Marine Weather and Tide Forecast for Mayo, MD

KEY MESSAGES
- 1) Record warmth this afternoon with a few gusty showers and thunderstorms possible this evening and again Friday.

- 2) Temperatures 10 to 15 degrees below average this weekend. Dry, but with areas of frost possible and near freezing temperatures, mainly west of I-95, Saturday night and Sunday night.

DISCUSSION
KEY MESSAGE 1....Record warmth this afternoon with a few gusty showers and thunderstorms possible this evening and again Friday.

Record breaking heat for some this afternoon. Preliminary data shows a new record likely at IAD of 88 degrees beating the old record of 86 back in 1975. Records are also being challenged at DCA where temperatures 88 degrees was observed beating the old record of 87 back in 1975. Meanwhile, BWI hit 88 degrees beating the 86 degree record from 1975. Mid to high level clouds along and north of I-70 combined with showers and even a few embedded t-storms over northeast MD have limited temperatures a bit compared to areas further south. This will likely limit any records at HGR and MRB this afternoon. See climate section below for a list of today's record highs.

The leading piece of shortwave energy continues to exit southeast PA and north-central MD early this afternoon while the cold front drops down out of southwest PA/southeast Ohio. The front looks to push toward western MD and the eastern WV mountains during the late afternoon commute before sinking down into northern VA and the Baltimore/DC metros this evening and into the overnight hours. 12z hi-res CAMS remain about the same in regards to timing (give or take and hour) and coverage with a general focus for thunderstorm coverage, mainly west of the Blue Ridge/US-15 and north of US-48/I- 66.

Current timing puts convection over the western MD and eastern WV mountains between 21-00z/5-8pm before advancing south and east toward northern VA and the DC/Baltimore metros around 23-03/7-11pm.
CAPE values will hover between 600-900 j/kg with 0-6 km bulk effective shear values around 35-45 kts mainly north of I-66/US-50.
With that said, a Marginal Risk (Level 1 out of 5) for severe weather continues for locations west of US-15 and back into the western MD/eastern WV mountains. The greatest confidence for organized convection appears to be from Romney, WV/Cumberland, MD west to Oakland, MD and south toward Franklin, WV/Moorefield, WV.
Elsewhere convection becomes a bit more isolated with more in the way of showers given the decrease in instability beyond the diurnal period along with downslope flow east of the mountains. Any storms that do form will have the capability of damaging winds and locally heavy rainfall.

The front stalls near/south of the region Thursday morning as high pressure over southeast Ontario wedges down the mountains. This will return temperatures back into the mid to upper 60s under cloudy skies and on/off shower chances throughout the entirety of the day.
The front retreats back to the north before washing out over the northern 2/3rds of the forecast area Thursday afternoon into Thursday night. This is due in part to the wedging high pressure system over southeast Ontario shifting toward the southern New England coast allowing winds to switch back to the southerly direction. The wedge will erode quickly as a result allowing for a quick spike in temperatures ahead of a stronger front Friday morning into Friday afternoon.

Gusty showers and a few thunderstorms are possible Friday afternoon and evening (Marginal Risk (Level 1 out of 5) mainly east of US-15 and toward the I-95 metros) as a true strong (Fall) cold front crosses the region. It will get breezy Friday afternoon as mid-level heights quickly fall and the surface pressure gradient tightens in response to a deepening low tracking to our north. Peak wind gusts of 35-45 mph are possible in the mountains, and 30-40 mph elsewhere.
Wind Advisories may be needed for some portion of the Alleghenies and Blue Ridge Friday afternoon into Friday night although model trends continue to decrease winds over a large spatial area (i.e immediate surge along the front and disjointed trough compared to the pressure rises on the back end). A squeegee line of gusty showers and some thunderstorms are expected late Friday afternoon and evening ahead of the front. If thunderstorms can tap into the increasing winds aloft, there certainly could be a few strong to severe wind gusts.A potent upper trough passes through the region Friday night, bringing a reinforcing cold front that pushes out any lingering precipitation.

Highs Friday push into the upper 70s and low 80s early in the day before falling into 60s and 70s (40s and 50s mountains) Friday evening. Expect overnight lows in the 40s (30s mountains) Friday night.

