Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/04/18
Previous forecast discussion below...
Latest analysis indicating that the warm front is becoming
diffuse while finally pushing N through the local area. A light
SSW flow now seen in obs over most places, though with winds
still less than 10 kt, a local seabreeze still is affecting
areas near the Bay and coast. Expect the mixing to increase over
the next hr or so and should see SSW winds increase a bit more.
For late this aftn/early evening have added 20-30% PoPs across
the north for a few showers developing along the remnant
boundary. Expect these to diminish towards sunset or slightly
thereafter. temperatures this aftn have genly risen into the
60s with 70s in NE NC, and still some 50s over the far north.
For tonight, anticipate nearly steady temperatures, perhaps even
rising a bit after midnight as the southerly flow increases
ahead of the the cold front approaching from the west. Lows will
avg 55-60 F N to low 60s central and south (locally in the
lower 50s eastern shore coast). Mainly dry through 12Z/Wed
morning, though a few showers may make it into the far western
portions of the CWA between 09-12Z.
The cold front moves into the Piedmont Wednesday morning and
nears the coast by early aftn and pushes offshore by late
aftn/early evening. The local area has been outlooked for a
slight risk for severe across roughly the eastern 2/3 with a
marginal risk across the Piedmont. The main threat will be wind
given a fairly uniform wind from the SSW. Speed shear is rather
strong so this is genly a conditional severe threat in that
anything that does develop will have the potential for strong
winds. Overall, continue to think that the best chance for
strong to severe storms will be favored in Se VA and NE NC from
early to mid aftn. This is where precip holds off longer in the
morning, allowing for more heating and somewhat higher (though
still marginal) sfc-based instability. Farther NW still looks
like the precip arrives too early for anything more than a line
of showers with potential for a few embedded tstms. The NAM/GFS
remain similar with respect to timing with likely PoPs
progressing across the area Wednesday, mainly in the morning
through midday W, and early/mid aftn E. Highs temperatures range
from the 60s NW to lower 70s SE. Appears enough dry air arrives
from the NW to lower PoPs significantly over the NW 1/2 of the
CWA before 21Z (potentially as early as 18z) and all areas by
00Z.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Dry/becoming mostly clear Wednesday night and mostly sunny and
cooler for Thursday. Lows in the 30s most areas Wednesday night
(potentially upper 20s NW). Highs Thursday in the low 50s NE to
the mid/upper 50s elsewhere. Partly cloudy with lows in the mid
30s to mid 40s Thu night. Increasing SW flow ahead of the next
front on Fri will allow for warming temperatures. Partly cloudy
south and mostly cloudy north. Highs mainly in the 60s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Rain overspreads the entire CWA late Friday night into Saturday
morning as surface low pressure approaches western NC. At the same
time, a frontal boundary will be situated across the VA/NC border.
Temperatures will likely be in the low-mid 50s Saturday morning
south of the boundary in NE NC, while we will see 30s in our
northwestern counties/low-mid 40s in the Richmond metro to the
Eastern Shore. The frontal boundary will slowly push southward
through NC while precipitation is falling over the entire CWA during
the day on Saturday. Therefore, we will likely have steady or slowly
falling temperatures. By Saturday evening, the boundary will be well
south of the CWA as low pressure pulls offshore. If/when we will see
a changeover to snow in parts of our CWA is still our main forecast
question.
Continued to lean toward a GFS solution for this event. Latest
03/12z GFS has the changeover occurring from an LKU-EZF-Dover line
by noon Saturday with a rain/snow mix possible from RIC-SBY
northward by evening as the precipitation starts to wind down from
northwest to southeast. Latest 03/12z CMC is similar to the GFS,
while the 03/12z ECMWF is slightly farther south with the track of
the low pressure system. At this time, it looks like there is the
possibility of a light accumulation on grassy surfaces in our far
northwestern counties.
Lows Sunday morning will be at or below freezing inland/around 35-
40F near the coast in the wake of the low pressure system. Expect a
cool but dry day Sunday with highs in the 50s. More rain is possible
on Monday as another storm system approaches the area. Temperatures
will remain below average on Monday-Tuesday with highs in the 50s
and lows in the 30s-low 40s.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
Whatever is left of the surface warm front is moving northward
through the forecast area at this time. A few sprinkles/light
showers are possible early this evening at RIC and SBY, but
latest upstream observations show CIGS around 10000ft with -RA
so these sprinkles should be of little consequence and will not
be included in the terminal forecast.
VFR conditions will continue for this evening into the overnight
for the area. Some MVFR cigs may move northward into NE NC and
the VA Tidewater later tonight as increased moisture moves
northward. In addition, some LLWS is possible tonight at RIC and
SBY.
The cold front approaches the area late tonight and moves
through the region late Wed morning into Wed aftn. A narrow line
of showers and scattered thunderstorms are expected with this
line. MVFR to even brief IFR conditions possible for a short
period of time as this line of showers/storms move through.
Could certainly see some gusty winds with any stronger storm on
Wednesday, especially PHF/ORF/ECG. However, these showers/storms
will be short lived and it will quickly dry out and clear out
behind the front later Wed aftn. W-NW winds will also become
quite gusty with gusts 25-30kt not out of question.
Outlook:
High pressure builds in from the NW Wednesday night and passes
over the area Thursday, with dry conditions and VFR. High
pressure moves offshore Thursday night and Friday as another
cold front approaches from the NW Should remain predominantly
VFR. The cold front drops through the region Friday night with
low pressure tracking across the Carolinas Saturday and expect
deteriorating conditions with flight restrictions possible by
Sat/Sat night.
&&
.MARINE...
Latest sfc analysis shows a weak stationary frontal bndry in the
vicinity with strong low pressure over the Midwest. That low will
track to the ENE tonight, dragging a cold front towards the Mid
Atlc. Ahead of the cold front, southerly flow strengthens especially
overnight into Wed morning. Went ahead and put all headlines in
effect with SCA conditions expected to commence within about 12 hr
or so, and also included the rivers/Sound/Lwr James. Winds further
increase into the day Wed, with gusts up to 30 kt expected over the
wtrs. Some occasional gusts up to 35 kt also psbl over the coastal
wtrs/Bay. Seas up to 5-7 ft. The front pushes offshore Wed aftn,
with SCA conditions expected to continue post frontal especially
over the Bay and northern coastal wtrs. Benign marine conditions
then for Thu as high pressure builds into the region. Next chance
for SCA conditions arrives Fri as low pressure passes off to the
north.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 7 PM EDT Wednesday for ANZ633-
635>638-656-658.
Small Craft Advisory until midnight EDT Wednesday night for
ANZ630>632-634-650-652-654.
