Scientific Forecaster Discussion
fxus61 kakq 190321
Area forecast discussion
National Weather Service Wakefield Virginia
1121 PM EDT Fri Aug 18 2017
a cold front will arrive late tonight or early Saturday morning
and exit the region by Saturday afternoon. High pressure builds
in for Saturday night through early next week.
Near term /until 6 am Saturday morning/...
convection continues to shift off the coast...at least the nrn
portion. The srn portion lags behind...and will be tracking
through mainly southeast Virginia well into the overnight hours.
Drying/lowering of dew points will be very slow as main cold
front is sluggish to push across the area from the west-northwest. Keeping
highest pops across the ern parts of the forecast area oavernight. Lows
from the l70s northwest to M-u70s elsewhere.
Short term /6 am Saturday morning through Monday/...
the models are still struggling on how much push is there to
get the front through the region on Saturday. With a strong
shortwave trough digging through the Ohio Valley, it makes sense
that the front will temporarily stall waiting for the shortwave
trough to move past. This should allow the front to finally get
south of the area and off the coast by Saturday evening. So
have kept a low chance for showers and afternoon storms over NE
NC and the Tidewater area on Saturday.
High pressure builds into the area on Saturday night into Sunday
and lingers through Monday. Temperatures will be a couple
degrees cooler, but the humidity will be much less making for
more comfortable conditions.
For temperatures, highs on Saturday will still be in the upper
80s to the lower 90s and that will continue on Sunday and
Monday. But overnight lows Saturday night and Sunday night will
be cooler with readings in the upper 60s NW to low to mid 70s
Long term /Monday night through Friday/...
sfc high pressure builds north of the area with stacked high
pressure residing off the southeast coast through Mon night. A
thermal trough develops in the Lee of the Appalachians for
Tue/Tue night, and then a cold front is expected to track
through the area on Wed...exiting the coast Thu morning.
Conditions will become increasingly more humid ahead of the
front. Thunderstorm activity expected to become widely scattered
Tue as convection develops invof Lee trough. The frontal passage
Wed/Wed night will provide a better focus for more organized
thunderstorms to occur. Lingering showers/storms possible far
southeast Virginia/NE NC on Thu. Otherwise, cool Canadian high pressure
builds across the Midwest with dry conditions anticipated for
the mid Atlantic region Thu night-Fri night.
Highs Tue-Wed generally upper 80s to lower 90s; low-mid 80s
beaches. Highs Thu/Fri low-mid 80s; mid-upper 70s beaches.
Lows Mon-Tue nights generally 70-75f. Lows Wed night
mid-upper 60s northwest to 70-75f southeast. Lows Thu/Fri nights around
60f northwest to around 70f southeast.
Aviation /02z Saturday through Wednesday/...
nearly solid line of tstms now moving through central Virginia-southeast Maryland
and will continue east through 02-04z/19 W/ possible gusty winds
and lower/vrb cigs-vsbys (mainly at ric/sby). Did hold onto
vcsh/thunderstorms in the vicinity invof the rest of the sites through about 04-06z/19 as
convection is slow to wane overnight. Mainly VFR conditions Sat
though possible isolated tstms in the afternoon southeast Virginia-NE NC invof
lingering weakening frontal boundary. VFR Sat night-Mon as high
pressure builds back into the region. Some early morning fog
possible both Sunday and Monday mornings.
a cold front approaches the region through this evening with
isolated to scattered thunderstorms developing along a weak
boundary along the mid Atlantic coast. Winds generally south
10-15kt the rest of today with locally higher gusts of 20-30kt
possible in thunderstorms. The front crosses the waters late
tonight with more widespread and organized thunderstorms
anticipated. Strong wind gusts above 30kt, heavy rainfall, and
frequent lightning will be the primary impacts. Seas 2-3ft build
to 3-4ft this evening and during the frontal passage later
tonight...subsiding closer to daybreak Sat morning. Waves will
average 1-3ft through tonight. Synoptic Small Craft Advisory conditions still not
anticipated tonight except with the thunderstorms associated
with the front. If any headlines are necessary, they can be
handled with short- fused mws or smw products.
Winds light and variable aob 10kt by mid-morning Sat through sun
as the front stalls near the mid Atlantic coast. Winds become
more onshore Sun night into Mon as the front sags well south of
the area. Seas subsiding from 2-3ft Sat aftn to 2ft by late Sat
night through most of Tuesday. South winds Tue/Tue night as a
thermal trough develops inland with seas building to 2-3ft
Tue/3-4ft Tue night. Winds SW around 15kt Bay/ocean
Tue night/Wed as the next cold front is expected to cross the
region. Seas/waves average 2-3ft. Winds north-NE aob 15kt behind
front Thu/Fri. Seas 2-3ft/waves 1-2ft.
minor coastal flooding is expected for areas adjacent to ches
Bay invof Bishops Head late this evening. Water levels should
reach 3.5ft around high tide, which occurs at 1136 PM this
evening. Cambridge is expected to reach 3.1ft, thus remaining
below minor flooding thresholds.
Maryland...coastal flood advisory until 2 am EDT Saturday for mdz021>023.