910
FXUS61 KLWX 050739
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
339 AM EDT MON MAY 5 2025
SYNOPSIS
A COLD FRONT WILL SLOWLY PROGRESS EASTWARD ACROSS THE REGION
THROUGH TUESDAY, THEN PULL OFFSHORE TUESDAY NIGHT. HIGH PRESSURE
WILL FOLLOW BRIEFLY FOR WEDNESDAY. A POTENT COLD FRONT IS EXPECTED
TO MOVE SOUTHEAST FROM THE EASTERN GREAT LAKES TO AND ACROSS THE
MID-ATLANTIC LATE IN THE WEEK. HIGH PRESSURE WILL LIKELY FOLLOW
THROUGH THE UPCOMING WEEKEND.
NEAR TERM /THROUGH TONIGHT/
EARLY MORNING SATELLITE AND SURFACE OBSERVATIONS REVEAL A
BLANKET OF LOW CLOUDS ADVECTING WESTWARD. THESE CLOUDS ARE
LIKELY TO REACH AS FAR WEST AS THE FOOTHILLS NEAR AND WEST OF
I-81 WHERE A COLD FRONT LIES THROUGH MID MORNING. CLOUDS WILL
THEN GRADUALLY RETREAT, LIFT AND BURN OFF.
THE COLD FRONT OVER WESTERN PARTS OF THE AREA THIS MORNING IS
THE SAME ONE THAT HAS BEEN EVER SO SLOWLY DRIFTING EAST FROM
THE OHIO VALLEY OVER THE PAST FEW DAYS, AND IS ASSOCIATED WITH
A DEEP CUTOFF UPPER-LEVEL LOW. THE ARRIVAL OF THIS SYSTEM SHOULD
MARK AN UPTICK IN SHOWER AND THUNDERSTORM ACTIVITY LATER TODAY,
BUT THE EXTENT AND MAGNITUDE OF CONVECTION IS SOMEWHAT MIRED IN
UNCERTAINTY DUE TO A FEW CAVEATS AS OF EARLY THIS MORNING.
FIRST, THE ABOVE MENTIONED BLANKET OF CLOUDS WILL HINDER HEATING
AS LONG AS IT PERSISTS. THERE IS SOME UNCERTAINTY AS TO WHEN
EXACTLY THESE CLOUDS BREAK, WITH THE CLOUD COVER HANGING ON
LONGER FURTHER EAST. SECOND, EARLY DAY SHOWER ACTIVITY COULD USE
UP SOME OF THE MUCAPE THAT EXISTS EARLY THIS MORNING. THIRD,
FORECAST SOUNDINGS INDICATE ELONGATED, STRAIGHT-LINE HODOGRAPHS
WHICH WOULD BE FAVORABLE FOR CELL SPLITS; IF CELLS MULTIPLY TOO
QUICKLY AND BECOME TOO NUMEROUS, THEN THIS MAY HINDER INTENSITY
AS THEY WILL ALL BE FIGHTING OVER THE SAME INFLOW/CAPE.
THAT BEING SAID, COLD TEMPERATURES ALOFT WILL RESULT IN LOW
FREEZING LEVELS AROUND 700 HPA THROUGH TONIGHT. MID-LEVEL LAPSE
RATES IN THE STANDARD 700-500 HPA LAYER LOOK MODESTLY STRONG
NEAR 7 DEG C/KM, BUT ARE NOTABLY STEEPER IN FORECAST SOUNDINGS
AT HIGHER/COLDER LEVELS OF THE ATMOSPHERE. LOW-LEVEL MOISTENING
WITH SURFACE DEW POINTS RISING INTO THE LOW TO MID 60S F EAST
OF THE SURFACE FRONT SHOULD AFFORD 1000-1500 J/KG MLCAPE,
LOCALLY NEAR 2000 J/KG IF BETTER HEATING CAN BE REALIZED.
POCKETS OF DRY AIR ALOFT AS WELL AS MORE THAN HALF THE FORECAST
CAPE OVERLAYING THE -10 TO -30 C (HAIL GROWTH) ZONE RAISES THE
CONCERN FOR SEVERE THUNDERSTORMS. THE PRIMARY SEVERE RISK TODAY
MAY ULTIMATELY BE HAIL GIVEN THESE COLD TEMPERATURES ALOFT, AS
WELL AS BULK SHEAR IN THE CLOUD-BEARING LAYER NEARING 50 KNOTS.