&&
$$
SYNOPSIS...LKB
NEAR TERM...MRD/LKB
SHORT TERM...AJZ/LKB
LONG TERM...ERI
AVIATION...MRD
MARINE...MAS
Area Forecast Discussion
National Weather Service Binghamton NY
950 PM EDT Tue Apr 3 2018
.SYNOPSIS...
Showers will continue tonight as a warm front crosses the
region. Expect low temperatures early tonight, followed by
rising temperatures overnight. A pronounced cold front will
bring additional showers, and a chance for thunder, on
Wednesday morning. Strong, gusty winds and colder weather will
develop Wednesday afternoon and evening. Scattered power outages
will be possible due to the high winds.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
With our area getting into the warm sector south of a warm
front passing through overnight, we`re forecasting a non-
diurnal temperature trend with evening lows in the upper 30s-low
40s rising into the lower 50s early Wednesday morning. A look
at radar trends this evening show a break in the action between
rounds of showers. A cluster of showers over western PA looks to
primarily stay south of our region heading into the overnight
but additional showers and even a rumble of thunder or two will
move back into the region as we get closer to sunrise.
Over the past few hours fog has become locally dense across the
Poconos northeast into Sullivan county. HRRR and NARRE guidance
continue to insist on the dense fog becoming widespread
overnight. However, winds should start to increase ahead of a
cold front by sunrise. Also, these models may be overestimating
the snowcover which would lead to a low visibility bias in this
case. For now, we have opted to issue an SPS for these
locations into the overnight as some patchy dense fog is likely
in higher elevations and where any snowcover is.
Previous including discussion on wind headlines....
The main concern associated with the passing of deepening low
pressure moving across northern NY on Wednesday will be the
development of strong and gusty winds along and behind the
surface cold front. Cold FROPA is slated to traverse the area
between about 15Z-18Z followed by a well mixed low level
environment in moderate to strong cold advection. Isallobaric
rise/fall couplet slides mainly through the Finger Lakes region
into north Central NY. Within this favorable environment for
efficient momentum transfer, strong post frontal winds aloft of
50-60 knots should occasionally be realized at the surface.
Decided to upgrade a portion of our High Wind Watch areas to a
Warning from Yates to Oneida counties where the open terrain
along the lake plain, as well as channeling down the Mohawk
Valley will be the highest confidence locations for strong and
damaging winds. Further south, away from the low, winds will be
slightly less and thus better addressed with a Wind Advisory for
scattered wind driven problems such as downed wires and power
outages.
As the low and frontal system shifts to the northeast,
temperatures will steadily fall during the afternoon with any
showers mixing with and changing to snow showers on Wednesday
night. There should be some multi-band lake response as 850 mb
temperatures are progged to drop to around -15C. This should be
enough for scattered-numerous snow showers across the northern
zones with only nominal accumulations in April. Speed shear
across the lake looks a little tricky for much resident time of
the parcels.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Northwest flow of unseasonably cold air will keep an area of
lake effect snow of the northern zones into Thursday afternoon
before air mass modification and a more westerly flow ends the
activity. Shortwave and closed surface low over the upper lakes
pushes a warm front into the area Thursday night and early
Friday bring a bit of snow, followed by mixed precipitation and
rain on Friday. Cold front will follow the system late in the
day and begin a return back to colder air and snow showers.
Despite a bit of warming Friday, short term will continue the
trend of below normal temperatures with a broad upper trough
remaining in place.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Same old story with a broad upper trough over the easter third
of the U.S. and a stream of short waves racing through in the
fast flow.
Friday night will see some limited lake effect but the flow is
not quite as favorable as with previous events. Strong southern
stream storm is expected to pass well south of the area
Saturday night into Sunday spreading snow in areas that rarely
see such events in April. so while we`ll be cold, it doesn`t
look white.
Later SUnday, a closed upper low drops into western New England
reinforcing the cold air and bringing scattered instability snow
showers to the area into the overnight.
Surface high pressure overhead for Monday will hopefully
suppress the next low to the south as well, keeping the area
dry but cold.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
A warm front will lift north through the region overnight
followed by a vigorous cold front Wednesday morning. In general
Alternate Required conditions are forecast overnight with MVFR
visibility restrictions also at KRME/KSYR due to scattered
showers. At KITH, Alternate Min conditions are forecast with
improvement to Alternate Required around 03Z. At KBGM, IFR
conditions are expected until 09Z. Between 08Z-15Z,
MVFR/Alternate Required showers are forecast ahead of the cold
front. By mid morning conditions will be improving to VFR with
scattered light showers til early afternoon.
Low level wind shear will perists until frontal passage with
winds around 2K feet from the south/southwest at 40-50 knots.
Surface winds will be south/southeast at 8 to 15 knots shifting
to west to southwest Wednesday morning at 15 to 25 knots with
gusts around 30 knots then increasing during the early afternoon
from the west at 20 to 25 knots with gusts 35 to 45 knots.
Outlook...
Wednesday night...VFR-MVFR. Scattered snow showers with
restrictions possible.
Thursday and Friday...Occasional restrictions are foreseen, in
snow showers, or even a period of light snow.
Saturday-Sunday...Mainly VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Wind Advisory from 10 AM Wednesday to midnight EDT Wednesday
night for PAZ038>040-043-044-047-048-072.
NY...Wind Advisory from 10 AM Wednesday to midnight EDT Wednesday
night for NYZ022>025-044>046-055>057-062.
High Wind Warning from 10 AM Wednesday to midnight EDT
Wednesday night for NYZ009-015>018-036-037.
&&
$$
SYNOPSIS...JAB
NEAR TERM...JAB/MWG
SHORT TERM...DGM
LONG TERM...DGM
AVIATION...RRM
Area Forecast Discussion
National Weather Service Columbia SC
1006 PM EDT Tue Apr 3 2018
.SYNOPSIS...
A cold front will move across the forecast area Wednesday
bringing scattered showers and possibly thunderstorms. Dry high
pressure will build back into the region for Thursday and Friday
followed by another low pressure system over the weekend.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Upper-level trough over the northern Plains will move to the
Great Lakes region by early morning. Surface low will deepen and
track from the Midwest to the Great Lakes region overnight. The
trailing cold front will be approaching the region toward
morning. The HRRR brings showers into the western portion of the
forecast area by 11Z so adjusted pops slightly based on this and
other high resolution model output. QPF amounts are light given
unimpressive PWAT values and quick movement of the system.
