595
FXUS61 KLWX 160902
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
402 AM EST MON DEC 16 2024
SYNOPSIS
AS LOW PRESSURE TRACKS NORTH OF THE GREAT LAKES, A WARM FRONT WILL
REMAIN NEAR THE AREA TODAY, WITH THE TRAILING COLD FRONT SWEEPING
EASTWARD EARLY TUESDAY. BRIEF HIGH PRESSURE FOLLOWS TUESDAY
BEFORE ANOTHER LOW PRESSURE SYSTEM AFFECTS THE AREA WEDNESDAY.
HIGH PRESSURE WILL CROSS THE AREA THURSDAY WITH ANOTHER LOW
APPROACHING THE GREAT LAKES BY FRIDAY.
NEAR TERM /THROUGH TONIGHT/
A SHORTWAVE TROUGH IS OVER NEW YORK THIS MORNING WITH A
SHORTWAVE RIDGE OVER THE OHIO VALLEY. AT THE SURFACE, SLIGHTLY
WEAKER HIGH PRESSURE IS SOUTH OF NOVA SCOTIA WITH LOW PRESSURE
NEAR NORTHWEST MINNESOTA. WIDESPREAD RAIN IS NOW PUSHING EAST OF
THE BLUE RIDGE AND WILL LARGELY BE EAST OF THE CHESAPEAKE BY 8
AM. HOWEVER, PATCHY DRIZZLE WILL BE POSSIBLE IN THE WAKE AS SOME
DRYING OCCURS ALOFT BUT LOW LEVELS REMAIN SATURATED. SOME AREAS
IN THE NORTHWESTERN PORTION OF THE CWA REMAIN AT OR BELOW
FREEZING. HOWEVER, THE REMAINING HEADLINES WILL LIKELY BE
DROPPED SOON SINCE IT APPEARS IMPACTFUL PRECIPITATION HAS ENDED
AND MORE LOCATIONS ARE EDGING WARMER. SO FAR FOG HAS NOT BEEN
DENSE (OTHER THAN WHERE CLOUDS INTERSECT THE HIGHER TERRAIN),
BUT WILL MONITOR THAT AS THE STEADIER RAIN EXITS.
THE SHORTWAVE RIDGE WILL PROVIDE RELATIVELY DRIER CONDITIONS
MUCH OF THE DAY, ALTHOUGH AS MENTIONED DRIZZLE MAY CONTINUE WITH
SHALLOW OVERRUNNING OF THE REMNANT COLD AIR DAMMING AIR MASS. IT
SEEMS UNLIKELY LOW CLOUDS WILL BREAK GIVEN A WEAK PRESSURE
GRADIENT RESULTING IN LITTLE MIXING OF THE SHALLOW COLD AIR. THE
MOST LIKELY AREAS TO REACH THE 50S ARE THE CENTRAL SHENANDOAH
VALLEY AND SOUTHERN MARYLAND WHERE THE WEDGE FRONT WILL BE MORE
LIKELY TO CLEAR DESPITE THE CLOUDS. THE NORTHWESTERN COLD POCKET
MAY STRUGGLE TO REACH 40 HOWEVER.
A SHORTWAVE AHEAD OF THE NEXT SYSTEM WILL BRING ANOTHER ROUND OF
RAIN INTO THE AREA LATE THIS AFTERNOON INTO TONIGHT. THE HIGHEST
RAIN TOTALS WILL BE CLOSER TO THE PENNSYLVANIA BORDER, WITH
STILL SOME QUESTION JUST HOW FAR SOUTH PRECIPITATION REACHES
GIVEN THE TRACK OF THE BEST LIFT AND DEEP MOISTURE. A
STRENGTHENING GRADIENT WILL CAUSE SOUTHERLY WINDS TO INCREASE
OVERNIGHT, WITH TEMPERATURES HOLDING STEADY OR RISING. IF THE
SHALLOW STABLE LAYER HANGS ON THOUGH, FOG COULD DEVELOP. WIND
GUSTS COULD EXCEED 40 MPH ON THE HIGHER RIDGES.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
THE TRAILING COLD FRONT WILL PUSH THROUGH EARLY TUESDAY MORNING.
