423
FXUS61 KLWX 192020
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
420 PM EDT SAT JUL 19 2025
SYNOPSIS
SHOWER AND THUNDERSTORM CHANCES CONTINUE THROUGH THE
WEEKEND TODAY AS A WARM FRONT SLOWLY LIFTS NORTH OF THE REGION
TODAY. A COLD FRONT FOLLOWS SUNDAY NIGHT. LESS HUMIDITY AND DRIER
CONDITIONS TO START NEXT WEEK AS CANADIAN HIGH PRESSURE BUILDS
IN TO THE NORTH. AS THIS RIDGE OF HIGH PRESSURE MOVES INTO THE
CANADIAN MARITIMES, HEAT AND HUMIDITY RETURN LATE NEXT WEEK.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
THE SYNOPTIC SETUP IN PLACE MAINTAINS ABOVE AVERAGE HEIGHTS ACROSS
THE SOUTHERN PLAINS EASTWARD TO THE SOUTHWESTERN ATLANTIC OCEAN. TO
THE NORTH, A BROAD LONGWAVE TROUGH EXTENDS ACROSS CENTRAL/EASTERN
CANADA, WHILE A SERIES OF PERTURBATIONS IN THE FLOW TRAVERSE THROUGH
THE GREAT LAKES INTO THE MID-ATLANTIC. BEING RIGHT ALONG THE
INTERFACE WITH RIDGING TO THE SOUTH AND STRONGER JET ENERGY TO THE
NORTH, A SURFACE BOUNDARY REMAINS QUASI-STATIONARY ALONG U.S. 50.
WITHIN THIS WARM/MOIST SECTOR, MULTIPLE STORM CLUSTERS HAVE
DEVELOPED AND BEGUN TO TRACK IN AND AROUND THE I-64 CORRIDOR. THE
MORE ROBUST NATURE OF A COUPLE OF THESE CELLS HAS WARRANTED A PAIR
OF SEVERE THUNDERSTORM WARNINGS ACROSS ALBEMARLE COUNTY. WHILE
DOWNDRAFT CAPE VALUES ARE SUBDUED (500-700 J/KG) FOR TYPICAL SEVERE
STANDARDS, THERE APPEARS TO BE PLENTY OF INSTABILITY AND SHEAR TO
MAINTAIN A NOTABLE SEVERE WEATHER THREAT. WITH THAT IN MIND, A
SEVERE THUNDERSTORM WATCH IS IN EFFECT UNTIL 10 PM ACROSS THIS
PORTION OF I-64 EASTWARD ACROSS CENTRAL VIRGINIA INTO FAR
SOUTHERN MARYLAND.
OFF TO THE NORTH, THE CONVECTIVE TRENDS ARE MORE SUBDUED WITH LITTLE
TO NO LIGHTNING BEING OBSERVED. GIVEN THE DEGREE OF THICK ANVIL
CIRRUS OVERSPREADING AREAS DOWNSTREAM TO THE EAST, ADDITIONAL
DEVELOPMENT TOWARD I-95 IS LOOKING LESS LIKELY. GIVEN THE DEGREE OF
WARM AND HUMID CONDITIONS IN PLACE, WILL MAINTAIN THUNDERSTORMS IN
THE FORECAST THROUGH THE EARLY EVENING HOURS.
BESIDES THE SEVERE WEATHER THREAT, A CONCERN FOR FLASH FLOODING
REMAINS ACROSS THE CENTRAL SHENANDOAH VALLEY ACROSS THE CENTRAL
VIRGINIA PIEDMONT TOWARD I-95. THIS BROAD AREA REMAINS IN A FLOOD
WATCH FOR FLASH FLOODING UNTIL 10 PM GIVEN THE CONTINUED THREAT OF
VERY HIGH RAINFALL RATES. AREAS MOST AT RISK WOULD BE LOCATIONS THAT
SAW EARLIER HEAVY RAINFALL IN THE PAST DAY OR SO. WITHIN THE MOST
PROLIFIC CORES, A QUICK 1 TO 2 INCHES OF RAIN ARE POSSIBLE IN 30
MINUTES. STORM TOTALS MAY APPROACH 2 TO 4 INCHES UNDER THE STRONGEST
STORMS.
