENDED INTO SATURDAY NIGHT.
MORE TRANQUIL WEATHER EARLY NEXT WEEK UNDER A CANADIAN AIRMASS.
&&
.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES WILL INCREASE A BIT DUE TO THE SOUTHERLY
FLOW...BUT WITH THE WIND DIRECTION BEING JUST WEST OF SOUTH WATER
LEVELS WILL LIKELY BE BELOW THRESHOLDS FOR MINOR COASTAL FLOODING.
THE CLOSEST WATER LEVELS WILL COME TO MINOR FLOODING THRESHOLDS
WILL BE LATE TONIGHT DURING THE HIGHER OF THE TWO HIGH TIDES.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
ANZ530>534-536-537-539>543.
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 6 PM EDT THIS
EVENING FOR ANZ535-538.
&&
$$
SYNOPSIS...BJL
NEAR TERM...BJL
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...BAJ/BJL
MARINE...BAJ/BJL
TIDES/COASTAL FLOODING...BJL
000
FXUS61 KLWX 230129
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
929 PM EDT WED MAY 22 2013
.SYNOPSIS...
HIGH PRESSURE PERSISTING OVER THE ATLANTIC WITH WARM AND HUMID
CONDITIONS UNTIL A COLD FRONT THURSDAY NIGHT. AN UPPER TROUGH
WILL LINGER OVER THE AREA FRIDAY WITH HIGH PRESSURE BUILDING
THROUGH SATURDAY. A FRONTAL BOUNDARY STALLS OUT ACROSS THE MID-
ATLANTIC SUNDAY NIGHT THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
CONVECTIVE ACTIVITY ON THE DECREASE ACRSS CWA ATTM. LOOKING AT
LINE OF SHRA/TSRA ROUGHLY ALONG I-81 THAT WILL SLOWLY MAKE ITS WAY
ACROSS THE CWA LATE TONIGHT. EXPECTING MAINLY SHOWERS WITH ISLTD
ELEVATED TSTM IN THIS ACTIVITY AS THE UPPER-LEVEL TROUGH
CONTINUES TO SLIDE CLOSER TO OUR AREA. MIN TEMPS TONIGHT WILL
RANGE FROM THE 50S IN THE MOUNTAINS TO THE LOWER AND MIDDLE 70S IN
DOWNTOWN WASHINGTON/BALTIMORE. AREAS THAT RECEIVED RAINFALL TODAY
WILL BE APT TO FOG-UP OVERNIGHT.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
HGTS CONT TO DROP THU AS CDFNT APPROACHES. ALTHO INSTBY WL BE
LWR...SHEAR WL BE GREATER. THERE MAY BE TWO ROUNDS OF WX...FIRST
COMING MIDDAY WITH THE DISTURBANCE AND RIBBON OF INSTBY...AND THEN
SECOND NEARER THE CDFNT AND DIURNAL HEATING. HV RAISED POPS INTO
THE DEF RANGE RATHER QUICKLY...AND HOLDING IT THERE THRUT THE DAY.
CFP THU NGT. WL SCALE BACK POPS AND TRANSITION FM TSRA TO SHRA IN
THE EVNG. AFTER FROPA...ONLY LINGERING SHRA WL REMAIN.
FRIDAY...UPR TROUGH DRIFTS EAST OVER THE AREA WITH BACK EDGE OF
CLOUDS SLOW TO COME IN THE AFTERNOON. GUSTY NWLY FLOW FRIDAY
CONTINUES AS HIGH PRESSURE BUILDS THROUGH SATURDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
SHORTWAVE FROM TN VLY ON SUNDAY NOW LOOKS TO EXPAND EAST ACROSS THE
SOUTHERN-CENTRAL MID-ATLANTIC. CONVERGENCE ALONG THIS BOUNDARY WOULD
SET OFF SHOWERS. PATTERN IS STALLED INTO MID NEXT WEEK...SO A
PROLONGED CLOUDY/RAINY PERIOD IS POSSIBLE. THIS WOULD RESULT IN
BELOW NORMAL TEMPS.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
VFR-MVFR CONDITIONS AT ALL TERMINALS OVRNGHT. THREAT FOR STORMS
CONT TIL CFP THURSDAY NIGHT. NWLY FLOW WITH GUSTS 25 TO POSSIBLY
30 KT WITH MID LEVEL CIGS FRIDAY. NWLY FLOW CONTINUES THROUGH
SATURDAY AS HIGH PRESSURE BUILDS.
