329
FXUS61 KLWX 231838
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
238 PM EDT FRI AUG 23 2019
SYNOPSIS
A COLD FRONT WILL MOVE INTO THE SOUTHERN MID-ATLANTIC AND
SOUTHEAST STATES TONIGHT INTO SATURDAY. STRONG HIGH PRESSURE
WILL BUILD NORTH OF THE REGION TONIGHT AND SETTLE OVER NORTHERN
NEW ENGLAND AND ATLANTIC CANADA THROUGH EARLY NEXT WEEK. A
TROPICAL CYCLONE COULD FORM OVER THE WEEKEND AND MOVE NEAR THE
SOUTHEAST COAST AND OUT TO SEA.
NEAR TERM /THROUGH TONIGHT/
THE COLD FRONT HAS CLEARED THROUGH ALMOST THE ENTIRE REGION,
WITH THE EXCEPTION BEING THE SOUTHERN TIP OF SAINT MARYS COUNTY
IN MD AND NELSON AND SOUTHERN ALBEMARLE COUNTIES IN VA. A
SURFACE WAVE IS POSITIONED ALONG THE BOUNDARY ACROSS CENTRAL AND
WESTERN VA AND THIS WILL MOVE EASTWARD ALONG THE FRONT THROUGH
THE AFTERNOON HOURS AND BE POSITIONED NEAR THE SOUTHERN DELMARVA
BY THIS EVENING. WIDESPREAD RAIN SHOWERS ARE OCCURRING ACROSS
THE REGION, AND SOME HEAVIER RAIN HAS BEEN NOTED JUST TO THE
NORTH OF THE SURFACE LOW/FRONT AND THIS WILL CONTINUE WITH
LOCALIZED RATES AS HIGH AS ONE INCH PER HOUR. AHEAD OF THE
FRONT AND SURFACE LOW, ENOUGH INSTABILITY IS PRESENT FOR SOME
ISOLATED TO SCATTERED THUNDERSTORMS, AND AN ISOLATED SEVERE
THUNDERSTORM IS POSSIBLE. THE RISK FOR THIS MAINLY EXISTS ACROSS
NELSON AND SOUTHERN ALBEMARLE COUNTIES AND ONLY FOR THE NEXT 1-2
HOURS.
TEMPERATURES HAVE COOLED CONSIDERABLY WITH MID AFTERNOON
READINGS IN THE 60S TO NEAR 70F.
RAIN SHOWERS WILL END FROM NW TO SE LATE TODAY AND THIS EVENING
WITH DRIER AIR FILTERING IN OVERNIGHT. LOWS TONIGHT WILL BE IN
THE 50S/60S.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
HIGH PRESSURE WILL BUILD NORTH OF THE REGION ON SATURDAY WITH
NORTH TO NORTHEASTERLY FLOW CONTINUING. ALOFT AN UPPER LEVEL
TROUGH WILL ROTATE ACROSS THE REGION. THIS WILL LEAD TO A MIX OF
SUN AND CLOUDS WITH MORE CLOUDS SOUTH, BUT EVERYWHERE SHOULD AT
LEAST SEE A SCATTERED CUMULUS DECK. AN ISOLATED SHOWER IS ALSO
POSSIBLE, ESPECIALLY NEAR THE CHESAPEAKE BAY WHERE INSTABILITY
WILL LOCALLY BE HIGHER DUE TO WARMER WATER TEMPERATURES.HIGHS
WILL RANGE THROUGH THE MID TO UPPER 70S. LOWS SATURDAY NIGHT IN
THE 50S/60S.
THE RIDGE WILL STRENGTHEN DOWN THE MID-ATLANTIC COASTLINE ON
SUNDAY WITH FLOW TURNING MORE EASTERLY. A MIX OF SUN AND CLOUDS
IS EXPECTED AGAIN, ALTHOUGH LIKELY MORE CLOUDS THAN SATURDAY. AN
ISOLATED SHOWER REMAINS POSSIBLE AGAIN AS WELL. HIGHS IN THE 70S
TO NEAR 80F. LOWS SUNDAY NIGHT IN THE 50S/60S.
LONG TERM /MONDAY THROUGH FRIDAY/
AN UPPER-LEVEL RIDGE WILL BUILD IN OVER THE REGION ON MONDAY AND
TUESDAY. MEANWHILE, AT THE SURFACE, HIGH PRESSURE SETS UP ACROSS THE
NORTHEAST, RESULTING IN RIDGING ALONG/EAST OF THE APPALACHAINS.