KEY MESSAGE 2...Temperatures 10 to 15 degrees below average this weekend. Dry, but with areas of frost possible and near freezing temperatures, mainly west of I-95, Saturday night and Sunday night.

A strong mid-level disturbance will quickly transverse the region Saturday. High pressure will build into the region later Saturday through Tuesday. Gusty northwest and northerly winds will diminish through the day Saturday as the last of any precipitation moves out and east of southern Maryland. Clearing skies and less wind expected the remainder of the weekend. With such conditions, areas of frost have a better opportunity to form across a large part or the region, especially west of the I-95 corridor. Frost and/or freeze headlines may be needed for Saturday night and early Sunday. As mentioned before, the mountains typically have their first freeze October 11, Shenandoah Valley area October 21, and east of the Blue Ridge November 1. High pressure will move overhead and then east early next week. This will allow for temperatures to modify more closer to average with dry conditions continuing.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/
VFR conditions will continue at most of the terminals through at least 20-21z/4-5pm. Skies will trend mostly sunny to partly cloudy with SCT-BKN CIGS generally above 060-120 kft (along and north of I- 66/US-50). A spotty shower cannot be ruled out before 20z mainly north of I-70/I-68 although coverage will be fairly sparse given the shallow moisture in the altocumulus deck.
Increased shower coverage and peRhaps a few thunderstorms arrive later this afternoon between 21-04z/5pm-12am. Thunderstorms will mainly be confined to areas west of MRB with showers further east into the corridor terminals. Storms will enter areas west of CBE between 20-22z/4-6pm before advancing toward MRB/IAD/BWI between 23z-03z/7-11pm. Precipitation may not even make it to CHO given the orientation of the boundary and timing.
Drizzle will likely impact this area when the front stalls Thursday morning. As a result, expect periods of sub-VFR conditions this afternoon through Thursday afternoon. MVFR cigs and vsbys are likely at most terminals with a brief window for IFR conditions Thursday morning into Thursday afternoon, especially in locations west of I-95 corridor terminals as the wedge settles in. Winds today will remain out of the west and southwest at 5 to 15 kts with occasional gusts up to 20 kts at times. Winds switch to the north and northwest tonight into Thursday morning before turning southerly late Thursday afternoon into Thursday night.

Conditions will improve as result with the wedge eroding in southerly flow late Thursday afternoon and night ahead of the next strong cold front/upper level trough set to cross Friday. The strong cold front moves through Friday afternoon into Friday night. A noticeable increase in winds is expected along with a squeegee line of gusty showers and thunderstorms. Southwest winds gust 25-30 knots Friday afternoon, then turn northwest behind the front Friday night.

VFR conditions Saturday through Sunday night. Winds northwest 15 to 20 knots gusts up to 30 knots Saturday, diminishing northwest to northeast 5 to 10 knots Saturday night. Winds variable 5 to 10 knots Sunday and Sunday night.

MARINE
No marine hazards are expected through at least 5pm this afternoon.
A front approaches the waters from the north later this afternoon and evening bringing a scattered showers and perhaps a gusty thunderstorm. The front will kick northerly winds back into SCA criteria later this evening into Thursday morning with gusts up to 20 kts. Winds will shift from the south back to the north and northwest behind the front. Winds gradually diminish Thursday afternoon and evening. SCA conditions are expected to develop across all the waters by Friday morning, then Gale conditions are possible Friday afternoon into Saturday. Gale Watches may be issued later today to encompass this threat, especially over the lower waters of the bay and tidal Potomac.

There could be Gales Saturday, followed by Small Craft Advisories Saturday night into Sunday morning. Afterwards, winds should diminish enough to have no additional headlines Sunday afternoon and night. Winds northwest 15 to 25 knots gusts 30 to 35 knots possible Saturday, diminishing north to northeast 15 to 20 knots gusts 25 to 30 knots Saturday night. Winds becoming northeast 10 to 15 knots Sunday and Sunday night.

CLIMATE
Below are the record highs for today, October 14.

Oct 14 Climate Site Record High Washington-National (DCA) 87F (1975)
Washington-Dulles (IAD) 86F (1975)
Baltimore (BWI) 86F (1975)
Annapolis (NAK) 85F (1975)
Hagerstown (HGR) 84F (1975)
Charlottesville (CHO) 94F (1954)
Martinsburg, WV (MRB) 90F (1928)

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.