IF EARLIER CLOUDS AND CONVECTIVE ACTIVITY LEAVE BEHIND ENOUGH
INSTABILITY, THEN A MORE ORGANIZED AND WIDESPREAD SEVERE THREAT
COULD DEVELOP HEADING INTO THIS EVENING. SHEAR WILL INCREASE
TOWARD SUNSET ATTENDANT TO A RATHER POTENT NEGATIVE-TILT
MID/UPPER WAVE ROUNDING THE UPPER LOW. THE REGION WILL BE IN THE
RRQ OF A 70-80 KT 300 HPA JET, AND BENEATH 50-60 KT FLOW AT 500
HPA AS WELL AS 30-40 KT FLOW AT 700 HPA. LOW-LEVEL WINDS IN THE
LOWEST COUPLE KM AGL AS WELL AS LOW VALUES OF SRH SHOULD
PRECLUDE A MORE NOTABLE TORNADO THREAT, THOUGH A BRIEF SPIN UP
CAN'T BE RULED OUT ESPECIALLY WITH ANY RIGHT-TURNING DISCRETE
CELLS THAT INTERACT FAVORABLY WITH BOUNDARIES SUCH AS OUTFLOW,
DIFFERENTIAL HEATING, OR BAY/RIVER BREEZES/TERRAIN CIRCULATIONS.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
THE PERSISTENT UPPER-LEVEL LOW AND ASSOCIATED SURFACE COLD FRONT
WILL CONTINUE THEIR SLOW EASTWARD TREK ON TUESDAY, EVENTUALLY
PULLING OFFSHORE TUESDAY NIGHT. PRIOR TO THE PASSAGE OF THE
FRONT, ADDITIONAL SHOWERS AND A FEW THUNDERSTORMS WILL REMAIN
POSSIBLE. THE THREAT FOR THUNDERSTORMS, A FEW OF WHICH COULD
CONTAIN GUSTY WINDS OR HAIL GIVEN COOL TEMPERATURES ALOFT, WILL
PEAK FROM MIDDAY THROUGH LATE AFTERNOON ON TUESDAY.
A LACK OF MORE ROBUST COLD ADVECTION IN THE WAKE OF THE FRONT
MEANS THAT TEMPTRESS WEDNESDAY SHOULD BE NEAR TO OR SLIGHTLY
ABOVE THE VALUES OBSERVED ON TUESDAY. A COUPLE OF POP UP SHOWERS
ARE POSSIBLE, BUT THE VAST MAJORITY OF THE TIME SHOULD BE DRY.
LONG TERM /THURSDAY THROUGH SUNDAY/
A BLOCKY PATTERN REMAINS IN PLACE FOR THE LATTER PART OF THE WEEK,
MEANING THAT THERE COULD BE SOME PREDICTABILITY ISSUES. THE FIRST
CLOSED LOW SHOULD BE FILLING OVER NEW ENGLAND THURSDAY, BUT ANOTHER
TROUGH WILL BE DROPPING SOUTHEAST AROUND THE MID CONTINENT RIDGE IN
ITS WAKE. THIS TROUGH WILL LIKELY CLOSE OFF INTO A LOW BY EARLY
FRIDAY. THE COMPOSITE SOLUTION PUSHES THE ASSOCIATED COLD FRONT
THROUGH ON THURSDAY, WHICH WILL BRING THE HIGHEST CHANCE OF RAIN
SHOWERS. THERE IS UNCERTAINTY IN THE EXTENT OF MOISTURE RETURN
AND INSTABILITY, WHICH WOULD IMPACT RAIN AMOUNTS AND THE RISK
OF THUNDERSTORMS. THE CLOSED LOW COULD BE CLOSE ENOUGH FRIDAY TO
RESULT IN SOME LINGERING SHOWERS, BUT A DRYING TREND WILL BE
LIKELY. IT IS WORTH NOTING SOME MORE COMPLEX INTERACTIONS COULD
TAKE PLACE THAT RESULT IN MORE RAIN (E.G., 04/12Z ECMWF), BUT
THIS IS CURRENTLY AN OUTLIER. NEAR TO SLIGHTLY ABOVE NORMAL
TEMPERATURES ON THURSDAY LIKELY DROP BELOW NORMAL FRIDAY INTO
FRIDAY NIGHT.
AS LONG AS THE CLOSED LOW REMAINS TO THE EAST, HIGH PRESSURE WILL
LIKELY PROVIDE DRY AND SEASONABLE WEATHER FOR THE WEEKEND. NBM DOES
HAVE 20 PERCENT POPS THROUGH THE PERIOD, SUGGESTING A LOW CHANCE
THAT SOMETHING COULD EVOLVE OUT OF THE GENERAL TROUGHING ACROSS
THE EASTERN U.S.
