052
FXUS61 KLWX 081921
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
321 PM EDT TUE JUL 8 2025
SYNOPSIS
A COLD FRONT WILL DROP CLOSER TO THE AREA TONIGHT AND WILL THEN
STALL AND WAVER NEARBY THROUGH THE WEEKEND.
NEAR TERM /THROUGH TONIGHT/
LINE OF STORMS HAS FORMED EAST OF I-81 AND IS PROGRESSING TO THE
EAST AROUND 23 KT. LATEST NUCAPS DATA FROM 1736Z SHOWS AN
INSTABILITY GRADIENT EAST OF ROUTE 15, SO EXPECTING STORMS TO
STRENGTHEN AS THEY MOVED EAST OF THE BLUE RIDGE MOUNTAINS.
NUCAPS DATA ALSO SHOWED 925-850 MB MOISTURE MAXIMIZED ACROSS
NORTHEAST MD FROM CARROLL EAST TO CECIL COUNTIES. EXPECT NEW
STORMS TO DEVELOP IN THAT AREA ALONG THE BAY BREEZE WELL IN
ADVANCE OF LINE OF STORMS CURRENLY CROSSING I-81. MID-LEVEL
LAPSE RATES ARE POOR, BUT STRONG INSTABILITY WITH CAPE VALUES
UPWARD OF 3500 J/KG WILL OFFSET THE WARM TEMPS ALOFT. DAMAGING
WINDS, VERY HIGH INSTANTANEOUS RAIN RATES, AND FREQ LIGHTNING
ARE THE MAIN THREATS. THE CURRENT LINE IS MOVING AROUND 23 KT,
BUT LINE MAY SLOW DOWN AS IT APPROACHES/ENCOUNTERS THE BAY
BREEZE.
CONVECTION WILL GRADUALLY WANE THIS EVENING WITH AREAS OF FOG/LOW
CLOUDS LATE GIVEN THE WARM AND MOIST AIRMASS OVERHEAD. LOWS WILL
FALL BACK INTO THE UPPER 60S OVER THE MOUNTAINS WITH MID 70S ALONG
AND EAST OF I-81.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
SHARPER LOW-MID LEVEL TROUGH WILL CROSS THE AREA WED AFTERNOON
AND PROVIDE BETTER/STRONGER SFC CONVERGENCE TO TRIGGER MORE
WIDESPREAD CONVECTION THAN TODAY. LOOKS LIKE AREAS ALONG AND
EAST OF I-95 WILL BE THE AREAS WITH THE MOST CONCENTRATED
ACTIVITY. SIGNAL FOR HEAVY RAIN FOR WED IS STRONGER THAN TODAY
DUE TO BETTER/STRONGER FORCING AND BETTER MOISTURE POOLING ALONG
THE FRONT. ANTICIPATE ANOTHER FLOOD WATCH TOMORROW WITH GREATER
RISK OF FLOODING/FLASH FLOODING. SCENARIO REPEATS ITSELF
THURSDAY WITH MORE SHOWERS AND THUNDERSTORMS AS FRONTAL ZONE
DISSIPATES OVER THE AREA.
