049
FXUS61 KLWX 291308
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
908 AM EDT MON JUN 29 2026
WHAT HAS CHANGED
CLOSELY MONITORING INCOMING GUIDANCE REGARDING ANTICIPATED HEAT
AND EVENTUALLY SEVERE THUNDERSTORM POTENTIAL LATE THIS WEEK.
KEY MESSAGES
- (1) HEAT AND HUMIDITY GRADUALLY BUILD ACROSS THE REGION EARLY THIS
WEEK.
- (2) POTENTIALLY EXTREME HEAT COULD PERSIST THROUGH THE INDEPENDENCE
DAY WEEKEND, ALONG WITH A RETURN OF SHOWERS & THUNDERSTORMS.
DISCUSSION
KEY MESSAGE 1...HEAT AND HUMIDITY GRADUALLY BUILD ACROSS THE REGION EARLY
THIS WEEK.
LOW CLOUDS AND FOG ARE LIFTING AS OF MID MORNING. CONDITIONS
ARE EXPECTED TO REMAIN DRY ACROSS THE MAJORITY OF THE FORECAST
AREA TODAY, BUT A FEW POPUP AFTERNOON SHOWERS OR A BRIEF
THUNDERSTORM CAN'T BE RULED MAINLY OUT WEST OF US-15,
ESPECIALLY ACROSS THE HIGHER TERRAIN. TEMPERATURES ARE FORECAST
TO CLIMB INTO THE MID TO UPPER 80S TODAY, PERHAPS NEAR 90 WHERE
THE SUN BREAKS OUT EARLIER (BALTIMORE AREA, FOR EXAMPLE), WITH
DEWPOINTS IN THE UPPER 60S TO LOWER 70S. THIS RESULTS IN HEAT
INDEX VALUES AROUND OR A COUPLE DEGREES ABOVE THE AIR TEMPS.
STRONG UPPER RIDGING WILL GRADUALLY BUILD IN FROM THE WEST
THROUGH WEDNESDAY, WITH A CLOSED MID-LEVEL ANTICYCLONE BECOMING
CENTERED OVER THE CENTRAL APPALACHIANS BY WEDNESDAY. HEAT AND
HUMIDITY WILL CONTINUE TO BUILD ACROSS THE REGION EACH
SUCCESSIVE DAY, WITH TEMPERATURES AT LOWER ELEVATIONS CLIMBING
INTO THE UPPER 80S TO LOWER 90S ON TUESDAY, AND THEN UPPER 90S
TO AROUND 100 ON WEDNESDAY. DEWPOINTS WILL INCREASE INTO THE
LOWER 70S TO THE WEST OF THE BLUE RIDGE ON TUESDAY, WITH 60S
FURTHER EAST. LOWER 70S DEWPOINTS ARE EXPECTED TO OVERSPREAD THE
MAJORITY OF THE FORECAST AREA BY WEDNESDAY. HEAT INDICES ARE
FORECAST TO REACH INTO THE UPPER 80S TO MID 90S FOR MOST ON
TUESDAY, BUT COULD APPROACH 100 JUST IN THE LEE OF THE
ALLEGHENIES FROM NEAR CUMBERLAND TO PETERSBURG. HEAT ADVISORIES
MAY POTENTIALLY NEED TO BE CONSIDERED FOR THOSE LOCATIONS ON
TUESDAY. HEAT INDICES ARE THEN FORECAST TO REACH 100-110 ACROSS
ALL LOWER ELEVATIONS ON WEDNESDAY. HEAT HEADLINES WILL ALMOST
CERTAINLY BE NEEDED FOR WEDNESDAY. CONDITIONS ARE LARGELY
EXPECTED TO REMAIN DRY ON TUESDAY AND WEDNESDAY AS LARGE SCALE
SUBSIDENCE INCREASES AHEAD OF THE APPROACHING UPPER RIDGE AXIS,
BUT A STRAY POPUP AFTERNOON SHOWER OR STORM CAN'T BE RULED OUT
IN THE MOUNTAINS.
KEY MESSAGE 2...SIGNIFICANT HEAT RISK THIS WEEK HEADING INTO THE
INDEPENDENCE DAY HOLIDAY.