Expect increasing cloudiness especially after midnight. Minimum
temperatures expected to fall into the low to mid 60s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
A cold front will move into the forecast area (FA) from the west
Wednesday morning. Weak moisture transport and westerly 850 mb
winds do not support widespread rainfall. Convection allowing
models also suggest that the line of showers will become
scattered as they move across the FA in the morning. Total
rainfall from the system will likely be less than 0.25 inches
for most areas. We can`t rule out a chance for thunderstorms
through the day, mainly in the east where the frontal passage
will better coincide with the daytime heating. However tall,
skinny CAPE profiles and near neutral LI values suggest the
chance for severe weather will be isolated. PWAT values at 1.5
inches or less with decent storm movement do not support heavy
rain concerns from individual cells. High pressure along with
cooler and drier air will begin building back into the region
Wednesday evening and be centered over the region Thursday
afternoon and night. Afternoon high temperatures will be in the
mid 70s on Wednesday and the mid to upper 60s Thursday with
overnight lows in the upper 30s to low 40s Wednesday night and
mid 40s Thursday night.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Broad upper level troughing and embedded shortwaves support
unsettled weather through the long term. High pressure will move
in behind the front for Thursday and will move away from the
region on Friday as the next low pressure system approaches from
the west. There is a large spread in guidance for the track of
the low pressure system that will move into the eastern US over
the weekend. Decent moisture transport and forcing along a
frontal boundary suggests rainfall is likely at some point
during the weekend. Temperatures will be near normal Friday and
Monday with below normal for Saturday and Sunday.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Low-level wind shear, possible thunderstorms, and breezy
conditions will be the main issues during during the 24-hour TAF
period.
The approaching cold front will move through the area during the
middle of the day Wednesday. A strong low-level jet will be
associated with the front. There will be diminished surface wind
because of less mixing associated with nocturnal cooling tonight
into Wednesday morning. Based on the NAM we have included low-
level wind shear during the 04z to 14z time frame.
Based on the HRRR a band of showers or thunderstorms will begin
moving into the area around 11z ahead of the cold front.
There may be enough instability associated with the low-level
jet combined with h5 temperatures near -13 C to support mainly
elevated thunderstorms. The high shear indicates strong wind
gusts will be possible with any stronger convection.
The HRRR suggests drying beginning 15z to 16z. It will remain
breezy along and behind the front. The GFS LAMP and NAM bufkit
momentum transfer tool suggests gusts 18 to 22 knots.
EXTENDED AVIATION OUTLOOK...Widespread MVFR or IFR conditions
may occur Friday night into Sunday associated with a frontal
system. The greatest chance of most significant restrictions is
Saturday and Saturday night.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
846 PM CDT Tue Apr 3 2018
.DISCUSSION...
Just made a few changes to the grids given the current situation
and trends. Shorter term models are going a tad slower with the
front, which means the rain chances near the coast may bleed into
the 06Z-10Z time frame. As a result, did adjust the POPs for
tonight to account for this. Latest HRRR (which at times can be
over-doing rain chances) is still showing some convection as the
boundary moves down. Thus, did not want to lower or adjust POPs
too much, although it appears that (based on the 1 km
reflectivity) it is hinting more at scattered convection. Could
still not rule out a strong storm or two Victoria area and NE
coastal counties. Any good convection heading toward the gulf may
require a SMW as the winds will be elevated with any convection
along the front. Adjusted temperatures and dew points to fit
better with observations and current trends (brought the Forecast
Monitor to green at least for now).
Finally, will monitor for possible Wind Advisory for the coastal
areas as winds have the potential to gust to 40 mph or more for an
hour or two. Want to see the new meso-models before pulling the
trigger on that.
Products have been updated.
&&
.MARINE...
Sustained winds behind front are expected to be below 30 knots but
could have some gusts to 35-40 knots along fropa. At this time,
since surrounding areas are keeping SCA conditions will not pull
the trigger on any gale conditions at this time, but we could have
some gusts 35 knots or so with the front. Will monitor.
&&
.PREVIOUS DISCUSSION... /Issued 638 PM CDT Tue Apr 3 2018/
DISCUSSION...
See .AVIATION discussion for the 00Z TAFs.
AVIATION...
Main issue is the timing of the front and the possible convection
with it, then how strong the winds will be behind it. Do have
TEMPO TSRA for the thunder at all but KLRD, where not very likely
to happen there. TEMPO group is associated with the timing of the
front, expected sometime around 03Z at KVCT, and 05Z-06Z at the
other three terminals. Winds will be NNE with increasing winds
likely above 20 kts sustained at eastern terminals. Will likely
have some MVFR conditions with the front at the eastern terminals
as well, with MVFR likely continuing after 12Z at KCRP (but
improving AOA 18Z), but improving before that at the other
terminals. Winds will remain elevated and gusty but diminish
during the afternoon, lastly as usual at KCRP with gusty winds
continuing through most of the afternoon with the NE flow from the
bays.
PREVIOUS DISCUSSION... /Issued 407 PM CDT Tue Apr 3 2018/
SHORT TERM (Tonight through Wednesday night)...
A strong cold front positioned across Central Texas will continue
on its southward track into the region tonight as an upper level
trough digs into the Central Plains. Although the region has been
fairly capped this afternoon, anticipate the cap to begin to
erode late this afternoon into this evening as the front
approaches and a series of shortwaves moves out from northern
Mexico and across the region. Hi-res models continue to indicate
that our CWA will be more on the tail end of the stronger
developing convection, and will continue with the highest PoPs
across the northern Coastal Bend into the Victoria Crossroads.
Given MUCAPE values still around 2000 to 2500 J/kg this evening,
forcing from the front, and the upper level support overhead,
some strong storms will be possible. Widespread severe storms are
not anticipated, but an isolated severe storm cannot be ruled out,
especially across northeast portions of the Victoria Crossroads
where SPC has outlined a Slight Risk. The majority of convection
will move through generally before midnight, with some scattered
storms lingering a bit longer into the early morning hours.
Breezy to windy north winds can be anticipated to develop across
South Texas and the Middle Texas Coastal Waters during the early
morning hours. A Small Craft Advisory is already in effect for
early Wednesday morning through the afternoon. Strong gusts will
be possible overland, especially along the coastal areas late
tonight through the early morning. Winds will gradually relax
through the day on Wednesday.
Much cooler air will filter into the region tonight, with lows in
the mid 50s to low 60s. Tomorrow will be much cooler, with highs
struggling to get into the low 70s during the afternoon. Similar
temperatures will then redevelop tomorrow night.
LONG TERM...
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 58 71 61 79 70 / 50 10 10 20 10
Victoria 54 72 53 79 68 / 60 10 10 20 10
Laredo 56 72 60 82 68 / 10 10 10 0 10
Alice 59 71 58 81 68 / 30 10 10 20 10
Rockport 60 72 63 77 71 / 50 10 10 20 10
Cotulla 53 72 57 81 67 / 10 10 10 0 10
Kingsville 60 71 59 81 69 / 40 10 10 20 10
Navy Corpus 63 73 65 78 72 / 50 10 10 20 10
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory from 3 AM to 7 PM CDT Wednesday For the
following zones: Coastal waters from Baffin Bay to Port
Aransas out 20 NM...Coastal waters from Port Aransas to
Matagorda Ship Channel out 20 NM...Waters from Baffin Bay
to Port Aransas from 20 to 60 NM...Waters from Port Aransas
to Matagorda Ship Channel from 20 to 60 NM.
