Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/08/21
Area Forecast Discussion
National Weather Service Bismarck ND
955 PM CDT Wed Apr 7 2021
.UPDATE...
Issued at 939 PM CDT Wed Apr 7 2021
Light rain continues to slowly diminish over the southern James
River Valley this evening. Cloudy skies over the southeast quarter
of the state with clear skies west and mainly high thin cloudiness
central and into northeast ND. For the late evening update we did
drop temperatures a little lower over portions of the west and
central as a very dry atmosphere remains over the area and a good
radiational cooling setup with surface high pressure over the
area, light winds and clear skies west or thin high clouds
central. Updated text products will be sent shortly.
UPDATE Issued at 553 PM CDT Wed Apr 7 2021
Low pressure system remains situated over the central plains with
a band of deformation rain clipping our far southeast CWA. Latest
guidance shows rain continuing in the same general area this
evening and into the overnight, but gradually weakening as the
vorticity weakens as it becomes more sheared within this area.
Then Thursday as another vorticity lobe rotates east to west from
Minnesota into the Dakotas on the north side of the upper low
another round of light rain may push into the southern James
River Valley after a brief break Thursday morning. Farther west,
high pressure at the surface and aloft will remain over the
western Dakotas into Manitoba. This will make for a mainly clear
night tonight, with cool low temperatures. Previous forecast had a
good handle on this. Will take a closer look at temperatures with
the late evening update. Made some minor tweaks to sky and precip
based on the latest radar and satellite trends, otherwise no
changes to the going forecast.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 230 PM CDT Wed Apr 7 2021
Highlights of the short term include rain continuing into tonight
in Dickey and LaMoure Counties, near critical fire weather further
west, and a strong cold frontal passage Thursday night.
As of early afternoon, a complex middle- and upper-level low was
located over the Central Plains, with its northern-most vorticity
maxima over eastern SD. The associated midlevel deformation and
frontogenesis and related warm air advection aloft north of that
low continues to yield rain in southeastern ND, and as far west
as Dickey and LaMoure Counties. A sharp gradient in the rainfall
footprint exists to its west where a wedge of dry low-level air
is in place in the subsidence regime away from the ascent aloft,
but the rainfall has tended to be a bit further west than most
global models had expected at this point in the day. In contrast,
rapid-refresh guidance including recent HRRR cycles are assimilating
the rainfall shield well and so we relied on them to construct
PoPs through tonight, but with rainfall remaining in the southern
James River valley.
In south central ND, the overlap of low humidities and gusty winds
on the periphery of the stronger low-level wind fields associated
with the low to the south has been minimized in space and time so
far. High-level clouds may be impeding the full mixing potential
to an extent, and while forecast soundings suggest near-critical
fire weather conditions will continue through early evening in
Emmons, Kidder, McIntosh, and Logan Counties in particular,
observational trends to this point suggest that we do not need to
upgrade them to a Red Flag Warning.
Otherwise, transitory shortwave ridging aloft will across western
and central ND tonight and Thursday in advance of a deepening and
progressive shortwave trough that will dig into eastern MT and WY
by 12 UTC Friday. Given light winds and clear skies a relatively
cool night is expected tonight, especially in the Hettinger, Mott,
Glen Ullin, and Beulah/Hazen areas where a surface ridge axis will
be in close proximity. Thus, we relied on the cooler edge of NBM
membership for forecast lows, particularly in that area, similar
to what the prior forecast was advertising, and based in part on
trends from last night in a similar scenario.
On Thursday, the recently-well-verifying time-lagged RAP and HRRR
cycles suggest widespread minimum humidities in the teens, but
low-level flow within the well-mixed boundary layer is forecast to
be relatively weak, precluding the need for any fire weather
headlines at this time. A surface warm front is forecast to move
into western ND during the afternoon, and low-level west-southwest
flow and a thermal ridge characterized by temperatures at 850 mb
in the 12 to 14 C range suggests highs will likely reach the low
to mid 70s F in the west on Thursday, closer to the 75th+
percentile of NBM membership.
