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FXUS61 KAKQ 142004
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
304 PM EST Thu Dec 14 2017

.SYNOPSIS...
High pressure builds over the area tonight, then moves off the Mid
Atlantic coast Friday. Low pressure develops off the southeast coast
Friday, then tracks northeast across the Vacapes Friday night. High
pressure returns over the weekend.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Sfc high to the north slides east to a position near the NJ coast by
12Z Fri. Dry with more clouds after midnight. Lows in the 20s except
lwr 30s SE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Sfc high slides offshore Fri morning with another clipper system and
its associated moisture progged to track east staying well north of
the area Fri nite.

Tricky part of the forecast comes from the south as a wave of low
pressure develops off the NC OBX Friday, then tracks NE across the
Vacapes Fri nite.  Latest data now shows the track of this low and
assctd moisture closer to the coast Fri before lifting ne and away
from the coast Fri night. NAM most aggressive throwing back moisture
as far west as the I95 corridor while the GFS/SREF/ECMWF limit any
measurable QPF to the nrn neck and ern shore areas. Bufkit sndgs
suggest about a 4-6 hour period of pcpn between 18Z-00Z with pcpn
lingering along the ern shore thru about 03Z Sat. Thermal profiles
suggest mainly snow (across the lwr Md ern shore) with a buffer
area of a rain/snow mix to snow across the nrn neck with just rain
over the south mixing with or changing to a snow shwr before ending.

Next concern will be sfc temps as they stay above freezing limiting
snow accumls Fri before falling by sunset. After coord with WPC and
neighboring offices, kept a dry forecast along and south of I64. Slght
chc pops ramping up to high chc to low end likely across the lwr Md
ern shore. For now, kept any snow accumls limited the lwr Md ern shore
where the likely pops will be. Generally under one inch expected with
the most ivof OXB. Highs Fri mid-upr 30s north, low- mid 40s south
except nr 50 across the OB.

Any lingering snow shwrs push of the coast before midnite Fri nite
with decreasing clouds after midnite. Lows mid 20s NW to lwr 30s SE.

High pressure builds over the sern states Sat then moves offshore
Sun. Dry through this period except for a slght chc shwrs late Sun
across wrn most zones. Highs Sat in the mid- upr 40s. Lows Sat nite
mid 20s NW- mid 30s SE. Highs Sun upr 40s- mid 50s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...

...Update to be issued shortly...

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
VFR conditions expected through the forecast period. SCT-BKN high
mid level clouds this aftrn will dissipate this evening as high
pressure builds over the area. The gusty WNW wind diminish this
aftrn as well. Developing low pressure along the se coast will
allow a BKN mid level deck to push north along coastal sections
Fri morning. Any pcpn associated with this systm is expected to
be after 18Z Fri and mainly along the eastern shore.

OUTLOOK...
Quick shot of snow and MVFR CIGS at SBY Fri aftrn and evening
as coastal systm makes closest apprch. High pres returns to the
area over the weekend.

&&

.MARINE...
Coastal low continues to exit into the western Atlantic while weak
high pressure over the Ohio Valley continues to slide east and will
be over the waters tonight into Early Friday.  The next system will
be a wave of low pressure that slides off the Carolina Coast and
deepens quickly Friday afternoon.  Expect an increase in winds
across the southern waters late in the day, getting close to SCA
levels late in the day for the southern bay and coastal waters.
With the values being marginal SCA values of around 20 KT in the
Bay and gust to 25 kt over the coastal waters, will not raise the
SCA flag yet.  But the model trend has been gradually getting
stronger with this system and if that trend continues the SCA will
be needed.

Behind this wave, cold advection will increase after 6z on Sat
through about 18z, which should cause more sca level winds,
especially in the northern coastal waters.  High pressure moves back
over the area late Saturday afternoon and will remain in control of
the regions weather through the weekend.  This will allow for a
period of light winds, going from a northerly direct Sat night to a
southwest direction by Sunday afternoon.

Winds will remain light on Monday, but expect a strong increase on
Tuesday as a frontal boundary and developing surface low approach
the area, followed by another shot of cold air for the midweek time
frame.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 7 PM EST this evening for
 ANZ650-652.

