507
FXUS61 KLWX 281314
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
914 AM EDT SUN JUN 28 2026
WHAT HAS CHANGED
OVERALL THINKING REMAINS THE SAME. SOME PRETTY EFFICIENT RAIN
SHOWERS WERE AFFECTING THE WESTERN DC SUBURBS AS OF MID MORNING
WITH OTHER SHOWER ACTIVITY IN EASTERN WV AND WESTERN VA.
KEY MESSAGES
- (1) A WEAK FRONTAL BOUNDARY WILL LINGER ACROSS THE REGION
THROUGH TODAY DELIVERING WAVES OF SHOWERS AND THUNDERSTORMS.
- (2) SIGNIFICANT HEAT RISK NEXT WEEK HEADING INTO THE
INDEPENDENCE DAY HOLIDAY.
DISCUSSION
KEY MESSAGE 1...A WEAK FRONTAL BOUNDARY WILL LINGER ACROSS THE
REGION THROUGH TODAY DELIVERING WAVES OF SHOWERS AND THUNDERSTORMS.
AN MCV IS PRESSING EASTWARD FROM EASTERN WV INTO WESTERN VA.
LIFT AHEAD OF THIS FEATURE ALONG A FRONT STALLED FROM PETERSBURG
WV TO SOUTHERN MD IS RESULTING IN A LOT OF SHOWER ACTIVITY.
GIVEN THE HIGH MOISTURE CONTENT, ESPECIALLY IN THE LOWER
ATMOSPHERE WHERE THESE SHALLOW SHOWERS ARE OCCURRING, EFFICIENT
DOWNPOURS ARE BEING OBSERVED WITH RATES APPROACHING 1 IN/HR.
THE AFOREMENTIONED MCV WILL TRACK OVER THE CENTER OF THE
FORECAST AREA FROM WEST TO EAST LATE THIS MORNING THROUGH THE
MID AFTERNOON HOURS. BEHIND THIS DISTURBANCE THE DENSE OVERCAST
WILL START TO CLEAR OUT FROM WEST TO EAST. FAR WESTERN AND
SOUTHWESTERN PORTIONS OF THE FORECAST AREA WILL START TO SEE
BREAKS OF SUN BY AROUND NOON, AND ADDITIONAL SHOWERS AND STORMS
WILL FORM SHORTLY THEREAFTER IN RESPONSE TO DAYTIME HEATING. AS
A RESULT, THE MAIN FOCUS FOR A SECOND ROUND OF SHOWERS AND
STORMS THIS AFTERNOON IS EXPECTED TO BE ACROSS WESTERN AND
SOUTHWESTERN PORTIONS OF THE FORECAST AREA (ALLEGHENIES, POTOMAC
HIGHLANDS, CENTRAL SHENANDOAH VALLEY, AND CENTRAL VIRGINIA).
THE BACKGROUND ENVIRONMENT WILL AGAIN BE VERY SUPPORTIVE OF
PRODUCING VERY HEAVY RAIN IN THOSE AREAS THIS AFTERNOON
(SLIGHTLY LOWER PWATS, BUT HIGHER CAPE THAN AREAS FURTHER EAST
THIS MORNING). AN ISOLATED INSTANCE OR TWO OF FLOODING CAN'T BE
COMPLETELY RULED OUT, BUT THE ONGOING DROUGHT CONDITIONS IN
THOSE LOCATIONS SHOULD HELP TO LIMIT THE THREAT. ANY SHOWERS AND
THUNDERSTORMS SHOULD WIND DOWN WITH LOSS OF DAYTIME HEATING
THIS EVENING. PATCHY FOG MAY BE POSSIBLE OVERNIGHT, ESPECIALLY
IN LOCATIONS THAT RECEIVE RAIN DURING THE DAY TODAY.
UPPER RIDGING WILL START TO BUILD IN FROM THE WEST ON MONDAY AND
TUESDAY. LARGELY DRY CONDITIONS ARE EXPECTED BOTH DAYS, BUT A
STRAY AFTERNOON SHOWER OR THUNDERSTORM COULD POTENTIALLY POP UP
OVER THE HIGHER TERRAIN TO THE WEST OF THE BLUE RIDGE.
TEMPERATURES WILL GRADUALLY START TO WARM, WITH HIGHS IN THE MID
TO UPPER 80S ON MONDAY, AND THEN LOWER 90S ON TUESDAY.
KEY MESSAGE 2...SIGNIFICANT HEAT RISK NEXT WEEK HEADING INTO THE
INDEPENDENCE DAY HOLIDAY.
INCREASED CONFIDENCE FOR A PROLONGED PERIOD OF EXTREME HEAT AND
HUMIDITY THROUGH THE INDEPENDENCE DAY JULY 4TH HOLIDAY WEEKEND.