LONG TERM /FRIDAY THROUGH TUESDAY/
NOT MUCH CHANGE IN THE EXTENDED PATTERN AS THERE IS NO REAL
PROGRESSIVE STORM SYSTEM TO CLEAN US OUT OF THIS WARM, MUGGY, AND
STORMY PATTERN. TEMPERATURES WILL TREND SLIGHTLY COOLER FOR THE END
OF THE WORKWEEK AND INTO THE WEEKEND GIVEN ADDED CLOUD COVER WITH
THE STALLED FRONT NEARBY. PIECES OF SHORTWAVE ENERGY WILL CONTINUE
TO RIDE ALONG THE STALLED BOUNDARY AS IT BISECTS THE AREA. CURRENT
12Z SYNOPTIC GUIDANCE SHOWS THE FRONT STALLING SOMEWHERE IN THE
VICINITY OF SOUTHWEST PA, CENTRAL MD, AND NORTHERN VA DURING THE
SATURDAY AND SUNDAY TIMEFRAME. WITH THE FRONT NEARBY EXPECT
CONTINUED CHANCES FOR SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON
AND EVENING HOURS. AS FOR SEVERE WEATHER, UNCERTAINTY REMAINS GIVEN
THE PLACEMENT OF THE FRONT AND TIMING OF SHORTWAVE ENERGY AS IT
PIVOTS ACROSS. CURRENT CSU LEARNING MACHINE GUIDANCE, CIPS PATTERN
RECOGNITIONS, AND LONG RANGE NSSL PROBS ARE LEANING TOWARD THE
SATURDAY AND SUNDAY TIMEFRAME AS THE NEXT POTENTIAL PERIOD FOR
ORGANIZED CONVECTION. EITHER WAY THUNDERSTORMS WILL HAVE THE
POTENTIAL OF PRODUCING LOCALLY DAMAGING WINDS AND INSTANCES OF FLASH
FLOODING EACH AFTERNOON. THIS IS DUE LARGELY IN PART TO THE STAGNANT
WARM AND MOIST AIRMASS HANGING TOUGH OVER THE REGION. TEMPERATURES
FRIDAY THROUGH THE WEEKEND WILL RANGE FROM THE MID TO UPPER 80S AND
LOW 90S. HEAT INDICES WILL MAKE IT FEEL MORE LIKE THE MID TO UPPER
90S.
BEYOND SUNDAY, UNCERTAINTY CONTINUES IN REGARDS TO A POTENTIAL
FRONTAL PASSAGE. 12Z SYNOPTIC/ENSEMBLE GUIDANCE SHOW A COLD
FRONT EJECTING OUT OF THE MIDWEST AND OHIO RIVER VALLEY SOME
TIME MONDAY INTO TUESDAY NEXT WEEK. THIS FRONT DOES NOT APPEAR
TO ARRIVE UNTIL MID NEXT WEEK LEADING TO A CONTINUATION OF DAILY
SHOWER AND THUNDERSTORM CHANCES UNTIL IT PASSES THROUGH.
TEMPERATURES AND PRECIPITATION WILL CONTINUE TO REMAIN ABOVE
AVERAGE WITHIN THE BACK HALF OF THE LONG TERM PERIOD.
AVIATION /19Z TUESDAY THROUGH SUNDAY/
TEMPORARY SUB-VFR REDUCTIONS ARE LIKELY AT ALL TERMINALS BEYOND
THIS POINT THROUGH 01-02Z DUE IN PART TO SCATTERED TO NUMEROUS
THUNDERSTORMS BUBBLING UP OVER THE AREA. CLUSTERS OF STORMS WILL
GRADUALLY WORK FROM WEST TO EAST ACROSS THE AREA FIRST
IMPACTING KMRB/KSHD BEFORE 21Z. STORMS WILL WORK INTO THE
CORRIDOR BETWEEN 19-21Z WITH A SLOW LAG TO THE EAST OF DCA/BWI
HEADING INTO THE EARLY EVENING HOURS. REPETITIVE ROUND OF
THUNDERSTORMS ARE LIKELY WITH CHAOTIC AND ERRATIC STORM MOTIONS
EXPECTED LEADING TO FURTHER UNCERTAINTY IN WHEN AND WHERE THEY
POP UP. FOR THAT REASON, TRIED TO KEEP 3 TO 4 HOUR TEMPO
WINDOWS AT EACH TERMINAL. STORM THREATS WILL INCLUDE VERY HEAVY
RAIN, FREQUENT LIGHTNING, AND POTENTIAL DOWNBURSTS TO 50 KT.
WINDS WILL REMAIN OUT OF THE SOUTH AND SOUTHWEST AT LESS THAN
10 KTS. STORM COVERAGE DECREASES AFTER 02-03Z WITH AREAS OF FOG
AND LOW CLOUDS EXPECTED OVERNIGHT. THIS IS ESPECIALLY TRUE FOR
TERMINALS WEST OF THE CORRIDOR AND IN DEEPER RIVER VALLEYS.
