Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
331 FXUS61 KLWX 250800 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 400 AM EDT Thu Aug 25 2016 .SYNOPSIS...
-- Changed Discussion --
High pressure remains over the region today. A cold front will cross the region on Friday. High pressure will return for the weekend. Another front may slowly slide southward into the area by the middle of next week.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
-- Changed Discussion --
High pressure is offshore this morning, extending to the southern Appalachians. Decaying convection is moving into the upper Ohio Valley. The remnants of the convection and associated vort max has led to some timing changes in the forecast, albeit minor due to high uncertainty. Some showers may reach the northern Potomac Highlands shortly after daybreak, generally dissipating as they continue eastward. Despite the diurnal minimum, some showers may survive in an environment of theta-e advection/isentropic lift. Diurnal convection along the terrain which was originally forecast, may be minimized in the wake of the vort max, which will skim the northern part of the area. It may be difficult for much to develop toward the I-95 corridor due to lessening instability and the building upper level ridge. Decaying convection originating from near Lake Erie may make a run at the northern Potomac Highlands late this evening, but should have a difficult time making it into our area. In summary, convection may have more of a nowcasting component today, but definitely lowering chances with SE extent across the area. Otherwise, expect a good bit of cirrus originating from the convection, at least for the first part of the day. This may take a slight edge off temperatures, but locations from DC/CHO east have a reasonable shot at 90F. Dew points will also be rising into the lower 70s. For tonight, those higher dew points will prevent many from falling below 70F.
-- End Changed Discussion --
-- End Changed Discussion --
&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
-- Changed Discussion --
High pressure is offshore this morning, extending to the southern Appalachians. Decaying convection is moving into the upper Ohio Valley. The remnants of the convection and associated vort max has led to some timing changes in the forecast, albeit minor due to high uncertainty. Some showers may reach the northern Potomac Highlands shortly after daybreak, generally dissipating as they continue eastward. Despite the diurnal minimum, some showers may survive in an environment of theta-e advection/isentropic lift. Diurnal convection along the terrain which was originally forecast, may be minimized in the wake of the vort max, which will skim the northern part of the area. It may be difficult for much to develop toward the I-95 corridor due to lessening instability and the building upper level ridge. Decaying convection originating from near Lake Erie may make a run at the northern Potomac Highlands late this evening, but should have a difficult time making it into our area. In summary, convection may have more of a nowcasting component today, but definitely lowering chances with SE extent across the area. Otherwise, expect a good bit of cirrus originating from the convection, at least for the first part of the day. This may take a slight edge off temperatures, but locations from DC/CHO east have a reasonable shot at 90F. Dew points will also be rising into the lower 70s. For tonight, those higher dew points will prevent many from falling below 70F.
-- End Changed Discussion --
-- End Changed Discussion --
&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
Guidance remains in relatively good agreement in the long term. Sunday morning a ridge of high pressure aloft will be sitting squarely over the region. A weak shortwave passing to the north will weaken the high a bit on Monday but it will remain over the region. Another shortwave may then slowly slide southward into the area by Wednesday...possibly accompanied by a weak cold front. While we will start mostly dry early Sunday with the surface high sliding to the northeast...increasingly southerly flow will promote moisture advection which will help some terrain convection going. This will be aided by the weak disturbance and front by Wednesday. This so far ignores any potential impacts of any tropical systems which various pieces of guidance are depicting impacting the United States. Uncertainty becomes very high as we head into the middle of next week.
-- End Changed Discussion --
&& .AVIATION /08Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
Increasing high clouds this morning, which should put a damper on fog, although MRB is nearing its dew point. Today`s forecast is somewhat uncertain in regards to convection, as activity currently over Ohio should diminish as it crosses the mountains, although a few showers could survive, especially to MRB. Very little storms may redevelop however, and ones that do should be isolated. Mention will not be included in the TAFs at this time. Due to possibility of cloud cover and a light wind, fog formation for tonight is also in question. A weak front will slip through the area on Friday, with little more than a wind shift. While a rogue storm can`t be ruled out, it`s a very low probability. VFR conditions expected Saturday with high pressure to the north. Mainly VFR in the long term.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
Increasing high clouds this morning, which should put a damper on fog, although MRB is nearing its dew point. Today`s forecast is somewhat uncertain in regards to convection, as activity currently over Ohio should diminish as it crosses the mountains, although a few showers could survive, especially to MRB. Very little storms may redevelop however, and ones that do should be isolated. Mention will not be included in the TAFs at this time. Due to possibility of cloud cover and a light wind, fog formation for tonight is also in question. A weak front will slip through the area on Friday, with little more than a wind shift. While a rogue storm can`t be ruled out, it`s a very low probability. VFR conditions expected Saturday with high pressure to the north. Winds mainly sub SCA in long term.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING...
-- Changed Discussion --
Increased southerly flow will cause water levels to rise today. By tonight, caution stage will be reached at several sites on the Bay. Annapolis could approach minor flood, although not all guidance sources support that solution. Winds will become west on Friday, so there should not be a concern beyond the Thursday night cycle.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 2 AM EDT Friday for ANZ531>533- 539>541. Small Craft Advisory until 6 AM EDT Friday for ANZ534-543. Small Craft Advisory until 6 AM EDT early this morning for ANZ536-537.
-- End Changed Discussion --
&& $$ SYNOPSIS...RCM NEAR TERM...ADS SHORT TERM...ADS LONG TERM...RCM AVIATION...ADS/RCM MARINE...ADS/RCM TIDES/COASTAL FLOODING...HTS/RCM

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.