Small Craft Advisory from 3 AM to 1 PM CDT Wednesday For the
following zones: Bays and Waterways from Baffin Bay to Port
Aransas...Bays and Waterways from Port Aransas to Port
O`Connor.
&&
$$
GW/86...SHORT TERM
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1050 PM EDT Tue Apr 3 2018
.SYNOPSIS...
A cold front will approach from the west late tonight and cross the
forecast area by mid-morning Wednesday. Cool and dry high pressure will
build across the region Thursday and linger into Friday. Then
another moist frontal system affects the area on Saturday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 1040 pm: Pre-frontal strong to severe convection, which is
steadily taking on a more linear QLCS/MCS-ish character, currently
extends from southern Middle Tennessee/northwest AL into
east-central Kentucky, while isolated showers have been gradually
increasing in coverage ahead of the frontal band across East TN. A
Severe Thunderstorm Watch is in effect until 07Z for much of East Tn
and eastern Kentucky. As one would expect, a progged decline in
instability parameters (despite steep mid-level lapse rates
associated with remnant elevated mixed layer air) and deeper forcing
passing north of the area is expected to result in a continued
diminishing trend in convection over the next several hours. This is
very much supported by the latest HREF output, which basically
depicts little in the way of substantive updraft speeds or helicity
by the time the frontal band makes landfall in the southern
Appalachians circa 06Z. The threat for severe convection over our
area therefore appears to be dependent upon one or more
strong/organized cold pools developing in association with the
developing QLCSs to our west. This doesn`t seem entirely likely
given the environment, and it makes sense to us that SPC is sticking
to their guns in maintaining only a sliver of a marginal risk across
southwest NC. (Having said that, the HRRR suggests perhaps a
marginal risk exists southeast of I-85 as well, where it does depict
some enhanced cellular activity developing along the leading edge of
the frontal band toward daybreak). The Hazardous Weather Outlook
will be repositioned to mention the potential for damaging winds
across the western-most tier (or so) of counties in NC, and a very
marginal threat across southern Piedmont areas.
Otherwise, min temps tonight will be well above normal in most
areas, although strong cold advection will be sweeping through the
far western mtns by sunrise. Gusty NW winds develop behind the cold
front Wed, clearing out much of the cloudiness and introducing much
cooler air. Max temps are forecast to top out several degrees below
climo in most areas, or about 15 degrees cooler than the last couple
of days.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 215 PM EDT Tuesday: A surface high will build in quickly from
the west Wednesday night, allowing for good radiational cooling
conditions outside of the mountains as wind diminishes in the early
morning hours Thursday. The guidance continues to suggest low temps
dropping down into the frost range over parts of Upstate SC,
northeast GA, and the NC southern foothills and piedmont. The
guidance also suggests freezing temps across the northeast Georgia
mountains but only the highest peaks of the Upstate mountains seeing
freezing. Therefore, will go with a Freeze Watch for the northeast
Georgia mountains where conditions are more favorable and more
widespread. Still too early for a Frost Advisory, especially with
concerns about the winds, but this will have to be monitored. The
upper flow remains fast thru Thursday and into Friday, so the sfc
high will move past and offshore by Thursday night. Highs will be
about five degrees below normal Thursday with lows near normal
Thursday night. A cold front moves southeast toward the area Friday.
The continued moist southwesterly flow ahead of the front will help
bring a chance of rain to the mountains during the afternoon. Highs
Friday will be near normal.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 230 PM Tue: An action-packed medium range period is in store,
featuring not one but two frontal passages, Saturday and Monday,
each of which will be accompanied by a wave of low pressure. While
timing is fairly well agreed upon, enough model spread is still
seen in the smaller details to keep confidence lower than usual.
Precip chances increase Friday night as the first front approaches
from the NW. Most likely precipitation will be all liquid to start;
some guidance depicts cold air filtering in during the day Saturday
and beginning a transition to wintry p-types at that time, but the
most likely scenario appears to be for precip to remain liquid until
Saturday night, when the aforementioned sfc wave has passed east of
the area and PoPs will be tapering off overall. High pressure will
build east out of the Midwest on the cool side of the front, and
there is a chance that in-situ CAD will develop over WV/VA. Temps
are likely to remain 10-13 degrees below normal, but right now
the really impactful temps (i.e. those that would support wintry
wx during the day) don`t look likely to occur as far south as
our CWFA. Dry but continued cool conditions are expected Sunday
following the departure of the first front.
As sfc high pressure sets up over the Eastern Seaboard Sunday night,
and as the next cyclone enters from the west, the GFS expects that
CAD will develop again, this time far enough south to "wedge in"
at least our northeastern zones, and produce another precip event
for the area. The previous (03/00z) run of the EC agreed broadly
on this, but the new 12z run instead keeps us dry on Monday, and
accordingly not as cool. If precip does occur early Monday, sfc
temps in parts of the mtns could support a wintry mix, though warm
advection over the wedge makes this a complex fcst, and confidence
is low in p-types.
Max temps remain two or three categories below normal through the
end of the period, though mins Sun and Monday night will be only
slightly below normal.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and Elsewhere: The main issue during this forecast cycle
will be cold frontal passage that will occur beginning early Wed
morning, and the showers and potential thunderstorms that will
accompany the front. High resolution models are speeding up the
timing of the front, as they often do (typically with a good bit of
accuracy) in organized convective situations. Additionally, some
upslope shower activity/possible TSRA may develop due to terrain
effects well ahead of the frontal band. (These would primarily
impact KAVL). As such, timing of SHRA onset has been moved earlier a
couple of hours at most sites. TSRA along with gusty winds have been
included in a tempo at KAVL and KAND. Outside of those terminals, TS
chances are a bit iffy, as the overall trend should be toward toward
weakening of the frontal band. Nevertheless, at least a VCTS mention
has been included at all other terminals. Flight conditions have
generally been maintained at the low VFR or MVFR level in
association with the showers, but would not rule out brief periods
of IFR, especially low visby associated with RA+.
Winds will remain S/SW at around 10 kts (with higher gusts possible)
through the evening and into the early part of the overnight. Winds
will then turn to the W and NW by late morning, with gusts to around
20 kts possible (likely higher than that at KAVL). Otherwise,
clearing skies/improving flight conditions will accompany the
shifting winds.
