textproduct: Wakefield

WHAT HAS CHANGED

A Small Craft Advisory has been issued for the Chesapeake Bay from Wednesday evening through Thursday morning.

KEY MESSAGES

1) A warming trend is expected through Thursday with mostly dry conditions.

2) An unsettled pattern develops late Thursday into the weekend with daily chances for showers or thunderstorms.

DISCUSSION

As of 255 PM EDT Tuesday...

KEY MESSAGE 1...A warming trend is expected through Thursday with mostly dry conditions.

An upper ridge is building in from the W this afternoon as an upper trough lifts NE over Atlantic Canada. At the surface, high pressure is centered near the VA/NC border. Mostly sunny with temperatures in the lower to mid 80s. The wind is light, generally 5-10 mph, and ENE on the southern periphery of the high, and SSW on the northern side of the high. The surface high very slowly slides offshore tonight, but lags back into S-central VA and interior NE NC. Therefore, low temperatures in these areas potentially fall into the upper 50s/around 60F with a calm to light wind under a clear sky. Farther N, low temperatures are forecast to be 60-65F as very light southerly return flow develops.

An upper trough slides N of the Great Lakes Wednesday allowing the upper ridge to flatten with more of a zonal flow pattern developing. A a result, the surface high will slide farther offshore. A warming trend will commence. However, moisture recovery will be slow. 850mb temperatures of 15-18C support high temperatures in the upper 80s/near 90F inland, with mid 80s at the coast. Mostly clear and milder Wednesday night with low temperatures in the mid 60s to around 70F. The upper ridge becomes further suppressed Thursday as more robust troughing develops over ON/QB, which will push a cold front SE through the Great Lakes. 1000-850mb thicknesses surge ahead of the cold front. Legacy 1000-850mb thicknesses schemes from the NAM/ECMWF support high temperatures in the lower/mid 90s, with mid/upper 90s from the GFS. The current forecast is for lower to locally mid 90s. Dewpoints rise, but generally into the mid 60s to near 70F. There is some uncertainty across the northern tier of the area as some guidance (NAM/RRFS) have some convection tracking off the northern Blue Ridge later Thursday afternoon. A SW wind of 10-15 mph with gusts up to 20 mph is expected to develop Thursday afternoon.

KEY MESSAGE 2...An unsettled pattern develops late Thursday into the weekend with daily chances for showers or thunderstorms.

The cold front likely slows down as it approaches from the N Thursday afternoon as it becomes aligned parallel to the mid level flow. Most guidance has little to no QPF across the northern tier of the local area through 00z Friday, and the NAM and RRFS are outliers suggesting earlier convection. There is only a thin strip of 20-30% PoPs across the northern tier of the local area 18z Thursday through 00z Friday. Otherwise, showers/tstms are not expected during the day Thursday. The cold front limps through the region Thursday night. The best chc of showers/tstms will be across the northern tier of the area Thursday evening into the early overnight hours (30-60% chc), with mainly dry conditions across southern VA/NE NC. Given the later timing and the better forcing remaining well to the N, the potential for any strong to severe tstms will be quite limited. A few additional showers/tstms are possible Friday across far southern portions of the area, but that will depend on how far south the cold front gets by early Friday. Behind the cold front, CAA will be lacking so temperatures only cool back to near normal Friday and Saturday with lower 90s potentially returning by Sunday through Tuesday of next week. Some semblance of a front lingers over the area Saturday with chances of showers/tstms persisting. This boundary gradually washes out Sunday through Tuesday with PoPs diminishing Sunday, and generally 20% or less by Monday/Tuesday.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

As of 150 PM EDT Tuesday...

High pressure was centered near the VA/NC border as of 18z. VFR with FEW-SCT CU and an ENE wind of 5-10kt on the southern periphery of the high, and SSW 5-10kt on the northern side of the high. VFR conditions are expected to prevail tonight through Wednesday under a mainly clear sky. The wind will generally be calm to very light out of the S tonight, and then SSW 8-12kt by late Wednesday morning into the aftn.

Outlook: Mainly dry/VFR conditions continue through most of the day Thursday. The next chc for showers/tstms arrives later Thursday/Thursday night as a cold front approaches from the north. This boundary lingers near the VA/NC border Friday through Sunday with daily chances of showers/storms (highest chc south and greatest Saturday).

MARINE

As of 245 PM EDT Tuesday...

Key Messages:

- High pressure lingers over the region tonight with light winds.

- S to SW winds increase later Wed into Thu. Small Craft Advisories have been issued for the Chesapeake Bay and lower James River, and are possible for the northern coastal waters.

Latest analysis reveals ~1026mb high pressure centered over the local waters this afternoon. Winds averaged ~5 kt out of the W-SW over the Bay and rivers, but remain light/onshore over the coastal waters. Waves are around 1 foot in the bay with seas 2-4 ft offshore (highest far SE waters).

Relatively benign boating conditions persist tonight and early Wednesday, as high pressure lingers over the area, sliding offshore late tonight and through Wednesday. Winds become SE 5-10 kt this evening. As the high moves farther offshore, winds will veer to the S late tonight and through Wednesday, increasing to 10-15 kt, gusting to ~20 kt in the lower Bay and over the coastal waters. A cold front associated with low pressure well north of the area approaches the region Wednesday night into Thursday. The compressing pressure gradient ahead of the front should result in a slight increase in S-SW winds Wednesday evening, and Small Craft Advisories have been issued over the Bay and lower James River. SSW winds increase to 15-20 kt with gusts to 25 kt in the Chesapeake Bay and lower James River, 20-25 kt with gusts 25-30 kt for the coastal waters N of Cape Charles Light. Confidence in seeing sustained SCA conditions is much lower for the nearshore coastal waters, with the best chance over the northern waters north of Parramore Island early Thu morning.

Model guidance continues to slow the frontal passage a bit, with the boundary now not looking to cross into the area until later Thu night into early Friday. Minimal CAA behind this front, and therefore not expecting strong NW winds in the post- frontal airmass. However, NNE swell/wind wave could briefly build seas near 5 ft over the northern waters Thursday night. Otherwise, waves build to 2-3 ft in the bay Wednesday night and Thursday, with seas averaging 2-4 ft S and 4-5 ft N. Looking ahead, the flow turns onshore later Friday into the weekend, trending back to the SSW later Saturday into early next week.

Low Rip Risk tomorrow and through late week.

Coastal Flooding...

Water levels remain elevated due to the recent lunar perigee earlier this week, and ahead of the new moon cycle later this week. For that reason, tides look remain elevated for the next 2-3 days, and could approach minor coastal flood threshold during the astronomically higher evening/early AM tide cycle through late week. Any minor tidal flooding would likely be limited to the Chesapeake Bay side of the Maryland Eastern Shore and perhaps into the lower Potomac basin over the VA northern Neck. While no additional Coastal Flood Advisories or Statements have been issued to this point, they may be needed across the northern bay Wednesday night and Thursday as water remains trapped in the Bay due to persistent southerly fetch and southerly flow strengthens ahead of the next cold front.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 7 PM Wednesday to 10 AM EDT Thursday for ANZ630>632-634. Small Craft Advisory from 10 PM Wednesday to 7 AM EDT Thursday for ANZ639.