GIVEN A WESTERLY DOWNSLOPING WIND AND LACK OF COLD AIR BEHIND
THE FRONT, TEMPERATURES WILL ACTUALLY BE WARMER TUESDAY, RANGING
FROM THE MID 50S TO MID 60S. HIGH PRESSURE QUICKLY CROSSES THE
AREA TUESDAY NIGHT WITH LOWS NEAR TO SLIGHTLY ABOVE NORMAL.
THE NEXT LOW PRESSURE SYSTEM WILL SKIRT THE AREA WEDNESDAY INTO
WEDNESDAY NIGHT. ANOTHER WAVE OF RAIN IS LIKELY, ALTHOUGH THERE
IS STILL SOME MODEL SPREAD ON THE AMOUNTS AND COVERAGE. IF
PRECIPITATION STARTS EARLY ENOUGH, THERE IS A VERY SMALL CHANCE
OF SOME WINTRY PRECIPITATION IN THE MOUNTAINS TO START. HOWEVER
THE AIRMASS WILL BE MILD OVERALL (HIGHS REACHING THE 40S AND
50S), SO RAIN SHOULD PREVAIL. THUNDERSTORMS MAY NOT BE THAT FAR
SOUTHEAST OF THE AREA. GUSTY WINDS, ESPECIALLY IN THE MOUNTAINS,
WILL OCCUR AS THE COLD FRONT CROSSES WEDNESDAY NIGHT. IN THE
WESTERN UPSLOPE AREAS OF THE ALLEGHENIES, PRECIPITATION WILL
CHANGE OVER TO SNOW, BUT AMOUNTS APPEAR TO BE LIGHT AT THIS
TIME.
LONG TERM /THURSDAY THROUGH SUNDAY/
WITH THE COLD FRONT EAST OF THE AREA, NW FLOW WILL PERSIST THURSDAY.
A FEW UPSLOPE SNOW SHOWERS ARE POSSIBLE DURING THE MORNING HOURS
ACROSS THE ALLEGHENIES THURSDAY, BUT SHOULD END BY MIDDAY AS DRIER
AIR MOVES IN. COME FRIDAY, A CLIPPER EMBEDDED IN NW FLOW WILL BRING
THE POTENTIAL FOR ADDITIONAL SNOW CHANCES ACROSS THE ALLEGHENIES.
SOME MODELS HAVE A LITTLE MOISTURE SPILLING EAST OF THE MOUNTAINS,
BUT LOW CONFIDENCE IN THAT OCCURRING AT THIS TIME. UPSLOPE SNOW
SHOWERS WITH A GREAT LAKE ENHANCEMENT COULD CONTINUE INTO SATURDAY
BEFORE HIGH PRESSURE BUILDS BACK IN SUNDAY.
THE BIG STORY WILL BE THE WELL BELOW NORMAL TEMPERATURES LATER THIS
WEEK INTO THIS WEEKEND. HIGHS THURSDAY WILL BE NEAR TO SLIGHTLY
BELOW AVERAGE. THIS WILL BE THE WARMEST DAY OF THE LONG TERM, WHICH
IS NOT SAYING MUCH. A CONTINUED DOWNWARD TREND IN TEMPS IS EXPECTED
THROUGH THE WEEKEND AS MODIFIED CANADIAN/ARCTIC AIR MOVES INTO THE
AREA. HIGHS SUNDAY MAY BE THE COLDEST OF THE SEASON THUS FAR. SINGLE
DIGIT TO TEENS WIND CHILLS POSSIBLE FRIDAY THROUGH SUNDAY,
ESPECIALLY OVERNIGHT AND EARLY IN THE MORNING.
AVIATION /09Z MONDAY THROUGH FRIDAY/
IFR TO LIFR CONDITIONS ARE EXPECTED THROUGH MUCH OF THE TAF
PERIOD WITH ANY LIFTING OF THE CEILINGS EXPECTED TO BE FLEETING.