&&

$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...MPR
LONG TERM...AJB
AVIATION...MPR
MARINE...ESS

FXUS61 KAKQ 142046
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
346 PM EST Thu Dec 14 2017

.SYNOPSIS...
High pressure builds over the area tonight, then moves off the Mid
Atlantic coast Friday. Low pressure develops off the southeast coast
Friday, then tracks northeast across the Vacapes Friday night. High
pressure returns over the weekend.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Sfc high to the north slides east to a position near the NJ coast by
12Z Fri. Dry with more clouds after midnight. Lows in the 20s except
lwr 30s SE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Sfc high slides offshore Fri morning with another clipper system and
its associated moisture progged to track east staying well north of
the area Fri nite.

Tricky part of the forecast comes from the south as a wave of low
pressure develops off the NC OBX Friday, then tracks NE across the
Vacapes Fri nite.  Latest data now shows the track of this low and
assctd moisture closer to the coast Fri before lifting ne and away
from the coast Fri night. NAM most aggressive throwing back moisture
as far west as the I95 corridor while the GFS/SREF/ECMWF limit any
measurable QPF to the nrn neck and ern shore areas. Bufkit sndgs
suggest about a 4-6 hour period of pcpn between 18Z-00Z with pcpn
lingering along the ern shore thru about 03Z Sat. Thermal profiles
suggest mainly snow (across the lwr Md ern shore) with a buffer
area of a rain/snow mix to snow across the nrn neck with just rain
over the south mixing with or changing to a snow shwr before ending.

Next concern will be sfc temps as they stay above freezing limiting
snow accumls Fri before falling by sunset. After coord with WPC and
neighboring offices, kept a dry forecast along and south of I64. Slght
chc pops ramping up to high chc to low end likely across the lwr Md
ern shore. For now, kept any snow accumls limited the lwr Md ern shore
where the likely pops will be. Generally under one inch expected with
the most ivof OXB. Highs Fri mid-upr 30s north, low- mid 40s south
except nr 50 across the OB.

Any lingering snow shwrs push of the coast before midnite Fri nite
with decreasing clouds after midnite. Lows mid 20s NW to lwr 30s SE.

High pressure builds over the sern states Sat then moves offshore
Sun. Dry through this period except for a slght chc shwrs late Sun
across wrn most zones. Highs Sat in the mid- upr 40s. Lows Sat nite
mid 20s NW- mid 30s SE. Highs Sun upr 40s- mid 50s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A welcomed return to south-southwesterly flow on Sunday will bump
temperatures into the middle 50s. High pressure slowly meanders
offshore to the east on Sunday night and into Monday, allowing for
an uptick in moisture advection across the south.

The European is beginning to lean towards a drier, GFS-like solution
for Monday. Better chances for measurable rainfall exist across our
NC counties and extreme southeastern VA Monday aft/eve. Temperatures
during the day will rise into the upper 50s, so no worries about any
wintry precip.

Tuesday's temps will strive for the low 60s in the afternoon, with
one caveat being cloud cover. The GFS and EURO begin to disagree
during this timeframe, with the EURO being much drier at the mid
levels than the GFS. As such, the GFS is more bullish on cloud cover
and rain chances Tuesday afternoon and evening. Leaned more towards
the EURO solution, trimming back PoPs Tuesday...will wait for better
model agreement to increase confidence on Tuesday being any drier
than currently forecast.

The spigot abruptly shuts off early Wednesday morning as any
moisture slides off the coast. Expect highs Wednesday and Thursday
to be 7-10 degrees cooler than Tuesday.

&&

.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
VFR conditions expected through the forecast period. SCT-BKN high
mid level clouds this aftrn will dissipate this evening as high
pressure builds over the area. The gusty WNW wind diminish this
aftrn as well. Developing low pressure along the se coast will
allow a BKN mid level deck to push north along coastal sections
Fri morning. Any pcpn associated with this systm is expected to
be after 18Z Fri and mainly along the eastern shore.

OUTLOOK...
Quick shot of snow and MVFR CIGS at SBY Fri aftrn and evening
as coastal systm makes closest apprch. High pres returns to the
area over the weekend.

