Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1004 am EDT Friday Aug 22 2014
a frontal boundary remains nearly stationary across the area into
the first part of the weekend. High pressure from New England is
slow to build over the region from Sunday through early next week.
Near term /until 6 PM this evening/...
initial short wave exiting the CST this morning resulting in overnight
rain showers/thunderstorms now moving well off the Atlantic CST. Most areas should be
dry through midday aside from weakening -shra drifting into the
Piedmont counties late this morning. Otherwise...starting out p/mcldy
Northwest flow remains over the region today. A second...ptntlly more vigorous
short wave from the eastern Ohio drops through the flow across the area beginning
this afternoon. This system expected to provide best chance of and greatest areal
coverage of rain showers/thunderstorms across the forecast area due to more
favorable/stronger upper jet support. Pockets of MDT to heavy rain are
possible given modest moisture and favorable upper support. The
sky becomes mainly cloudy across the forecast area by midday/afternoon hours. Hi temperatures from
the l/m80s near the CST...to the M/u80s elsewhere.
Short term /6 PM this evening through Sunday/...
a continued hi probability for rain showers/thunderstorms tonight into Sat morning as short wave dives southeast
through area then offshore. Additionally...surface winds become east-northeast and
cloudiness remains widespread. Locally MDT/heavy rain will continue to be
possible. Will hang onto widespread cloudiness and chance probability of precipitation Sat afternoon into
Sat night as onshore winds continue. Have confined possible thunderstorms to areas
away from the CST (would not be surprised that due to limited/no
instability that any thunderstorms will be well S and/or west of the fa).
Surface hi pressure over New England Sat slowly pushes S and into the
region by Sunday. This will push a remnant surface front S of the
area. Sun expected to be p/msny...W/ slight chance probability of precipitation mainly confined to
coastal sections in southeast Virginia/NE NC. Winds will continue to be from the NE...a
bit breezy at the CST.
Hi temperatures Sat 80 to 85f (u70s along the Atlantic beaches)...W/
u70s to l80s Sunday. Lows ranging from the u60s to l70s tonight...then
mainly in the 60s Sat night.
Long term /Sunday night through Thursday/...
extended forecast period will consist of mainly NE flow as high
pressure to the north ridges south while an area of low pressure
emerges from the Bahamas. This pattern will maintain a cooler
maritime airmass in place over the area through Wednesday before high
pressure at the surface and aloft begin to center themselves over
the forecast area. At this point subsidence will prevail and will help to dry
the atmosphere. Precipitation along the Virginia/NC coast can not be completely
ruled out due to the influx of moisture north as the surface low
forms to the south. There is some model discrepancy in regards to
the position and strength of the low over the tropical Atlantic. And
due to the large degree of change in model runs...at this point...
will not modify the previous forecast too much.
Temperatures will remain below average for much of the extended period
with highs around 80 Monday and Tuesday...warming slightly into the middle 80s
Wednesday and Thursday. Seasonal low temperatures in the low to middle 60s are likely
as the maritime airmass will limit significant overnight cooling.
Aviation /14z Friday through Tuesday/...
as of 11z...a frntal boundary is stalled over the middle Atlantic with hi
pressure located over the NE states. The combo of calm/light winds along
the front and decent low-level moisture has led to low ceilings and visibilities
Erly this morng in some areas. Any MVFR/IFR should end by later
this morng...with light winds and some low/mid-level clouds sticking
around through the day. Isolated/scattered rain showers/thunderstorms can be expected mainly
late in the day or during the eveng hours...but chance is not hi
enough to warrant a mention in the tafs at this time.
Outlook...shra/tstm chances continue into Saturday with dry
weather forecasted beginning Sunday. MVFR/IFR due to stratus or fog
will be a potential a few hours around sunrise through Sunday
no headlines necessary with this forecast package. Stationary frntal boundary
remains over the area this morng...leading to light/vrb winds. Low pressure
will form along the front today...with winds becoming north/NE behind the low
this afternoon. Expect mainly 2 feet seas over coastal waters and 1-2 waves over
the Bay. The front pushes S of the area Friday night as hi pressure noses S from
the NE states. Energy streaming southeast will help form an area of low pressure
off the Carolina CST. This synoptic setup will enhance the pressure
gradient across the waters causing near Small Craft Advisory wind gusts over the Bay
(18-20 kt) and coastal waters (23-25 kt) on Sat. Due to the wind
direction and fetch...expect seas to build to 4-5 feet over the ocean
by Sat eveng. With this being mainly 4th period...will not issue a
Small Craft Advisory at this time. Hi pressure begins to position itself over the area by Monday/Tuesday
but low pressure emerging from the S may help to maintain the pressure
gradient and persistent onshore flow through the middle of next week.