387
FXUS61 KLWX 151929
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
329 PM EDT WED JUL 15 2026
WHAT HAS CHANGED
HAVE HELD OFF ON ANY HEAT ADVISORIES FOR THURSDAY DUE TO
UNCERTAINTIES IN BOTH HUMIDITY AND SMOKE AFFECTING TEMPERATURES
AND HEAT INDEX VALUES. SO FAR TODAY, TEMPERATURES HAVE BEEN A
BIT SLOWER TO RISE AND DEW POINTS A BIT SLOWER TO FALL,
RESULTING IN HEAT INDEX VALUES AROUND WHERE THEY WERE EXPECTED
TO BE. ADDED A SLIGHT CHANCE OF THUNDERSTORMS THURSDAY LATE
AFTERNOON AND EVENING ACROSS NORTHERN AND EASTERN AREAS DUE TO A
WEAK COLD FRONT DROPPING IN.
KEY MESSAGES
- 1) HEAT CONTINUES THROUGH FRIDAY.
- 2) THUNDERSTORM CHANCES INCREASE THIS WEEKEND AND COULD
POTENTIALLY LINGER INTO EARLY NEXT WEEK AS A FRONT DROPS INTO
THE REGION.
DISCUSSION
KEY MESSAGE 1...HEAT CONTINUES THROUGH FRIDAY.
ALTHOUGH TEMPERATURES WILL LIKELY PEAK THIS AFTERNOON, ABOVE
NORMAL TEMPERATURES WILL PERSIST THROUGH FRIDAY.
THE 12Z KIAD RAOB SHOWED 850 HPA TEMPS AROUND 23 C, A PINCH
HIGHER THAN THEY WERE DURING THE HEAT WAVE EARLIER THIS MONTH.
RECENT NUCAPS DATA FROM 18Z SHOWS 925 HPA TEMPS AROUND 30 C
WHICH IF MIXED DRY ADIABATICALLY TO THE SURFACE WOULD RESULT IN
TEMPS IN THE LOWER 100S. MIXING HAS BEEN A BIT SUBDUED SO FAR
TODAY DUE TO THIN SMOKE ALOFT, SIMILAR TO HOW MIXING IS LIMITED
IN THE PRESENCE OF A SAHARAN AIR (DUST) LAYER. THIS HAS ALSO
HELD DEW POINTS UP IN THE UPPER 60S TO LOWER 70S, HIGHEST
NORTHEAST OF THE POTOMAC RIVER WHERE LATEST NUCAPS DATA SHOWS A
RELATIVE MAX IN 850 HPA TDS. IT IS POSSIBLE THAT AREAS OF EVEN
SLIGHTLY DEEPER MIXING COULD SEE SFC TEMPS JUMP SEVERAL DEGREES
THROUGH LATE AFTERNOON (WITH A CORRESPONDING DROP IN DEW POINTS).
EITHER WAY, THE HEAT INDEX VALUES WILL REMAIN THE SAME - GENERALLY
100 TO 105 (SLIGHTLY HIGHER EAST OF I-95).
THERE IS UNCERTAINTY IN JUST HOW HIGH TEMPERATURES GET BOTH
THURSDAY AND ESPECIALLY FRIDAY AS SMOKE FROM WILDFIRES OVER
CANADA CONTINUES TO TREK TOWARD THE MID-ATLANTIC. THERE ARE ALSO
QUESTIONS AROUND HOW MUCH DEW POINTS MIX OUT THURSDAY AFTERNOON
IN PARTICULAR, SO HAVE HELD OFF ON ANY ADDITIONAL HEADLINES. OF
NOTE, THE RRFS-A MAY BE ONTO SOMETHING IN HOW IT RESOLVES THE
INCOMING SMOKE WITH SLIGHTLY LOWER AIR TEMPS AND HIGHER DEW
POINTS THE NEXT FEW DAYS WHEN COMPARED TO OTHER GUIDANCE.
AFTER SIMILAR TEMPERATURES THURSDAY, LOWERING THICKNESSES AND
INCREASING SMOKE ALOFT SUPPORT THE IDEA OF TEMPERATURES BEING
SEVERAL DEGREES LOWER ON FRIDAY. THE FORECAST MAY NEED TO BE
LOWERED FURTHER IF SMOKE IS THICKER, OR A PASSING WEAK COLD
FRONT IS A BIT STRONGER/PUSHES FURTHER SOUTH.
KEY MESSAGE 2...THUNDERSTORM CHANCES INCREASE THIS WEEKEND AND
COULD POTENTIALLY LINGER INTO EARLY NEXT WEEK AS A FRONT DROPS
INTO THE REGION.