The 00 through 12 UTC global deterministic and ensemble guidance
is in strong agreement that a surface cold front will move across
western ND Thursday night. Strong low-level cold air advection and
increasing winds aloft with 40 kt speeds at 850 mb suggest post-
frontal northwest winds will be gusty, with a reasonable worst-
case scenario suggesting near-advisory winds are possible across
southwestern ND for a time Thursday night. DCVA aloft behind the
front could also generate light precipitation in the west Thursday
night, as supported by ensemble-driven PoPs in the 40-60 percent
range.
.LONG TERM...(Friday through Wednesday)
Issued at 230 PM CDT Wed Apr 7 2021
The main highlights for the long term period will be the potential
for near critical fire weather conditions Friday and Saturday
afternoons, along with a couple chances for light precipitation.
At the beginning of the long term period, a shortwave trough will
begin to eject from the Central Rockies in Wyoming and Colorado into
the Central Great Plains. This system will push a cold front through
North Dakota, entering the state from the west Thursday night. It is
looking increasingly likely that a few light rain and/or snow
showers will accompany the front in western, especially
southwestern, portions of our CWA. Most guidance keeps the
precipiation confined to this area, but we will continue to
monitor how this system evolves. In general, most areas receiving
precipitation will see a tenth or less of QPF according to the
latest NBM runs and GEFS ensemble member means.
Behind the front, relatively strong northwesterly winds around 15-25
knots will usher in even drier air with minimum afternoon relative
humidities potentially dripping into the upper teens across the far
west. The combination of winds and low relative humidities would
result in near critical fire weather conditions Friday afternoon
despite any morning precipitation, mainly to the west of Highway 83
as cloud cover will keep relative humidity from dropping as low to
the east. Saturday afternoon will likely see near critical fire
weather conditions as well with minimum relative humidities in the
upper teens more widespread across the area, however winds appear to
be slightly weaker at this time and thus will be a limiting factor.
The next chance for precipiation will be more widespread, albeit
light, and arrive Saturday night into Sunday. A deeper H500 trough
is expected to follow behind the exiting shortwave trough as it
transitions into a closed low across the Midwest. This deeper trough
and its associated weak surface low will likely provide enough
dynamic support for widespread light rain/snow showers across North
Dakota, but just how much precipitation and where it falls remains
highly questionable. WPC cluster analysis shows good agreement with
the arrival time of this system, but is still showing obvious
differences in QPF amounts. A few GEFS members showing over an
inch, along with the Canadian and GFS deterministic forecasts which
are also relatively high, remain outliers with regards to QPF Sunday-
Monday. However, analysis of all available guidance including the
NBM shows little confidence in accumulations above a tenth of an
inch during this time period, with the highest totals being across
the north-central.
Temperature wise, expect mild temperatures to continue into the
weekend with slightly below normal temperatures to begin next
week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 939 PM CDT Wed Apr 7 2021
MVFR ceilings possible at KJMS late tonight and Thursday.
VFR conditions expected at all other TAF sites through the
forecast period with only some mid and high level clouds.
Northerly surface flow will continue at KJMS and KBIS through the
forecast period with breezy conditions at KJMS Thursday afternoon.
Generally light and variable winds at KDIK KXWA and KMOT tonight,
becoming southeast on Thursday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...CJS
LONG TERM...Gale
AVIATION...TWH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
834 PM MDT Wed Apr 7 2021
.UPDATE...
Issued at 829 PM MDT Wed Apr 7 2021
Quiet night with only minor grid adjustments in the short term,
the forecast is in good shape.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 251 PM MDT Wed Apr 7 2021
Upper level ridging moved over Colorado today creating subsident
flow and drier conditions. There was enough of a low level
pressure gradient to create gusty winds especially over the
eastern plains. Some of the stronger gusts have reached around 45
mph.