&&

.MARINE...
Coastal low continues to exit into the western Atlantic while weak
high pressure over the Ohio Valley continues to slide east and will
be over the waters tonight into Early Friday.  The next system will
be a wave of low pressure that slides off the Carolina Coast and
deepens quickly Friday afternoon.  Expect an increase in winds
across the southern waters late in the day, getting close to SCA
levels late in the day for the southern bay and coastal waters.
With the values being marginal SCA values of around 20 KT in the
Bay and gust to 25 kt over the coastal waters, will not raise the
SCA flag yet.  But the model trend has been gradually getting
stronger with this system and if that trend continues the SCA will
be needed.

Behind this wave, cold advection will increase after 6z on Sat
through about 18z, which should cause more sca level winds,
especially in the northern coastal waters.  High pressure moves back
over the area late Saturday afternoon and will remain in control of
the regions weather through the weekend.  This will allow for a
period of light winds, going from a northerly direct Sat night to a
southwest direction by Sunday afternoon.

Winds will remain light on Monday, but expect a strong increase on
Tuesday as a frontal boundary and developing surface low approach
the area, followed by another shot of cold air for the midweek time
frame.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Low Water Advisory until 6 PM EST this evening for ANZ637.
     Small Craft Advisory until 7 PM EST this evening for ANZ650-
     652.

