Area Forecast Discussion
Issued by NWS Wakefield, VA

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408 FXUS61 KAKQ 240250 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 950 PM EST Thu Jan 23 2020 .SYNOPSIS... High pressure continues to slide offshore tonight. Low pressure tracks across the region Friday night and Saturday morning. Another area of high pressure builds toward the area early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 1000 PM EST Thursday... Surface high pressure continues to pull off to the northeast, allowing warming and more humid air to move into the region. Temperatures have quickly dropped into the 30s (low 40s along the southeast VA and northeast NC coast). Temperatures are expected to remain steady throughout the night with overcast skies and increasing dew points. The upper ridge slides farther offshore tonight as the aforementioned (vigorous) closed upper low digs across the Mississippi Valley. High clouds continue to increase through the night while low stratus overspreads the western half of the CWA from the south late tonight. Lows tonight range from the low 30s NW to upper 30s/low 40s SE, and these values will likely be achieved during the evening to early overnight hours, before becoming steady inland and rising toward the coast (especially after 4 AM). Cannot rule out a sprinkle or two over the Piedmont later tonight, but have kept PoPs aob 14% throughout the CWA through 12z/7 AM Friday. In addition, there is a chance of some patchy fog across portions of srn VA/NE NC (where some model soundings show an increase in low- level moisture along w/ a developing inversion). 12z/23 HREF probs of VSBY < 1/2 mile are ~50% in parts of interior NE NC after 4 AM. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/... As of 330 PM EST Thursday... The upper-level low moves NE through the Ohio Valley toward the Ern Great Lakes Friday into Saturday. Moisture will be transported north due to SSW flow aloft through the day Friday allowing for a chc of showers W of I-95 beginning by late morning/early afternoon. However any showers during the daylight portion of the day will be isolated and very light ahead of the main line of convective showers arriving overnight. In-situ wedging appears weaker given a slower onset to rain in the piedmont and have therefore increased highs to the low- mid 50s over the piedmont and Ern Shore, to the mid-upper 50s across central VA, and to the low-60s for far SE VA/NE NC. The main line of showers appears to be delayed, per latest guidance, until late Friday night into early Saturday morning. However, the line will move quickly and any one location can expect a window of about 3 hours of precip once the line reaches you. That being said, latest guidance suggests that the line will be more robust/convective than previously expected and therefore rain will be moderate to occasionally heavy. The line also appears to stay intact further east than originally expected. Have therefore increased QPF to 1.0- 1.25 inches west of I-95, 0.5- 1.0 inches over most of the CWA east of I-95, and 0.25- 0.5 inches in far SE VA/NE NC. Cannot completely rule out a stray rumble of thunder, but thunder is not expected at this time. Temperatures Friday night will be mild and range from the mid-upper 40s across the piedmont and NE counties through the Ern Shore and from the low-mid 50s in central Va southward into NE NC. Saturday will be another mild day with highs in the mid-upper 50s everywhere except SE VA and NE NC where low 60s are possible once again. Clouds clear out by Saturday night allowing temperatures to cool to the low 30s in the NW to the upper 30s in the SE. High pressure returns Sunday with near seasonal temperatures in the upper 40s to low 50s across the CWA. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 330 PM EST Thursday... Dry/seasonable conditions prevail through at least Wednesday with west to northwest flow at the surface and aloft along w/ weak sfc high pressure to our N. Any Arctic air will be well to our north (across central/nrn Canada) through the extended period and potentially well beyond that. Highs will mainly range from the upper 40s-mid 50s from Mon-Wed, with morning lows in the low-mid 30s in most areas (except for some upper 30s across coastal SE VA/NE NC). There is less agreement in the models as we head into the late week period. The 12z/23 GFS is forecasting high pressure to settle across the area by late Thu night, while upper troughing deepens over the central CONUS (w/ sfc low pressure developing along the wrn Gulf coast). The ECMWF/GEM are forecasting a weak shortwave trough to approach our area from the W during by Thursday timeframe as low pressure develops off the Carolina coast. The ECMWF/GEM solution would allow for rain chances to increase by Thu. For now, went with a blended solution w/ PoPs of 15-25% for the area from Thu AM-Thu night. Highs Thursday range from the mid 40s NW to the mid 50s SE. Lows Thu night mainly in the 30s. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... As of 700 PM EST Thursday... High pressure will slide offshore tonight with clouds continuing to thicken and lower, but CIGs are expected to remain VFR most of the night. However, CIGs have dropped to MVFR at RIC and is expected to remain for a few more hours before returning to VFR later on tonight. The latest guidance continues to suggest that MVFR stratus spreads northward into central VA and northeast NC by Friday morning, so have included BKN MVFR CIGs at RIC and ECG Friday morning. In addition, there is some potential for fog at ECG tonight. CIGS will lift during the late morning Friday with only brief SCT MVFR conditions possible. Low pressure will pass across the region Friday night into early Saturday bringing rain and degraded flight conditions. Upper level low pressure crosses the region Saturday into Sunday, which should only bring passing mid-clouds and a 20-30% of showers (mainly Saturday aftn from RIC-SBY). Weak high pressure builds in from the W Monday aftn. && .MARINE... As of 355 PM EST Thursday... Late this aftn, high pressure was centered off the New England coast. This was resulting in N/NE winds 5-15 kts across the waters. Waves in the bay were 1-2 ft. Seas were 3-4 ft for the coastal waters from Virginia Beach up to the MD eastern shore, and 4-6 ft for the Srn VA coastal waters and NE NC waters. The elevated seas over the srn two coastal waters will now persist through at least Sat, due to NE or E winds becoming SE then S, as the next low/front approaches from the WSW. Winds will become more easterly on Fri, as the high continues to move NE away from the area. Wind speeds will pick up to 10-15 kts with gusts around 20 kts by late in the day Fri, then become SE and increase to 15-20 kts with gusts up to 25 kts for Fri night into Sat morning ahead of the approaching low pressure system. Waves/seas build throughout the day on Fri with the persistent easterly flow, and by Sat morning expect 3-4 ft waves in the bay and seas 5-8 ft. Cold front associated with the low pressure system crosses the area waters Sat morning into early Sat aftn. Westerly flow expected after the frontal passage. At this time, have SCAs for the Ches Bay and coastal waters for this event from late Fri/Fri evening into or thru Sat morning/aftn. May need it in the other waters, esply Fri night. High pressure builds in late Sun and remains in place for the early part of next week with sub-SCA conditions expected. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 10 PM Friday to 1 PM EST Saturday for ANZ632-634. Small Craft Advisory from 10 PM Friday to 10 AM EST Saturday for ANZ630-631. Small Craft Advisory from 4 PM Friday to 4 PM EST Saturday for ANZ650-652-654. Small Craft Advisory until 4 PM EST Saturday for ANZ656-658. && $$ SYNOPSIS...AJZ NEAR TERM...CP/ERI SHORT TERM...RMM LONG TERM...ERI AVIATION...CP/ERI MARINE...CMF/TMG

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