Tonight, dry weather will continue with slightly above normal low
temperatures. Winds will relax as the mixing in the boundary layer
decreases after sunset.
Upper level ridging will continue to be over Colorado tomorrow
although it will flatten between a trough over the Midwest and
another one over the northern Rockies. No precipitation is expected
and there should be minimal cloud cover. Highs will be around 10
degrees above normal with gusty winds that could reach 35 mph
across the plains. The mild, dry, and windy conditions will lead
to critical fire danger across the northern I- 25 corridor and the
eastern plains. This fire danger is discussed further in the fire
weather section below.
.LONG TERM...(Thursday night through Wednesday)
Issued at 251 PM MDT Wed Apr 7 2021
Our up and down pattern is expected ton continue into next week,
with a few passing systems wedged between warmer and dry days.
Winds will decrease overnight Thursday night and moisture should
increase slightly ahead of an approaching shortwave trough. The
trough and its associated surface cold front should pass across
the area on Friday, bringing much cooler temperatures (highs in
the low to mid 50s) and a return of windy conditions to the
plains. Strong QG descent should be located over the area with
40kt mid level flow. As the previous long term discussion
mentioned, 30-40 mph winds with higher gusts still looks likely
during the afternoon. Over the mountains, there is just enough
moisture for a few rain and snow showers, but otherwise no
precipitation is expected with this next system.
Ridging quickly builds back in on Saturday with much warmer
temperatures anticipated. Winds will also die down a bit as the
flow aloft weakens a bit. Another system works its way into the
area Sunday, with yet another cold front. Early signals indicate
more moisture than the Friday "storm" and there could be some
light rain or snow across the area by Sunday night.
Forecast guidance also indicates an unsettled pattern as we start
next week, with the potential for another storm system or two
through mid-week. It`s too early to begin speculating when, where,
or how much precipitation falls, but I`ll note that ensemble
guidance is a bit more optimistic than this forecaster as we head
into mid-April.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 829 PM MDT Wed Apr 7 2021
Northerly winds will weaken and switch to drainage by 06z with
VFR conditions. During the late morning tomorrow, gusty northwest
winds redevelop with gusts up to 25 knots. No precipitation or
ceilings are expected.
&&
.FIRE WEATHER...
Issued at 251 PM MDT Wed Apr 7 2021
A few factors will lead to critical fire danger tomorrow which
prompted the issuance of a Red Flag Warning. Above normal highs
in the upper 60s to low 70s mean conditions will be warm enough
for critical fire danger. Models differ on dew points with the
HRRR having dew points in the low single digits across the plains
while the NAM Nest has dew points in the upper teens to low 20s.
The HRRR usually over-mixes and the NAM Nest is typically too
moist in the boundary layer so I split the difference with dew
points forecast to be in the low teens. This will result in
relative humidities reaching the low teens across all of the
plains. There will be enough low level flow and boundary layer
mixing to generate gusty winds. Most areas will see gusts between
30-35 mph which meets Red Flag criteria. Despite the above normal
precipitation for March and early April, the fuels have not
"greened up" enough to subdue fire weather. The only exception is
the Palmer Divide which saw the most snowfall yesterday and should
stay moist enough to limit fire danger. A Red Flag Warning was
issued for the northern I-25 corridor and eastern plains from noon
to 7pm Thursday.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 7 PM MDT Thursday for COZ238-
242>251.
&&
$$
UPDATE...Cooper
SHORT TERM...Danielson
LONG TERM...Hiris
AVIATION...Cooper
FIRE WEATHER...Danielson
Area Forecast Discussion
National Weather Service Grand Forks ND
957 PM CDT Wed Apr 7 2021
.UPDATE...
Issued at 954 PM CDT Wed Apr 7 2021
Forecast working out as expected. Did usual tweeking to pops...to
tighten up the western edge and to decrease chances rest of the
night in our southeastern fcst area. 500 mb low drifting north
into far SE ND with dry slot moving into Wadena/Park Rapids area.
