textproduct: Wakefield

WHAT HAS CHANGED

Updated for 12Z TAFS.

Added a slight chance of showers tonight across the far north. In addition, added a slight chance of Sunday afternoon showers/thunderstorms across central Virginia.

Marine: Small Craft Advisory has been issued for the nearshore Atlantic coastal waters.

KEY MESSAGES

1) Above normal temperatures today. A slight chance for showers across the far north tonight.

2) Well above normal temperatures Sunday through Wednesday. A small chance for showers/storms across central VA Sunday afternoon. Otherwise, little appreciable rainfall is expected until at least Wednesday night or later.

DISCUSSION

As of 215 AM EDT Saturday

KEY MESSAGE 1...Above normal temperatures today. A slight chance for showers across the far north tonight.

Surface high pressure has shifted off the coast and upper heights will build today. Other than some high clouds, expect a mostly sunny day with temperatures rising above normal into the mid 80s inland and lower 80s closer to the coast. Latest guidance suggests that a few showers may move eastward tonight across the far north in response to a weakening short wave over Iowa and Wisconsin. The 00z CAMS suggest the best chance for this activity will stay north of the area, however there is enough support from the CAMS to introduce slight chance PoPs across the far north into the MD eastern shore tonight. Rainfall, if any, will not amount to much due the very dry air aloft.

KEY MESSAGE 2...Well above normal temperatures Sunday-Wednesday. A small chance for showers/storms across central VA Sunday afternoon. Otherwise, little appreciable rainfall is expected until at least Wednesday night or later.

Big story through Wednesday will be the summer-like high temperatures each day. Sunday will be the start of widespread temperatures in the 90s. Many places away from the immediate coast and eastern shore will see temperatures in the lower 90s with the multi-model ensemble showing an 80%+ probability of 90F+, although mid 90s not expected with multi-model ensemble showing <10% probability of 95F+ on Sunday. The REFS and NBM suggest some isolated convective development Sunday afternoon over central Virginia given the MLCAPE values of nearly 1000 j/kg. However, given the building heights across the region, the atmosphere may remain capped through the afternoon. Nonetheless, the lee trough may be just enough for an isolated storm on Sunday afternoon and have maintained the slight chance PoPs from the NBM on Sunday afternoon.

Otherwise, the remainder of the week through Wednesday looks dry and hot. Ensemble guidance suggests broad support for widespread temperatures in the low to mid 90s each day through Wednesday as 850mb temps are around 18C. There is overall a very low 1-3 deg interquartile range for MaxT each day so confidence is high in these temperatures each day. Fortunately, while it will be quite hot, dew points will struggle to rise out of the low 60s each day so heat index values will not be much different than the actual temperature. In fact, the NBM essentially has a 0% probability of heat index values rising to 100 or greater next week.

Still a great amount of uncertainty regarding the frontal system for Thursday. Will maintain PoPs from Wed afternoon through Friday, with the highest PoPs on Thursday. This front will be slow to move south of the area, so there will likely be a period of unsettled weather later next week. However, given the zonal flow aloft with any significant moisture from the Gulf being cut off from the area, am not expecting significant precipitation amounts. In fact, the NBM only shows about a 60% probability of at least 0.50" with less than a 30% probability of 1".

AVIATION /18Z SATURDAY THROUGH THURSDAY/

As of 135 PM EDT Saturday...

VFR conditions prevail for the 18z/16 TAF period as high pressure remains locked in offshore. SKC skies as of latest satellite. Will see an increase in cloud cover later this evening as a disturbance aloft passes by, primarily at RIC and SBY. There is a non-zero chance of a passing shower at SBY from this disturbance, but probs are too low for even a prob30 group. SW winds continue through the period, becoming less gusty overnight and tomorrow.

Outlook...VFR conditions expected through early next week as high pressure remains in control. There is a small chance for a storm in central Virginia Sunday afternoon. South winds each afternoon may gust to 10-20kt as high pressure remains stationary off the coast. Next chance of rain not expected until late Wed or Thursday.

MARINE

As of 320 AM EDT Saturday...

Key Messages:

- Mainly Sub-SCA conditions are expected over the rivers, Currituck Sound and the Chesapeake Bay through the weekend and into early next week with primarily southerly winds.

- Building seas could result in a brief SCA over the nearshore Atlantic coastal waters Saturday night into early Sunday morning.

Latest observations reflect SSW winds ~ 10 kt across the local waters early this morning. Waves are averaging ~1 ft, with seas 2-3 ft nearshore and 3-4 ft offshore. Surface high pressure centered just off the coastal Carolinas will continue to slide farther offshore through tonight. This will allow winds to shift to the SW through midday before backing to the SSE and increasing slightly to 10-15 kt with the afternoon seabreeze. A few gusts to 20 kt will be possible late this afternoon and this evening in the bay, but likely not quite persistent enough for SCA.

An increasingly choppy and briefly confused sea state will develop late today and evening, with seas comprised of a SE wind wave (4-6 second periods) overriding a lingering E-NE swell (8-10 second periods). This combination will build significant wave heights to 4-6 ft tonight, with the highest seas located north of Cape Charles. A short-fused SCA has been issued for this evening for the far southern coastal waters, and a slightly longer SCA was issued for tonight/overnight through early Sunday morning for nearshore coastal waters north of the VA/NC border. Seas will gradually diminish thereafter Sunday morning, remaining 2-4 ft through early next week.

Thereafter, high pressure settles into typical summertime Bermuda High configuration for Sunday into the middle of next week. Winds remain primarily SSW around 10 kt outside of the daily mid to late-afternoon nearshore seabreeze. The afternoon breeze will likely bring additional localized gusts of 15-20 kt to the lower Chesapeake Bay and nearshore ocean waters each afternoon before winds veer back offshore and diminish through the overnight. Expect generally benign marine conditions to prevail through midweek.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 6 PM this evening to 10 AM EDT Sunday for ANZ650. Small Craft Advisory from 6 PM this evening to 6 AM EDT Sunday for ANZ652-654-656. Small Craft Advisory from 6 PM this evening to 1 AM EDT Sunday for ANZ658.