321 FXUS61 KAKQ 121115 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 715 AM EDT Wed Jul 12 2023 .SYNOPSIS... High pressure remains centered across the area today, then slowly becomes centered off the Carolina coast tonight and Thursday. Low pressure will extend from the Plains to the Great Lakes on Thursday, and will gradually move into the local area Thursday night into Friday, bringing scattered showers and thunderstorms. A series of weak disturbances aloft will keep scattered showers and storms in the forecast through the upcoming weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 245 AM EDT Wednesday.. The latest analysis indicates a broad area of sfc high pressure centered from the TN Valley to the mid-Atlantic. Aloft, A deep upper low is centered over Hudson Bay Canada, with a broad upper ridge across the SW CONUS, allowing for a WNW flow through the FA. A very weak shortwave is passing from the OH Valley through the FA, bringing just a few SCT clouds. Temperatures are primarily ranging from the upper 60s to the lower 70s, with a few warmer spots near the coast in the SE and some locally cooler mid 60s in the piedmont, and will tend to drop another few degrees through sunrise. Ground fog is isolated to a few spots in south central VA and interior NE NC. Expect another dry day today as the high slowly becomes centered along or just off the coast by late aftn into this evening. Low level thicknesses/850mb temperatures rise a bit today, with highs expected to be about 3-5 degrees warmer than on Tuesday (into the 90-95F range for most). Still anticipate deep mixing of a rather dry airmass today, so dew pts this aftn will mostly drop into the low-mid 60s, keeping heat indices close to actual air temperatures. mainly sunny this morning, then partly-mostly sunny this aftn with SCT cumulus. Tonight, a somewhat more significant shortwave is forecast to pass through the base of the upper trough, but will stay N of the FA, across the Great Lakes and OH Valley. Mostly clear tonight with humidity slowly increasing, bringing a warmer night with lows ranging from the upper 60s in the piedmont to 70-75 F elsewhere. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 345 AM EDT Wednesday... The next cold front associated with the trough moving in the Great Lakes approaches later Thursday then stalls out over the area for the weekend. Thursday will see a noticeable increase in humidity though it will still not be as humid as what follows for Fri and beyond. Some of the CAMs show spotty shower development well out ahead of the approaching system Thu aftn mainly to the E of I-95, but suspect this is overdone. Have generally a dry fcst through late aftn, with just a slight chc for tstms into the far NW after 21Z. Still think the best chance for storms will be Thu evening across the northern areas as the next shortwave tracks from the OH Valley to the nrn mid- Atlantic. The frontal boundary becomes stationary over the middle Atlantic for Friday with high chc PoPs continuing. GFS suggests precipitable water values above 2.00 inches across the SE on Friday and as such will need to watch for heavy rain from any storm Fri afternoon/evening. SPC has backed off the marginal SVR threat Thu given overnight timing and poor lapse rates. Temperatures will remain seasonably warm in the low-mid 90s on Thu, then perhaps a tad lower Fri given more clouds and higher PoPs (highs fri upper 80s to lower 90s). The increasing humidity will allow heat index readings to reach as high as 100-104 F both Thu/Fri. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 355 AM Wednesday... Note that given the somewhat unsettled pattern and high humidity (aftn dew pts remaining in the low-mid 70s), the high temperatures have been trended down about 1-3F compared to the previous forecast for the weekend. Highs will mostly be in the lower 90s with lows in the low-mid 70s, along with mainly diurnal showers/tstms (aftn/evening). Given that precipitable water values are forecast by the models to continue to average 2.00"+ through the weekend will keep the PoPs at high chc (40-50%) which is above climo. Certainly will be the potential for locally heavy rain and at least localized flooding over the weekend and WPC has a Marginal risk ERO both Sat and Sunday. Peak heat indices are expected to be at least 100 F for all areas both Sat/Sunday, and at or above 105F across the SE. The clouds and higher chances for storms make this a bit uncertain at this time, but this would certainly suggest a possibility of heat advisories eventually being issued for the weekend at least for SE VA and NE NC. PoPs/precipitable water values and overall forcing looks to drop off a bit next week, but it remains hot with highs into the low-mid 90s and lows mainly in the 70s. Similar heat indices as dew pts will tend to drop a little compared to the weekend. && .AVIATION /11Z WEDNESDAY THROUGH SUNDAY/... As of 700 AM EDT Wednesday... VFR conditions expected through the period with high pressure across the region. Mostly sunny today, with FEW-SCT cumulus at 5000-7000ft this afternoon. Generally light and variable winds to start, becoming W to SW winds 5-10 kt (locally shifting to the NE to SE near the coast). Light southerly winds tonight w/ SCT clouds. Outlook: Dry wx and VFR conditions prevail for most of Thu. Chances for storms develop Thu evening and increase Thu night, and linger through Friday. Mainly aftn/evening showers/storms then continue over the weekend. && .MARINE... As of 315 AM EDT Friday... 1016mb high pressure is centered over eastern Tennessee and southwest Virginia. Aloft, there is broad troughing over the eastern CONUS with a strong ridge remaining over New Mexico and Arizona. Winds are generally SW 5-10 kt across the local waters. Waves in the bay are around 1 foot with seas 2 ft or less. High pressure moves over the area today and offshore this evening as a weak surface trough sets up over the Piedmont. Expect a modest increase in winds to 10-15 kt this evening as the sea breeze combines with a steepening pressure gradient. Gusts to 20 kt are possible this evening, especially across southern and western portions of the Ches Bay. Local wind probability guidance argues against Small Craft headlines this evening but will let the day shift take another look with the 12z guidance. Flow becomes S and SSW on Thursday, generally 10-15 kt through the afternoon before a sharpening lee trough and high pressure offshore tighten the gradient during the evening and overnight hours. Expecting 15-20 kt with gusts to 25 kt in the bay (and perhaps the lower James) with 20- 25 kt and gusts up to 30 kt offshore, generally from Cape Henry northward. Will hold off on headlines for now given some lingering uncertainty regarding winds this evening but SCA flags are likely for the bay and northern coastal waters Thursday evening into Friday. S and SSW flow continues through the weekend but generally below SCA thresholds at ~10 kt in the Ches Bay and 10-15 kt offshore. Chances for showers and storms ramp back up Thursday evening through the weekend with a stalled frontal boundary near the region. Waves increase to 2-3 ft along with the winds late afternoon and evening, becoming 2 ft late into the first half of Thursday. Waves build back to 2-3 ft Thursday evening into Friday but subside to ~2 ft for the weekend. Seas generally 2-3 ft through late Thursday morning then build 4-6 ft N and 3-4 ft S into early Friday. Guidance shows 5 ft seas lingering north of Parramore Island into early Friday afternoon. Heights subside back to 2-4 ft into early next week. Low rip current risk at the beaches today. Moderate rip risk for the Eastern Shore beaches Thursday as surf heights increase during the afternoon. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...LKB/MRD NEAR TERM...LKB SHORT TERM...LKB LONG TERM...LKB/MRD AVIATION...AM/LKB MARINE...RHR