ANOTHER ROUND OF STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE
WEDNESDAY AFTERNOON AND EVENING. THIS THREAT APPEARS TO BE ACROSS
THE LOWER HALF OF THE CORRIDOR FROM IAD/DCA POINTS SOUTH TOWARD
KCHO/KRIC. ONCE AGAIN DAMAGING WINDS AND INSTANCES OF FLASH FLOODING
WILL BE THE PRIMARY CONCERNS. EXPECT SUB-VFR REDUCTIONS IN AROUND
STORMS ALONG WITH CHAOTIC/ERRATIC WINDS/STORM MOTIONS. A SIMILAR
PATTERN IS EXPECTED THURSDAY THROUGH THE WEEKEND WITH DAILY
AFTERNOON/EVENING THUNDERSTORMS. THIS WILL LEAD TO CONTINUED SUB-VFR
REDUCTIONS AT TIMES MAINLY DURING THE AFTERNOON/EVENING AND DURING
THE OVERNIGHT WITH PATCHY FOG/LOW CLOUDS DEVELOPING IN THE WAKE ANY
THUNDERSTORMS. WINDS WILL REMAIN LESS THAN 10KTS.
MARINE
SCATTERED TO NUMEROUS THUNDERSTORMS LOOK TO IMPACT THE WATERS
ANYTIME AFTER 18-20Z/2-4PM THIS AFTERNOON. SPECIAL MARINE WARNINGS
WILL BE NEEDED TO COVER THIS THREAT WITH STORMS CAPABLE OF PRODUCING
SEVERE DOWNBURSTS WINDS AND HEAVY RAINFALL. HIGHEST COVERAGE OF
STORMS LOOK TO BE BETWEEN 4-9PM THIS EVENING BEFORE DIMINISHING
OVERNIGHT. ADDITIONAL SHOWERS AND THUNDERSTORMS ARE POSSIBLE
WEDNESDAY AS THE FRONT SHIFTS FURTHER SOUTH AND STALLS ACROSS THE
WATERS. STORM COVERAGE WILL ONCE AGAIN BE WIDESPREAD, MAINLY
CONFINED TO WATERS NEAR SOUTHERN MD AND THE NORTHERN NECK OF VA.
WIND WILL BE THE PRIMARY THREAT WITH STORMS ALONG WITH FREQUENT
LIGHTNING AND HEAVY RAINFALL. ADDITIONAL SMWS WILL BE NEEDED TO
ENCOMPASS THIS THREAT. WINDS WILL REMAIN LIGHT OUT OF THE SOUTH
OUTSIDE OF THUNDERSTORMS, WITH OUTFLOWS LIKELY DISRUPTING
OPPORTUNITIES FOR SOUTHERLY CHANNELING.
SUB-SCA LEVEL WINDS ARE EXPECTED THURSDAY THROUGH THE UPCOMING
WEEKEND DESPITE A STALLED FRONT NEARBY. GRADIENTS WILL REMAIN FAIRLY
WEAK WITH VARIABLE WIND DIRECTIONS DICTATED BY THE PLACEMENT OF THE
FRONT. ONCE AGAIN SMWS WILL BE NEEDED AT TIMES DURING THE AFTERNOON
AND EVENING HOURS GIVEN DAILY CONVECTIVE DEVELOPMENT.
LWX WATCHES/WARNINGS/ADVISORIES
DC...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR DCZ001.
FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR DCZ001.
MD...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR MDZ008-011-013-
014-016>018-508.
FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR MDZ005-006-008-011-
013-014-016>018-503>508.
VA...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR VAZ053>057-527.
FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR VAZ053-054-506-526-
527.
WV...NONE.
MARINE...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ530.
FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR ANZ530.
SYNOPSIS...LFR
NEAR TERM...LFR
SHORT TERM...LFR
LONG TERM...EST
AVIATION...LFR/EST
MARINE...LFR/EST
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page