SO FAR DENSE FOG HAS NOT BEEN AN ISSUE, BUT VISIBILITIES WILL
LIKELY BE LOW THROUGH AT LEAST MID MORNING. ON WAVE OF RAIN WILL
MOVE EAST BY 12Z, ALTHOUGH PATCHY DRIZZLE COULD OCCUR MUCH OF
THE DAY. WINDS WILL BE LIGHT, GRADUALLY TURNING FROM NE TO SE.
ANOTHER WAVE OF RAIN WILL MOVE ACROSS THE AREA THIS EVENING.
THERE ARE SOME UNCERTAINTIES WITH FOG AND LOW CLOUDS THROUGH THE
NIGHT, DEPENDING ON HOW MUCH INCREASING SOUTHERLY FLOW CAN ERODE
THE SURFACE STABLE LAYER. IF IT CAN, GUSTS TO AROUND 20 KT CAN
BE EXPECTED, IF NOT, THERE COULD BE LLWS. AS THE COLD FRONT
CROSSES EARLY TUESDAY MORNING, WINDS WILL SHIFT TO THE WEST AND
LOW CLOUDS WILL CLEAR OUT.
HIGH PRESSURE SHOULD PROVIDE VFR CONDITIONS INTO TUESDAY NIGHT.
SUB-VFR CONDITIONS ARE POSSIBLE WEDNESDAY INTO WEDNESDAY NIGHT
AS ANOTHER LOW PRESSURE SYSTEM BRINGS RAIN TO THE REGION.
SUB-VFR CONDITIONS POSSIBLE EARLY THURSDAY BEFORE IMPROVEMENT BY THE
AFTERNOON. VFR CONDITIONS LIKELY PERSIST THROUGH FRIDAY, THOUGH A
SYSTEM MAY BRING RESTRICTIONS LATER IN THE DAY.
MARINE
LIGHT N TO E WINDS WILL CONTINUE TO GRADUALLY TURN SOUTHERLY BY
TONIGHT. WINDS WILL INCREASE OVERNIGHT, ALTHOUGH THERE IS SOME
UNCERTAINTY ON HOW MUCH GIVEN A LINGERING NEAR SURFACE STABLE
LAYER. HAVE ISSUED AN ADVISORY ALONG THE BAY FOR NOW. A COLD
FRONT WILL CROSS THE AREA EARLY TUESDAY. WESTERLY POSTFRONTAL
WINDS MAY REQUIRE AND ADVISORY FOR MAINLY NORTHERN PORTIONS OF
THE WATERS, BUT CONFIDENCE IS LOW. LIGHT WINDS WITH HIGH
PRESSURE ARE EXPECTED TUESDAY NIGHT INTO WEDNESDAY. ANOTHER LOW
PRESSURE SYSTEM WILL LIKELY RESULT IN SCA CONDITIONS BEGINNING
WEDNESDAY NIGHT.
SCA CONDITIONS ARE POSSIBLE ACROSS ALL WATERS THURSDAY AS THE SYSTEM
DEPARTS WITH A REMNANT GRADIENT LEFT BEHIND OVER THE WATERS. WINDS
LIKELY SUBSIDE LATE THURSDAY INTO FRIDAY BELOW SCA CRITERIA.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST
TUESDAY FOR MDZ008.
WINTER STORM WARNING UNTIL 7 AM EST THIS MORNING FOR MDZ001-
501.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR MDZ003-
502.
VA...WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR VAZ027-
028-031.
WV...WINTER STORM WARNING UNTIL 7 AM EST THIS MORNING FOR WVZ501-
503.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR
WVZ050>053-055-502-504.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST
TUESDAY FOR ANZ530>534-537-539>541-543.
SYNOPSIS...ADS
NEAR TERM...ADS
SHORT TERM...ADS
LONG TERM...CPB
AVIATION...ADS/CPB
MARINE...ADS/CPB
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