&&

$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...MPR
LONG TERM...AJB/BMS
AVIATION...MPR
MARINE...ESS



Office: RNK FXUS61 KRNK 142008 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 308 PM EST Thu Dec 14 2017 .SYNOPSIS... Variably cloudy skies will continue through tonight. A weak disturbance passing through the region Friday may produce light wintry precipitation during the morning hours. Though amounts are not significant, it may impact the Friday morning commute. High pressure then returns Friday afternoon through Sunday. After Friday, the next chance for precipitation is Sunday night into early next week. && .NEAR TERM /THROUGH FRIDAY/... As of 306 PM EST Thursday...Variably cloudy afternoon across the central Appalachians, Piedmont and mid-Atlantic region this afternoon. Still some shallow moisture being drawn southeastward on lower-tropospheric northwesterly flow, despite surface ridging building into the region. Broad cyclonic mid- level flow exists across the eastern two-thirds of CONUS. In that flow, a shortwave trough/vort max now over the central Plains will serve as a focal point for sensible weather into the morning hours Friday. Though sky conditions are variable currently, greatest further west one goes, a west-east increase in cloud cover is expected per bufkit soundings during the late-evening/around midnight, especially for the northern/central half of the forecast area. Should see good radiational cooling in most areas through that period of time with most locations in the 20s to low 30s around midnight. Beyond midnight, forecast becomes a bit less certain given some discrepancies in 12z NWP solutions on extent of QPF. Though it's really a difference between no QPF and limited QPF, the potential for significant impact is possible for locales in/around the Blue Ridge, as much of what falls may be in the form of freezing drizzle. Aformentioned mid-level trough acts on low-level frontal zone, and generates limited to no QPF as it moves eastward, inducing weak cyclogenesis off the NC coast later Friday. The NAM and the higher- resolution CAM solutions generate QPF values less than 0.05", but closer inspection of the sounding indicates the moisture layer is shallow and confined between -2 and -8C, suggesting supercooled droplets with a dry ice crystal layer. Using the top- down methodology, this leads to either freezing drizzle or flurries within about 30 miles either side of the Blue Ridge for the pre- dawn hours into mid-morning Friday. On the other hand, the GFS/ECMWF depict hardly any QPF as the wave aloft makes its way into the mid- Atlantic region. From an impact perspective, freezing drizzle produces the same level of impact as light freezing rain: potential for accidents and glazed trees. Given that confidence in the NAM solution is low, will not issue any winter advisories at this time but will allude to the potential for difficult travel during the morning commute from freezing drizzle in the HWO. Temperatures should slowly warm into the mid/upper 30s with decreased clouds in the afternoon. The upper Piedmont of NC should see highs in the lower 40s. As clouds clear, westerly winds increase with some occasional breezes to 25 mph. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... As of 301 PM EST Thursday... Will see increasing subsidence as well as drier air punch into the region Friday night into Saturday behind the passing complex of shortwave energy from later Friday. This along with high pressure should make for quiet weather to start the weekend with little more than a flurry far northwest mountains Friday night. However will again see northwest winds ramp up behind the departing system with the next shot of modest cold advection. Expect strongest speeds Friday night as the 850 mb jet increases to around 40 kts and the inversion lowers but for now soundings indicate speeds below advisory levels. Should see winds diminish on Saturday as surface high pressure builds across allowing for a switch to warm advection in the afternoon. Otherwise partly cloudy Friday night with lows in the 20s to mainly sunny on Saturday with highs in the 40s. Heights slowly build Saturday night with southeast ridging taking shape Sunday into Sunday night. However residual upper low heading northeast out of Texas looks to ride up along the west side of ridging across the Tennessee Valley Saturday night/Sunday with some of this lift spilling east toward the region by Sunday night. Models remain inconsistent in just how much deeper moisture will make it into the area given westerly flow and ridging aloft as some solutions dry most precip up crossing the ridges at this point. Thus will continue the trend of bringing low shower chances into the west later Sunday and chance pops most sections Sunday night. Should be warm enough for all rain given late day arrival with temps in the 40s Sunday, and only falling into the 30s to around 40 Sunday night. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 301 PM EST Thursday... Appears mild period to maintain itself for much of next week as flatter upper flow around ridging across the southeast states remains in place for most of the period. Will see some digging northern stream shortwave energy make for a brief return to passing eastern troffiness around midweek but overall weaker now with each run. Other than for much warmer temperatures, main concern will be with shower chances that could linger into Monday, and then perhaps expand again Tuesday with a residual shearing upper system from Mexico that will attempt to undercut the ridge. Guidance spread remains quite large in northward extent of deeper moisture into westerly flow aloft as well as timing through Tuesday night. Appears initial system much weaker so only running with low pops into Monday night with somewhat higher chances Tuesday pending added support coming out of the southwest. Should finally see a cold front cross from the northwest Wednesday allowing for drier but only slightly cooler weather before temperatures rebound again Thursday as high pressure slides offshore. Highs to rebound to well above normal levels for early next week with mostly 50s to near 60 east before cooling some to 40s/near 50 mountains to 50-55 east Thursday. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... As of 1256 PM EST Thursday... General mix of VFR/MVFR ceilings across the TAFs, though MVFR upslope stratus mainly for Lewisburg and Bluefield. Ceiling trends should continue through midnight. Northwest winds initially 6-12 kts gusts to 20 kts abate through early evening to light and variable as boundary layer winds ease. Until then, potential for mountain wave clouds/turbulence in and around the Blue Ridge. Aviation forecast then trends less certain looking into the overnight and midday Friday period. Another mid-level disturbance traverses the region around 07z. Recent 12z GFS and NAM solutions are at odds in terms of precipitation as this upper-level system ripples through our area. The NAM is the wettest, and examination of forecast soundings support potential for light snow/flurries or freezing drizzle between 07-15z along the Blue Ridge and adjacent terminals. Have sided toward the worst-case NAM with -FZDZ indicated in most TAFs except Bluefield and Danville. Freezing drizzle would produce slick runways and greater mixed-ice accumulation on wings. Ceilings trend MVFR most TAFs except at Danville where VFR conditions should prevail. Light and variable winds, tending light east/northeast through the rest of the TAF period. High confidence in aviation elements through midnight. Medium confidence on ceilings and winds after midnight, Medium to low confidence on weather type and visbys after midnight. Extended Discussion... Should see conditions improving toward VFR late Friday afternoon into the evening as aforementioned upper disturbance/weak surface low moves off the Atlantic coast. VFR conditions should prevail until Sunday night. A better shot exists for sub- VFR conditions from a system system forecast to emanate from the mid-Mississippi Valley Monday into Tuesday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AL NEAR TERM...AL SHORT TERM...JH LONG TERM...JH AVIATION...AL
Office: LWX FXUS61 KLWX 141838 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 138 PM EST Thu Dec 14 2017 .SYNOPSIS... High pressure will build overhead through tonight. Low pressure will develop along the North Carolina coast Friday and move out to sea Friday night. High pressure will return for Saturday before weak low pressure impacts the area early next week. && .NEAR TERM /THROUGH TONIGHT/... Cold front has crossed the region with blustery northwest flow occurring this afternoon area-wide. Strato-cumulus has been gradually scattering out and diminishing, and this trend should continue for the rest of the afternoon. At the same time, high clouds will once again be increasing late in the day and overnight in response to a developing jet max and next fast- approaching system. Temperatures should still be able to fall quite a bit overnight with lows in the teens and 20s. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... Northern stream upper level trough will be quickly approaching the region during the morning Friday. At the same time, additional shortwave energy will be rapidly pushing eastward from the lower Mississippi River Valley and across the Appalachians by the afternoon. These two shortwaves are expected to remain un-phased until well offshore, which will keep any precipitation on the low side. That being said, surface low pressure is expected to develop along the baroclinic zone left by today's frontal passage near the North Carolina coastline Friday morning and move northeastward and offshore Friday afternoon. This now looks like it will be just close enough, when combined with the forcing from the northern stream trough and intensifying jet max to bring some light snow to portions of the region on Friday. Model differences still exist with respect to westward extent, but the trends today have been for high chances for our region. Have increased snow probabilities to likely across portions of southern Maryland and to chance as far west as the I-95 corridor for late Friday morning, peaking in the afternoon, and ending during the early evening. Have shown accumulations of less than one inch for the Maryland counties that border the Chesapeake Bay, going to a trace or less west of I-95. However, uncertainty is still quite high at this time. Highs during the daytime remain on the cold side, in the 30s area-wide. Flow will turn northwest following the system's departure Friday night, with a brief period of upslope snow showers likely along the Allegheny Front. Accumulations will be low though as moisture will be quite shallow, up to about an inch of snow or so. Lows Friday night in the 20s. High pressure will then build in south of the region on Saturday, with dry conditions expected. Highs Saturday in the upper 30s to mid 40s and lows Saturday night in the 20s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... High pressure, centered to our south on Sunday, will generate southerly flow over our region, allowing for high temperatures to reach the mid to upper 40s for most of our CWA. A shortwave trough will move across the area Sunday night into early Monday. This will increase PoPs over our area, but still uncertain how much QPF will be associated with it and any p-types. Guidance suggests that mid to upper level energy could bring a slight chance of precipitation between Monday and Tuesday with still above normal temperatures -reaching the 50s. A front could bring a chance of precipitation Tuesday night into early Wednesday. High pressure builds behind this front Wednesday into Thursday bringing dry and more near-normal high temperatures. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... Predominantly VFR conditions are expected through Saturday night. Gusty northwest winds up to around 25 knots are expected through today, diminishing by sunset. A period of light snow or snow showers are possible across the eastern terminals later Friday...but confidence is low at this time. This may bring a period of reductions, with highest chances at DCA/BWI/MTN. High pressure will then build in for Saturday. Mainly VFR conditions expected early Sunday into Tuesday. However periods of sub-VFR conditions are possible at times as showers could move through the terminals. && .MARINE... SCA is in effect through the rest of the afternoon for all waters with gusty northwest winds following the frontal passage this morning. Winds will gradually lessen this evening and tonight, but will likely remain gusty enough over much of the Chesapeake Bay and lower tidal Potomac to keep SCA going until midnight. Winds will then drop below SCA criteria later tonight and remain that way through Friday as high pressure moves overhead. Low pressure will then develop and move out to sea later Friday. Gusty winds will develop behind the front Friday night into Saturday. SCA goes into effect Friday night and may need to be extended into Saturday. Winds are expected to stay below small craft advisory threshold Sunday into Tuesday. Winds could increase Tuesday night. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until midnight EST tonight for ANZ531>534- 537-539>541-543. Small Craft Advisory from 8 PM Friday to 6 AM EST Saturday for ANZ530>534-537-539>541-543. Small Craft Advisory until 6 PM EST this evening for ANZ530- 535-536-538-542. && $$ SYNOPSIS...MM NEAR TERM...MM SHORT TERM...MM LONG TERM...IMR AVIATION...MM/IMR MARINE...MM/IMR