AVIATION /07Z MONDAY THROUGH FRIDAY/
MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS ARE ANTICIPATED,
FOCUSED ON THE AFTERNOON AND EVENING HOURS THE NEXT TWO DAYS.
SOME STORMS, PARTICULARLY LATE THIS AFTERNOON AND EVENING, COULD
PRODUCE SOME HAIL OR LOCALLY GUSTY WINDS. DESPITE THE LIKELIHOOD
OF THUNDERSTORMS ACROSS THE BROADER REGION, THE EXACT TIMING OF
IMPACTS AT ANY GIVEN TERMINAL REMAINS A BIT LOW AS OF EARLY THIS
MORNING. THEREFORE, HAVE STUCK WITH PROB30 GROUPS FOR A SOMEWHAT
BROAD TIME PERIOD, BUT IT SHOULD BE NOTED THAT MULTIPLE ROUNDS
ACCOMPANIED BY MVFR/IFR CONDITIONS AND PERHAPS WIND/HAIL ARE
POSSIBLE. THE POTENTIAL FOR IMPACTFUL THUNDERSTORMS PEAKS THIS
EVENING. OTHERWISE, LOW CIGS THIS MORNING SHOULD LIFT BETWEEN
15Z-18Z AMID EAST TO SOUTHEAST WINDS. THE WINDS MAY INCREASE A
BIT THIS AFTERNOON INTO EARLY EVENING TO 8-13 KNOTS, WITH A FEW
GUSTS OF 17-22 KNOTS POSSIBLE OUTSIDE OF THUNDERSTORMS. WINDS
WILL BECOME LIGHTER AND SHIFT TO THE SOUTH TONIGHT, SOUTHWEST
TUESDAY, THEN WEST TO NORTHWEST TUESDAY NIGHT THROUGH WEDNESDAY.
AN APPROACHING COLD FRONT COULD BRING A CHANCE OF SHOWERS AND A FEW
THUNDERSTORMS THURSDAY. OTHERWISE, VFR CONDITIONS ARE LIKELY
THROUGH FRIDAY.
MARINE
THE MOST IMPACTFUL WEATHER FOR MARINE INTERESTS OVER THE NEXT 24
TO 48 HOURS WILL BE THE POTENTIAL FOR THUNDERSTORMS. MULTIPLE
WAVES OF SHOWERS AND THUNDERSTORMS ARE POSSIBLE THROUGH TUESDAY
AFTERNOON AND EARLY EVENING DUE TO AN UPPER-LEVEL LOW AND
SURFACE COLD FRONT SLOWLY APPROACHING FROM THE WEST. STORMS
COULD POSE HAZARDS SUCH AS GUSTY WINDS, LOCALLY HIGHER WAVES,
HAIL, LIGHTNING, AND REDUCED VISIBILITY IN HEAVY RAIN.
THERE IS ALSO AT LEAST SOME POTENTIAL FOR PATCHY DENSE MARINE
FOG REDUCING VISIBILITY TO 1 NM OR LESS, PARTICULARLY DURING
THE LATE OVERNIGHT INTO MORNING HOURS EACH OF THE NEXT TWO DAYS.
EAST WINDS OF 5-10 KNOTS THIS MORNING WILL BECOME SOUTHEAST AND
INCREASE THIS AFTERNOON AND EVENING TO 10-15 KNOTS. A FEW GUSTS
TO NEAR 20 KNOTS ARE POSSIBLE, ESPECIALLY GIVEN FAVORABLE FLOW
DIRECTION FOR SOME CHANNELING OR ENHANCEMENT OF BAY/RIVER
BREEZES, BUT THE WEAK BACKGROUND GRADIENT AND RELATIVELY WARMER
AIR OVER COOLER WATER PRECLUDED THE ISSUANCE OF SCAS AS OF EARLY
THIS MORNING. WINDS BECOME SOUTHERLY OVERNIGHT, SOUTHWESTERLY ON
TUESDAY, THEN WEST TO NORTHWEST TUESDAY NIGHT INTO WEDNESDAY AT
GENERALLY LIGHT SPEEDS OF 5-10 KNOTS.
A COLD FRONT WILL DROP THROUGH THURSDAY AND SHIFT WINDS TO THE
NORTH. SHOWERS AND A FEW THUNDERSTORMS MAY ACCOMPANY THE FRONT. SCAS
MAY BE NEEDED BY THURSDAY NIGHT INTO FRIDAY, ESPECIALLY ALONG THE
BAY WHERE THE NORTHERLY WINDS COULD CHANNEL.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
SYNOPSIS...DHOF
NEAR TERM...DHOF
SHORT TERM...DHOF
LONG TERM...ADS
AVIATION...ADS/DHOF
MARINE...ADS/DHOF
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