&&
.MARINE...
HIGH PRESSURE WILL REMAIN OVER THE ATLANTIC OCEAN OVERNIGHT. A
SOUTHERLY FLOW WILL CONTINUE OVER THE WATERS DURING THIS TIME. A
SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR PORTIONS OF THE WATERS
THROUGH TONIGHT. SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE
LATER THIS AFTERNOON AND EVENING. ANY THUNDERSTORMS THAT DO
DEVELOP WILL BE CAPABLE OF PRODUCING GUSTY WINDS AND HAIL.
SLY FLOW AHEAD OF A LATE THURSDAY NIGHT COLD FRONT. SCA EXPANDED
THROUGH THURSDAY. EXPECT AN EXTENSION THURSDAY NIGHT FOR PREFRONTAL
SLY FLOW...THEN NWLY FLOW AROUND 25 KT FRIDAY THROUGH SATURDAY AS
HIGH PRESSURE BUILDS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THURSDAY FOR ANZ530>534-
536-537-539>543.
SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EDT THURSDAY FOR ANZ535-
538.
&&
$$
000
FXUS61 KLWX 221920
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
320 PM EDT WED MAY 22 2013
.SYNOPSIS...
HIGH PRESSURE PERSISTING OVER THE ATLANTIC WITH WARM AND HUMID
CONDITIONS UNTIL A COLD FRONT THURSDAY NIGHT. AN UPPER TROUGH
WILL LINGER OVER THE AREA FRIDAY WITH HIGH PRESSURE BUILDING
THROUGH SATURDAY. A FRONTAL BOUNDARY STALLS OUT ACROSS THE MID-
ATLANTIC SUNDAY NIGHT THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIPRES REMAINS IN THE WRN ATLC WHILE LOPRES RESIDES OVER THE
GRTLKS. SLY FLOW ACRS MID ATLC STATES CREATING A WARM UNSTBL AMS.
TSRA DVLPG ALONG THE WVA APLCHNS...WHERE DEWPTS HIER AND TEMPS
ALOFT A PINCH COOLER. OROGRAPHIC UPLIFT ALSO ASSISTING IN TSTM
DVLPMNT. THIS INITIATION IN LINE W/ WHAT MESOSCALE GDNC HAS
SUGGESTED. NOW THAT THE CAP HAS BEEN BROKEN...THERE/S PLENTY OF
INSTBY TO FEED OFF OF...BUT FEATURES FOR ORGANIZATION SLIGHTLY
LACKING. STILL DO NEED TO MONITOR THE UPR OHVLY WHERE HGTS LWR AS
THIS AREA RIPE FOR DVLPMNT. THAT POSES A SITUATION WHERE THESE
STORMS MAY PROPAGATE INTO AREA. AM KEEPING A LINEUP WHERE LKLY
POPS CONFINED TO THE MTNS AND CHC/SCHC ALONG I-95. THERE IS A
THREAT FOR LOCALLY DAMAGING WIND GUSTS AND LARGE HAIL IN ANY
THUNDERSTORMS THAT DO DEVELOP DUE TO THE HIGH INSTABILITY.
CONVECTION WILL LIKELY DISSIPATE LATER THIS EVENING DUE TO THE LOSS
OF DAYTIME HEATING. HOWEVER...AN UPPER-LEVEL DISTURBANCE IS EXPECTED
TO PASS THROUGH THE REGION LATE TONIGHT AS THE UPPER-LEVEL TROUGH
CONTINUES TO SLIDE CLOSER TO OUR AREA. PLENTY OF MOISTURE AND
FORCING FROM THE UPPER-LEVEL DISTURBANCE MAY RESULT IN SCATTERED
SHOWERS/T-STORMS TOWARD MORNING. RAISED APLCHNS TO LKLY. MIN TEMPS
TONIGHT WILL RANGE FROM THE 50S IN THE MOUNTAINS TO THE LOWER AND
MIDDLE 70S IN DOWNTOWN WASHINGTON/BALTIMORE.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
HGTS CONT TO DROP THU AS CDFNT APPROACHES. ALTHO INSTBY WL BE
LWR...SHEAR WL BE GREATER. THERE MAY BE TWO ROUNDS OF WX...FIRST
COMING MIDDAY WITH THE DISTURBANCE AND RIBBON OF INSTBY...AND THEN
SECOND NEARER THE CDFNT AND DIURNAL HEATING. HV RAISED POPS INTO
THE DEF RANGE RATHER QUICKLY...AND HOLDING IT THERE THRUT THE DAY.
