195
FXUS61 KLWX 061427
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1027 AM EDT SAT SEP 6 2025
SYNOPSIS
A STRONG COLD FRONT WILL CROSS THE AREA THIS AFTERNOON. THE
FRONT WILL BRING STRONG TO SEVERE THUNDERSTORMS TO PORTIONS OF
THE AREA, FOLLOWED BY ANOTHER PROLONGED STRETCH OF COOLER
WEATHER. CANADIAN HIGH PRESSURE WILL BUILD IN FROM THE WEST
MONDAY BEFORE SETTLING TO THE NORTH OF THE AREA TUESDAY AND
WEDNESDAY. A DRY COLD FRONT WILL APPROACH THURSDAY, WITH HIGH
PRESSURE RETURNING TO END THE WEEK.
NEAR TERM /THROUGH TONIGHT/
A DEEP TROUGH WILL REMAIN IN PLACE ACROSS MUCH OF EASTERN
CONUS, WITH THE PRIMARY TROUGH AXIS EXTENDING FROM HUDSON BAY
SOUTHWARD THROUGH THE GREAT LAKES AND MISSISSIPPI VALLEY. A
SHORTWAVE/MID-LEVEL SPEED MAX WILL TRACK FROM THE OHIO VALLEY
TOWARD THE ST. LAWRENCE VALLEY THIS AFTERNOON. LOCALLY, WE'LL
EXPERIENCE WEAK HEIGHT FALLS ALOFT, AND ALSO BECOME LOCATED
WITHIN THE EQUATORWARD ENTRANCE REGION OF AN UNSEASONABLY STRONG
UPPER JET STREAK. AT THE SURFACE, THE SYSTEM'S COLD FRONT WILL
TRACK SOUTHEASTWARD ACROSS THE AREA THIS AFTERNOON INTO EARLY
EVENING. THUNDERSTORMS WILL INITIATE ALONG THIS BOUNDARY
ESPECIALLY IN AREAS ALONG AND EAST OF I-81 EARLY TO MID
AFTERNOON (12-4PM) BEFORE ADVANCING TOWARD THE BALTIMORE/DC
METROS BY LATE AFTERNOON/EARLY EVENING (3-8PM). AS OF 10AM,
RADAR IS INDICATING MODERATE SHOWERS DEVELOPING OVER NORTHERN
WEST VIRGINIA NEAR AND EAST OF THE INTERSECTION BETWEEN I-79 AND
I-68 NEAR MORGANTOWN, WV.
MODEL SOUNDINGS CONTINUE TO SHOW AROUND 1000-2000 J/KG OF
MLCAPE AND AROUND 35-50 KNOTS OF EFFECTIVE BULK SHEAR. WELL
ORGANIZED THUNDERSTORMS ARE EXPECTED AS A RESULT, WITH BOTH
MULTICELLS AND EVEN A FEW SUPERCELLS POSSIBLE. DAMAGING WINDS
SHOULD BE THE PRIMARY THREAT, BUT AN INSTANCE OR TWO OF LARGE
HAIL CAN'T BE RULED OUT IN ANY SUPERCELLS THAT FORM. HODOGRAPHS
ARE PRIMARILY STRAIGHT AND THERE ALSO ISN'T MUCH LOW-LEVEL SHEAR
PRESENT, SO TORNADOES AREN'T EXPECTED. WITH THE STRONG FLOW IN
PLACE ALOFT, STORMS SHOULD BE RATHER PROGRESSIVE. AS A RESULT,
FLASH FLOODING ISN'T EXPECTED TO BE A MAJOR ISSUE. HOWEVER, A
STRAY INSTANCE OF FLOODING CAN'T BE RULED OUT IF THUNDERSTORMS
WERE TO TRAIN OVER A HIGHLY URBANIZED LOCATION. BOTH SPC AND WPC
HAVE LOCATIONS ROUGHLY TO THE EAST OF I-81 OUTLOOKED IN
MARGINAL RISKS FOR SEVERE THUNDERSTORMS AND FLASH FLOODING,
RESPECTIVELY. A SLIGHT RISK FROM SPC CLIPS FAR NORTHEASTERN
PORTIONS OF MARYLAND (HARFORD AND CECIL COUNTIES). THE BEST
PARAMETER SPACE MAY RESIDE JUST TO THE NORTHEAST OF THE AREA
(I.E NJ/NY). THUNDERSTORMS WILL CLEAR SOUTHERN MARYLAND BY MID
EVENING (9PM), WITH JUST A FEW LINGERING LIGHT SHOWERS AND
PATCHY FOG POSSIBLE OVERNIGHT. WINDS WILL SHIFT TO OUT OF THE
NORTH TO NORTHWEST BEHIND THE FRONT, ALLOWING COOLER AND DRIER
AIR TO FILTER INTO THE REGION OVERNIGHT.