AFTER SPENDING THE AFTERNOON WELL INTO THE 80S TO LOW 90S, THE
WARM/HUMID AIR MAINTAINS ITS PRESENCE INTO THE OVERNIGHT HOURS.
FORECAST LOW TEMPERATURES FALL INTO THE UPPER 60S TO MID 70S,
LOCALLY DOWN INTO THE MID 60S ACROSS MOUNTAIN LOCATIONS. GIVEN LIGHT
WINDS AND A SATURATED BOUNDARY LAYER, PATCHY FOG WILL AGAIN BE
POSSIBLE, ESPECIALLY WEST OF I-95.
SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/
EXPECT SOME LINGERING PATCHY FOG ACROSS THE AREA, PARTICULARLY
ACROSS THE LOW-LYING RIVER AND MOUNTAIN VALLEYS. WITH THE MID-JULY
SOLAR INSOLATION ANGLE KICKING IN, ANY FOG SHOULD MIX OUT 2 TO 3
HOURS AFTER SUNRISE. FOR SUNDAY, A RESIDUAL SEVERE WEATHER RISK
LOOMS AHEAD OF THE NEXT COLD FRONT THAT ARRIVES LATER IN THE
EVENING/NIGHT. FORECAST MODELS FAVOR AN UPTICK IN TEMPERATURES
WITH AREA-WIDE HIGHS RISING BACK INTO THE LOW 90S. THIS
CONTRIBUTES TO INCREASING INSTABILITY LEVELS, COUPLED WITH AN
UPTICK IN VERTICAL SHEAR WITH THE APPROACH OF THE UPPER TROUGH.
HOWEVER, DESPITE THIS DECENT COMBINATION OF INSTABILITY/SHEAR,
THE 12Z SUITE OF HIGH-RESOLUTION MODELS ARE NOT VERY ENTHUSED AS
NOTED BY THE LACK OF MEMBERS IN THE 40 DBZ PAINTBALL PLOTS.
WITH THE SIGNAL REMAINING STRONG ENOUGH, THE STORM PREDICTION
CENTER HAS MAINTAINED A MARGINAL RISK ACROSS THE ENTIRE REGION.
A SEASONABLY STRONG COLD FRONT SWEEPS THROUGH THE AREA ON SUNDAY
NIGHT BEFORE FULLY CLEARING THE AREA BY EARLY MONDAY. HOWEVER,
THE FULL INFLUENCE OF THIS BOUNDARY DOES NOT REALLY KICK IN
UNTIL SUBSEQUENT DAYS. THUS, EXPECT LOW TEMPERATURES IN THE
UPPER 60S TO MID 70S ON SUNDAY NIGHT, WHILE LOW/MID 60S ARE MORE
COMMONPLACE WEST OF I-81.
BY MONDAY MORNING, THE COLD FRONT IS FORECAST TO BE CROSSING THE
VIRGINIA/NORTH CAROLINA BORDER. A SHIFT TO NORTHERLY WINDS
ENSUES AS A STRONG DOME OF CANADIAN HIGH PRESSURE CROSSES THE
ONTARIO/QUEBEC BORDER. A NOTABLE FALL IN TEMPERATURES AND DEW
POINTS OCCURS GIVEN THIS PATTERN CHANGE. ANY SHOWER CHANCES WILL
LIKELY BE RELEGATED TO THE POTOMAC HIGHLANDS BEFORE DIMINISHING
THROUGH THE EVENING HOURS. A COOL NIGHT LIES AHEAD WITH
WIDESPREAD LOW TEMPERATURES IN THE LOW/MID 60S. SOME POCKETS OF
MID/UPPER 50S ARE POSSIBLE ALONG THE ALLEGHENY FRONT.
