textproduct: Wakefield

WHAT HAS CHANGED

06z Aviation discussion.

KEY MESSAGES

1) Above average temperatures are expected Thursday through midday Friday.

2) A cold front crosses the region Friday afternoon and evening bringing a chance of showers.

3) Cooler temperatures return this weekend.

DISCUSSION

As of 300 PM EDT Wednesday...

KEY MESSAGE 1...Above average temperatures are expected Thursday through midday Friday.

WNW flow aloft prevails across the Mid-Atlantic region this afternoon downstream of a broad ridge that is centered over the Intermountain West. At the surface, high pressure is centered offshore. Temperatures this afternoon range from the lower to mid 50s toward the coast (upper 40s MD coast), to the upper 50s/lower 60s inland under a mostly sunny sky. The wind is light and generally S inland and E/SE along the coast.

Partly cloudy to mostly clear tonight with passing cirrus clouds as high pressure settles farther offshore. Lows tonight will mainly be in the mid 40s to around 50F. Temperatures moderate into the mid/upper 70s inland Thursday with mid 60s to lower 70s toward the coast. A SW wind increases to 10-15 mph with gusts to 20-25 mph. Very mild Thursday night in advance of a cold front with lows in the upper 50s to lower 60s. 25/12z guidance has trended slightly quicker with the front pushing in through central VA by early/mid afternoon. Therefore, high temperatures may struggle to reach 70F across the N, while areas ahead of the front across southern VA/NE NC likely rise into the upper 70s/lower 80s, with a transition zone of more uncertainty in between.

KEY MESSAGE 2...A cold front crosses the region Friday afternoon and evening bringing a chance of showers.

The next chance for showers comes Friday afternoon/Friday evening, as the previously referenced cold front crosses the area. Forcing still looks rather weak, and with zonal flow aloft. QPF with this system does not look very impressive. However, the EPS 50th percentile did increase to 0.25-0.4" across the northern tier of the area (along and N/NE of I-64) with 0.1-0.25" farther S. Meanwhile, GEFS/GEPS are generally 0.25" or less. Most of the rainfall is anafrontal. Therefore, thunder chances are quite limited and mainly across the southern Piedmont counties. Temperatures will quickly drop post- frontal Friday night into the 30s and 40s on gusty NNE winds.

KEY MESSAGE 3...Cooler temperatures return this weekend.

Cool high pressure rebuilds into the region for the upcoming weekend, with below average temperatures and dry conditions. Forecast highs Saturday look similar to those of yesterday, averaging in the upper 40s to mid 50s (mildest inland). These values are at least 10F below seasonal means. Forecast lows Saturday night are in the upper 20s to mid 30s, followed by highs Sunday moderating back to near average with mid 50s to lower 60s. Also potentially very dry post-frontal, with some potential fire danger concerns this weekend, if QPF remains minimal, but will be mitigated if QPF is in excess of 0.1". Ensemble guidance showing PW values of only 25-40% of normal Saturday and 50-70% of normal by Sunday. High pressure shifts offshore by Monday with a moderating trend commencing.

AVIATION /06Z THURSDAY THROUGH MONDAY/

As of 200 AM EDT Thursday...

High pressure is centered offshore early this morning. VFR flying weather in place over area terminals will persist through the 06z Taf period. Gradually clearing clouds through sunrise, with SCT/BKN cirrus clearing out, as noted on early morning satellite imagery. S winds 5-10 kt should become SW with time later this morning and through tonight, ahead of the next cold frontal passage. Could see some gusts 20-25 kt late this morning and this afternoon, highest N where the pressure gradient will be tightest. Low-level wind shear develops across the terminals after 00z tonight/early Friday, gradually easing with onset of diurnal mixing Friday morning.

Outlook: A cold front drops N-S across the area from Friday late morning into Friday afternoon. A wind shift from SW to NNE will accompany the front. Showers are expected to develop behind the front across the area Friday aftn into Friday evening, ending from N to S late Fri night. Brief flight restrictions are possible in the wake of the cold front, likely coinciding with the rain Friday evening. VFR conditions return later Friday night, and prevail over the weekend and through Monday, as cool high pressure builds into and across the region.

MARINE

As of 300 PM EST Wednesday...

Key Messages:

- Mostly quiet conditions tonight as high pressure continues to shift offshore.

- Small craft advisory conditions possible starting potentially as early as late Thursday afternoon and continuing into Friday ahead of a strong cold front.

- Small craft advisories will likely continue into Saturday as winds turn north-northeast behind the cold frontal passage Fri Aftn/Evening.

High pressure over the area this afternoon will slowly shift south and east through Thursday. Winds of less than 10 kt today will shift to the SE then slowly increase to 10-15 kt tonight.

As the cold front approaches from the NW on Thursday, the pressure gradient will tighten across the waters, with southerly winds increasing to 15-20 kt in the bay and 15 to 25 kt over the coastal waters by Thu evening. As frequently happens with southerly winds events, the NWP winds may be a little overdone but with this tight of gradient, small craft advisory criteria wind and gusts are expected. Will hold off on issuing any SCA with this issuance as the event is expected to start in the 3rd period.

Winds will likely weaken slightly immediately ahead of the cold front that pushes through the area Fri afternoon into Friday evening. However, this will be very short lived as a strong push is expected behind the front as the winds turn N-NE. Would expect winds to be briefly rather gusty immediately behind the front, and would not be shocked if there is an hour or two of gale force gusts. In fact, local wind probailities suggest a 10 percent probability of gale force gusts in the late afternoon and early evening in the coastal waters and southern Chesapeake Bay. Seas of 3 to 5 feet on Friday build to 4 to 7 feet by Saturday morning before subsiding back to 3 to 5 feet Sat evening.

North to northwest winds will remain gusty and at SCA criteria through Saturday morning, then gradually diminish as high pressure builds in from the northwest. Quiet marine conditions expected for Sunday.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...None.