SYNOPTICALLY, SUBTROPICAL HIGH PRESSURE AND A BUILDING UPPER-LEVEL
RIDGE WILL ALLOW TEMPERATURES AND HUMIDITY VALUES TO CLIMB TOWARD
RECORD LEVELS OVER A MULTI-DAY PERIOD MID TO LATE NEXT WEEK.
TEMPERATURES WEDNESDAY THROUGH SUNDAY WILL BE THE PEAK OF THE
DANGEROUS HEAT WITH HIGHS FOR MOST IN THE UPPER 90S AND LOWER 100S.
HEAT INDICES EACH AFTERNOON WILL RUN BETWEEN 102-108 DEGREES WITH A
FEW READINGS AROUND 110 ALONG THE IMMEDIATE I-95 METRO CORRIDOR,
WESTERN SHORE OF THE BAY/SOUTHERN MD, AND DOWN ACROSS THE VA
PIEDMONT REGION. MINIMAL RELIEF IS EXPECTED ACROSS THE MOUNTAINS
WITH HIGHS IN THE MID 80S AND LOW 90S AND HEAT INDICES IN THE MID TO
UPPER 90S AS THE HEAT PEAKS MID TO LATE WEEK. NO RELIEF AT NIGHT
EITHER WITH WIDESPREAD LOWS IN THE UPPER 60S TO MID 70S (UPPER
70S-80 URBAN AREAS) WEDNESDAY THROUGH SATURDAY. WITH THAT SAID,
LOOKING AT MAJOR TO EXTREME HEAT RISK ACROSS THE REGION DURING
THIS PERIOD. HEAT HEADLINES WILL LIKELY BE NEEDED AND EVALUATED
AS THE EVENT GETS CLOSER. MORE AT WEATHER.GOV/LWX/HEAT.
MODEL GUIDANCE HAS COME INTO BETTER ALIGNMENT IN REGARDS TO
TEMPERATURES NEXT WEEK WITH ONLY A FEW DEGREES OF SPREAD. ON THE
OTHER SIDE OF THE SPECTRUM, SOME UNCERTAINTY REMAINS IN REGARDS TO
STORM CHANCES GIVEN THE PLACEMENT OF BOUNDARIES AND ANY WAVES OF LOW
PRESSURE THAT MAY CLEAR AWAY THE HEAT. THE RIDGE LOOKS TO SHUNT
EASTWARD LATE WEEK INTO THE WEEKEND. THIS WOULD KEEP STORM
CHANCES SUPPRESSED ACROSS MOST OF THE REGION OUTSIDE OF THE
MOUNTAINS THROUGH THURSDAY GIVEN THE LACK OF ANY REAL FORCING
MECHANISMS OUTSIDE THE TERRAIN OR PERHAPS BAY/RIVER BREEZES. THIS
CHANGES THURSDAY THROUGH THE WEEKEND WHERE STORM CHANCES MAY BE
AMPLIFIED GIVEN A FEW PIECES OF ENERGY PIVOTING OVER THE TOP OF THE
UPPER-LEVEL RIDGE IN WEST TO NORTHWEST FLOW.
WITH EXCESSIVE HEAT AND HUMIDITY THERE WILL BE PLENTY OF INSTABILITY
TO WORK WITH. YOU COMBINE THIS WITH ANY POTENTIAL RIPPLES OF LOW
PRESSURE MOVING AROUND THE RIDGE OR A BAY/RIVER BREEZE TO GET
CONVECTIVE DEVELOPMENT. THIS IS ILLUSTRATED BY CSU/CIPS/NSSL
(15-40 PERCENT PROBABILITIES) OUTLOOKS ALONG WITH GOOGLE WXNEXT
AI MODEL WHICH SUGGEST THE RISK FOR SEVERE WEATHER DURING THE
THURSDAY JULY 2ND TO SATURDAY JULY 4TH TIMEFRAME. SOMETHING
WE'LL CONTINUE TO MONITOR IN SUBSEQUENT FORECAST SHIFTS GIVEN
ALL THE ONGOING OUTDOOR ACTIVITIES ACROSS THE REGION.