LONG TERM /TUESDAY THROUGH SATURDAY/
A STRONG AREA OF HIGH PRESSURE WILL BUILD TO OUR NORTH ON TUESDAY.
NORTHERLY FLOW WILL ADVECT COOLER AND DRIER AIR INTO THE AREA,
LEADING TO BELOW NORMAL TEMPERATURES AND LESS HUMID CONDITIONS.
MOSTLY SUNNY SKIES ARE EXPECTED, WITH HIGHS IN THE LOW TO MID 80S
AND DEWPOINTS DROPPING INTO THE 50S AND LOWER 60S. SOME OF THE
COOLEST OVERNIGHT LOWS IN SOME TIME ARE EXPECTED TUESDAY NIGHT, WITH
MANY LOCATIONS DROPPING BACK INTO THE 50S AND LOWER 60S.
HIGH PRESSURE WILL SHIFT EASTWARD OFF THE NEW ENGLAND COASTLINE ON
WEDNESDAY. WINDS WILL GRADUALLY SHIFT FROM EASTERLY TO SOUTHERLY
OVER THE COURSE OF THE DAY, WHICH MAY LEAD TO A SLIGHT UPTICK IN
HUMIDITY, WITH DEWPOINTS CLIMBING BACK INTO THE LOWER 60S. SKIES
SHOULD REMAIN MOSTLY SUNNY, AND TEMPERATURES WILL REMAIN BELOW
NORMAL, WITH HIGHS IN THE LOW TO MID 80S.
HIGH PRESSURE WILL PROGRESS FURTHER OFFSHORE LATE IN THE WEEK AS
UPPER RIDGING BUILDS IN ALOFT FROM THE OHIO VALLEY. WINDS WILL
REMAIN SOUTHERLY AS THE THE HIGH SHIFTS FURTHER OFFSHORE, WHICH WILL
LEAD TO A RETURN OF THE HEAT AND HUMIDITY. DEWPOINTS WILL CLIMB
WELL INTO THE 60S ON THURSDAY, BEFORE RETURNING INTO THE 70S ON
FRIDAY. TEMPERATURES WILL BE ON THE INCREASE AS WELL, WITH HIGHS ON
THURSDAY IN THE LOW TO MID 90S, AND THEN MID TO POTENTIALLY EVEN
UPPER 90S BY FRIDAY. WITH THE UPPER RIDGE BUILDING IN FROM THE WEST,
SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN LIMITED, OR
POTENTIALLY EVEN NON-EXISTENT ON THURSDAY. COVERAGE OF STORMS IS
EXPECTED TO REMAIN LOW ON FRIDAY AS WELL, BUT WITH LIKELY AT LEAST A
FEW STORMS AROUND AS THE UPPER LEVEL RIDGE STARTS TO WEAKEN SLIGHTLY.
AVIATION /20Z SATURDAY THROUGH THURSDAY/
A BROAD CLUSTER OF SHOWERS AND THUNDERSTORMS CONTINUE TO
PROGRESS EASTWARD AWAY FROM THE SHENANDOAH VALLEY. MOST OF THE
CURRENT RESTRICTIONS ARE TIED TO THE TERMINALS AT KCHO AND KMRB.
FURTHER DOWNSTREAM, CONDITIONS ARE QUIET AT THE D.C. AND
BALTIMORE TERMINALS. GIVEN THE LACK OF THUNDER NORTH OF I-66 AND
LACKLUSTER APPEARANCE OF ECHOES WELL TO THE WEST, HAVE PULLED
ANY THUNDER WORDING AT THESE LOCATIONS THIS AFTERNOON/EVENING.
CONVECTION WINDS DOWN ACROSS THE AREA TONIGHT WITH SOME PATCHY
FOG POSSIBLE, ESPECIALLY ACROSS KCHO AND KMRB.