Outlook: Drier/VFR conditions will persist through the end of the
work week. Another moist low pressure is expected to bring
precipitation and restrictions to the area during the first half of
the weekend, with drying likely returning by Sunday.
Confidence Table...
03-09Z 09-15Z 15-21Z 21-00Z
KCLT High 100% High 100% High 98% High 100%
KGSP High 100% Med 75% High 100% High 100%
KAVL High 100% High 98% High 100% High 100%
KHKY High 100% High 98% High 100% High 100%
KGMU High 100% Med 73% High 100% High 100%
KAND High 100% High 82% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Freeze Watch from late Wednesday night through Thursday
morning for GAZ010-017.
NC...None.
SC...None.
&&
$$
SYNOPSIS...ARK
NEAR TERM...JDL
SHORT TERM...RWH
LONG TERM...Wimberley
AVIATION...JDL
Area Forecast Discussion
National Weather Service Houston/Galveston TX
942 PM CDT Tue Apr 3 2018
.NEAR TERM [Through Tonight]...
Update forecast to remove counties from the northern half of the
forecast area as capping and front under cutting storms has caused
a diminished severe weather threat. Front and outflow continues to
rush south across I-10 cooridor with a stronger cluster of storms
over Colorado County. Overall convection should remain weak with
strong capping evident in AMDAR airplane soundings.
Overpeck
&&
.PREV DISCUSSION /Issued 809 PM CDT Tue Apr 3 2018/...
Updated forecast for ongoing trends based on radar. Cap holding
strong south of the front and seems to be the limiting factor in
the convection over Walker County. Cold front is approaching the
strong storms so may see an up tick in activity. Jet streak still
west of the area but lift from it seems to be weak at this time as
there has not been much convection to form west of the area. There
are a few storms near La Grange to Bastrop so possible storms
could fill in along the front between this activity and the Walker
County activity. HRRR model trends seem on track so latest update
to the forecast follows those trends.
Hopefully we can clear some of the northern counties from the
severe thunderstorm watch before 10PM depending upon how far south
the front reaches.
Overpeck
.AVIATION [00Z TAF Issuance]...
Challenging forecast timing the collision of the oncoming front
and storms ongoing ahead of the front. Additionally, lots of
questions as to how much the cap will erode farther downstream
towards the Houston metro.
With these uncertainties, have mainly chosen to tweak the timing
of prevailing TSRA at all sites based on latest radar and
satellite trends. With the complex evolution of these storms, it
may require further amendments until we reach a more steady state
after dark in which the front dominates.
Luchs
.MARINE...
Onshore flow has relaxed somewhat with the approach of a cold front
stretching from near Little Rock AR to Pecos TX and have allowed the
Small Craft Should Exercise Caution statement to expire for the
nearshore waters. Have continued it for the offshore waters where
seas remain elevated. Despite this weakening wind trend, there will
be little time for seas to fall further before the cold front moves
off the coast around midnight and dramatically increasing northerly
winds behind the front will allow for seas to build further. Strong
offshore winds in the 20-30 knot range across the coastal waters
will result in seas building into the 5 to 7 feet range nearshore
and 6 to 8 feet range offshore. Winds will begin decreasing by
Wednesday afternoon as surface ridging builds into Texas.
A line of strong to possibly severe thunderstorms is expected to
accompany the cold front tonight and may result in locally enhanced
winds and waves before clearing the waters by sunrise. Patchy or
light sea fog with visibilities in the 4-6 NM range will be possible
across the waters before the cold front clears the coast.
Huffman
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 48 68 50 76 64 / 70 0 0 10 10
Houston (IAH) 54 71 50 76 64 / 70 0 0 20 10
Galveston (GLS) 60 69 61 75 68 / 50 10 0 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory from 4 AM to 1 PM CDT Wednesday for the
following zones: Coastal waters from Freeport to the
Matagorda Ship Channel out 20 NM...Coastal waters from High
Island to Freeport out 20 NM...Galveston Bay...Matagorda
Bay...Waters from Freeport to the Matagorda Ship Channel
from 20 to 60 NM...Waters from High Island to Freeport from
20 to 60 NM.
SMALL CRAFT SHOULD EXERCISE CAUTION until 4 AM CDT Wednesday for
the following zones: Waters from Freeport to the Matagorda
Ship Channel from 20 to 60 NM...Waters from High Island to
Freeport from 20 to 60 NM.
&&
$$
NEAR TERM...Overpeck
SHORT TERM...Luchs
LONG TERM...Huffman
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
912 PM CDT Tue Apr 3 2018
...SEVERE WEATHER EXPECTED INTO TONIGHT...
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
Squall line of thunderstorms moving quickly through the region
this evening. Earlier the line of storms produced widespread wind
damage in the northwestern portion of the forecast area (mainly
over the Arklamiss Delta) where instability was greater. Through
the heart of the region wind damage has been more sporadic,
although some tree damage continues, but most of the wind gusts
likely are remaining in the 40 to 60 mph range. Slightly
concerned, especially after viewing LIX`s 00Z sounding, that
better low level moisture just north of the coast will seep north
into locations across southeastern MS to reinvigorate convection
before the worrisome activity clears east of MEI and HBG (before
1 AM). Will we keep a close eye on this situation and be quick to
issue warnings on portions of the line (or other pre-frontal
cells) that look to be intensifying and were previously not
covered by warnings.
Otherwise, the cold front itself is lagging the line of convection
by at least 100 miles, but potential for any vigorous showers and
storms right along the boundary is very low owing to preceding
convection eating up all the moisture. This front will work from
northwest to southeast across the Lower Mississippi late tonight
and bring cooler air (and continued gusty north winds) to all
areas by dawn Wednesday. Temperatures will be especially chilly up
along and north of the Highway 82 corridor where lows in many of
those spots will be down near 40 degrees. /BB/
Prior discussion below:
.Tonight through Wednesday: The primary concern will be the risk of
severe weather for late this afternoon into the overnight hours.
Latest rap and satellite imagery showed an upper trough moving
through the Plains toward the Mississippi Valley. Southwest flow
aloft in flat ridging was observed across the region. On the surface
the combination of low pressure to the west northwest and high
pressure to the east was bring gusty winds mainly across the delta
region. Portions of the delta region were under a wind advisory.
Otherwise a cold front was approaching from the northwest. In the
warm sector readings were in mainly in the upper 70s to lower 80s.
Area radars were picking up some convection across portions of the
ArkLaTex where weather watches were in effect.
For late this afternoon into the overnight hours severe parameter
still look favorable in the latest model runs. The cold front will
be pushing into the northwest delta by early this evening. Latest Hi-
res CAM guidance still shows a QLCS like line that will pass over
the region from late this afternoon into the overnight hours.
