Area Forecast Discussion
Issued by NWS Wakefield, VA
Issued by NWS Wakefield, VA
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617 FXUS61 KAKQ 041903 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 303 PM EDT Thu Jul 4 2024 .SYNOPSIS... High pressure off the coast gradually settles south into the western Atlantic through late this week. Heat and humidity build over the region today through early next week. Daily chances of mainly afternoon and evening showers and thunderstorms also return today into the upcoming weekend. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 935 AM EDT Thursday... Key Messages: - Hot and humid conditions return today. - Rain chances return to the forecast for the afternoon into the evening on Independence Day and again on Friday and Saturday. Best rain chances remain W-NW of the Richmond Metro area into the VA Piedmont. Latest analysis reveals upper ridge building across the southeast from the gulf coast this morning, with a trough over Great Lakes. At the surface, high pressure continues to push farther offshore of the mid-Atlantic coast, with a cold front well to the NW of the region approaching the Ohio Valley. A warmer and slightly more humid start to the day with temperatures in the upper 70s to lower 80s and dewpoints around 70F this morning. A hotter and more humid Independence Day is expected, courtesy of increasing SSW flow w/the surface high pushing out into the western Atlantic. High temperatures range from the upper 80s/lower 90s along the coast, to the mid 90s inland. NBM dewpoint numbers already verifying a few degrees to high, and will continue to undercut them by about a category today. Nonetheless, more humid today, with PWs to climb to ~2.00 by this evening. Forecast dewpoints in the upper 60s to around 70F during peak heating result in heat indices well into the upper 90s to lower 100s. There is a potential for widely scattered showers/tstms later today. Shortwave energy will ride along the northern periphery of the sub-tropical ridge over the Ohio Valley and interior northeast through this afternoon. Isolated to widely scattered convection is then expected to develop to our northwest, focused along the pre-frontal/lee trough by early this afternoon. Showers and storms are then shown by a majority of CAMs pushing E-NE into the local area late this afternoon, before slowly weakening and decreasing in areal coverage this evening. Best rain chances are around 60% for the NW Piedmont, but again taper to 20-40% central VA to the VA northern neck and eastern shore in the late afternoon and evening as storms gradually weaken. A convective Marginal Risk remains in place from the SPC for the far NW, with gusty winds from wet microbursts the main hazard. Mainly dry overnight, aside from a lingering shower or two over the eastern shore. Some patchy fog/low stratus possible late tonight/early Friday. Otherwise partly cloudy, warm and muggy/humid tonight with lows in the lower to mid 70s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... As of 340 AM EDT Thursday... Key Messages: - Heat and humidity build for Friday and Saturday. Heat index values around 100 are expected on the eastern shore, with heat indices in the 103-108F range west of the bay. Heat Advisories are likely to be needed for much of the area both Friday and Saturday. - Additional chances for late day showers and storms will exist both days, again mainly focused over the piedmont. PWs trend up further for Friday, reaching 2-2.25" by Friday morning (*near daily max value for WAL), with daily maxes possibly exceeded (PW 2.25-2.5") by Saturday. Forecast highs Friday and Saturday should be similar to those of today. However, it will be a bit more humid and with dewpoints slightly higher, heat indices at or above 105F are likely for central and SE VA and into NE NC, and Heat Advisories are likely to be needed for much of the area. There is chance of afternoon showers/tstms Friday along the lee trough lingering over the area. Partly cloudy, warm, and muggy Friday night with lows in the mid to upper 70s. The weakening cold front drops into the area Saturday. Once again hot and very humid ahead of the boundary with highs in the lower to mid 90s and again heat indices of 105-109F are looking increasingly likely. This boundary should become the focus for more showers/tstms by afternoon. A very moist and unstable airmass will be in place and the H5 flow does increase to 30-35kt across the NW, so some stronger tstms are possible. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 300 PM EDT Thursday... Key Message: - Near or slightly above normal temperatures, but very humid through the period. Remaining a bit unsettled with a chance for mainly afternoon and evening showers and storms each day. Not as hot through the period, but high temps will still be near or slightly above normal ranging from the upper 80s to lower 90s. It will still be very humid across the area, and with lee troughs or weak frontal boundaries in the vicinity of the region, expect chances for mainly aftn/evening showers/tstms each day. Heat indices will mainly range from the mid 90s to lower 100s Mon through Wed. Warm and muggy nights with lows ranging from the upper 60s to mid 70s. