999
FXUS61 KLWX 180126
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
926 PM EDT MON AUG 17 2026
WHAT HAS CHANGED
NO MAJOR CHANGES WERE MADE TO THE EVENING PACKAGE EXCEPT
TRACKING CONVECTION FOR IMPACTS TO LOCAL AVIATION INTERESTS.
KEY MESSAGES
- 1) SCATTERED SHOWERS AND THUNDERSTORMS REMAIN POSSIBLE UNTIL A
COLD FRONT CROSSES TONIGHT, WITH A CHANCE POSSIBLY PERSISTING
INTO TUESDAY.
- 2) THUNDERSTORM CHANCES RETURN WEDNESDAY NIGHT INTO THURSDAY,
AND CONTINUE INTO NEXT WEEKEND.
DISCUSSION
KEY MESSAGE 1...SCATTERED SHOWERS AND THUNDERSTORMS REMAIN
POSSIBLE UNTIL A COLD FRONT CROSSES TONIGHT, WITH A CHANCE
POSSIBLY PERSISTING INTO TUESDAY.
CONVECTIVE ACTIVITY WHICH DEVELOPED DURING DAYTIME HEATING HAS
SINCE PUSHED DOWN INTO SOUTHERN MARYLAND. THESE CONTINUE TO
PRODUCE FREQUENT LIGHTNING STRIKES, WHICH ALSO INCLUDES SOME
POTENTIAL OF NEAR-SEVERE CALIBER WIND FIELDS. ALTHOUGH THE
BOUNDARY LAYER IS SLOWLY STABILIZING, THERE APPEARS TO BE ENOUGH
RESIDUAL INSTABILITY TO MIX SOME HIGHER WINDS DOWN TO THE
SURFACE. HOWEVER, SUCH GUSTS SHOULD BE SOMEWHAT SPORADIC AND
ISOLATED IN NATURE.
THE LOW-LEVEL SYNOPTIC COLD FRONT WILL CROSS THE REGION
TONIGHT. THEREFORE, A FEW ADDITIONAL SHOWERS ARE POSSIBLE, BUT
THE THREAT FOR THUNDERSTORMS SHOULD START DIMINISHING AFTER
MIDNIGHT. AREAS WHICH CLEAR OUT TONIGHT COULD HAVE PATCHY FOG.
MOST GUIDANCE FAVORS THE WESTERN RIVER VALLEYS AT THIS TIME.
WHILE THE SURFACE FRONT WILL LIKELY BE SOUTH OF THE AREA
TUESDAY, IT WILL BE LOSING ITS DEFINITION, AND SOME LOW AND MID
LEVEL MOISTURE MAY LINGER, ESPECIALLY ACROSS THE SOUTHERN HALF
OF THE AREA. WITH DAYTIME HEATING, THIS WILL RESULT IN SOME WEAK
INSTABILITY. SOME MODELS HAVE SCATTERED SHOWERS AND STORMS
DEVELOPING OFF THE TERRAIN AND MOVING EASTWARD DURING THE
AFTERNOON ACROSS THE SOUTHERN QUARTER TO HALF OF THE FORECAST
AREA (MOSTLY SOUTH OF I-66 IF NOT I-64). THE WEAK INSTABILITY
WILL LIMIT THE STRENGTH OF THIS ACTIVITY DESPITE SHEAR WHICH
COULD APPROACH 30 KT. TEMPERATURES AND DEW POINTS WILL BE A
TOUCH LOWER TODAY, BUT STILL SEASONABLE WITH HIGHS IN THE MID TO
UPPER 80S.
KEY MESSAGE 2...THUNDERSTORM CHANCES RETURN WEDNESDAY NIGHT INTO
THURSDAY, AND CONTINUE INTO NEXT WEEKEND.
HIGH PRESSURE BUILDING FROM THE OHIO VALLEY WILL KEEP DRY
CONDITIONS TUESDAY NIGHT INTO WEDNESDAY. TEMPERATURES MAY TICK
BACK UP CLOSER TO 90. THE NEXT COLD FRONT WILL APPROACH FROM
THE NORTHWEST WEDNESDAY NIGHT, BUT THE TIMING FOR RAIN CHANCES
HAS GENERALLY BEEN PUSHED TO THE SECOND HALF OF THE NIGHT, WHICH
WOULD REDUCE THE THREAT FOR THUNDERSTORMS. WHERE THIS COLD
FRONT ENDS UP BY THURSDAY AFTERNOON WILL HAVE AN EFFECT ON THE
COVERAGE AND STRENGTH OF SHOWERS AND THUNDERSTORMS. WHILE
EVERYONE COULD SEE SOME RAIN, THERE IS UNCERTAINTY WITH THE
AMOUNT OF INSTABILITY AND HOW MUCH IT WOULD OVERLAP WITH SHEAR.