GENERALLY EXPECTING DRY CONDITIONS ON MONDAY, BUT CAN'T RULE OUT
SOME STRAY SHOWERS ACROSS THE HIGHER ELEVATIONS, AS 850-700MB FLOW
SEEMS TO BE MORE EASTERLY. THIS IS IN RESPONSE TO A LOW PRESSURE
SYSTEM RIDING ALONG THE NC COASTLINE THROUGHOUT THE DAY. RAIN
CHANCES WILL BE HIGHEST ALONG/EAST OF THE BLUE RIDGE, BUT STILL NOT
ALL THAT HIGH ON MONDAY. TEMPERATURES WILL REMAIN BELOW AVERAGE,
WITH HIGHS IN THE LOW 80S OR SO.
MONDAY NIGHT INTO TUESDAY, RAIN CHANCES INCREASE, AS LOW PRESSURE
SLIDES BY TO THE SOUTHEAST, HIGH PRESSURE STILL TO THE NORTHEAST.
THIS RESULTS IN EASTERLY LOW-MID LEVEL FLOW, AND LIKELY A HIGHER
RAIN CHANCE. COULD EVEN SEE SOME EMBEDDED THUNDERSTORMS, AS
TEMPERATURES WILL BE A BIT WARMER (HIGHS AROUND THE MID 80S) AND THE
ATMOSPHERE WILL BE MORE MOIST. ADDITIONALLY, AN UPPER TROUGH WILL BE
APPROACHING FROM THE WEST, LENDING SOME UPPER-LEVEL SUPPORT AS WELL.
A COLD FRONT, ASSOCIATED WITH A LOW MOVING FROM THE GREAT LAKES INTO
ONTARIO, WILL PUSH THROUGH THE REGION ON WEDNESDAY, BEFORE POSSIBLY
STALLING OVERHEAD INTO THURSDAY. AHEAD OF THIS FRONT, SOUTHERLY FLOW
RETURNS, BRINGING HIGHS INTO THE MID-UPPER 80S AS WELL AS MORE
HUMIDITY. SHOWERS AND THUNDERSTORMS WILL AGAIN BE POSSIBLE ON BOTH
DAYS, ESPECIALLY ON WEDNESDAY. MOST OF THE UPPER-LEVEL SUPPORT IS
DISPLACED FAR TO THE NORTH, SO NOT SEEING AN ORGANIZED SEVERE THREAT
AT THIS TIME.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
MVFR CEILINGS WITH SHOWERS EXPECTED FOR MUCH OF THE AFTERNOON ACROSS
THE TAF SITES. LOCALIZED HEAVIER RAIN WITH REDUCED VISIBILITIES
ARE ALSO LIKELY. A FEW STRONGER THUNDERSTORMS ARE POSSIBLE NEAR
CHO THIS AFTERNOON. CONDITIONS WILL IMPROVE THIS EVENING AND
ESPECIALLY TONIGHT. VFR THEN EXPECTED SATURDAY AND SUNDAY.
VFR EXPECTED FOR MONDAY AND TUESDAY FOR THE MAJORITY OF THE TIME AT
ALL TERMINALS. HOWEVER, AN ISOLATED SHOWER OR STORM COULD BRING
CONDITIONS TO MVFR AT TIMES, PRIMARILY NEAR MRB AND CHO, AND WITH
BEST CHANCES ON TUESDAY AFTERNOON.
MARINE
SCA IS IN EFFECT INTO THIS EVENING FOR PORTIONS OF THE TIDAL
POTOMAC AND CENTRAL CHESAPEAKE BAY THROUGH THIS EVENING FOR
GUSTY NORTHERLY WINDS AS A FRONT MOVES SOUTHWARD ACROSS THE
WATERS. IN ADDITION, SOME SMWS MAY BE REQUIRED FOR THE FAR
SOUTHERN WATERS THIS AFTERNOON AS SCATTERED THUNDERSTORMS MOVE
ALONG THE FRONT. IMPROVING WEATHER TONIGHT AS COLD FRONT PUSHES
SOUTH, BUT ADDITIONAL NORTHERLY FLOW WILL CREATE SCA CONDITIONS
LATER TONIGHT INTO SATURDAY. ADDITIONAL SCAS MAY BE NEEDED FOR
NORTHEASTERLY WINDS SATURDAY NIGHT THROUGH MONDAY WITH STRONG
GRADIENT BETWEEN HIGH PRESSURE ACROSS NEW ENGLAND LOW PRESSURE
NEAR THE SOUTHEASTERN US COASTLINE.
WINDS SHOULD RELAX BY TUESDAY, AROUND 10 KNOTS, WITH NO MARINE
HAZARDS EXPECTED AT THIS TIME.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 3 AM TO NOON EDT SATURDAY FOR
ANZ531>534-537-539>541-543.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ532-
533-540-541.
SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ534-
537-542-543.
SYNOPSIS...MM
NEAR TERM...MM
SHORT TERM...MM
LONG TERM...CJL
AVIATION...MM/CJL
MARINE...MM/CJL
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