AMPLE SUBSIDENCE AND DRY AIR ALOFT ARE EXPECTED TO START THE DAY
ON THURSDAY. HEIGHT FALLS/PVA WILL BE NEGLIGIBLE AS MOST FORCING
FOR ASCENT WILL BE ASSOCIATED WITH SHORTWAVES IN CYCLONIC FLOW
PASSING TO THE NORTH AND NORTHEAST. HOWEVER, A HALT IN HEIGHT
RISES PAIRED WITH A SLOWLY SOUTHWARD SAGGING COLD FRONT AND
POTENTIALLY BAY BREEZES IN AREAS WHERE LOW-LEVEL FLOW GOES WEAK
IN THE VICINITY OF THE FRONT, MAY BE ENOUGH WHEN COUPLED WITH
HEATING TO RESULT IN A COUPLE OF ISOLATED THUNDERSTORMS. THERE
IS FURTHER UNCERTAINTY GIVEN CONTINUED SMOKE ALOFT, AS THAT
COULD HAMPER HEATING AND INSTABILITY/CONVECTIVE INITIATION.
UPSTREAM OVER NE PA INTO NJ AND THE NYC TRI-STATE AREA MAY OFFER
A CLUE THIS AFTERNOON AS WE WILL BE IN A SIMILAR ENVIRONMENT
ACROSS THE MD/PA BORDER TOMORROW AFTERNOON. ANY STORMS THAT
MANAGE TO DEVELOP WILL HAVE AMPLE MLCAPE (2000-3000 J/KG) AND
DCAPE (1000-1500 J/KG) TO WORK WITH, AS WELL AS NOTABLE FLOW IN
THE MID AND UPPER LEVELS FOR MID JULY (40-50+ KTS). IF ANY
STORMS MANAGE TO DEVELOP BY LATE AFTERNOON, THEY COULD AT LEAST
BRIEFLY CONGEAL INTO A SMALL CLUSTER AND PROPAGATE SOUTH/
SOUTHEAST TOWARD AND ACROSS THE CHESAPEAKE BAY DURING THE
EVENING HOURS. DAMAGING WINDS WOULD BE THE PRIMARY (CONDITIONAL)
RISK, BUT LARGE HAIL IS ALSO POSSIBLE GIVEN AMPLE CAPE, SHEAR,
AND LOW SEASONABLY LOW WET-BULB ZERO HEIGHTS AROUND 11.5 KFT.
THE SURFACE FRONT WILL DROP FURTHER SOUTHWARD FRIDAY. ADDITIONAL
SMOKE LIKELY MIXES INTO THE REGION. ANY CONVECTION ON FRIDAY
WILL LIKELY BE LIMITED TO THE HIGHER TERRAIN AS THE FRONT WASHES
OUT AND PAIRS WITH OROGRAPHIC LIFT. AGAIN, ANY STORM THAT DOES
FORM COULD BE ON THE STRONG SIDE.
FRIDAY NIGHT, THE AFOREMENTIONED FRONT WILL BEGIN TO LIFT NORTH
AHEAD OF A WAVE OF LOW PRESSURE AND STOUT SHORTWAVE APPROACHING
FROM THE UPPER MIDWEST/GREAT LAKES. INCREASING MLCAPE LATE AT
NIGHT WITH SOME MOISTURE ADVECTION AND MODEST LOW-LEVEL FLOW
OVERTOP THE FRONT MAY RESULT IN A FEW THUNDERSTORMS HEADING INTO
EARLY SATURDAY MORNING, ESPECIALLY EAST OF THE BLUE RIDGE WHERE
A BIT RICHER LOW-LEVEL THETA-E RIDGE LOOKS TO PIVOT THROUGH.
FORCING AND SHEAR WILL BE AMPLE ON SATURDAY, BUT THE AMOUNT OF
INSTABILITY IS IN QUESTION DUE TO POTENTIAL MORNING PRECIP.
SHOULD ENOUGH INSTABILITY DEVELOP, SEVERE WEATHER IS CERTAINLY
POSSIBLE WITH ALL HAZARDS (DAMAGING STRAIGHT-LINE WINDS, LARGE
HAIL, A FEW TORNADOES, AND ISOLATED INSTANCES OF FLASH FLOODING)
ON THE TABLE.
IF THE FRONT DOES NOT MAKE IT ENTIRELY THROUGH THE AREA,
REPEATED STRONG STORMS WILL BE POSSIBLE ON SUNDAY.
