Air Resources Laboratory banner image
Air Resources Laboratory web site National Oceanic and Atmospheric Administration (NOAA)

va discuss


Office: AKQ

FXUS61 KAKQ 180002
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
802 PM EDT Tue Jul 17 2018

.SYNOPSIS...
A cold front crosses the region late this evening and overnight.
High pressure builds into the area Wednesday and Thursday, then
shifts off the New England coast over the weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 230 PM EDT Tuesday...

Latest surface analysis has the cold front still to our west
close to the mountains and moving very slowly. A pre-frontal
trough across the piedmont and south central VA was helping to
trigger convection aided by a weak upper shortwave. Hi res
models in decent agreement in developing a first round of
convection this afternoon along the prefrontal trough, moving
slowly east, then another wave of showers and storms with the
front later this evening. Much of central VA and NE NC should
experience a round or two of showers and storms between now and
04z. Some models suggest less coverage across MD, but will
anticipate a round of showers and storms just ahead and along
the front even in MD.

Stronger storms this aftn and evening will produce frequent
lightning and with precip loading and DCAPE around 700 j/kg
expect some downbursts mostly producing 35 to 45 mph with some
isolated downbursts reaching severe limits. Due to some weak
shear and a storm motion of around 20 kt do not anticipate much
in the way of flooding though with PWAT of 2.25 inches rain will
be heavy at times resulting in some rapid accumulations of up
to one inch of rain which may cause some temporary issues due to
runoff.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
As of 230 PM EDT Tuesday...

High pressure builds in from the N Wed though the front will
still be near the Albemarle Sound come daybreak Wed and some
guidance suggests a few lingering shwrs across nern NC early Wed
morning. Wed will be generally mostly sunny and cooler with
less humidity as dew points drop into the upper to lower 60s and
highs top out in the mid 80s.

Even cooler come Wed night with Mstly skies. Lows in the 60s
except nr 70s close to the SO coast. Mstly sunny Thur and very
peasant with highs remaining in the 80s and RH rather low.
Temps warm a little come Fri as the high moves offshore and flow
start to return from the S.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 400 PM EDT Monday...

A sustained chance of showers and thunderstorms through the extended
period, with temperatures in the mid 80s to low 90s, is in store. A
low pressure system is expected to develop over the Outer Banks of
NC by 06z Saturday and quickly propagate northeastward. In turn, the
greatest chance for showers and thunderstorms Saturday will be along
and east of I-95, especially focused along the immediate coast. Wrap-
around moisture will be the culprit for continued showers into
Saturday night over the northeastern CWA (VA/MD).

Attention quickly turns to the west-southwest as southerly flow
pumps in respectable amounts of moisture. Sun-Tue will be
underscored by an upper level trough that parks itself atop the
area, allowing for scattered showers and thunderstorms each
day...mainly during the afternoon hours. Not everyone wins the rain
lottery, but if you do get caught underneath a storm, expect a quick
burst of moderate to heavy rainfall.

Temperatures each day will generally be in the mid 80s to low 90s,
with overnight lows in the low to middle 70s. This weather pattern
is virtually "shooting par" for the middle of July.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 800 PM EDT Tuesday...

Latest analysis reveals surface cool front just to the west of
the terminals at 00z. Numerous showers have developed along and
ahead of pre-frontal trough this afternoon, and have noted some
short-lived flight restrictions back to MVFR/IFR cigs in heavier
convection.

Majority of Convective activity is waning at SBY/RIC, with some
iso/sct storms still possible through midnight (04z) or so
PHF/ORF/ECG. CAMs indicating best chance of heavier
storms/flight restrictions remain to the SW of the terminals,
but some similarly short-lived convection could reach
previously referenced SE terminals over the next few hours.
Frequent lightning will accompany any of these these storms.

The cold front pushes through late evening and overnight across
the sern TAF sites so some lingering showers are possible in
the southeast overnight. Generally VFR late tonight along with
a wind shift to the NNW, with drier air pushing in and VFR
conditions for Wednesday.

Outlook: Aside from some early morning fog/MIFG Thu/Fri
morning, predominate VFR conditions across terminals through
Friday. More unsettled weather will bring an increased
shower/storm chance over the weekend into early next week.



Outlook:
VFR conditions mid-late week as high pressure dominates.

&&

.MARINE...
As of 345 PM EDT Tuesday...

No headlines are expected for the next few days. Southerly flow
late this afternoon into this evening at 15-20kt ahead of the
cold front will shift NW-N later tonight post frontal and
diminish to 10-15kt. Winds gradually shift to the NE by Thursday
as high pressure builds across New England. Some model
differences into the weekend as the models suggest an area of
low pressure will develop over the Carolinas and move over the
Delmarva. Regardless of the exact track of the low, will likely
see east to southeast flow increasing Friday night into
Saturday.