SUNDAY'S CONVECTIVE THREATS APPEAR MORE UNCERTAIN, BUT OVERALL
PARAMETERS STILL SUPPORT SOME DEGREE OF CONCERN. HAVE PLAYED IT
MORE CONSERVATIVELY WITH JUST A PREVAILING -SHRA GROUP AT THE
D.C. AND BALTIMORE TERMINALS FROM 20-00Z SUNDAY. HOWEVER, COULD
EASILY SEE THIS UPGRADED TO -TSRA IN FUTURE TAF ISSUANCES.
FOR MONDAY, WINDS SHIFT TO NORTHERLY AS CANADIAN HIGH PRESSURE
BUILDS TO THE NORTH. THIS WILL SUPPORT VFR CONDITIONS WITH DRIER
WEATHER AHEAD.
VFR CONDITIONS ARE EXPECTED ON BOTH TUESDAY AND WEDNESDAY. WINDS
WILL BE OUT OF THE NORTH TO NORTHEAST ON TUESDAY AND START OUT
EASTERLY ON WEDNESDAY, BEFORE TURNING OUT OF THE SOUTH BY THE END OF
THE DAY.
MARINE
GRADIENTS REMAIN ON THE WEAK SIDE SO THERE ARE NO MARINE HAZARDS
TIED TO THE BACKGROUND WIND FIELDS. HOWEVER, ALL ISSUES WILL BE
RELATED TO ANY STRONG TO SEVERE THUNDERSTORMS THAT TRACK ACROSS
THE WATERWAYS. THE MOST NOTABLE THREAT FOR SPECIAL MARINE
WARNINGS WOULD BE ACROSS THE SOUTHERN WATERS WHERE A SEVERE
THUNDERSTORM WATCH IS IN EFFECT UNTIL 10 PM.
THE RISK FOR ADDITIONAL STORMS LOOMS ON SUNDAY AHEAD OF A MORE
FORMIDABLE COLD FRONT THAT TRACKS THROUGH LATE SUNDAY. THIS MAY
CAUSE SOME HAZARDOUS CONDITIONS FOR BOATERS, PARTICULARLY DURING
THE AFTERNOON AND EVENING HOURS. ADDITIONALLY, AN UPTICK IN
NORTHWEST TO NORTHERLY WINDS ON SUNDAY NIGHT INTO MONDAY
MORNING. SOME CHANNELING EFFECTS MAY FURTHER ENHANCE THESE
WINDS. SMALL CRAFT ADVISORIES MAY BE NEEDED DURING THIS PERIOD
OF UPTICK.
SUB-SCA LEVEL WINDS ARE EXPECTED ON BOTH TUESDAY AND WEDNESDAY.
WINDS WILL BE OUT OF THE NORTH TO NORTHEAST ON TUESDAY, AND
GRADUALLY TURN FROM OUT OF THE EAST TO OUT OF THE SOUTH OVER THE
COURSE OF THE DAY WEDNESDAY.
TIDES/COASTAL FLOODING
LIGHT WINDS ACROSS THE AREA WILL MAINTAIN ELEVATED TIDAL ANOMALIES.
AT THIS POINT, ONLY ANNAPOLIS COULD SEE A RUN AT MINOR TIDAL
FLOODING, MAINLY DURING THE HIGHER OF THE ASTRONOMICAL TIDES. THESE
WILL OCCUR DURING THE MIDDLE OF THE NIGHT THIS WEEKEND. A STRONG
COLD FRONT MOVES THROUGH THE WATERS LATE SUNDAY WHICH SHOULD HELP
LOWER WATER LEVELS INTO NEXT WEEK.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...FLOOD WATCH UNTIL 10 PM EDT THIS EVENING FOR VAZ025-026-
036>040-050-051-055>057-502-507-508.
WV...NONE.
MARINE...NONE.
SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...KJP
AVIATION...BRO/KJP
MARINE...BRO/KJP
TIDES/COASTAL FLOODING...BRO
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