614
FXUS61 KLWX 201240
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
840 AM EDT MON APR 20 2026
WHAT HAS CHANGED
THIS MORNING'S WEATHER BALLOON REVEALED DEEP MIXING AND STEEP
LAPSE RATES UP TO ABOUT 14,300 FEET. A FEW SHOWERS WERE PIVOTING
NORTHWEST TO SOUTHEAST ACROSS THE NORTHERN HALF OF THE AREA.
GIVEN THE STEEP LAPSE RATES AND LOW FREEZING LEVELS, SOME OF
THESE SHOWERS COULD PRODUCE GUSTY WINDS OR GRAUPEL.
KEY MESSAGES
- (1) COLDER EARLY THIS WEEK WITH A FIRE WEATHER THREAT TODAY.
- (2) WIDESPREAD FREEZE EXPECTED TONIGHT INTO TUESDAY MORNING.
- (3) WARMER TEMPERATURES MID TO LATE WEEK, THEN BECOMING
UNSETTLED THIS WEEKEND.
DISCUSSION
KEY MESSAGE 1...COLDER EARLY THIS WEEK WITH A FIRE WEATHER
THREAT TODAY.
VERY DRY AIR WILL MOVE OVERHEAD TODAY. HOWEVER, THERE IS A
LAYER BETWEEN ROUGHLY 6,000 AND 12,000 FEET WHERE NOTABLE
MOISTURE IS PRESENT. THE THOUGHT IS SCATTERED TO BROKEN STRATOCU
AND WAVE CLOUDS WILL DEVELOP OUT OF THIS, ESPECIALLY AS THE
SECONDARY FRONT PUSHES THROUGH EARLY TODAY, THEN THE TRAILING
SHORTWAVE/UPPER-LEVEL TROUGH PIVOT OVERHEAD THIS AFTERNOON. A
FEW SPRINKLES OR A POP UP SHOWER CAN'T BE RULED OUT (WITH A
LITTLE SNOW LIKELY ABOVE 2500 FEET OVER THE MTNS). THE NOSE OF
THE SHORTWAVE ALOFT CROSSES ROUGHLY BETWEEN I-70 AND I-64 TODAY,
AND EVEN IF PRECIP EVAPORATES BEFORE HITTING THE GROUND
(VIRGA), VERY STEEP LOW-LEVEL LAPSE RATES COULD RESULT IN SOME
ENHANCED GUSTINESS. FREQUENT GUSTS OF 20 TO 30 MPH ARE EXPECTED
AGAIN THIS AFT, WITH PEAK GUSTS OF 35 TO 40 MPH POSSIBLE, MAINLY
AT HIGHER ELEVATIONS OR IN THE VICINITY OF SHOWERS.
DRY AND BREEZY CONDITIONS ARE EXPECTED THROUGH EARLY THIS WEEK.
PLEASE REFER TO THE FIRE WEATHER SECTION BELOW FOR MORE DETAILS
ON THE FIRE WEATHER THREAT TODAY.
KEY MESSAGE 2...WIDESPREAD FREEZE EXPECTED TONIGHT INTO TUESDAY
MORNING.
HIGH PRESSURE BUILDS OVERHEAD TONIGHT INTO TUE LEADING TO
LIGHTER WINDS. THE COLD, DRY AIRMASS, CLEAR SKIES AND LIGHT TO
CALM WINDS TONIGHT INTO TUE MORNING ARE LIKELY TO BRING
WIDESPREAD FREEZE CONDITIONS ASIDE FROM THE MAJOR URBAN CENTERS
AND AWAY FROM LARGER BODIES OF WATER. THEREFORE, HAVE UPGRADED
ENTIRE FREEZE WATCH TO A FREEZE WARNING.
THIS IS ~10 DAYS PAST THE MEDIAN DATE OF THE LAST SPRING FREEZE
BASED ON 1991-2020 CLIMATOLOGY FOR AREAS ALONG/EAST OF I-81.
GIVEN THE WARMTH EARLY THIS SPRING, MANY AREAS ARE AHEAD OF
SCHEDULE FROM A GROWTH STAND POINT SO THIS FREEZE COULD BE
RATHER IMPACTFUL.
THERE ARE NO FROST/FREEZE HEADLINES FOR THE ALLEGHENIES AS THE
GROWING SEASON HAS NOT STARTED THERE YET.
KEY MESSAGE 3...WARMER TEMPERATURES MID TO LATE WEEK, THEN BECOMING
UNSETTLED THIS WEEKEND.
AS CANADIAN HIGH PRESSURE SLIDES OFF TOWARD THE S, A QUICK
MOVING CLDFRNT CROSSES THE REGION BY MID-WEEK. THERE WILL NOT
BE A WHOLE LOT OF MOISTURE TO WORK WITH, SO ANY RAINFALL AMOUNTS
ARE LIKELY TO BE MEAGER IN NATURE. SOME INSTABILITY IN THE
ATMOSPHERE COULD PRODUCE A FEW THUNDERSTORMS, PARTICULARLY
DURING THE AFT HOURS.
