394
FXUS61 KLWX 010119
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
919 PM EDT MON JUN 30 2025
SYNOPSIS
A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON TUESDAY, BEFORE
MOVING THROUGH TUESDAY NIGHT INTO WEDNESDAY MORNING. HIGH
PRESSURE WILL BUILD INTO THE REGION ON THURSDAY AND REMAIN IN
CONTROL THROUGH THE END OF THE WEEK.
NEAR TERM /UNTIL 7 AM TUESDAY MORNING/
SHOWERS AND THUNDERSTORMS CONTINUE TO TRACK ACROSS THE FORECAST
AREA WITH THE FLOOD WATCH REMAINING IN EFFECT UNTIL 11PM.
DESPITE THE LOSS OF DAYTIME HEATING, THERE IS PLENTY OF
INSTABILITY WITH THE 00Z KLWX UPPER AIR SOUNDING MEASURING 4242
J/KG OF CAPE. ALONG WITH INSTABILITY, THE 00Z SOUNDING SHOWS
PLENTY OF MOISTURE MEASURING 2.13" OF PRECIPITABLE WATER. WE
WILL CONTINUE TO MONITOR THE SEVERE AND FLASH FLOODING THREAT
AS STORMS TRACK EASTWARD. NO CHANGES WERE MADE TO THE FORECAST
WITH THE PREVIOUS FORECAST DISCUSSION BELOW.
FLOOD WATCH HAS BEEN ISSUED FOR PARTS OF THE BALTIMORE AND
WASHINGTON METRO AREAS UNTIL 11 PM FOR SLOW MOVING THUNDERSTORMS
THAT COULD TRAIN AND BE CAPABLE OF PRODUCING INTENSE RAINFALL
RATES THAT COULD CAUSE FLASH FLOODING. CAREFUL SATELLITE
ANALYSIS SHOWS CUMULUS CONGESTUS FORMING IN BETWEEN RT 15 AND
I-83. ALSO, NUCAPS GRIDDED DATA SHOWS IN THIS AREA A MAX OF 17C
850 MB DEWPOINTS CENTERED ACROSS FREDERICK COUNTY MD INTO
GETTYSBURG PA. 12Z HREF MAX UPDRAFT VALUES INDICATE THAT
CONVECTION COULD LAST WELL THROUGH THE EVENING INTO THE
OVERNIGHT HOURS. FOR THIS REASON, FLOOD WATCH HAS BEEN ISSUED.
THREAT FOR DAMAGING WIND GUSTS REMAINS LOW DUE LACK OF DRY AIR
ALOFT.
SHORT TERM /7 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/
A COLD FRONT WILL ENTER THE AREA TOMORROW AND BE FOCUS FOR
WIDESPREAD SHOWERS AND THUNDERSTORMS. ABUNDANT MOISTURE, STRONG
INSTABILITY, AND HEIGHT FALLS INDICATE THE POTENTIAL FOR A VERY
ACTIVE AFTERNOON AND EVENING. WHILE THE MID-LEVEL FLOW WILL BE
STRONGER SUGGESTING FASTER STORM MOTIONS, THE LOW TO MID-LEVEL
FLOW WILL BE SOMEWHAT PARALLEL TO THE SFC BOUNDARY WHICH
SUGGESTS SOME TRAINING OR REPEATED STORMS IS POSSIBLE. A LARGER
FLOOD WATCH WILL LIKELY BE REQUIRED. STRONGER FLOW ALOFT AND
STRONG INSTABILITY ALSO INDICATE POTENTIAL FOR DAMAGING WIND
GUSTS DUE TO WET MICROBURSTS. ACTIVITY MAY PERSIST WELL INTO THE
OVERNIGHT ACROSS SOUTHERN MD BEFORE EXITING OR DISSIPATING EARLY
WED.