CFP THU NGT. WL SCALE BACK POPS AND TRANSITION FM TSRA TO SHRA IN
THE EVNG. AFTER FROPA...ONLY LINGERING SHRA WL REMAIN.
FRIDAY...UPR TROUGH DRIFTS EAST OVER THE AREA WITH BACK EDGE OF
CLOUDS SLOW TO COME IN THE AFTERNOON. GUSTY NWLY FLOW FRIDAY
CONTINUES AS HIGH PRESSURE BUILDS THROUGH SATURDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
SHORTWAVE FROM TN VLY ON SUNDAY NOW LOOKS TO EXPAND EAST ACROSS THE
SOUTHERN-CENTRAL MID-ATLANTIC. CONVERGENCE ALONG THIS BOUNDARY WOULD
SET OFF SHOWERS. PATTERN IS STALLED INTO MID NEXT WEEK...SO A
PROLONGED CLOUDY/RAINY PERIOD IS POSSIBLE. THIS WOULD RESULT IN
BELOW NORMAL TEMPS.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
SHOWERS AND THUNDERSTORMS DVLPG...BUT STAYING W OF THE TERMINALS
ATTM. CONCERNED THAT THESE STORMS MAY DRIFT CLOSER...SPCLY FOR
CHO/MRB. HV VCTS IN ALL TAFS FOR THE EVNG DUE TO INSTBY PRESENT...
WHICH MAY LEAD TO ADDTL STORMS DVLPG. SOME OF THE THUNDERSTORMS
WILL BE CAPABLE OF PRODUCING GUSTY WINDS AND LARGE HAIL.
WL HV A RESPITE LT EVNG AS DIURNAL COMPONENT LOST. HWVR...ANOTHER
DISTURBANCE WL BE MOVING IN TWD MRNG...LEADING TO POTENTIALLY
ANTHR ROUND OF TSTMS. IFR CONDS POSSIBLE IN THE HEAVIEST ACTIVITY.
THREAT FOR STORMS CONT TIL CFP THURSDAY NIGHT. NWLY FLOW WITH
GUSTS 25 TO POSSIBLY 30 KT WITH MID LEVEL CIGS FRIDAY. NWLY FLOW
CONTINUES THROUGH SATURDAY AS HIGH PRESSURE BUILDS.
&&
.MARINE...
HIGH PRESSURE WILL REMAIN OVER THE ATLANTIC OCEAN THROUGH TONIGHT. A
SOUTHERLY FLOW WILL CONTINUE OVER THE WATERS DURING THIS TIME. A
SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR PORTIONS OF THE WATERS
THROUGH TONIGHT. SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE
LATER THIS AFTERNOON AND EVENING. ANY THUNDERSTORMS THAT DO
DEVELOP WILL BE CAPABLE OF PRODUCING GUSTY WINDS AND HAIL.
SLY FLOW AHEAD OF A LATE THURSDAY NIGHT COLD FRONT. SCA EXPANDED
THROUGH THURSDAY. EXPECT AN EXTENSION THURSDAY NIGHT FOR PREFRONTAL
SLY FLOW...THEN NWLY FLOW AROUND 25 KT FRIDAY THROUGH SATURDAY AS
HIGH PRESSURE BUILDS.
&&
.TIDES/COASTAL FLOODING...
