553
FXUS61 KLWX 051429 AAA
AFDLWX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1029 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/
UPPER LOW OVER SCNTRL KY WILL INCH CLOSER TO THE FCST AREA THIS
AFTERNOON INTO THIS EVENING WITH A VORT MAX EXPECTED TO ROTATE
NORTHWARD FROM SOUTHWEST VA INTO WESTERN VA LATE TODAY INTO
EARLY THIS EVENING. MODERATE TO STRONG UPPER LEVEL DIVERGENCE IS
SEEN ON MODEL FIELDS OVER LOW-LEVEL CONVERGENCE SET UP ACROSS
WESTERN PARTS OF THE FCST AREA. GIVEN THINNER CLOUDS IN THOSE
AREAS AND EASILY ATTAINABLE CONVECTIVE TEMPERATURES, EXPECT
NUMEROUS T-STORMS TO DEVELOP BY EARY AFTERNOON. LARGE HAIL WILL
BE THE PRIMARY THREAT GIVEN SEASONABLY CHILLY MID-LEVEL
TEMPERATURES, ALTHOUGH ISOLATED WIND DAMAGE CAN'T BE RULED OUT.
STORMS MAY CONTINUE INTO THE MID-EVENING BEFORE A DIMINISHING
TREND AFTER 10 PM.
PREVIOUS AFD...
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 /14Z 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...LFR
NEAR TERM...LFR
SHORT TERM...DHOF
LONG TERM...ADS
AVIATION...ADS/LFR
MARINE...ADS/LFR
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