LONG TERM /THURSDAY THROUGH MONDAY/
A WEAK COLD FRONT WILL DROP THROUGH THE REGION THURSDAY BRINGING
SPOTTY SHOWER OR THUNDERSTORM CHANCES TO AREAS WEST OF THE BLUE
RIDGE. MOST LOCATIONS WILL REMAIN DRY WITH SEASONABLE TEMPERATURES
IN THE MID TO UPPER 80S AND LOW 90S. THE HUMIDITY WILL LOWER EVEN
FURTHER BEHIND THE FRONT THURSDAY NIGHT INTO FRIDAY WITH DEWPOINTS
DROPPING INTO THE UPPER 50S AND LOW 60S. THE WEAK FRONT WILL SET US
UP FOR A GREAT JULY 4TH HOLIDAY WEATHER WISE AS WELL AS START TO THE
HOLIDAY WEEKEND. HIGHS FRIDAY WILL FALL BACK INTO THE 80S WITH
DEWPOINTS IN THE UPPER 50S AND LOW TO MID 60S. LOWS FRIDAY NIGHT
WILL FALL INTO THE UPPER 50S AND LOW TO MID 60S WITH URBAN LOCATIONS
IN THE UPPER 60S. THIS WILL MAKE FOR EXCELLENT CONDITIONS FOR
VIEWING FIREWORKS DISPLAYS ACROSS THE REGION. SIMILAR CONDITIONS ARE
EXPECTED SATURDAY WITH HIGHS IN THE MID TO UPPER 80S TO AROUND 90 AS
1020 MB HIGH PRESSURE SITS OVERHEAD. THE HIGH WILL SLIDE SOUTH AND
EAST OF THE AREA SUNDAY ALLOWING A COLD FRONT TO APPROACH FROM THE
OHIO RIVER VALLEY AND GREAT LAKES REGION. THIS FRONT WILL BRING
RENEWED CHANCES FOR SPOTTY SHOWERS AND THUNDERSTORMS MAINLY WEST OF
THE BLUE RIDGE FOR THE END OF THE WEEKEND INTO THE START OF NEXT
WEEK. HIGHS SUNDAY AND MONDAY WILL PUSH INTO THE UPPER 80S AND LOW
90S ON SOUTHWESTERLY RETURN FLOW.
AVIATION /01Z TUESDAY THROUGH SATURDAY/
SCATTERED T-STORMS THIS AFTERNOON THROUGH THIS EVENING, THEN
WIDESPREAD SHOWERS AND THUNDERSTORMS TUE AFTERNOON AND EVENING.
POTENTIAL FOR TRAINING T-STORMS TUE WITH POTENTIAL DAMAGING WIND
GUSTS AND TORRENTIAL RAINFALL.
VFR CONDITIONS ARE MOST LIKELY FOR WEDNESDAY THROUGH SATURDAY WITH
HIGH PRESSURE NEARBY.
MARINE
SCA CONDITIONS DEVELOPING LATE TONIGHT ACROSS THE MIDDLE AND
SOUTHERN WATERS, THEN SPREADING ACROSS THE REST OF THE WATERS
TUE AHEAD AND BEHIND A COLD FRONT. T-STORMS MAY ALSO REQUIRE
SMWS. SCA CONDITIONS MAY LAST INTO WED MORNING.
SUB-SCA LEVEL WINDS ARE EXPECTED WEDNESDAY THROUGH SATURDAY AS HIGH
PRESSURE BUILDS OVER THE REGION. A DRY COLD FRONT WILL PASS THROUGH
THE AREA FRIDAY INTO THE START OF THE HOLIDAY WEEKEND.
LWX WATCHES/WARNINGS/ADVISORIES
DC...FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR DCZ001.
MD...SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR MDZ008.
FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR MDZ004>006-011-
013-014-503>506.
VA...FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR VAZ053-054-506.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ530-531-536-
538-539.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ532>534-537-
540>543.
SYNOPSIS...LFR
NEAR TERM...AVS/LFR
SHORT TERM...LFR
LONG TERM...EST
AVIATION...LFR/EST
MARINE...LFR/EST
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