UPPER-LEVEL RIDGING WILL REMAIN CENTERED OVER THE APPALACHIANS
POTENTIALLY THROUGH THE END OF THE WEEK, ALLOWING TEMPERATURES AND
HUMIDITY TO CONTINUALLY INCREASE INTO THE INDEPENDENCE DAY HOLIDAY
WEEKEND. BEGINNING THURSDAY, CONDITIONS COULD BEGIN TO BECOME AN
EXTREME HEAT RISK AS DEFINED BY THE NWS HEATRISK GUIDANCE. WITH
WIDESPREAD DEWPOINTS IN THE LOWER 70S DUE TO SUBTROPICAL HIGH
PRESSURE BRINGING MOIST AIR IN, AIR TEMPERATURES RANGING BETWEEN
THE UPPER 90S-LOW 100S COULD CAUSE HEAT INDICES APPROACHING 110
IN SOME AREAS WEDNESDAY THROUGH SUNDAY.
TOWARDS THE END OF THIS PERIOD, A SHORTWAVE TROUGH COULD DEVELOP
OVER THE MID-ATLANTIC FRIDAY AND SATURDAY. THIS COULD POTENTIALLY
REINTRODUCE WIDESPREAD SHOWERS AND THUNDERSTORMS THROUGHOUT THE
REGION, WITH THUNDERSTORMS HAVING THE POTENTIAL TO BECOME SEVERE DUE
TO THE EXTENDED HEAT & HUMIDITY. MULTIPLE ML AND AI MODEL OUTPUTS
CURRENTLY SHOW A 15%-40% PROBABILITY FOR SEVERE WEATHER TO
MATERIALIZE BETWEEN FRIDAY JULY 3RD TO SUNDAY JULY 5TH AS THIS
TROUGH MOVES THROUGH. GIVEN ALL THE ONGOING OUTDOOR ACTIVITIES
ACROSS THE REGION DURING THIS TIMEFRAME, WILL HAVE TO CONTINUE
TO CLOSELY MONITOR THE SYNOPTIC SETUP AHEAD OF THIS TIME PERIOD.
EARLY MODEL GUIDANCE SUGGESTS THAT UPPER-LEVEL RIDGING OFFICIALLY
BEGINS TO EXIT THE REGION TOWARDS THE START OF NEXT WEEK,
POTENTIALLY SIGNALING A BREAKDOWN IN THE HEAT TOWARDS THE END OF
THE FORECAST PERIOD.
AVIATION /12Z MONDAY THROUGH FRIDAY/
IMPROVEMENT BACK TO VFR CONDITIONS IS EXPECTED BY 15Z.
THEREAFTER, VFR CONDITIONS ARE FORECAST TO PERSIST THROUGH
WEDNESDAY. WINDS WILL BE LIGHT OUT OF THE NORTHEAST FOR MUCH OF
THE DAY, BEFORE TURNING OUT OF THE SOUTH LATER THIS EVENING.
WINDS ARE EXPECTED TO REMAIN OUT OF THE SOUTH ON TUESDAY, BEFORE
BECOMING SOUTHWESTERLY ON WEDNESDAY.
PREVAILING VFR CONDITIONS ARE EXPECTED THURSDAY THROUGH FRIDAY
MORNING. BEGINNING FRIDAY AFTERNOON & EVENING, THUNDERSTORM
CHANCES INCREASE. SHOULD THUNDERSTORMS MATERIALIZE, SOME COULD
BECOME SEVERE. INTERMITTENT SUB-VFR CONDITIONS ARE POSSIBLE
FRIDAY & SATURDAY AS A RESULT, AS WELL AS CHANGES IN WIND SPEED
AND DIRECTION.
MARINE
LIGHT AND VARIABLE WINDS ARE EXPECTED OVER THE WATERS THROUGH
MID-AFTERNOON. WINDS THEN TURN SOUTHERLY THIS EVENING, AND COULD
BRIEFLY NEAR LOW-END SCA FOR A FEW HOURS. WINDS REMAIN SOUTHERLY
FOR TUESDAY AND WEDNESDAY, WITH SCAS LIKELY IN SOUTHERLY
CHANNELING EACH AFTERNOON AND EVENING.
WINDS STAY BELOW SCA THRESHOLDS THURSDAY AND THROUGH THE
WEEKEND. THUNDERSTORM CHANCES OVER THE WATERS INCREASE FRIDAY
AND SATURDAY, WHICH COULD BECOME SEVERE. SHOULD THESE CONDITIONS
MATERIALIZE, SPECIAL MARINE WARNINGS COULD BECOME NECESSARY.
WINDS GENERALLY FLOW SOUTH TO SOUTHWESTERLY THURSDAY & FRIDAY.
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...DHOF/KJP/SRT
AVIATION...DHOF/KJP/SRT
MARINE...DHOF/KJP/SRT
CLIMATE...DHOF
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