Looking at the favorable severe parameters vertical totals upper
20s, midlevel lapse rates around 6.5 to 7.5C, deep layer shear 40 to
55 knots, MUCAPE around 1500 J/KG. While tornadoes cannot be ruled
out, the orientation of the 0-3km shear vectors are not as
supportive for this threat. As we go through the night the
instability will weaken as the QLCS tracks east southeast which is
reflected on the CAM guidance. The primary risks will be golf ball
size, damaging winds, and possible tornadoes. SPC has an enhanced
risk across portions of the northern delta region with a slight risk
elsewhere. Also the latest CAM guidance shows the post frontal gusty
winds across the delta through through 08z. So will extend the wind
advisory for a few more hours until 08z. The cold front will exit
the region prior to dawn. PWATs will be around 1.6 to 1.7 inches
which will may bring some locally heavy down pours. Due to the
progressive nature of this system not expecting any major flooding
concerns.
For Wednesday isolated showers will depart the Pine Belt area early.
A 1025 mb surface high will filter in a cooler airmass across the
region during the day. As far as temperatures are concern cooler
lows will range from the lower 40s to the lower 50s. Highs will
range from the middle 50s northwest to the middle 60s
southeast./17/
.Wednesday night through Monday night...Cold high pressure will
build in over the area Wednesday night behind the cold front.
Temperatures overnight Will fall into the 30s, with some areas
experiencing some patchy frost. This may have to be highlighted
in future HWO/Graphicasts. High pressure ridging will continue to
persist on Thursday from a high centered over the Ohio Valley.
Highs will climb to around 70 degrees across the area. As the
surface flow increases out of the southeast Thursday night into
Friday, so will the moisture. PWATS will climb to 1.3 to 1.5
inches across most of the area by Friday afternoon. Showers and
thunderstorms will be on the increase by Friday afternoon into the
evening hours, as a warm fronts pushes back north, out ahead of
another short wave and associated frontal system that will move
across the area overnight.
The front will sweep south across the area Friday night into
Saturday morning. Currently it looks like there will be enough
shear/instability for the possibility of another round of strong
to severe storms, and this will have to continue to be monitored.
The GFS/ECMWF differ on the timing of the back edge of the precip
on Saturday, with the ECMWF a little slower with moving the
precipitation out of the area. High pressure and dry/cool
conditions will return for Saturday, but the ECMWF/GFS diverge
Sunday night and Monday with a cold front across the area. Both
models have this feature, but the GFS is much stronger and
wetter. Will blend the two models and go with low end chance for
showers through this period. High pressure and dry/cool conditions
will return Monday night. /15/
&&
.AVIATION...
00Z TAF discussion:
Gusty showers and thunderstorms are expected to race from west to
east across the region through midnight to 1 am, although they may
not entirely clear through the PIB/HBG area until 3 am or so. With
these storms anticipate westerly wind gusts up to 50 mph or more
with brief flight cat reductions down to IFR levels. Ahead of the
storms southwest winds will blow from 10 to 20 mph with a wind
shift to the northwest as the front comes through and conditions
remaining gusty. VFR conditions should prevail in all areas by mid
morning tomorrow as clouds thin and clear. However, north winds
will continue to gust up to 20 to 25 miles in all areas tomorrow
through the day. /BB/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 46 61 40 72 / 91 1 1 2
Meridian 49 63 37 71 / 88 5 1 2
Vicksburg 45 61 42 72 / 92 0 1 2
Hattiesburg 54 67 39 73 / 85 19 1 1
Natchez 48 63 41 73 / 85 0 1 1
Greenville 42 57 41 68 / 97 0 1 2
Greenwood 42 58 39 69 / 97 0 1 2
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Wind Advisory until 3 AM CDT Wednesday for MSZ018-019-025-026-
034-035.
LA...None.
AR...Wind Advisory until 3 AM CDT Wednesday for ARZ074-075.
&&
$$
15/17/BB
Area Forecast Discussion
National Weather Service Lake Charles LA
1045 PM CDT Tue Apr 3 2018
.UPDATE...
Just a quick update is coming at the top of the hour to drop the
nwrn zones...possibly as far east as Rapides Parish depending on
radar trends...from the watch. Otherwise inherited grids/zones are
handling the current situation well. The squall line currently
noted on radar may be outrunning the grids a little, but not
enough to warrant full-scale changes at this time.
25
&&
.PREV DISCUSSION... /issued 639 PM CDT Tue Apr 3 2018/
AVIATION...
Regional radar imagery shows a line of thunderstorms currently
moving SE across portions of Central Louisiana and adjacent East
Texas. MVFR ceilings and areas of VCSH will affect areas ahead of
the thunderstorms through this evening. Periods of IFR conditions
along with gusty winds of 30 knots or greater and possibly small
hail will be possible with the stronger thunderstorms. Currently,
the timing of the greatest potential operational impacts due to
thunderstorms is expected to be: now through 02Z at KAEX, 02Z
through 05Z at KBPT and KLCH, and 03Z through 07Z at KARA and
KLFT. The surface cold front is expected to push through the
region behind the thunderstorms and result in winds becoming
northerly at 15 to 20 knots with gusts of 25 to 30 knots through
the overnight period. Conditions are expected to improve to VFR by
mid morning as skies clear, but winds will remain elevated out of
the north.
PREV DISCUSSION... /issued 621 PM CDT Tue Apr 3 2018/
UPDATE...
Severe Thunderstorm Watch #29 was issued for the area generally
along/north of Texas 105/Interstate 10...with the exceptions of
Lafayette and St. Martin Parishes...until 05z/midnight CDT. Local
88Ds show convection along an old outflow boundary...some
possibly strong to severe...developing/moving into the nwrn zones
at this time, continuing ewd with a further srn development
through the evening in an area of good instability/adequate
shear/steep lapse rates. Additional storms along the cold front
will likely also begin impacting the nwrn zones later this
evening. Will have to monitor as these storms cross the area
through this evening to see if further watches will be needed
downstream.
25
DISCUSSION...
PREV DISCUSSION... /issued 325 PM CDT Tue Apr 3 2018/
DISCUSSION...
Wx map shows cold front over N TX & SE OK this afternoon. Ahead of
the front shows a tight pressure gradient with fairly brisk southerly
winds this afternoon. Expecting winds to diminish by late this
afternoon into early evening as the frontal trough approaches.
Radar showing thunderstorms continuing over C and NE TX.
Latest HRRR guidance continuing the timing and structure of the
thunderstorms to enter our area of SE TX by 4-5 PM this afternoon
with this initial batch of thunderstorms ahead of the front. Once
this area moves east, another area of thunderstorms will likely
develop along and just ahead of the cold front, which will spread
southeast across our area by late this evening into the early
morning hours. This next area of convection is expected to be a
more organized line of strong to possibly severe thunderstorms
developing along or just ahead of the cold front. SPC continuing
slight risk of severe thunderstorms for entire area. With this,
all modes of severe will be possible from a blend of QLCS features
(LEWPs/bows), embedded supercells, and perhaps a few discrete to
semi-discrete supercells ahead of the main line.
