836
FXUS61 KLWX 230604
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
204 AM EDT WED JUL 23 2025
SYNOPSIS
CANADIAN HIGH PRESSURE OVER THE REGION BRINGS CONTINUED SEASONABLE
AND DRY CONDITIONS THROUGH THURSDAY. AS HIGH PRESSURE STARTS TO
SHIFT EAST, A FRONTAL BOUNDARY AND MULTIPLE UPPER-LEVEL DISTURBANCES
WILL IMPACT THE REGION INTO THIS WEEKEND AND EARLY NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
CANADIAN HIGH PRESSURE OVER FAR SOUTHERN NEW ENGLAND SLOWLY DRIFTS
OFFSHORE THROUGH TONIGHT. THIS CAUSES LOCAL WINDS TO BECOME MORE
SOUTHEASTERLY AS DRY CONDITIONS PERSIST. MID-LEVEL RIDGING OVER THE
OH VALLEY TO DEEP SOUTH STARTS TO ENCROACH ON THE MID-ATLANTIC. THIS
BRINGS A TAD WARMER TEMPS THIS AFTERNOON WITH HIGHS IN THE MID TO
UPPER 80S. STILL GOING TO SEE LOWER HUMIDITY VALUES TODAY, DEW
POINTS ARE MOSTLY GOING TO STAY IN THE MID 60S. SEASONAL TEMPS
CONTINUE TONIGHT WITH LOWS IN THE 60S.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
VERY WARM AND MORE HUMID CONDITIONS ARRIVE IN THE AREA ON THURSDAY
AS HIGHS ARE FORECAST TO REACH THE UPPER 80S TO LOW 90S. MID-LEVEL
RIDGING SHIFTS EAST, BECOME CENTERED OVER THE CAROLINAS AND ITS
INFLUENCE EXTENDS ACROSS THE REST OF THE MID-ATLANTIC. THE SURFACE
HIGH OFFSHORE OF NEW ENGLAND BECOMES ELONGATED AS IT DRIFTS EASTWARD
TO THE CENTRAL ATLANTIC. THE AXIS OF THAT SURFACE RIDGE BUILDS
TOWARD THE CAROLINAS, BRINGING A WARM SOUTHERLY FLOW TO OUR AREA.
THIS ADVECTS IN A MOIST AIRMASS THAT INCREASES DEW POINTS TO AROUND
70F. BROAD SUBSIDENCE FROM THE MID-LEVEL RIDGE KEEPS CONDITIONS DRY.
MUGGY CONDITIONS RETURNS THURSDAY NIGHT WITH LOWS IN THE 70S.
HOT AND HUMID SUMMERTIME CONDITIONS RETURN WITH A VENGEANCE TO END
THE WEEK. HIGH REACH THE MID TO UPPER 90S FRIDAY AFTERNOON WITH PEAK
HEAT INDICES BETWEEN 100-108. HEAT ADVISORIES ARE LIKELY NEEDED FOR
MOST OF THE AREA. THE MID-LEVEL RIDGE/HEAT DOME BREAKS DOWN AS
SHORTWAVE TROUGHS EMBEDDED IN MOSTLY ZONAL FLOW ALOFT OVER THE UPPER
PLAINS TO GREAT LAKES STARTS TO SHIFT CLOSER TO THE MID-ATLANTIC.
THIS CAUSES A WEAK FRONT TO SAG SOUTH INTO THE AREA FRIDAY AFTERNOON
AND LIKELY STALL OVERHEAD FRIDAY NIGHT. THE FRONT HELPS TO FIRE OFF
SCATTERED AFTERNOON THUNDERSTORMS IN THE ALLEGHENIES AND POTOMAC
HIGHLAND. ELSEWHERE, COVERAGE OF STORMS IS FORECAST TO BE LOW DUE TO
DEEP WESTERLY FLOW. WARM AND MUGGY FRIDAY NIGHT AS TEMPS SETTLE IN
THE LOW TO MID 70S.
LONG TERM /SATURDAY THROUGH TUESDAY/
STARTING THIS WEEKEND, THE MID-ATLANTIC REGION WILL RETURN TO A VERY
ACTIVE WEATHER PATTERN AS THE RIDGE THAT HAD BEEN IN PLACE STARTS TO
QUICKLY BREAK DOWN. AS THIS OCCURS, SEVERAL PIECES OF SHORTWAVE
ENERGY WILL MOVE ACROSS, OR JUST NORTH OF, THE REGION. A WEAK
FRONTAL BOUNDARY WILL GRADUALLY DROP SOUTHWARD IN THIS TIMEFRAME,
WHICH COULD ACT AS A FOCAL POINT FOR THUNDERSTORM DEVELOPMENT. THE
AIR MASS WILL REMAIN HOT AND HUMID INTO THE WEEKEND, SO ANY STORMS
THAT DEVELOP COULD POTENTIALLY BRING SEVERE WINDS, LARGE HAIL, AND
VERY HEAVY RAINFALL. WILL HAVE TO MONITOR CLOSELY FOR ANY TARGETED
HIGHER END THREATS FOR EITHER SEVERE OR FLOODING, BUT BOTH DAYS
COULD BE VERY ACTIVE.