AFTER A BRIEF LULL POSSIBLE ON MONDAY, ANOTHER STRONG WAVE MAY
APPROACH BY MID WEEK NEXT WEEK.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE END OF THE
WEEK. ONE EXCEPTION MAY BE LATE THURSDAY NIGHT INTO FRIDAY IN
PARTICULAR AS SMOKE FROM CANADIAN WILDFIRES MIXES SOUTH AND
CLOSER TO THE SURFACE BEHIND A WEAK COLD FRONT. WINDS WILL VARY
BETWEEN N/NW AND SW OVER THE NEXT FEW DAYS AS THAT FRONT STAYS
NEARBY. A THUNDERSTORM CAN'T BE RULED OUT THURSDAY LATE
AFTERNOON AND EVENING, MAINLY EAST OF THE BLUE RIDGE AND IN
NORTHERN MD BUT CONFIDENCE IS VERY LOW. CAN'T RULE OUT A
THUNDERSTORM NEAR THE MOUNTAINS FRIDAY AFTERNOON.
PERIODS OF SUB-VFR ARE LIKELY THIS WEEKEND IN EARLY MORNING LOW
CIGS OR PATCHY FOG, AND AFTERNOON/EVENING CONVECTION.
MARINE
WINDS WILL WAVER BETWEEN N/NW AND SW OVER THE NEXT FEW DAYS AS A
COLD FRONT DANGLES NEAR THE WATERS. DEPENDING ON THE STRENGTH OF
THE FRONT AND HOW FAR NORTH OR SOUTH IT PUSHES, THERE MAY BE AT
LEAST BRIEF/MARGINAL PERIODS OF SCA LEVEL GUSTS, THOUGH THESE
CURRENTLY APPEAR TOO BRIEF WITH CERTAINTY TOO LOW FOR ANY
HEADLINES AT THE MOMENT. A COUPLE OF THUNDERSTORMS CAN'T BE
RULED OUT ALONG THE COLD FRONT THURSDAY LATE AFTERNOON AND
EVENING, AND ANYTHING THAT DOES MANAGE TO FORM COULD PRODUCE
RATHER GUSTY WINDS.
WAVES OF SHOWERS AND THUNDERSTORMS ARE ANTICIPATED THIS WEEKEND.
SPECIAL MARINE WARNINGS MAY BE NEEDED IN STRONGER CONVECTION.
CLIMATE
WELL ABOVE NORMAL TEMPERATURES WILL PERSIST THROUGH THURSDAY.
BELOW IS A LIST OF RECORD DAILY HIGH AND WARM LOW TEMPERATURES FOR
JULY 15 (WEDNESDAY) AND JULY 16 (THURSDAY).
=================================================================
JULY 15 RECORD DAILY HIGH/WARM LOW TEMPERATURES
=================================================================
BALTIMORE MD 102 (2024, 1995) 79 (1995, 1936)
WASHINGTON DC 102 (2024) 81 (2024)
STERLING-DULLES AIRPORT VA 99 (2024) 75 (2024)
BALTIMORE (DOWNTOWN) MD 101 (2024) 85 (1988)
ANNAPOLIS MD 101 (1995) 81 (1896)
HAGERSTOWN MD 102 (1954) 78 (2024)
MARTINSBURG WV 107 (1936) 75 (1995)
CHARLOTTESVILLE VA 102 (1954) 76 (1936)
=================================================================
JULY 16 RECORD DAILY HIGH/WARM LOW TEMPERATURES
=================================================================
BALTIMORE MD 104 (2024, 1988) 78 (1879)
WASHINGTON DC 104 (2024, 1988) 84 (1983)
STERLING-DULLES AIRPORT VA 104 (1988) 74 (2013)
BALTIMORE (DOWNTOWN) MD 105 (2024) 85 (2013)
ANNAPOLIS MD 98 (1997, 1900) 79 (2024, 2013, 1955)
HAGERSTOWN MD 104 (1988) 76 (2024)
MARTINSBURG WV 107 (1988) 77 (1983)
CHARLOTTESVILLE VA 102 (1988) 82 (1983)
PERIOD OF RECORD (POR) INFORMATION (RECORDS SINCE):
BALTIMORE MD - JULY 1872
WASHINGTON DC - JANUARY 1872
STERLING - DULLES AIRPORT VA - JANUARY 1960
BALTIMORE (DOWNTOWN) MD - JULY 1950
ANNAPOLIS MD - JANUARY 1894
HAGERSTOWN MD - JANUARY 1899
MARTINSBURG WV - JANUARY 1891
CHARLOTTESVILLE VA - JANUARY 1893
LWX WATCHES/WARNINGS/ADVISORIES
DC...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR DCZ001.
MD...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MDZ003>006-008-
011-013-014-016>018-502>508.
VA...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR VAZ026>031-040-
051-053>057-501-502-505-506-526-527.
WV...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR WVZ050>053-055-
502-504.
MARINE...NONE.
DISCUSSION...DHOF/CPB/EST
AVIATION...DHOF/CPB/EST
MARINE...DHOF/CPB/EST
CLIMATE...LWX
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