Area Forecast Discussion
Issued by NWS Sterling, VA

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252 FXUS61 KLWX 240743 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 343 AM EDT Mon Oct 24 2016 .SYNOPSIS... A cold front will cross the central Mid-Atlantic this morning. High pressure will return to the region through midweek. Low pressure will cross to the north late in the week with the cold front crossing the area Thursday into Thursday night. High pressure returns for Friday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A cold front currently stretches across Pennsylvania and down the Ohio Valley. Clouds and showers can be found behind the front, where better vorticity resides. However, there is a southwesterly low level jet ahead of the front containing winds of 50-55 kt. RAP soundings suggest the jet drops as low as 1500-2000 ft. Since midnight there have been a few 40-45 kt gusts. Have opted to issue a short-fused wind advisory for the mountains. Am running this through 12 UTC. Guidance suggests threat may diminish an hour or two earlier than that, but want to cover whole threat window. The front itself sags across the forecast area this morning. It`s moisture starved so am not anticipating any showers (not really even in the mountains), but there could be some associated cloud cover. A wind shift to northwest will be the primary indicator of a frontal passage. Although cold advection will be ongoing after that, so will downslope flow. MOS overall running fairly consistent, and not much cooler than yesterday (except for the Potomac Highlands). Have made no adjustments to current high temperature forecast. Model sounding suggest that winds will diminish with fropa. Mixing behind the front supports 25-30 kt-- a breezy day but not headline- able. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... The gradient will relax a bit and decouple as well. Although the airmass will be chilly, it will remain well mixed which will impede radiational cooling. Do not have any frost concerns tonight due to those winds. The Central Shenandoah Valley may prove to be an exception, but it would be premature to issue Frost Advisories at this juncture. Highland and Pendleton even have freeze potential. That will be placed in the Hazardous Weather Outlook. Tuesday and Wednesday will be quieter days as high pressure builds. That will allow for decoupling and radiational cooling Tuesday night. Hence, there is a strong possibility for areas of frost over a good portion of the area. Growing seasons could end for some counties. This too will be placed in the HWO. Temperatures both days will likely be in the 50s. Solutions becoming a little more progressive, bringing in isentropic lift Wednesday night...primarily west of the Blue Ridge. Guidance has gone more aggressive with POPs, and have included a chance for overnight rain in the aforementioned areas. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Low pressure will be moving across the southern Great Lakes Thursday while an associated strong cold front moves through the Ohio Valley. Southerly flow will increase Thursday and showers are expected to move from west to east Thursday and Thursday night. Windy conditions are possible behind the frontal passage. The cold front will move to the east by late Thursday night/Friday morning and showers will taper off across the region. Rainfall amounts should stay under a half inch through Friday. High pressure will briefly move into the region Friday and Friday night before another low pressure system moves into the Great Lakes. A cold front should cross the region this weekend. Temperatures should be seasonable if not cooler than normal through the weekend. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... Low level wind shear risk early this morning as a 40-50 kt jet resides at/above 1500 ft above the surface. Have included comment in TAFs. Thats the primary concern as VFR conditions will prevail. A dry cold front will cross the terminals this morning. Winds will veer northwesterly during the morning push. Behind fropa, mixing will support gusts 25-30 kt through sunset. Will still have northwest flow Tuesday, but winds will be on the order of 10-20 kt during the day, and become light Tuesday night. A cold front will cross the terminals Thursday-Friday and may cause flight restrictions. && .MARINE... Southwest winds on the waters will veer northwest this morning as a cold front crosses. Small Craft Advisory being realized on the Bay and lower Potomac. There is a low level jet with higher winds inland. Do not believe mixing will be present to bring these winds down. Behind the front mixing will improve, but winds at that time will be in the 25-30 kt range. Therefore have maintained SCA for all waters. Have extended Advisory for the Bay and lower Potomac into Tuesday as momentum transfer looks like it will support at least minimal SCA gusts. A cold front will approach the waters Thursday and SCA possible Thursday-Friday. && .FIRE WEATHER... Will have gusty northwest winds today. Where the winds forecast to be the greatest (gusts up to 30 mph), relative humidity may fall just above Red Flag criteria (near 40%). Lower RHs will coincide with less wind. Fuels also look to be on the edge. Will advise dayshift to consult with Fire Officials this morning. A statement may prove to be prudent. && .TIDES/COASTAL FLOODING... Water level currently below astronomical normals. Strong northwest winds will arrive today, which will be responsible for blow out tides. Levels could drop greater than a foot below normal. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Wind Advisory until 8 AM EDT this morning for MDZ501. VA...Wind Advisory until 8 AM EDT this morning for VAZ503-504-507- 508. WV...Wind Advisory until 8 AM EDT this morning for WVZ501>503-505- 506. MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ530>534- 537>543. Small Craft Advisory from 9 AM this morning to midnight EDT tonight for ANZ535-536. && $$ SYNOPSIS...HTS/HSK NEAR TERM...HTS SHORT TERM...HTS LONG TERM...HSK AVIATION...HTS/HSK MARINE...HTS/HSK FIRE WEATHER...HTS TIDES/COASTAL FLOODING...HTS is the U.S. government's official web portal to all federal, state and local government web resources and services.