EVENTUALLY AS WE HEAD INTO EARLY NEXT WEEK, A TROUGH BUILDS MORE
FIRMLY IN PLACE OVER THE NORTHEAST CONUS, WITH A RIDGE OVER THE
CENTRAL CONUS. BETWEEN THAT, OUR AREA WILL BE STUCK WITHIN A REGION
OF NW FLOW ALOFT. HISTORICALLY, THIS PATTERN RESULTS IN MULTIPLE
CHANCES FOR THUNDERSTORMS AS MESOSCALE CONVECTIVE SYSTEMS (MCSS)
DEVELOP TO OUR WEST IN MOVE IN OUR GENERAL DIRECTION. HOWEVER, THIS
PATTERN IS ALSO VERY DIFFICULT TO PREDICT HISTORICALLY IN TERMS OF
WHICH PARTICULAR DAY COULD POSE A HIGHER RISK FOR ANYTHING SEVERE. A
HOT AND HUMID AIR MASS WILL BE IN PLACE, SO REALLY ANY DAY COULD
POSE A THREAT FOR SOME SEVERE STORMS. HOWEVER, IT WILL REALLY DEPEND
ON HOW MESOSCALE FEATURES SETUP, WHICH WE JUST DON'T HAVE THOSE
DETAILS AT THIS TIME.
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
VFR CONDITIONS ARE FORECAST TO PERSIST ACROSS THE AREA THROUGH THE
END OF THIS WEEK. A FEW SHOWERS AND THUNDERSTORMS RETURN TO THE
FORECAST FRIDAY AFTERNOON, THOUGH COVERAGE IS FORECAST TO BE LOW.
MRB IS THE MOST LIKELY TO SEE IMPACTS FROM FRIDAY'S POSSIBLE
THUNDERSTORM ACTIVITY.
SUB-VFR CONDITIONS ARE POSSIBLE ON BOTH SATURDAY AND SUNDAY, AS
THUNDERSTORMS ARE LIKELY ON BOTH DAYS. OUTSIDE OF THUNDERSTORMS, VFR
CONDITIONS ARE EXPECTED DURING THE DAYTIME HOURS, WITH LIGHT AND
VARIABLE WINDS. DURING THE OVERNIGHT/EARLY MORNING HOURS, HIGH
HUMIDITY AND RAINFALL FROM THE PREVIOUS DAYS WILL LIKELY RESULT IN
SOME PATCHY FOG. WHETHER THAT DEVELOPS OVER ONE OF THE TERMINALS HAS
YET TO BE SEEN, BUT IT IS A POSSIBILITY IN THIS TYPE OF PATTERN.
MARINE
SOUTH TO SOUTHEAST WINDS SLOWLY INCREASE TODAY THROUGH THURSDAY
NIGHT. WHILE WINDS ARE FORECAST TO REMAIN BELOW SCA LEVELS FOR THE
MOST PART, THERE COULD BE A FEW PERIODS OF WINDS GUSTING AROUND 20
KNOTS DURING THIS TIME. THIS IS MOST LIKELY TO OCCUR IN THE MIDDLE
CHESAPEAKE BAY AND LOWER TIDAL POTOMAC. THIS IS MOST LIKELY TO OCCUR
THURSDAY EVENING INTO THURSDAY NIGHT.
WINDS TURN SOUTHWEST ON FRIDAY, THEN WEST TO NORTHWEST FRIDAY NIGHT
AS A WEAK FRONT MOVES INTO THE AREA. A FEW THUNDERSTORMS ARE
POSSIBLE FRIDAY LATE AFTERNOON TO EVENING THAT COULD POSE A THREAT
TO MARINERS FROM GUSTY WINDS AND LIGHTNING STRIKES.
SUB-SCA WINDS ARE EXPECTED ON SATURDAY AND SUNDAY AS HIGH PRESSURE
CONTINUES TO DOMINATE THE WEATHER PATTERN ACROSS THE MID-ATLANTIC
REGION. HOWEVER, EACH DAY IS LIKELY TO BRING THUNDERSTORMS TO THE
WATERS DURING THE LATE AFTERNOON/EVENING HOURS. SMWS MAY BE NEEDED
DURING THESE TIMES.
TIDES/COASTAL FLOODING
STRENGTHENING SOUTHERLY WINDS THROUGH FRIDAY AFTERNOON WILL CAUSE
WATER LEVEL TO RISE IN THE CHESAPEAKE BAY, WHICH COULD RESULT IN
MINOR COASTAL FLOODING AT ANNAPOLIS AND OTHER SENSITIVE LOCATIONS. A
WEAK FRONT MOVES INTO THE AREA AND STALLS FRIDAY NIGHT, THOUGH WINDS
ARE FORECAST TO SLACKEN AND TURN OFFSHORE THIS WEEKEND. THIS SHOULD
HELP TO LOWER WATER LEVELS IN THE BAY.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
SYNOPSIS...CJL
NEAR TERM...KRR
SHORT TERM...KRR
LONG TERM...CJL
AVIATION...KRR/CJL
MARINE...KRR/CJL
TIDES/COASTAL FLOODING...KRR
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