Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 151845 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 245 PM EDT Sun May 15 2022 .SYNOPSIS... A cold front will approach from the west today before passing through the area Monday. High pressure will briefly return for Tuesday before a warm front slowly passes through the area during the middle and latter portions of the week. && .NEAR TERM /THROUGH TONIGHT/...
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Low clouds that were in place this morning have mainly broken up and most of the region is experiencing partly to mostly sunny conditions. Some low broken clouds still remain in place around the Baltimore metro but I expect these clouds to continue eroding over the next few hours. Mostly clear conditions has allowed for good mixing and afternoon temperatures are currently in mid to upper 70s and lower 80s. Environmental destabilization has already occurred west of the Blue Ridge Mtns where clouds cleared our much early this morning. Showers along with with few thunderstorms have formed west of the I-81 corridor this afternoon ahead of a weak shortwave trough approaching from the west. Based on current HiRes guidance, it seems the HRRR has the right placement for storms but is running too slow on the timing. Based on models soundings, the lowest 5000 feet will become well mixed and there will be little to know CIN to prevent upward movement of air. Between 1000 and 1500 CAPE is forecast for most of the region this afternoon but mixed layer shear is expected to remain below 30s knots. I believe most of the region will experience some brief showers with isolated to scattered thunderstorms through this evening. Based on soundings, some storms have the potential to become strong to severe and produce some damaging winds and large hail. WPC has parts of our region in marginal risk for flooding mainly due to a slow storm motion but I believe the threat will be isolated in nature. The threat for thunderstorms should steadily drop off after 8pm this evening with dry conditions mainly expected overnight. Light winds and clearing of skies overnight night may lead some patchy dense fog.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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A strong neutrally to nearly negatively tilted upper level trough is expected to pass through the our region on Monday. At the surface, a strong cold front is forecast to approach from the west and pass through the region Monday into early Tuesday. Ahead of the frontal passage, a strong south to southwesterly flow will lead to advection of warm and moist air into the region. HiRes guidance has started trending upwards with some morning convection models show passing through areas along and east of the I-95 corridor on Monday. This pre-morning convection may work over areas along the I-95 corridor and slow afternoon destabilization ahead of the frontal passage. Elsewhere, daytime heating should combine with warm air advection to allow for a well mixed boundary layer ahead of the cold front. Winds are forecast to increase aloft with nearly unidirectional winds increasing to nearly 60s knots at 10,000 feet. The combination of strong speed shear, CAPE above 1500 j/kg and a strong frontal boundary/nearly negative trough will lead to an enhanced risk for severe weather on Monday. I believe the main storm mode will be QLCS in nature but I can`t rule out a few isolated pulse/supercells. The main hazards should be damaging winds, large hail and possibly a tornado. SPC has most of our region in an enhance risk for severe weather with a slight risk elsewhere. I believe the main window for storms will be between noon and 9pm. Showers should taper off by midnight and dry conditions are expected through Tuesday. High pressure builds over our region on Tuesday with near average temperatures and winds out of the west to northwest.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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Weak high pressure early on Wednesday will be moving offshore later in the day. Clouds and showers potentially associated with a decaying MCS over the OH Valley early Wed are fcst to roll through the area Wed afternoon and early evening. There won`t be enough moisture return yet to be concerned for severe wx yet at that time. A warm front will become established across southern VA late Wed night and Thursday. Guidance continue to suggest risk of one or two MCSs forming somewhere across the region, but continue to disagree in location and timing. During the past 24 hrs, the ECMWF has been the most consistent in terms of timing and location suggesting a complex of t-storms developing along a warm front in central VA generally south of I-64 while the GFS has been farther north generally north of I-64. There could be multiple episodes of t-storms moving through the region during the late Wed night - Thu evening time frame according to the ECMWF. At this time, it seems like the Thu afternoon-Thu evening poses the bigger risk of causing problems. By Fri afternoon, models agree in lifting warm front north of the area with t-storm chances decreasing. By the second half of the weekend, notable differences are seen among the global models when looking at 500 mb height plots with the ECMWF holding onto higher heights and GFS showing lower heights. There have also been less than optimal consistency among models to buy into any single solution.
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&& .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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Clouds have cleared over most of our terminals this after with some lingering MVFR ceilings over the BWI and MTN terminals. VFR conditions expected this afternoon at all terminals with a threat for some afternoon showers and thunderstorms. Low MVFR/IFR ceilings and visibilities are expected to return for all terminals during the overnight periods and into early Monday morning. An enhanced threat for severe thunderstorms will exist for our terminals on Monday. The main hazards will be strong gusty winds and possibly some hail. Dry and VFR conditions return on Tuesday. Risk of MCS Thu afternoon and evening across central VA. This is the time frame and location where models have been the most consistent showing convection.
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&& .MARINE...
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SubSCA conditions expected through Monday morning but some thunderstorms will be possible over our waters this evening. Further strong to severe thunderstorms will be possible due to a frontal passage. SCA conditions are likely Monday afternoon with further SCA conditions possible through Tuesday. Risk of t-storms seems to be the greatest concern in the Thu afternoon and evening primarily across the southern waters.
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&& .TIDES/COASTAL FLOODING...
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Action stages are possible next 36 hrs, but flooding appears unlikely at this time.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from noon to 6 PM EDT Monday for ANZ530>543. && $$ SYNOPSIS...BJL NEAR TERM...JMG SHORT TERM...JMG LONG TERM...LFR AVIATION...LFR/JMG MARINE...LFR/JMG TIDES/COASTAL FLOODING...LFR

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