The front should be moving through the region between midnight and
daybreak, with light stratiform rain lingering a few hours behind
the front as it continues south. Cooler and much drier air will
follow along with clearing skies by late Wednesday morning across
the area. This will set up for a fairly nice afternoon. Only
concern with this will be the northerly winds around 15-20 mph
with RH values around 30% could pose a enhanced fire danger,
however, with the expected rainfall, the vegetation should be
sufficiently damp.
The coolest morning will be Thursday, with lows near 40 across C
LA, to lower/mid 40s elsewhere. By the afternoon, the surface high
will have moved east, with a southeast return flow already in
place by late morning into the afternoon.
Quick changing weather pattern continues this week with the next
strong cold front bringing a significant shot of precipitation by
late Friday into early Saturday. A bit early in the game for
specifics in severe, but SPC has Day 4 area across NE TX
outlooked in 15% hatching. This front will be followed by cooler
air similar to Thursday.
DML
MARINE...
Southerly flow ahead of a cold front will diminish a bit this
evening, followed by strong offshore flow after midnight once the
cold front moves south. The front is expected to bring numerous
showers and strong thunderstorms this evening into the early
morning hours. A small craft advisory is in effect for most of
the day Wednesday. Northerly winds behind the frontal boundary
will tapper off by Wednesday evening as surface high pressure
ridge approaches from the north.
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 49 66 42 73 / 90 10 0 10
LCH 56 71 47 75 / 90 10 0 10
LFT 55 69 46 74 / 90 10 0 10
BPT 55 72 50 74 / 90 10 0 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...Small Craft Advisory until 5 PM CDT Wednesday for GMZ450-452-455-
470-472-475.
Small Craft Advisory for winds until 5 PM CDT Wednesday for
GMZ430-432-435.
&&
$$
PUBLIC...04
Area Forecast Discussion
National Weather Service Memphis TN
943 PM CDT Tue Apr 3 2018
.DISCUSSION...
The front has just about moved through the area. The winds have
diminished enough to allow the wind advisories to be cancelled.
The temperatures have started to drop and will fall into the 30s
in most places, however, the wind should keep away frost from
forming. Updated forecast will be out soon. TLSJr
&&
.PREV DISCUSSION... /issued 350 PM CDT Tue Apr 3 2018/
DISCUSSION...
A deep surface low is centered over E IL this afternoon while a
strong cold front extends through MO into NW AR. A broken line of
thunderstorms has developed ahead of the front in MO and AR. The
low will continue tracking northeastward while the cold front
moves quickly through the forecast area late this afternoon and
evening. A line of strong to severe thunderstorms will quickly
progress across the Midsouth along and just ahead of the cold
front late this afternoon and evening. Cannot rule out a semi
discrete cell or two to form just ahead of the line, especially
over NE AR late this afternoon. Damaging winds, large hail, and
possible tornadoes are all potential threats with any of these
storms. The best chance for tornadoes will be over NE AR and MO
Bootheel. All activity should be east of the forecast area before
midnight as the front pushes into middle TN and northern AL.
High pressure will build into the region Wednesday supporting an
unseasonably cold polar airmass advecting in from the NW. Frost
will be likely Wednesday night with some areas experiencing a
freeze.
Another system will provide rain Friday possibly mixing with or
changing to snow near the MO/KY border by Saturday morning as cold
air advects into the area. There is another risk for frost or
freezing temperatures Saturday night. More showers are possible by
the end of the weekend.
SWC
&&
.AVIATION...
00Z TAFs
TSRA had entered the MEM TRACON at discussion time and should exit
a hour or two prior to the onset of the inbound push. Primary
short term concern is winds associated with TSRA outflow. TMEM radar
showed a 50 to 70 KT rear inflow jet over east central AR, 35 NM
west of MEM at FL025.
By 03Z, main concern is wake low formation over eastern AR. This
type of feature often isn`t well modeled. The HRRR continued to
depict a 3 MB pressure depression over north central AR at 03Z,
but with little to no reflection in the wind field.
VFR to prevail overnight and Wednesday, with winds becoming nearly
calm for Wednesday evening`s MEM inbounds.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
845 PM EDT Tue Apr 3 2018
.DISCUSSION...
The evening update will be issued a little early as temperatures
have not fallen as much as forecast, and PoPs will be tweaked to
reflect the latest timing. Projecting the speed of the line of
storms in Middle TN bring them into our western counties around
05Z, and the latest HRRR supports this. Storms are expected to
have a weakening trend through the evening as surface-based
instability decreases, but shear will remain high and the 00Z OHX
sounding shows an elevated mixed layer and midlevel dry air that
will support some threat of severe storms in our area, mainly
damaging winds but also a marginal hail threat. The low observed
dewpoints and high LCL heights are not supportive of a tornado
threat.
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...None.
VA...None.
&&
$$
DGS
Area Forecast Discussion
National Weather Service Blacksburg VA
1018 PM EDT Tue Apr 3 2018
.SYNOPSIS...
A strong cold front will move across the region with an
opportunity for showers and thunderstorms tonight. High
pressure builds in behind the front with very gusty winds and
cooler temperatures for Wednesday into Thursday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 1020 PM EDT Tuesday...
Most significant update late this evening was to expand the wind
advisory for Wednesday into Wednesday night north of Roanoke to
include Alleghany Highlands and along the Blue Ridge to match
with advisory issued by Sterling office, and also added Tazewell
and Smyth counties mainly for higher elevations. Mixing during
the day looks good and model forecast sounding support good
momentum transfer at most locations along and west of Blue
Ridge. Even if winds don`t quiet reach advisory thresholds
everywhere, dead limbs and weak trees from the recent heavy snow
are a concern and there may be isolated power outages due to
these weakened or dead trees coming down. The entire advisory
area is out through Wednesday night bu it is likely it will be
cancelled early except for maybe the southern part of the Blue
Ridge where lowering inversion and mountain wave activity could
keep some stronger ridge gusts going much of the night.
Otherwise, based on upstream radar evolutions and most recent
high resolution model runs it looks like the broken line of
showers and storms will not reach far western counties until
07-08Z (3 to 4 AM), and should be weakening rapidly as it
arrives. Have continued to slow down time of arrival a bit more
in forecast grids. HRRR suggests a fine line with narrow band of
wind gusts that could reach up to 50 mph into parts of SE WV and
maybe Tazewell VA by this time, but weakening quickly after
that. Thus, one or two severe warnings are not out of the
question, but most likely these will be sub-severe shallow lines
of convection, with limited thunder by the time they arrive
given very limited instability.