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... As of 210 PM EDT Thursday... VFR conditions prevail as of 18z with surface high pressure centered off the Southeast coast. The wind is mainly S to SSW ~10kt with FEW-SCT CU developing with bases of 5-6kft. A cluster of showers/tstms has developed over the higher terrain to the W and is currently crossing the Blue Ridge. These showers/tstms are expected to approach RIC after 20z, and mainly in the 21-23z timeframe. The latest guidance suggests much of this activity dissipates from 23-01z prior to reaching the remaining terminals. These showers/tstms could produce some stronger wind gusts at RIC along with brief vsby restrictions in rain. Otherwise, VFR conditions should prevail tonight into Friday morning under a partly cloudy sky with a 5-10kt SSW wind. By Friday aftn, there is a ~30% chc of showers/tstms at RIC, and a 15-20% chc at the remaining terminals. The wind should mainly be SSW 8-12kt Friday aftn, but locally variable and gusty in and near any tstms. A weakening and slow moving cold front settles into the region Saturday. This will bring a higher chc (40-60%) of aftn/evening showers/tstms. This front settles near the coast Sunday and washes out, with a remnant boundary lingering over the area Monday/Tuesday. The highest chances (30-40%) shift into SE VA/NE NC Sunday, and then generally 30-40% inland and 15-30% toward the coast Monday and Tuesday. && .MARINE... As of 340 AM EDT Thursday... Key messages: - Small Craft Advisories are in effect across portions of the Chesapeake Bay and Virginia coastal waters late this afternoon into tonight. - There is a high rip risk today across the northern beaches and a moderate rip risk across the southern beaches. - A period of elevated, diurnally-driven southerly winds is possible Friday and Saturday with Small Craft Advisory conditions possible. High pressure remains offshore through the weekend with multiple shortwaves moving through, providing the chance for daily diurnal storms. Winds were generally S 10-15 kt with a few gusts up to 20 kt across the upper Ches Bay this morning. Meanwhile, waves and seas were 1-2 ft and 2-3 ft respectively. Expect winds to become SE/SSE this afternoon, increasing to 15-20 kt by mid-late afternoon. Gusts up to 25 kt are possible across the VA coastal waters late this afternoon into this evening. Wind probs for 18kt winds were 40-70% across the middle and lower bay with probs for 25 kt gusts across portions of the VA coastal waters of 20-30%. Wind probs were much lower across the upper bay. Therefore, SCAs are now in effect for the middle and lower bay from 4-10 PM and for the coastal waters from Chincoteague to Cape Charles Light from 6 PM until 4 AM Fri (due to a combination of gusts up to 25 kt and seas of 4-5 ft). Additionally, 00z CAMs have come into better agreement in showing a line of storms moving off the Blue Ridge mountains and towards the coast this afternoon into this evening. While uncertainty remains regarding coverage of storms, the outflow may move across the local waters this evening, allowing for winds to briefly become NW and gusty. Winds become S 10-15 kt with gusts up to 20 kt across the bay and 12- 20 kt across the coastal waters tonight, becoming SW late. While some hires guidance shows the potential for SCA conditions continuing across the bay, winds (and confidence) have trended lower. A period of diurnally driven elevated afternoon/evening S winds is likely to continue Fri and Sat. Each day, S/SSE winds increase to 15-20 kt with gusts up to 25 kt (mainly across the coastal waters) during the afternoon and evening before becoming SW/SSW overnight. As such, SCAs may be needed for either/both days. Winds diminish Sun into early next week as a weak cold front approaches and becomes washed out near/over the local waters. Additionally, daily chances for afternoon/evening storms are possible into the middle of next week. There is high rip risk today across the N beaches due to 12-14 second period SE swell amidst 3-4 ft waves. A moderate rip risk exists across the S beaches where the onshore swell direction is weaker and less shore normal for the long period 12-13 second swell and where the shore normal swell is 7-9 seconds. There is a moderate rip risk for all area beaches on Fri due to 9-10 second period onshore swell and 3-4 ft waves. There is a potential for an upgrade to a high rip risk Fri across the N beaches due to a more dominant (and stronger) SE swell (as opposed to conflicting swells like today). && .CLIMATE... Record High Temperatures Through Sat (July 4-6) 7/4 7/5 7/6 RIC 100/2002 102/2012 105/1977 ORF 98/1997 98/2012 102/1881 SBY 100/1919 102/2012 102/2010 ECG 100/1997 100/2012 99/2012 Record High Minimum Temperatures Through Sat (July 4-6) 7/4 7/5 7/6 RIC 77/1900 79/2012 80/2012 ORF 79/2012 80/1999 80/1999 SBY 78/2012 81/2012 77/2012 ECG 78/2012 77/2018 78/1999 && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ631- 632-634. Small Craft Advisory from 6 PM this evening to 4 AM EDT Friday for ANZ652-654. && $$ SYNOPSIS...AJZ/MAM NEAR TERM...AJZ/MAM SHORT TERM...AJZ/MAM LONG TERM...TMG AVIATION...AJZ MARINE...AM/RMM CLIMATE...AKQ