THE EXACT PLACEMENT OF THE FRONT AND ANY RESIDUAL CLOUD
DEBRIS/SHOWER ACTIVITY WORKING EAST FROM THE ALLEGHENIES IN THE
MORNING WILL HAVE A SIGNIFICANT EFFECT ON TEMPERATURES. OVERALL,
EXPECT HIGHS EAST OF OF THE BLUE RIDGE IN THE MID 80S TO LOW
90S. LOCATIONS FURTHER WEST WILL LIKELY SEE HIGHS IN THE 70S AND
LOW TO MID 80S. LOW-LEVEL MOISTURE WILL ALSO BE ON THE INCREASE
TO THE EAST OF THE FRONT WITH DEWPOINTS CLIMBING BACK INTO THE
UPPER 60S TO NEAR 70 ALONG AND EAST OF THE BLUE RIDGE. BY PEAK
HEATING, MOST GUIDANCE HAS THE FRONT EXTENDING FROM NORTH-
CENTRAL MARYLAND SOUTHWESTWARD THROUGH THE WESTERN DC SUBURBS
INTO THE SHENANDOAH VALLEY.
THE FRONT WILL MOVE OFFSHORE OVERNIGHT, AND MAY RESULT IN A WIDE
TEMPERATURE SPREAD RANGING FROM THE 40S OVER THE APPALACHIANS TO
THE MID 60S IN THE I-95 MAJOR CITY CENTERS.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
UPPER TROUGHING WILL CONTINUE TO MAKE SLOW EASTWARD PROGRESS ON
SUNDAY WITH A FINAL EMBEDDED SHORTWAVE TRACKING FROM THE OHIO
VALLEY TOWARD PENNSYLVANIA BY SUNDAY EVENING. A MIX OF SUN AND
CLOUDS IS EXPECTED, WITH MORE CLOUDS TOWARD THE SOUTHEAST AND
MORE SUN TOWARD THE NORTHWEST. A MORNING SHOWER OR TWO COULD
ALSO BE POSSIBLE NEAR/EAST OF I-95. WINDS WILL BE OUT OF THE
NORTHWEST, AND TEMPERATURES WILL BE MUCH COOLER, WITH HIGHS IN
THE 70S (60S IN THE MOUNTAINS). LOWS SUNDAY NIGHT WILL FALL INTO
THE UPPER 40S AND LOW 50S FOR MOST. MOUNTAIN LOCATIONS AND
RIVER VALLEY LOCATIONS WEST OF THE BLUE RIDGE WILL SEE LOWS IN
THE LOW TO MID 40S. SOME HIGH VALLEY LOCATIONS (I.E BITTINGER,
MD, CANAAN VALLEY, WV, AND MILL GAP, VA) COULD SEE LOWS DROP
INTO THE 30S.
SKIES WILL TREND MOSTLY SUNNY WITH AMPLE DRY AIR ADVECTION
FUNNELING INTO THE REGION ON MONDAY. HIGH TEMPERATURES MAY BE A
TOUCH WARMER THAN SUNDAY OWING TO MORE SUNSHINE. LOWS MONDAY
NIGHT WILL FALL BACK INTO THE MID 40S AND MID 50S; URBAN
LOCATIONS AND LOCATIONS DIRECTLY ALONG THE CHESAPEAKE BAY WILL
SEE LOWS IN THE UPPER 50S AND LOW 60S WITH MOUNTAIN AREAS SEEING
LOWS IN THE LOW TO MID 40S.