&&

.EQUIPMENT...
KDOX radar is inoperable due to a failure of the motor. Earliest
return to service is Wednesday.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.

&&

$$
SYNOPSIS...MPR/JAO
NEAR TERM...MPR/JAO
SHORT TERM...MPR
LONG TERM...BMS
AVIATION...MAM
MARINE...MRD
EQUIPMENT...



Office: RNK FXUS61 KRNK 172316 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 716 PM EDT Tue Jul 17 2018 .SYNOPSIS... A cold front will travel east across the region the evening and slide offshore tonight. High pressure follows the front by Wednesday with drier and somewhat cooler weather into the end of the week. && .NEAR TERM /THROUGH WEDNESDAY/... As of 710 PM EDT Tuesday... Best instability and storm coverage has exited the piedmont with just a few showers/storms across the mountains in a secondary axis of higher instability ahead of the front. High-res solution still painting a threat of showers in a scattered nature early this evening before things dry out, mainly in the NC portion of the forecast area. Otherwise, still some delay in drier air late will provide opportunity for fog formation overnight, especially in the mountains. No other major changes to the forecast from earlier. Previous discussion from early this afternoon... A cold front in the mountains this afternoon will move east tonight into Wednesday. Scattered to numerous showers and thunderstorms are expected ahead and along the cold front. A pre-frontal trough across the piedmont and southside trigger convection aided by a weak upper shortwave. SPC Mesoscale analysis at 18z showed CAPEs 2 to 3k j/kg and Lis from minus 1 to minus 3. Isolated severe thunderstorms may be possible this afternoon with gusty winds and hail as main threat. With high PWATs from 1.5 to 2.0 inches, some of the storms will contain heavy rains. Hiresw-ARW-EAST, HRRR and NAMnest showed a couple of clusters or bands moving east across the forecast area. The GFS and ECMWF also have showers and thunderstorms moving across the area this afternoon into tonight. The convection should diminish with the loss of solar heating tonight. The frontal boundary should push out of the region overnight allowing the flow to turn northwest with decent cool advection developing northwest half late as the upper trough passes across the region. Areas of fog will develop overnight into Wednesday morning. Low temperatures will range from the mid 50s in the northwest mountains to around 70 degrees in the piedmont. High pressure will build southeast out of the Ohio Valley on Wednesday in our region. High temperatures Wednesday will vary from the lower 70s in the mountains to the mid 80s in the piedmont. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 310 PM EDT Tuesday... High pressure over New England will wedge south into the Carolinas Wednesday night and linger into Friday morning. Most of the forecast area will remain dry with the exception of the Mountain Empire of West Virginia to the High Country of North Carolina where the wedge will erode and an inverted surface trough stretches north from the Tennessee Valley to the southern Ohio Valley Thursday. Coverage of convective will be isolated. Any afternoon showers will fade during the evening. Dry cooler air will bring a dramatic drop in humidities Wednesday night into Thursday night as dew points fall into the lower 50s. Overnight lows will also trend cooler with 50s across the mountains to lower 60s east. With dry air and abundant sunshine in the afternoon, Thursday's highs will range in the 80s with mid 70s along ridgetops. The wedge will hang around through Friday, but will erode from the west and southeast. An upper level trough is expected to become a close low over the Great Lakes on Friday. This low will send short waves into the Ohio Valley and erode the wedge from the west. Across the Southeastern states, a tropical disturbance is expected to track along the wedge boundary, then off the North Carolina coast Friday night. As this disturbance advances north, it will erode the wedge from the southeast. As the wedge erodes, the chances for showers and thunderstorms will increase, especially across the mountains Friday afternoon into the evening. Temperatures and humidity will also be on the increase Friday with highs in the upper 70s to lower 80s west of the Blue Ridge to the mid to upper 80s east. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 245 PM EDT Tuesday... On Saturday, the closed low expands into the Deep South and covers most of the US from the Mississippi Valley eastward. In the afternoon, there is a negative tilt to the trough in the eastern US that could bring active weather to the region. A weak cold front will then slide across the region Saturday night. Sunday, moreso Monday and Tuesday, could be active days with heating occuring under the cold pool as the closed low may dive south over the area. The area will remain under a trough through most of next week as a strong blocking ridge drifts westward in the Western Atlantic. Afternoon and evening showers and thunderstorms are likely each day from this weekend into the following week. Temperatures will run cooler than normal through the period. && .AVIATION /23Z TUESDAY THROUGH SUNDAY/... As of 713 PM EDT Tuesday... A cold front in the mountains will move east tonight. Most convection will be away from the terminals though could see a few showers still near enough to Danville to keep in the TAFS for now around 01-02z. Drier air will arrive Wed morning, so with some residual humidity and wet ground with clearing skies, fog will be likely in the mountains. KLWB is the taf site with the best chance for IFR/LIFR fog, with MVFR to IFR at times at BLF/BCB. High pressure building in from the north should bring widespread VFR under drier air for Wednesday. Medium confidence in ceilings, visibilities and winds during the taf period. Extended Aviation... Return flow looks to transport moisture back into the area Thursday and Friday but still looking at mainly VFR. Scattered showers and thunderstorms with sub- VFR conditions are expected Saturday ahead of the next cold front. Scattered showers and thunderstorms are likely on Sunday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK NEAR TERM...KK/WP SHORT TERM...RCS LONG TERM...RCS AVIATION...JH/KK/WP
