Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 010859 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 359 AM EST Fri Mar 1 2024 .SYNOPSIS...
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High pressure will move offshore of the Delmarva to a position southeast of New England through this evening, then move further offshore through Saturday while low pressure developing near the Southeast coast drifts northward. Low pressure will depart out to sea by early next week with high pressure briefly building in its wake. A cold front will approach from the Ohio River Valley as an area of low pressure approaches from the Gulf Coast during the middle of next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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With high pressure situated directly overhead, most locations have gone calm. Skies are also mostly clear, with just a few passing high clouds from the Central Shenandoah Valley to Southern Maryland. As a result, most locations have radiated well, with temperatures generally dropping back into the 20s. High pressure will progress offshore today, allowing for southerly return flow to develop. Mostly sunny skies are expected this morning, with clouds increasing through the afternoon hours. Conditions should remain dry through the daylight hours, with temperatures recovering nicely through the day. High temperatures will be in the upper 40s to mid 50s for most, with low-mid 40s in the mountains. A shortwave trough embedded in west-southwesterly flow aloft will approach the area from the Ohio Valley tonight. As warm/moist advection ensues at low levels out ahead of the shortwave, precipitation will break out across the area this evening into the first half of the overnight. This system should be all rain for the vast majority of the forecast area. However, precipitation is expected to start as freezing rain in the highest elevations of the Alleghenies. A Winter Weather Advisory is in effect for western Highland, western Pendleton, and western Grant counties, where a glaze to a tenth of an inch of ice is forecast. A brief period of freezing rain can`t be ruled out in the highest elevations of Garrett, eastern Highland, eastern Pendleton, Rockingham, and Augusta Counties, as well as along the Blue Ridge, but confidence was currently too low to issue Winter Weather Advisories. All locations should change over to all rain by around 2 AM. Rain will continue for all through the night.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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Low pressure will develop offshore and lift northeastward toward the southern New England coastline on Saturday. Conditions should start out rainy, but trend drier throughout the day. Storm total precipitation values are expected to be between a half of an inch and an inch for most. High temperatures on Saturday are forecast to be in the 50s for most. High pressure will build overhead for Sunday, leading to drier condtions and a warming trend. Mostly cloudy conditions are expected to start the day, with increasing sunshine during the afternoon. High temperatures are expected to be in the low-mid 60s for most, with upper 50s in the mountains.
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&& .LONG TERM /MONDAY THROUGH THURSDAY/...
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Much of next week looks rather unsettled as broad troughing moves slowly from the central to eastern CONUS. Embedded within this larger scale trough will be two main surface features of interest: (1) a surface cold front moving west-to-east from the Mississippi River and Ohio River Valleys, and (2) a surface low developing over the Gulf Coast that looks to trek northward. This spells a rather prolonged period of precipitation chances beginning Tuesday afternoon and lingering through the end of the week. At the moment, the highest potential (likely/55-74%) of rain appears to be Wednesday and Wednesday night. This is the most likely time period for precipitation from the low approaching from the south to ride up ahead of the cold front approaching from the west. Ensembles are indicating medium chances of rainfall amounts around 0.50-1.00"+ in the 24-hour period ending 12z/7am EST Thursday, which makes sense given forcing ahead of the trough/low/front combining with moisture streaming up from the Gulf of Mexico. Given that these are not particularly excessive amounts and we will be several days removed from any prior significant rain, flooding risk seems low. However, if there is more amplification and interaction between the two systems, and/or a slower progression allowing more anomalous moisture advection into the region, that risk level could go up. By the end of next week, guidance has a broad area of lower SLP anomalies to the south and west with broad troughing lingering over the central CONUS, signaling the potential for unsettled weather persisting into next weekend (CPC highlights a slight risk of heavy precipitation during this time in their Week 2 Hazards Outlook).
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&& .AVIATION /09Z FRIDAY THROUGH TUESDAY/...
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VFR conditions are expected through the daylight hours today. Winds will be light out of the southeast this morning, before increasing to around 10 knots out of the south to southeast this afternoon. Rain will overspread the area tonight and continue through tomorrow morning. IFR conditions appear likely late tonight into tomorrow morning in association with low ceilings. Slow improvement is expected through the day tomorrow, with VFR conditions again by tomorrow night. Sub-VFR conditions are possible Mon-Tue in light onshore flow.
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&& .MARINE...
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Winds will be light out of the southeast this morning, before picking up a bit this afternoon into this evening. A Small Craft Advisory is in effect for the majority of the waters this afternoon, with the SCA winds lingering through the evening across the widest waters of the Bay and Lower Tidal Potomac. After a brief decrease in the winds overnight, winds will pick up again out of the east across the Lower Tidal Potomac and central portions of the Bay tomorrow morning as low pressure passes to our south. SCA conditions are expected through the mid-afternoon hours tomorrow in those locations. Thereafter, sub-SCA winds are expected through Sunday. Generally light (sub-SCA) onshore flow is forecast Monday- Tuesday.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...Winter Weather Advisory from 5 PM this afternoon to 1 AM EST Saturday for VAZ503. WV...Winter Weather Advisory from 5 PM this afternoon to 1 AM EST Saturday for WVZ501-505. MARINE...Small Craft Advisory from 1 PM this afternoon to 7 PM EST this evening for ANZ531-532-536-538>540. Small Craft Advisory from 1 PM this afternoon to 11 PM EST this evening for ANZ533-534-537-541>543. Small Craft Advisory from 7 AM to 4 PM EST Saturday for ANZ533- 534-537-541>543.
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&& $$ SYNOPSIS...DHOF NEAR TERM...KJP SHORT TERM...KJP LONG TERM...DHOF AVIATION...DHOF/KJP MARINE...DHOF/KJP

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