HISTORICALLY, NEAR RECORD SUMMER HEAT OFTEN ENDS WITH
WIDESPREAD STRONG THUNDERSTORM ACTIVITY, AND LATEST GUIDANCE STARTS
TO BREAK DOWN THE HEAT NEXT WEEKEND (JULY 4) INTO EARLY NEXT
WEEK.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
LOW-END IFR (FL005-006) CIGS ARE BEING OBSERVED AT THE DC METRO
TAF SITES (IAD/DCA) AS OF 13Z/9AM EDT, AND WILL LIKELY PERSIST
IN A STAGNANT SATURATED PATTERN THROUGH 15Z-16Z BEFORE GRADUALLY
LIFTING, EVENTUALLY TO AND ABOVE FL010 BY AROUND 18Z. CIGS MAY
BRIEFLY LIFT IN STEADIER DOWNPOURS, BUT THESE DOWNPOURS COULD
ALSO REDUCE VSBY TO AROUND 1SM. SIMILAR CONDITIONS ARE BEING
OBSERVED AT MRB/CHO WITH INTERMITTENT LIFR. MEANWHILE, THE
BALTIMORE TAF SITES ARE CLOSER TO THE IFR/MVFR THRESHOLD AND
LIKELY STAY THAT WAY, LIFTING 1-2 HOURS SOONER THAN THE DC
SITES. MRB/CHO MAY HANG ON TO IFR WELL INTO THE AFTERNOON,
POSSIBLY AS LATE AS 19Z-20Z.
THE SIGNAL FOR THUNDERSTORMS THIS AFTERNOON SEEMS TO BE
STRONGEST ACROSS SOUTHERN AND WESTERN PORTIONS OF THE FORECAST
AREA, WITH MRB AND CHO STANDING THE GREATEST CHANCE FOR AN
AFTERNOON STORM. PROB30S FOR THIS AFTERNOON WERE PULLED OUT OF
THE MTN AND BWI TAFS, AND HAVE ALSO PULLED IT OUT AT DCA AND
IAD. WE'LL CONTINUE TO MONITOR TRENDS OVER THE NEXT FEW HOURS.
OTHERWISE, GRADUAL IMPROVEMENT TO MVFR AND THEN EVENTUALLY VFR
IS EXPECTED BY THIS EVENING. MVFR CEILINGS AND PATCHY FOG APPEAR
POSSIBLE AGAIN TONIGHT. SOME FOG MAY BE DENSE. IMPROVEMENT BACK
TO VFR IS EXPECTED ON MONDAY, WITH PREVAILING VFR CONDITIONS
THEREAFTER THROUGH TUESDAY. WINDS WILL BE LIGHT OUT OF THE
NORTHEAST TODAY, LIGHT OUT OF THE EAST TOMORROW, AND THEN TURN
OUT OF THE SOUTH ON TUESDAY.
VFR CONDITIONS MAINLY EXPECTED WEDNESDAY THROUGH THURSDAY
NIGHT. ANY HEAVY SHOWERS OR A THUNDERSTORM COULD BRIEFLY REDUCE
CONDITIONS TO MVFR AT THE DCA, BWI AND MTN TERMINALS. WINDS
SOUTH 5 TO 10 KNOTS EACH DAY.
MARINE
LIGHT AND VARIABLE WINDS ARE EXPECTED OVER THE WATERS TODAY.
SPECIAL MARINE WARNINGS ARE LOOKING UNLIKELY AS MORE STABLE
LOW-LEVEL AIR MOVES OVER THE WATERS. WINDS TURN LIGHT OUT OF
THE EAST TO NORTHEAST TONIGHT INTO TOMORROW, BEFORE BECOMING
SOUTHERLY ON TUESDAY. WINDS MAY POTENTIALLY APPROACH LOW-END SCA
LEVELS IN CHANNELED SOUTHERLY FLOW TUESDAY AFTERNOON.
NO MARINE HAZARDS EXPECTED WEDNESDAY THROUGH THURSDAY NIGHT.
WINDS SOUTH 5 TO 10 KNOTS BOTH DAYS.
CLIMATE
THERE IS A SIGNIFICANT HEAT RISK THIS WEEK. THE NUMBERS BELOW
AREN'T A FORECAST, BUT RATHER A REFERENCE FOR HISTORICAL CONTEXT
FOR COMPARISON. LATEST FORECAST: WEATHER.GOV/LWX.