A SOUTHERLY FLOW WILL CONTINUE OVER THE WATERS THROUGH THURSDAY
NIGHT...BUT THE FLOW MAY REMAIN JUST WEST OF SOUTH. TIDAL ANOMALIES
WILL LIKELY INCREASE A LITTLE...BUT WITH THE FLOW REMAINING WEST OF
SOUTH THE WATER LEVELS SHOULD REMAIN BELOW THRESHOLDS FOR MINOR
COASTAL FLOODING. THE CLOSEST WATER LEVELS WILL COME TO MINOR
FLOODING THRESHOLDS WILL BE DURING THE HIGH TIDE CYCLE LATE WEDNESDAY
NIGHT AND LATE THURSDAY NIGHT...THE HIGHER OF THE TWO HIGH TIDES.
TIDAL ANOMALIES WILL DECREASE FRIDAY BEHIND A COLD FRONT.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 6 PM EDT
THURSDAY FOR ANZ530-531-539.
SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EDT THURSDAY FOR ANZ535-
538.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THURSDAY FOR ANZ532-536-
540-542.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THURSDAY FOR ANZ533-534-
537-541-543.
&&
$$
000
FXUS61 KLWX 221405
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1005 AM EDT WED MAY 22 2013
.SYNOPSIS...
HIGH PRESSURE PERSISTING OVER THE ATLANTIC WITH WARM AND HUMID
CONDITIONS UNTIL A COLD FRONT THURSDAY NIGHT. AN UPPER TROUGH
WILL LINGER OVER THE AREA FRIDAY WITH HIGH PRESSURE BUILDING
THROUGH SATURDAY. A FRONTAL BOUNDARY STALLS OUT ACROSS THE MID-
ATLANTIC SUNDAY NIGHT THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE BOTH AT THE UPPER-LEVELS AND THE SURFACE WILL REMAIN
OVER THE ATLANTIC OCEAN THROUGH TONIGHT. AN UPPER-LEVEL TROUGH WILL
SLOWLY SHIFT FROM THE CENTRAL CONUS INTO THE GREAT LAKES. A
SOUTHERLY FLOW AROUND THE HIGH WILL CONTINUE TO USHER IN WARM AND
HUMID CONDITIONS ACROSS OUR AREA.
LOW CLDS AND FOG ASSOCD WITH THE NOCTURNAL INVERSION LESS
PRONOUNCED THAN YDA...AND ITS BURNING AWAY QUICKER. THEREFORE...
THERE SHUD BE LESS OF A MAXT SPREAD THAN THERE WAS YDA. STILL...HV
TWEAKED I-95 CRRDR DOWN A DEGF OR TWO TO ACCNT FOR ITS IMPACT.
THE WARM AND HUMID AIRMASS IN PLACE WILL LEAD TO HIGH AMOUNTS OF
INSTABILITY. UNMODIFIED LWX RAOB REFLECTS THIS...BUT ALSO
HIGHLIGHTS THE CAPPING INHIBITION BTWN H9-8. HGTS SHUD BE DROPPING
TAFTN AS TROF AXIS CROSSES THE WRN GRTLKS. MODIFYING THE SNDG FOR
T/TD 88/68 YIELDS ARND 3000 J/KG OF SBCAPE W/O A CAP. MLCAPE MUCH
MORE RESERVED AND SLGTLY INHIBITED.
TERRAIN CIRCULATIONS AND A SURFACE TROUGH WILL ACT AS LIFTING
MECHANISMS FOR CONVECTION THIS AFTERNOON. THIS IS ALSO SIMILAR TO
TUESDAY. THEREFORE...A BETTER CHANCE FOR THUNDERSTORMS EXISTS THIS
AFTERNOON AND EVENING...ESPECIALLY NEAR AND WEST OF THE I-95
CORRIDOR. HV ADJUSTED POPS SLGTLY TO PLACE MORE EMPHASIS ON
APLCHNS AND DEEMPHASIZE INVOF CHESPK BAY. HRRR /WRF-ARW4 BOTH
SUGGEST THAT TSRA SHUD FIRE TAFTN W OF THE BLURDG...SPCLY AFTR
18Z. WL NEED TO WATCH THAT TIMING THO...AS RADAR TRENDS IN WVA
ATTM SUGGEST IT MAY BE ERLR.
