Area Forecast Discussion
Issued by NWS Sterling, VA

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158 FXUS61 KLWX 180140 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 940 PM EDT Wed May 17 2017 .SYNOPSIS...
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High pressure will remain centered over Bermuda through Saturday. A cold front will move south through the area late Friday before stalling to our south on Saturday. The boundary will return north as a warm front Sunday before a stronger cold front from the west passes from the west through Monday into Monday night. High pressure looks to return to the region Tuesday.
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&& .NEAR TERM /THROUGH THURSDAY/...
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Models did a great job of identifying the low chance for thunder from the northern Shenandoah Valley NW to PA this afternoon over the past few days. That activity has waned. South winds and high clouds will keep temps up; generally mid to upper 60s inland to low 70s near shore. A nocturnal 35-40kt jet at 950 mb is expected to develop tonight in response to the contrast between the cold Atlantic and the warm air mass in place. However, inversion is quickly setting up and will not allow much of this wind to translate to the surface.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
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Thursday will start out much like today, but with surface dewpoints increasing 5-10 degrees above today, expecting more of an afternoon cumulus field. MAV guidance has decreased max temps by a couple of degrees for Thursday, but still expecting 90F+ in most areas. Blended ER Superblend with MAV/MET for temps. A weak trough in advance of the low crossing the Great Lakes Thursday provides slightly more forcing than today. Will add low chances for late afternoon/evening thunderstorms. Friday looks to have a good chance of showers and thunderstorms as a cold front drops through the region right about peak heating. Models CAPES are around 1000-1500 j/kg but only 20 kts of 0-6km shear, so expecting mainly non-severe day and evening.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Ridging aloft will persist over the area as high pressure wedges in from the northeast at the surface Saturday. The cold front that is forecast to cross the area from north to south at the end of the week will stall near the VA/NC border during this time, then return slowly north as a warm front by late Sunday. A broken overcast is likely over the weekend with easterly flow off the ocean. This will result in cooler temperatures closer to normal for this time of year (highs in the 70s, lows in the 50s). Despite the clouds, precipitation chances should be minimal over the weekend. Models continue to oscillate with regards to the timing of frontal passage on Monday. This front will bring the next chance of showers and possibly thunderstorms, but convective potential will rely heavily 1) on the exact timing of frontal passage, and 2) the amount of cloud cover/cloud debris from prior day`s convection over the Midwest. Moisture and shear both increase along/ahead of the cold front/shortwave driving it so storms that do develop will have the potential for organization if there is enough instability present. Behind the front, a slightly cooler/noticeably drier airmass will move in for later Tuesday into Wednesday of next week. && .AVIATION /02Z THURSDAY THROUGH MONDAY/...
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VFR conds continue through Thursday. Low chances for thunderstorms across the DC metros Thursday evening as a weak trough crosses. Chances for thunderstorms Friday as a cold front crosses from the north late. Sub-VFR psbl at times over the weekend w/ lower CIGS in moist ELY flow 10-15 kts.
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&& .MARINE...
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South winds generally 10 to 15 knots. Shrank SCA to southern MD waters where a few 18kt gusts have occurred. Midnight shift will continue to monitor and make adjustments as necessary. Southerly flow continues Thursday with more channeling possibility Thursday evening. Cold front pushes south through the waters late Friday. SCA possible Friday night. Small Craft Advisory conditions may continue for portions of the waters over the weekend in easterly flow between high pressure to the north and a stalled front to the south.
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&& .CLIMATE...
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Near record heat is expected to continue through Thursday. Below are the highs for today and record high temps for Thursday, May 18. Today`s (5/17) High and Record Highs: DCA: Today: 91F. Record remains 92 in 1974, 1896 and 1877 BWI: Today: 93F. Ties record with 1896 IAD: Today: 92F. Beats former record 89 in 1986 Thursday (05/18) Record Warm Lows: DCA: 72 in 2015 BWI: 68 in 1900 and 1896 IAD: 68 in 2015 Thursday (05/18) Record Highs: DCA: 96 in 1877 BWI: 97 in 1962 IAD: 91 in 1987
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 10 AM EDT Thursday for ANZ533-534- 537-543.
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&& $$ SYNOPSIS...BAJ NEAR TERM...BAJ/Lee SHORT TERM...Lee LONG TERM...DFH AVIATION...BAJ/Lee/DFH MARINE...BAJ/DFH CLIMATE...DFH/BAJ

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