AFTER A CHILLY START TO THE WORK WEEK, ENSEMBLES AGREE ON A MARKED
WARM UP THROUGH THE MIDDLE TO LATTER PORTIONS OF THE WEEK. HIGH
TEMPS COULD PUSH BACK INTO THE LOW/MID 80S BY FRI AHEAD OF
ANOTHER SYSTEM LIKELY TO BRING A RETURN OF RAIN BY THE SECOND
HALF OF FRI. A THREAT OF SHOWERS CONTINUES THROUGH MUCH OF THE
WEEKEND BEFORE THE FRONTAL SYSTEM EXITS EAST OF THE REGION BY
LATE IN THE WEEKEND. ON SUN, THE LATEST FORECAST PACKAGE CALLS
FOR HIGHS RETURNING TO THE 60S. THIS EVENTUALLY ALL LENDS ITSELF
TO A COOLER FINISH TO THE MONTH OF APRIL.
AVIATION /12Z MONDAY THROUGH FRIDAY/
A SECONDARY CLDFRNT WILL BRING GUSTS OF 20 TO 30 KNOTS TODAY
WITH A SPOTTY SHOWER POSSIBLE. CAN'T COMPLETELY RULE OUT SPOTTY
THUNDER GIVEN LOW FREEZING LEVELS AND SOME CAPE, BUT CONFIDENCE
IS TOO LOW FOR TS IN THE TAFS. HAVE ADDED TEMPOS FOR SHOWERS FOR
ABOUT AN HOUR AS THOSE SWING THROUGH LATE THIS MORNING.
OTHERWISE, VFR CONDITIONS TUE. WINDS SHIFT TO S BY TUE, THEN SW
WED. PREVAILING VFR CONDITIONS WED, ALTHOUGH A BRIEF REDUCTION
TO SUB-VFR CAN'T BE RULED OUT IN ANY SHRA.
BEHIND THE PROGRESSIVE MID-WEEK SYSTEM, VFR CONDITIONS ARE LIKELY
FOR THU INTO THE FIRST HALF OF FRI. WAA SHOWERS ARE POSSIBLE BY
FRI AFT WHICH COULD BE ACCOMPANIED BY A FEW RESTRICTIONS.
INITIAL WINDS WILL BE OUT OF THE NW ON THU BEFORE BECOMING
MAINLY W'LY ON FRI. A SHIFT TO SE'LY IS POSSIBLE BY FRI NIGHT.
MARINE
WINDS INCREASE AGAIN TODAY WITH A SECONDARY FRONT. A FEW SHOWERS
MAY BE ACCOMPANIED BY GUSTY WINDS LATE MORNING THROUGH MID
AFTERNOON, AND CAN'T RULE OUT AN SMW OR TWO. LIGHT WINDS
TONIGHT TURN S'LY TUE WITH ADDITIONAL SCAS POSSIBLE LATE TUE
INTO WED.
SUB-SCA LEVEL WINDS ARE EXPECTED LATE WED WITH WINDS OUT OF THE
SW/W.
EXPECT SUB-ADVISORY LEVEL WINDS FOR BOTH THU AND FRI. WEAK
GRADIENTS WILL FAVOR MULTIPLE WIND SHIFTS BEFORE TURNING MAINLY
S/SE BY FRI NIGHT.
FIRE WEATHER
SUBSTANTIAL DRYING OCCURRED YESTERDAY FOLLOWING A RELATIVELY
WEAK FRONTAL PASSAGE IN TERMS OF MOISTURE. GUSTY WINDS AND
MOSTLY SUNNY SKIES ALL AFTERNOON LIKELY SUFFICIENTLY DRIED FUELS
IN ANY AREAS THAT GOT LESS THAN A QUARTER INCH OF QPF. SOME
AREAS OF THE SHENANDOAH VALLEY AND CENTRAL VA PIEDMONT FALL
INTO THIS CATEGORY. THESE SAME AREAS HAVE BEEN THE DRIEST
RECENTLY, AND MAY ALSO END UP WITH THE LOWEST HUMIDITY THIS
AFTERNOON. THAT, COUPLED WITH THE BREEZY CONDITIONS, RESULTS IN
AN ELEVATED THREAT FOR THE RAPID SPREAD OF FIRES. THE POTENTIAL
OF A MORE SUBSTANTIAL CUMULUS FIELD, RECENT GREENUP, AND AT
LEAST SOME RAIN ACROSS THE AREA MAY KEEP A MORE SIGNIFICANT
THREAT AT BAY. HOWEVER, A FIRE DANGER SPECIAL WEATHER STATEMENT
REMAINS IN EFFECT FOR TODAY.
LWX WATCHES/WARNINGS/ADVISORIES
DC...FREEZE WARNING FROM 2 AM TO 10 AM EDT TUESDAY FOR DCZ001.
MD...FREEZE WARNING FROM 2 AM TO 10 AM EDT TUESDAY FOR MDZ003>006-
008-011-013-014-016>018-503>508.
VA...FREEZE WARNING FROM 2 AM TO 10 AM EDT TUESDAY FOR VAZ025>031-
036>040-050-051-053>057-501-502-505>508-526-527.
WV...FREEZE WARNING FROM 2 AM TO 10 AM EDT TUESDAY FOR WVZ051>053.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 PM EDT THIS EVENING FOR ANZ530-
531-535-536-538>540-542.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT TUESDAY FOR ANZ532>534-537-
541-543.
DISCUSSION...BRO/DHOF/CPB
AVIATION...BRO/DHOF/CPB
MARINE...BRO/DHOF/CPB
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