ALTHOUGH WIDESPREAD SEVERE WEATHER WILL LIKELY HOLD OFF TO OUR
WEST FOR LOCATIONS CLOSER TO THE UPPER-LEVEL TROUGH...THERE IS A
THREAT FOR LOCALLY DAMAGING WIND GUSTS AND LARGE HAIL IN ANY
THUNDERSTORMS THAT DO DEVELOP DUE TO THE HIGH INSTABILITY.
CONVECTION WILL LIKELY DISSIPATE LATER THIS EVENING DUE TO THE LOSS
OF DAYTIME HEATING. HOWEVER...AN UPPER-LEVEL DISTURBANCE IS EXPECTED
TO PASS THROUGH THE REGION LATE TONIGHT AS THE UPPER-LEVEL TROUGH
CONTINUES TO SLIDE CLOSER TO OUR AREA. PLENTY OF MOISTURE AND
FORCING FROM THE UPPER-LEVEL DISTURBANCE MAY RESULT IN SCATTERED
SHOWERS/T-STORMS TOWARD MORNING. MIN TEMPS TONIGHT WILL RANGE FROM
THE 50S IN THE MOUNTAINS TO THE LOWER AND MIDDLE 70S IN DOWNTOWN
WASHINGTON/BALTIMORE.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
THURSDAY LOOKS TO BE THE LAST ABOVE NORMAL TEMPERATURE DAY FOR
AWHILE AHEAD OF THE COLD FRONT THAT CROSSES THURSDAY NIGHT
TIMEFRAME. PREFRONTAL LINES/CLUSTERS OF SHOWERS/THUNDERSTORMS
PROGRESS EAST ACROSS THE AREA THURSDAY INTO THURSDAY NIGHT. GFS BUFR
SNDG FOR KIAD PROGS A 1.6 INCH PWAT WHICH IS CERTAINLY HIGH...BUT
JUST SHY OF THE 2 STDEV INDICATOR OF FLASH FLOODING. WITH
PROGRESSIVE NATURE OF THE ACTIVITY...ANY FLASH FLOODING WOULD BE
LOCALIZED. DAMAGING WIND THREAT...PARTICULARLY WITH HEATING ON
THURSDAY IS ABLE TO PEAK BEFORE ORGANIZED ACTIVITY MOVES THROUGH.
FRIDAY...UPR TROUGH DRIFTS EAST OVER THE AREA WITH BACK EDGE OF
CLOUDS SLOW TO COME IN THE AFTERNOON. GUSTY NWLY FLOW FRIDAY
CONTINUES AS HIGH PRESSURE BUILDS THROUGH SATURDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
SHORTWAVE FROM TN VLY ON SUNDAY NOW LOOKS TO EXPAND EAST ACROSS THE
SOUTHERN-CENTRAL MID-ATLANTIC. CONVERGENCE ALONG THIS BOUNDARY WOULD
SET OFF SHOWERS. PATTERN IS STALLED INTO MID NEXT WEEK...SO A
PROLONGED CLOUDY/RAINY PERIOD IS POSSIBLE. THIS WOULD RESULT IN
BELOW NORMAL TEMPS.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
LOW CLOUDS BURNING OFF ATTM. MVFR AT DCA/MTN...BUT ANTICIPATE VFR
EVERYWHERE BY 15Z.
SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP AFTN...PRIMARILY
INVOF MRB. SOME OF THE THUNDERSTORMS WILL BE CAPABLE OF PRODUCING
GUSTY WINDS AND LARGE HAIL. AREAS OF LOW CLOUDS ARE POSSIBLE LATE
TONIGHT ALONG WITH SCATTERED SHOWERS/T-STORMS.
THUNDERSTORMS THURSDAY INTO THURSDAY EVENING AHEAD OF A COLD FRONT.
IFR CONDS POSSIBLE IN THE HEAVIEST ACTIVITY. SLY FLOW UNTIL A COLD
FROPA THURSDAY NIGHT. NWLY FLOW WITH GUSTS 25 TO POSSIBLY 30 KT WITH
MID LEVEL CIGS FRIDAY. NWLY FLOW CONTINUES THROUGH SATURDAY AS HIGH
PRESSURE BUILDS.