LONG TERM /TUESDAY THROUGH FRIDAY/
HIGH PRESSURE WILL REMAIN OVERHEAD TUESDAY BRINGING MOSTLY SUNNY
SKIES. WHILE THE RIDGE REMAINS CENTERED OVER THE NORTHEASTERN U.S.,
AN APPROACHING LONGWAVE TROUGH WILL STRENGTHEN A STALLED FRONTAL
ZONE WHICH STRADDLES THE CAROLINA TO SOUTHEASTERN U.S. COAST. SOME
ISENTROPIC LIFT ATOP THIS BOUNDARY MAY EVEN SQUEAK OUT A FEW SHOWERS
OVER SOUTHERN MARYLAND ON WEDNESDAY. HOWEVER, THE CHANCES DO REMAIN
LOW AT THIS POINT, GENERALLY AROUND 15 TO 20 PERCENT. THIS DOES
INTRODUCE PLENTY OF CLOUD COVER FOR THOSE EAST OF THE BLUE RIDGE
MOUNTAINS, HOWEVER.
THE AMPLIFIED FLOW GRADUALLY TRACKS ANOTHER REINFORCING COLD FRONT
ACROSS THE REGION ON THURSDAY. GIVEN VERY LITTLE MOISTURE TO WORK
WITH, THIS SHOULD PROVE TO BE A DRY FRONTAL PASSAGE. THIS ALSO
ALLOWS FOR A RETURN TO MOSTLY SUNNY SKIES EACH DAY TO CONCLUDE THE
UPCOMING WORK WEEK.
FOR HIGH TEMPERATURES, MOST LOCATIONS CAN EXPECT DAILY READINGS IN
THE LOW/MID 70S (UPPER 50S TO LOW 60S ACROSS MOUNTAIN LOCALES). AT
NIGHT, MANY PERIODS OF AMPLE RADIATIONAL COOLING WILL DRAW LOW
TEMPERATURES INTO THE UPPER 40S TO MID 50S (LOW/MID 40S FROM I-81
WESTWARD). SOME UPTICK IN OVERNIGHT LOWS ARE POSSIBLE BY MID-WEEK
GIVEN THE INCREASED CLOUD COVER. ADDITIONALLY, THE POST-FRONTAL AIR
MASS ON THURSDAY MAY YIELD SOME HIGHS INTO THE LOW 80S OWING TO
DOWNSLOPING WINDS. TEMPERATURES DO COOL OFF IN THE WAKE OF THIS
BOUNDARY BY NEXT FRIDAY.
AVIATION /15Z SATURDAY THROUGH WEDNESDAY/
VFR CONDITIONS EXPECTED TO CONTINUE AT ALL TERMINALS THROUGH
MIDDAY. WINDS WILL SLOWLY TURN TO THE SOUTHWEST THIS AFTERNOON
AHEAD OF AN APPROACHING COLD FRONT. EXPECT SPEEDS NEAR 10 KTS
WITH GUSTS UP TO 15 KTS AS THE FRONT PASSES THROUGH.
THUNDERSTORMS WILL ALSO ACCOMPANY THE COLD FRONT AS IT PASSES.
HIGHEST CONFIDENCE FOR THUNDERSTORMS APPEARS TO BE AT TERMINALS
EAST OF KMRB AND KSHD MAINLY BETWEEN 17Z-00Z/1-8PM EDT.