Office: LWX FXUS61 KLWX 171836 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 236 PM EDT Tue Jul 17 2018 .SYNOPSIS... A cold front will cross the area this evening. High pressure will return for Wednesday and Thursday before moving offshore Friday. Low pressure may impact the area during the weekend. && .NEAR TERM /THROUGH TONIGHT/... Numerous showers and thunderstorms have developed across the area. As of 230 pm, the axis stretches from Frederick to Culpeper, with additional activity around metro Baltimore. While the echoes have been strong, there hasn't been much organization to them. This likely is using up the available instability, and an additional segment forming across southern Virginia will be capturing some of the moisture. The trend will be to continue pushing this axis across the Baltimore-Washington metro through 6pm. It remains to be seen how organized this will become. Local strong/severe wind gusts remain possible, but its running out of space for everything to come together. While local rainfall rates have been intense, there should been enough forward movement to preclude most hydro issues. The exception will be for repeated thunderstorms. Most convection will be pushing east of the Chesapeake Bay this evening. Some CAM guidance has been insistent at a secondary scattered line crossing the area this evening, so have not dropped chance PoPs. Confidence in this scenario is not high. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... High pressure will be sliding from the Great Lakes toward New England Wednesday into Thursday, providing sunny skies, low humidity, and temperatures a pinch below normal. && .LONG TERM /FRIDAY THROUGH TUESDAY/... High pressure will move off the New England coastline on Friday, leaving us with southeasterly flow at the surface. This southeasterly flow should allow some moisture return at the surface, with dewpoints climbing back into the 60s by day's end. The majority of the region is expected to stay dry, but some showers and thunderstorms may be possible over far western portions of the forecast area as ascent out ahead of a deep trough approaching from the Upper Midwest begins to overspread the area. The aforementioned trough will dig southeastward and approach the region this weekend. As it approaches, the trough will become largely cutoff from stronger westerly flow to the north. This will slow the eastward progression of the system, as it transitions into more of an upper low. Model guidance is also suggesting that a weak coastal low may develop off the North Carolina coast, along the a stalled out frontal boundary (the remnants of the front passing through our area currently). The coastal low is then picked up by the larger scale upper-level trough and tracks to the north along the Atlantic Seaboard. The interaction between the weak coastal low and the larger-scale trough will be a complex one, so confidence in the finer scale details is low at this point. Regardless, with the upper trough slowly approaching, it appears as though showers and thunderstorms are a good bet both days this weekend. Currently it looks like both the highest chances for precip, and the highest areal coverage of storms will be on Sunday. The majority of model guidance keeps the trough overhead on Monday as it begins to weaken and shear out. As a result, showers and thunderstorms will be possible once again on Monday. With the active weather around, temperatures should run at least slightly below normal Saturday through Monday. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Numerous thunderstorms congealing across the metros; believe most of this will be east of the terminals 21-22 UTC. Northwest winds this evening will advect drier air, precluding fog issues. VFR conditions are expected Wednesday through Friday with high pressure in control. Conditions may deteriorate to sub-VFR this weekend as a system approaches from the west. Thunderstorms will be possible each afternoon Saturday through Monday. && .MARINE... Small Craft Advisory in effect for all waters this afternoon and tonight. South flow has been gusting to 20kt, especially on the Bay south of Kent Island. Additional, local gusts will be possible in vicinity of thunderstorms. Anticipate a lull this evening as a cold front crosses the waters. Northwest flow will improve mixing tonight, which will remain favorable into Wednesday morning. Advisory will remain in effect until 11 am. There will be room to adjust the ending time if needed. High pressure will build across the waters Wednesday afternoon, and continue through Friday. Winds will be 10 kt or less through this period, from northeast veering southeast. Low end SCA winds may be possible Saturday through Monday as a system approaches from the west. Thunderstorms will be possible each afternoon Saturday through Monday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 11 AM EDT Wednesday for ANZ530>543. && $$ SYNOPSIS...HTS NEAR TERM...HTS SHORT TERM...HTS LONG TERM...KJP AVIATION...HTS/KJP MARINE...HTS/KJP