&&
.MARINE...
HIGH PRESSURE WILL REMAIN OVER THE ATLANTIC OCEAN THROUGH TONIGHT. A
SOUTHERLY FLOW WILL CONTINUE OVER THE WATERS DURING THIS TIME. A
SMALL CRAFT ADVISORY REMAINSS IN EFFECT FOR PORTIONS OF THE WATERS
THROUGH TONIGHT. SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE
LATER THIS AFTERNOON AND EVENING. ANY THUNDERSTORMS THAT DO
DEVELOP WILL BE CAPABLE OF PRODUCING GUSTY WINDS AND HAIL.
SLY FLOW AHEAD OF A LATE THURSDAY NIGHT COLD FRONT. SCA EXPANDED
THROUGH THURSDAY. EXPECT AN EXTENSION THURSDAY NIGHT FOR PREFRONTAL
SLY FLOW...THEN NWLY FLOW AROUND 25 KT FRIDAY THROUGH SATURDAY AS
HIGH PRESSURE BUILDS.
&&
.TIDES/COASTAL FLOODING...
A SOUTHERLY FLOW WILL CONTINUE OVER THE WATERS THROUGH THURSDAY
NIGHT...BUT THE FLOW MAY REMAIN JUST WEST OF SOUTH. TIDAL ANOMALIES
WILL LIKELY INCREASE A LITTLE...BUT WITH THE FLOW REMAINING WEST OF
SOUTH THE WATER LEVELS SHOULD REMAIN BELOW THRESHOLDS FOR MINOR
COASTAL FLOODING. THE CLOSEST WATER LEVELS WILL COME TO MINOR
FLOODING THRESHOLDS WILL BE DURING THE HIGH TIDE CYCLE LATE WEDNESDAY
NIGHT AND LATE THURSDAY NIGHT...THE HIGHER OF THE TWO HIGH TIDES.
TIDAL ANOMALIES WILL DECREASE FRIDAY BEHIND A COLD FRONT.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 6 PM EDT
THURSDAY FOR ANZ530-531-539.
SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EDT THURSDAY FOR ANZ535-
538.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 6 PM EDT
THURSDAY FOR ANZ532-536-540-542.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THURSDAY FOR ANZ533-534-
537-541-543.
&&
$$
SYNOPSIS...BJL
NEAR TERM...HTS/BJL
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...HTS/BJL/BAJ
MARINE...KLEIN/BJL/BAJ
TIDES/COASTAL FLOODING...BJL
000
FXUS61 KLWX 220801
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
401 AM EDT WED MAY 22 2013
.SYNOPSIS...
HIGH PRESSURE PERSISTING OVER THE ATLANTIC WITH WARM AND HUMID
CONDITIONS UNTIL A COLD FRONT THURSDAY NIGHT. AN UPPER TROUGH
WILL LINGER OVER THE AREA FRIDAY WITH HIGH PRESSURE BUILDING
THROUGH SATURDAY. A FRONTAL BOUNDARY STALLS OUT ACROSS THE MID-
ATLANTIC SUNDAY NIGHT THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE BOTH AT THE UPPER-LEVELS AND THE SURFACE WILL REMAIN
OVER THE ATLANTIC OCEAN THROUGH TONIGHT. AN UPPER-LEVEL TROUGH WILL
SLOWLY SHIFT FROM THE CENTRAL CONUS INTO THE GREAT LAKES. A
SOUTHERLY FLOW AROUND THE HIGH WILL CONTINUE TO USHER IN WARM AND
HUMID CONDITIONS ACROSS OUR AREA.
LOW-LEVEL MOISTURE TRAPPED UNDERNEATH THE NOCTURNAL INVERSION WILL
RESULT IN PATCHY FOG ALONG WITH AREAS OF LOW CLOUDS. THE BEST CHANCE
FOR LOW CLOUDS AND FOG WILL BE EAST OF THE BLUE RIDGE MOUNTAINS AND
IN SHELTERED VALLEYS WEST OF THE BLUE RIDGE MOUNTAINS. ANY LOW
CLOUDS AND FOG SHOULD BURN OFF BY MID-MORNING. SUNSHINE AND A
SOUTHERLY FLOW WILL CAUSE MAX TEMPS TO REACH THE MID AND UPPER 80S
ACROSS MOST LOCATIONS.