THUNDERSTORMS WILL WORK INTO AREAS AROUND KIAD/KCHO/KFDK BETWEEN
17Z-21Z/1-5PM EDT BEFORE QUICKLY RACING EAST TOWARD THE I-95
CORRIDOR TERMINALS BETWEEN 19Z-22Z/3-6PM. ALL OF THE ACTIVITY
SHOULD SINK SOUTH AND EAST OF THE CORRIDOR TOWARD KRIC BY
23Z-01Z/7-9PM EDT. OVERALL COVERAGE APPEARS SCATTERED SOUTH OF
KIAD GIVEN A LITTLE LESS FORCING. MORE LINEAR ORGANIZATION OF
STORMS WILL BE NOTED FROM IAD/DCA POINTS NORTHWARD TOWARD
KBWI/KPHL WHERE BETTER FORCING AND INSTABILITY RESIDE. DAMAGING
WINDS WILL BE THE PRIMARY THREAT WITH THUNDERSTORMS ALONG WITH
LOCALLY HEAVY RAINFALL AND PERHAPS ISOLATED LARGE HAIL. A PERIOD
OF PATCHY FOG/LOW CIGS IS POSSIBLE THIS EVENING INTO THE
OVERNIGHT, BUT CONFIDENCE IS LOW ESPECIALLY FURTHER NORTH GIVEN
A POTENTIAL INTRUSION OF DRIER AIR. VFR CONDITIONS RETURN SUNDAY
AS THE FRONT CLEARS THE AREA. A LEFTOVER SHOWER OR TWO IS
POSSIBLE OVER THE METRO CORRIDOR AS THE FRONT SLOWS EARLY SUNDAY
MORNING. WINDS WILL SHIFT TO THE NORTH AND NORTHWEST BEHIND THE
FRONT WITH GUSTS UP TO 15 KTS. LIGHTER NW TO NE WINDS ARE
EXPECTED MONDAY WITH VFR CONDITIONS.
A DRY PATTERN IS IN PLACE ON TUESDAY OWING TO BROAD CANADIAN HIGH
PRESSURE SETTLING OVER THE NORTHEASTERN U.S. THIS WILL ENSURE VFR
CONDITIONS. BY WEDNESDAY, A COASTAL BOUNDARY MAY INCREASE
CLOUDS EAST OF THE BLUE RIDGE. HOWEVER, THESE ARE NOT LIKELY TO
CAUSE ANY RESTRICTIONS. WIND FIELDS DURING THE PERIOD WILL
LARGELY BE EAST-NORTHEASTERLY AS HIGH PRESSURE TRACKS NORTH OF
THE AREA.
MARINE
WINDS INCREASE IN A CHANNELED SOUTHERLY FLOW THIS AFTERNOON AND
EVENING AHEAD OF AN APPROACHING COLD FRONT. SMWS WILL LIKELY BE
NEEDED THIS AFTERNOON/EVENING (2-9PM) AS GUSTY THUNDERSTORMS
MOVE OVER THE WATERS. WINDS WILL TURN OUT OF THE NORTH TO
NORTHWEST TONIGHT BEHIND THE COLD FRONT AND REMAIN NORTHWESTERLY
DURING THE DAY SUNDAY. A FEW SCA GUSTS MAY BE POSSIBLE IN NORTH
TO NORTHWESTERLY FLOW, AS WELL. LIGHTER NW TO NE WINDS ARE
EXPECTED MONDAY
THE COMBINATION OF HIGH PRESSURE OVER THE NORTHEASTERN U.S. AND A
FRONTAL ZONE OFF THE SOUTHEASTERN U.S. WILL INCREASE OVERALL
PRESSURE GRADIENTS TUESDAY; CONSEQUENTLY, SOME MARINE WINDS
COULD NEAR SMALL CRAFT ADVISORY LEVELS. GRADIENTS RELAX SOME
WEDNESDAY RESULTING IN SLIGHTLY LOWER WINDS.
TIDES/COASTAL FLOODING
A WIND SHIFT WILL FOLLOW THE PASSAGE OF A STRONG COLD FRONT
THAT SHOULD RESULT IN DECREASING WATER LEVELS TONIGHT THROUGH
AT LEAST EARLY MONDAY.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
SYNOPSIS...DHOF
NEAR TERM...KLW/DHOF
SHORT TERM...DHOF/KJP
LONG TERM...CPB
AVIATION...KLW/CPB
MARINE...KLW/CPB
TIDES/COASTAL FLOODING...KLW
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