AI/ML GUIDANCE HAS BEEN CONSISTENT THE PAST SEVERAL DAYS
SHOWING THE GREATEST RISK FOR ANY STRONGER THUNDERSTORMS BEING
ACROSS THE SOUTHERN OR SOUTHEASTERN PORTION OF THE FORECAST
AREA.
IT'S POSSIBLE THE FRONT WILL STALL OR ONLY MOVE JUST SOUTH OF
THE AREA, WHICH WILL PLAY A ROLE IN PRECIPITATION CHANCES
FRIDAY. IT WILL BE FAR ENOUGH SOUTH TO BRING A COOL DOWN, WITH
HIGHS IN THE 70S AND 80S BY FRIDAY.
A DEEPENING TROUGH OF LOW PRESSURE APPROACHING FROM THE GREAT
LAKES (POSSIBLY EVEN A CLOSED LOW) MAY RESULT IN ONE OR MORE
AREAS OF LOW PRESSURE DEVELOPING ALONG THE FRONT BETWEEN FRIDAY
AND THIS WEEKEND. THUS CHANCES OF RAIN HAVE BEEN TRENDING
UPWARD, EVEN IF WE ARE NORTH OF THE LOW TRACK. EXPECT
TEMPERATURES SLIGHTLY BELOW NORMAL GIVEN THE CLOUDS AND
POTENTIAL RAIN.
AVIATION /01Z TUESDAY THROUGH SATURDAY/
A COLD FRONT APPROACHES FROM THE NORTHWEST THROUGH TONIGHT. ANY
CONVECTIVE ACTIVITY HAS NOW MOVED WELL SOUTH AND EAST OF THE
TERMINALS. WINDS TURN MORE WESTERLY THIS EVENING BEFORE
SHIFTING TO NORTHERLY BY DAYBREAK TUE. IFR CIGS/FOG POSSIBLE
ESPECIALLY NEAR MRB/CHO AFTER 06Z TONIGHT, BUT GIVEN THE AMOUNT
OF UNCERTAINTY, KEPT VISIBILITY AT MVFR FOR NOW.
VFR WITH RETURN TO S FLOW WEDNESDAY, THEN POTENTIAL SHOWERS AND
THUNDERSTORMS RE-ENTER THE FORECAST AT TIMES THURSDAY THROUGH
SATURDAY. WINDS SHIFT BACK TO THE NW OR N THURSDAY IN THE WAKE
OF A COLD FRONT.
MARINE
GENERALLY LIGHT WINDS ARE EXPECTED THROUGH THE UPCOMING WEEK.
WINDS SHIFT TO WESTERLY THIS EVENING, THEN NORTHERLY TUESDAY
BEFORE RETURNING TO SOUTHERLY WEDNESDAY. A FEW ENHANCEMENTS ARE
POSSIBLE ALONG THE BAY DURING ANY OF THESE WIND SHIFTS DUE TO
CHANNELING, BUT PROSPECTS OF ADVISORY CONDITIONS ARE MARGINAL AT
BEST.
SPECIAL MARINE WARNINGS CONTINUE OVER THE MORE SOUTHERN WATERS
THIS EVENING. HOWEVER, NO OTHER ACTIVITY LOOMS BEHIND THESE
STORMS, SO THE PROSPECTS OF ADDITIONAL WARNINGS IS MINIMAL. A
COLD FRONT MAY BRING ADDITIONAL THUNDERSTORMS THURSDAY INTO
FRIDAY.
COASTAL LOW PRESSURE MAY DEVELOP AT SOME POINT BETWEEN FRIDAY
AND SATURDAY, BUT IT'S UNCERTAIN IF IT WILL BE STRONG ENOUGH TO
INCREASE THE WINDS MUCH.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
DISCUSSION...ADS/BRO/DHOF
AVIATION...ADS/BRO/DHOF
MARINE...ADS/BRO/DHOF
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