THE WARM AND HUMID AIRMASS WILL LEAD TO HIGH AMOUNTS OF INSTABILITY.
NAM/GFS BUFKIT INDICATE AROUND 2000-2500 J/KG OF MLCAPE THIS
AFTERNOON...SIMILAR TO TUESDAY. TERRAIN CIRCULATION AND A SURFACE
TROUGH WILL ACT AS LIFTING MECHANISMS FOR CONVECTION THIS AFTERNOON.
THIS IS ALSO SIMILAR TO TUESDAY. HOWEVER...THE CAPPING INVERSION
WILL BE WEAKER THAN TUESDAY DUE TO HEIGHT FALLS AS THE UPPER-LEVEL
TROUGH TO OUR WEST SLOWLY SHIFTS EASTWARD. THEREFORE...A BETTER
CHANCE FOR THUNDERSTORMS EXISTS THIS AFTERNOON AND
EVENING...ESPECIALLY NEAR AND WEST OF THE I-95 CORRIDOR. ALTHOUGH
WIDESPREAD SEVERE WEATHER WILL LIKELY HOLD OFF TO OUR WEST FOR
LOCATIONS CLOSER TO THE UPPER-LEVEL TROUGH...THERE IS A THREAT FOR
LOCALLY DAMAGING WIND GUSTS AND LARGE HAIL IN ANY THUNDERSTORMS THAT
DO DEVELOP DUE TO THE HIGH INSTABILITY.
CONVECTION WILL LIKELY DISSIPATE LATER THIS EVENING DUE TO THE LOSS
OF DAYTIME HEATING. HOWEVER...AN UPPER-LEVEL DISTURBANCE IS EXPECTED
TO PASS THROUGH THE REGION LATE TONIGHT AS THE UPPER-LEVEL TROUGH
CONTINUES TO SLIDE CLOSER TO OUR AREA. PLENTY OF MOISTURE AND
FORCING FROM THE UPPER-LEVEL DISTURBANCE MAY RESULT IN SCATTERED
SHOWERS/T-STORMS TOWARD MORNING. MIN TEMPS TONIGHT WILL RANGE FROM
THE 50S IN THE MOUNTAINS TO THE LOWER AND MIDDLE 70S IN DOWNTOWN
WASHINGTON/BALTIMORE.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
THURSDAY LOOKS TO BE THE LAST ABOVE NORMAL TEMPERATURE DAY FOR
AWHILE AHEAD OF THE COLD FRONT THAT CROSSES THURSDAY NIGHT
TIMEFRAME. PREFRONTAL LINES/CLUSTERS OF SHOWERS/THUNDERSTORMS
PROGRESS EAST ACROSS THE AREA THURSDAY INTO THURSDAY NIGHT. GFS BUFR
SNDG FOR KIAD PROGS A 1.6 INCH PWAT WHICH IS CERTAINLY HIGH...BUT
JUST SHY OF THE 2 STDEV INDICATOR OF FLASH FLOODING. WITH
PROGRESSIVE NATURE OF THE ACTIVITY...ANY FLASH FLOODING WOULD BE
LOCALIZED. DAMAGING WIND THREAT...PARTICULARLY WITH HEATING ON
THURSDAY IS ABLE TO PEAK BEFORE ORGANIZED ACTIVITY MOVES THROUGH.
FRIDAY...UPR TROUGH DRIFTS EAST OVER THE AREA WITH BACK EDGE OF
CLOUDS SLOW TO COME IN THE AFTERNOON. GUSTY NWLY FLOW FRIDAY
CONTINUES AS HIGH PRESSURE BUILDS THROUGH SATURDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
SHORTWAVE FROM TN VLY ON SUNDAY NOW LOOKS TO EXPAND EAST ACROSS THE
SOUTHERN-CENTRAL MID-ATLANTIC. CONVERGENCE ALONG THIS BOUNDARY WOULD
SET OFF SHOWERS. PATTERN IS STALLED INTO MID NEXT WEEK...SO A
PROLONGED CLOUDY/RAINY PERIOD IS POSSIBLE. THIS WOULD RESULT IN
BELOW NORMAL TEMPS.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
LOW-LEVEL MOISTURE WILL BE TRAPPED UNDERNEATH THE NOCTURNAL
INVERSION EARLY THIS MORNING. THIS MAY RESULT IN LOW CLOUDS AND
AREAS OF FOG...ESPECIALLY ACROSS THE EASTERN TERMINALS. IFR
CONDITIONS ARE POSSIBLE.