==================================================================
*** ALL-TIME RECORD HIGHS ***
==================================================================
BALTIMORE 107 (SET ON JUL 10, 1936)
WASHINGTON 106 (SET ON JUL 20, 1930 + AUG 06, 1918)
STERLING-DULLES AIRPORT 105 (SET ON JUL 22, 2011)
BALTIMORE DOWNTOWN 108 (SET ON JUL 07, 2012 + JUL 22, 2011)
ANNAPOLIS 106 (SET ON AUG 06, 1918)
HAGERSTOWN 105 (SET ON JUL 14, 1954)
MARTINSBURG 112 (SET ON JUL 11, 1936)
CHARLOTTESVILLE 107 (SET ON SEP 07, 1954 + 3 OTHER TIMES)
==================================================================
*** ALL-TIME RECORD WARM LOWS ***
==================================================================
BALTIMORE 83 (SET ON AUG 05, 1930 + 2 OTHER TIMES)
WASHINGTON 84 (SET ON JUL 24, 2011 + 2 OTHER TIMES)
STERLING-DULLES AIRPORT 79 (SET ON AUG 08, 2007)
BALTIMORE DOWNTOWN 88 (SET ON JUL 02, 2011 AND JUL 10, 1993)
ANNAPOLIS 92 (SET ON JUL 07, 1994)
HAGERSTOWN 86 (SET ON JUN 15, 1899)
MARTINSBURG 86 (SET ON JUL 21, 1930)
CHARLOTTESVILLE 85 (SET ON AUG 07, 1918)
==================================================================
*** JULY MONTHLY RECORD HIGHS ***
==================================================================
BALTIMORE 107 (SET ON JUL 10, 1936)
WASHINGTON 106 (SET ON JUL 20, 1930)
STERLING-DULLES AIRPORT 105 (SET ON JUL 22, 2011)
BALTIMORE DOWNTOWN 108 (SET ON JUL 07, 2012 + JUL 22, 2011)
ANNAPOLIS 105 (SET ON JUL 21, 1930 + JUL 02, 1901)
HAGERSTOWN 105 (SET ON JUL 14, 1954)
MARTINSBURG 112 (SET ON JUL 11, 1936)
CHARLOTTESVILLE 107 (SET ON JUL 10, 1936 + JUL 20, 1930)
==================================================================
*** JULY MONTHLY RECORD WARM LOWS ***
==================================================================
BALTIMORE 83 (SET ON JUL 21, 1930)
WASHINGTON 84 (SET ON JUL 24, 2011 + 2 OTHER TIMES)
STERLING-DULLES AIRPORT 78 (SET ON JUL 24, 2010 + JUL 08, 2010)
BALTIMORE DOWNTOWN 88 (SET ON JUL 22, 2011 + JUL 10, 1993)
ANNAPOLIS 92 (SET ON JUL 07, 1994)
HAGERSTOWN 83 (SET ON JUL 24, 2010)
MARTINSBURG 86 (SET ON JUL 21, 1930)
CHARLOTTESVILLE 84 (SET ON JUL 22, 1930)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: JUL 01
==================================================================
BALTIMORE 103 (1901) | 80 (1933 + 1901)
WASHINGTON 102 (1901) | 79 (1977)
STERLING-DULLES AIRPORT 96 (2012) | 72 (2017 + 3)
BALTIMORE DOWNTOWN 101 (2012) | 82 (2012)
ANNAPOLIS 103 (1901) | 79 (1945 + 1901)
HAGERSTOWN 100 (1901) | 74 (2017 + 1977)
MARTINSBURG 102 (1933) | 74 (1933)
CHARLOTTESVILLE 101 (2012 + 1945) | 78 (1901)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: JUL 02
==================================================================
BALTIMORE 103 (1901) | 80 (1901)
WASHINGTON 101 (1898) | 79 (2012 + 1872)
STERLING-DULLES AIRPORT 98 (1966) | 75 (2022)
BALTIMORE DOWNTOWN 102 (1966) | 84 (2002)
ANNAPOLIS 105 (1901) | 80 (1901)
HAGERSTOWN 100 (1966) | 74 (2018 + 1901)
MARTINSBURG 102 (1933 + 1931) | 75 (1933 + 1901)
CHARLOTTESVILLE 100 (1954) | 76 (1910)
==================================================================
*** DAILY RECORD HIGHS | WARM LOWS ***
VALID: JUL 03
==================================================================
BALTIMORE 104 (1898) | 80 (1898)
WASHINGTON 101 (1966 + 2) | 80 (2018)
STERLING-DULLES AIRPORT 103 (1966) | 73 (2018 + 2)
BALTIMORE DOWNTOWN 102 (1997) | 82 (2018 + 1983)
ANNAPOLIS 100 (1901) | 84 (1896)
HAGERSTOWN 102 (1966) | 76 (2002)
MARTINSBURG 102 (1941 + 1911) | 74 (1980)
CHARLOTTESVILLE 100 (1966 + 1954) | 79 (1911)
PERIOD OF RECORD (POR) CONTEXT...
AREA (OBS SITE) RECORDS SINCE
------------------------------------------------------------------
BALTIMORE (BWI) JAN 1872
WASHINGTON (DCA) JUL 1872
STERLING-DULLES AIRPORT (IAD) JAN 1960
BALTIMORE DOWNTOWN (DMH) JUL 1950
ANNAPOLIS (NAK) JAN 1894
HAGERSTOWN (HGR) JAN 1899
MARTINSBURG (MRB) JAN 1891
CHARLOTTESVILLE (CHO) JAN 1893
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
DISCUSSION...KLW/DHOF/KJP/EST
AVIATION...KLW/DHOF/KJP/EST
MARINE...KLW/DHOF/KJP/EST
CLIMATE...DHOF
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