No other changes to forecast at this time.
Previous discussion as of 755 PM EDT Tuesday...
Clearing taking place a little more quickly in the west than
expected before clouds fill back in again just ahead of line of
showers and probably still a few embedded thunderstorms along
the cold front that will not be arriving in the far west until
at least midnight if not closer to 2 or 3 AM. Recent HRRR runs
have slowed down timing until about 3 AM and made some
appropriate adjustments to PoP values for these trends but
still have mention of thunder arriving very soon after midnight
in far west. Temperatures may drop this evening under clearing
skies but will then steady out as clouds and showers move back
in, until finally dropping more quickly toward morning behind
the cold front. Likely will make a few additional adjustments to
timing with another update by 10 PM based on radar trends at
that time.
Prey discussion as of 300 PM EDT Tuesday...
An upper level trough will move from the northern Plains states to
the Great Lakes region overnight. Meanwhile, the associated surface
low will track from the Great Lakes to Toronto. The cold front
attached to this system will extend this evening from the Great
Lakes to southern Texas. By morning, this front will have moved east
to Pennsylvania stretching south into eastern Texas. The middle
portion of the front (Ohio and Tennessee Valleys) will approach SE
WV/SW VA after midnight.
The cold front will come roaring through the region Wednesday
morning, exiting the piedmont by the afternoon. A line of convection
will accompany the front. Strong gusty winds and heavy rain is
expected with this line, mainly across the mountains as it weakens
tracking east. Behind the front, strong pressure rises will bring
windy conditions to the area into Wednesday evening. For now, the
plan is to handle the line of convection with a special weather
statement (SPS) and warning on specific cells that exhibit severe
threat. There are no plans on extending the wind advisory as
threshold and confidence are low.
Since this system is quick, most of the rainfall will result in
runoff. Since creeks and streams are running very low due to some-
what dry antecedence conditions over the past couple of day, there
is a very low chance for any hydro issues. Rainfall amounts will
range from three quarters of an inch along western slopes of SE
WV/SW VA to a quarter of an inch in the piedmont.
With the wedge removed from the area and increasing southwest flow
ahead of the front, overnight temperatures will be close to normal
day-time highs for this time of year. Of course, the speed of the
passing front and subsequent cold air advection, temperatures will
fall into the mid 40s to lower 50s across the mountains. High
temperatures across the mountains may only warm a few degrees from
overnight low as northwest winds ushers in very cold air. East of
the Blue Ridge, overnight lows will remain mild and in the upper 50s
to lower 60s. Temperatures should warm at least 10 degrees in the
east with a delay of colder air and downsloping flow.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM EDT Tuesday...
Winter like temperatures will be found across our region
Wednesday night coupled with brisk northwest winds. 850mb
temperatures of -5 to -10 deg C will set stage for a chilly
start thursday with early morning lows ranging from the 20s
mountains to the lower 30s Piedmont. Upslope potential appears
limited, so not really expecting any significant snow shower
activity across the mountains and this has been reflected in the
minimal upslope flow pops.
After a chilly, below freezing morning early Thursday, abundant
sunshine and moderating temperatures aloft under the near zonal
flow will allow temperatures to top out only about 5-10 degrees
below normal in the 50s west to near 60 east, with 40s for the
highest elevations.
Another cold front will be approaching from the west late
Friday and affect the CWA over the weekend as this feature
stalls and becomes the focus for low pressure development.
Southwesterly flow ahead of the front Friday should allow for
warmer temperatures and perhaps even some showers in western
areas by Friday night.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 330 PM EDT Tuesday...
Challenging forecast for the weekend as front stalls across the
forecast area and becomes the focus for low pressure to develop
along existing baroclinic zone and move east. Models have
trended warmer and farther north with the cyclone development
suggesting mainly rain across the southern half of the CWA and
potential for a rain/snow mix across the higher elevations. If
enough cold air can infiltrate, then all snow would be possible
at these higher elevations, but given northward shift in storm
track, this "all snow" scenario may be limited to areas along
I-64 corridor. Until a better model consistency becomes
established, confidence is low on p-type as 1 or 2 degrees in
temperature can sway the outcome. Of greater certainty is
likelihood that Saturday will be a wet day with QPF of about a
half inch liquid equivalent. Models are relatively consistent on
timing with bulk of the precip coming through during the day
Saturday, followed by a dry Saturday night and Sunday. Yet
another wave moves along the front Monday, clouds and precip
returning for the first day of the work week.
For now, will continue to advertise possibility of accumulating
snow within the Hazardous Weather Outlook for Saturday. If it
does materialize, at least it will be another weekend instead
of a weekday event...which mitigates school closure concerns.
And with modest warmup forecast Sunday, if there is any
accumulation it should melt quickly under the now April sun
angle. Temperatures through the extended portion of the
forecast are expected to remain below normal, the outlook
through mid month trending that way as well, the jet stream
refusing to give up any ground resulting in a near persistent
tap to cold air residing over Canada.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
As of 810 PM EDT Tuesday...
VFR conditions at all TAF sites this evening as low clouds and
warm front have lifted north of the area, and skies actually
clearing well ahead of line of showers and storms along and
ahead of frontal boundary still over the Midwest this evening.
Showers and storms will be weakening as they move in from the
west after midnight and expect will bring primarily several
hours of MVFR conditions, but with brief IFR possible at KBLF
and KLWB from roughly 04Z or 05Z to 08Z. This convection will
also contain gusty winds as it rolls across the region between
midnight and dawn, with gusts as high as 30 to 40 kts. Strong
northwest winds will continue behind the front and increase
during the daytime hours Wednesday with mixing. Showers will
break up crossing the mountains early in the day and may reform
a line near Danville by early afternoon before quickly heading
east. Thunder is not likely at this time until the line moves
well east of the area. VFR conditions should prevail for
Wednesday afternoon through evening, and winds will begin to
subside Wednesday evening as well, other than along ridges.
Extended Aviation Discussion...
After some gusty northwest winds Wednesday evening, high
pressure should build over the Mid Atlantic by Thursday to
provide good flying weather. Another cold front should push
eastward on Friday to bring MVFR conditions and rain showers.
Some of the rain may change over to snow in the mountains.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Wind Advisory from 11 AM Wednesday to 8 AM EDT Thursday for
VAZ007-009>020-022>024-033>035.
NC...Wind Advisory from 11 AM Wednesday to 8 AM EDT Thursday for
NCZ001-002-018.
WV...None.
&&
$$
SYNOPSIS...RCS
NEAR TERM...RCS/SK
SHORT TERM...PM/RAB
LONG TERM...PM
AVIATION...MBS/NF/RCS/SK