ANY LOW CLOUDS WILL BURN OFF BY MID-MORNING AND VFR CONDITIONS ARE
EXPECTED THROUGH THIS EVENING. HOWEVER...SCATTERED SHOWERS AND
THUNDERSTORMS WILL DEVELOP. SOME OF THE THUNDERSTORMS WILL BE
CAPABLE OF PRODUCING GUSTY WINDS AND LARGE HAIL. AREAS OF LOW CLOUDS
ARE POSSIBLE LATE TONIGHT ALONG WITH SCATTERED SHOWERS/T-STORMS.
THUNDERSTORMS THURSDAY INTO THURSDAY EVENING AHEAD OF A COLD FRONT.
IFR CONDS POSSIBLE IN THE HEAVIEST ACTIVITY. SLY FLOW UNTIL A COLD
FROPA THURSDAY NIGHT. NWLY FLOW WITH GUSTS 25 TO POSSIBLY 30 KT WITH
MID LEVEL CIGS FRIDAY. NWLY FLOW CONTINUES THROUGH SATURDAY AS HIGH
PRESSURE BUILDS.
&&
.MARINE...
HIGH PRESSURE WILL REMAIN OVER THE ATLANTIC OCEAN THROUGH TONIGHT. A
SOUTHERLY FLOW WILL CONTINUE OVER THE WATERS DURING THIS TIME. A
SMALL CRAFT ADVISORY IS IN EFFECT FOR PORTIONS OF THE WATERS THROUGH
TONIGHT. SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE LATER THIS
AFTERNOON AND EVENING. ANY THUNDERSTORMS THAT DO DEVELOP WILL BE
CAPABLE OF PRODUCING GUSTY WINDS AND HAIL.
SLY FLOW AHEAD OF A LATE THURSDAY NIGHT COLD FRONT. SCA EXPANDED
THROUGH THURSDAY. EXPECT AN EXTENSION THURSDAY NIGHT FOR PREFRONTAL
SLY FLOW...THEN NWLY FLOW AROUND 25 KT FRIDAY THROUGH SATURDAY AS
HIGH PRESSURE BUILDS.
&&
.TIDES/COASTAL FLOODING...
A SOUTHERLY FLOW WILL CONTINUE OVER THE WATERS THROUGH THURSDAY
NIGHT...BUT THE FLOW MAY REMAIN JUST WEST OF SOUTH. TIDAL ANOMALIES
WILL LIKELY INCREASE A LITTLE...BUT WITH THE FLOW REMAINING WEST OF
SOUTH THE WATER LEVELS SHOULD REMAIN BELOW THRESHOLDS FOR MINOR
COASTAL FLOODING. THE CLOSEST WATER LEVELS WILL COME TO MINOR
FLOODING THRESHOLDS WILL BE DURING THE HIGH TIDE CYCLE LATE WEDNESDAY
NIGHT AND LATE THURSDAY NIGHT...THE HIGHER OF THE TWO HIGH TIDES.
TIDAL ANOMALIES WILL DECREASE FRIDAY BEHIND A COLD FRONT.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 6 PM EDT
THURSDAY FOR ANZ530-531-539.
SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EDT THURSDAY FOR ANZ535-
538.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 6 PM EDT
THURSDAY FOR ANZ532-536-540-542.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THURSDAY FOR ANZ533-534-
537-541-543.
&&
$$
SYNOPSIS...BJL/BAJ
NEAR TERM...BJL
SHORT TERM...BAJ
LONG TERM...BAJ
AVIATION...BAJ/BJL
MARINE...BAJ/BJL
TIDES/COASTAL FLOODING...BJL
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