Lingering rain band continues over the same area as 00z with some
slight movement north closer to Baudette while west edge holding
tight from near TVF to Crookston to Hillsboro. HRRR has some very
light precip eventually moving west as rain band diminishes
overnight. So kept low pop just west of where rain is currently.
UPDATE Issued at 711 PM CDT Wed Apr 7 2021
Compact 500 mb low in NE SD and it is not moving much and is
progged to eventually be absorbed into the main 500 mb low
currently in Kansas that is moving NNE. Rain area on the north and
west side of the SD upper low will continue thru the evening from
SE ND into north central MN in basically the same area it is now.
Not much push west is anticipated, though west edge could still
wobble west 20-30 miles or so. This position of the rain shield
looks to keep the rain east of Grand Forks, but some chance a
little bit could sneak west tonight.
Rainfall intensity will diminish overnight into Thu AM, then next
wave of rain will arrive into WC MN Thursday late morning/midday
and spread north as main 500 mb low moves NNE. Once again how far
west does this second wave of rain reaches is questionable, but
most models do have at least some rain reaching the immediate
northern RRV Thu night. T-storms are not expected in west central
MN so rainfall amounts with this second wave will not be as heavy
as which fell today..where 2-3 inches was common in parts of Otter
Tail, Grant and Wadena counties.
&&
.SHORT TERM...(This afternoon through Thursday night)
Issued at 323 PM CDT Wed Apr 7 2021
Near critical fire weather is ongoing across northeast ND, with
rain from the southern Red River Valley and across west central
MN.
Larger trough with a stronger closed mid/upper center location in
the souther plains and a secondary center further north over
SD/southern MN. This is responsible for a region of broad
deformation/synoptic ascent. Additional organization of rain bands
is coming from mid level frontogenesis and at least some instability
(better upright instability is further southeast in MN). Eventually
a second wave interacts and the initial deformation zone pivots
along an inverted trough axis tonight and Thursday, with lingering
(lighter) rain. Strongest signal for additional rain totals over an
inch is still from far southeast ND into west central MN, while
there will be a sharp cut off on amounts due to drier air in the
north and west. Best chance for measurable rainfall in the northern
RRV will be during/after this pivot later tonight/Friday, but that
will be near the edge (some member as still dry fro those areas).
Regarding fire weather: Dry BL flow on the northwest side of this
system has supported RH values in the upper teens/lower 20s across
the Devils Lake Basin, northeast ND, and far northwest MN this
afternoon. Winds are generally holding in the 15-20 mph, with only
sporadic higher gusts. This aligns with the idea of near critical
fire weather conditions, as previously messaged. As the system
evolves Td values eventually increase and while gusty winds continue
into Thursday (maybe even higher than today), lowest RH values will
tend to be above 40 percent in all but the far western part of the
Devils Lake Basin.
.LONG TERM...(Friday through Wednesday)
Issued at 323 PM CDT Wed Apr 7 2021
As we look forward into the weekend, precipitation chances for the
northern plains continue to be likely. As Friday moves forward, rain
will end from west to east, and skies will clear out for Saturday.
Due to this, high temperatures will reach the mid 50s to low 60s
from the Red River Valley west to the Devils Lake Basin, and the low
50s east of the valley into Minnesota.
Sunday into Monday, a low pressure system will cut itself off from
the jet stream and descend into western North Dakota in the upper
and mid levels. This low will produce rain showers all day Sunday
across eastern North Dakota and northwestern Minnesota, and the
chance for precipitation will last into Tuesday evening. The
uncertainty with this system lies in the mode of precipitation,
whether or not a change over will occur, and exact amounts. Thus,
confidence is on the lower end of the spectrum.
Heading into the future, there is uncertainty and significant model
spread as to how this system will break down. Some members point to
a blocking pattern setting up, however, confidence is low at this
range.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 711 PM CDT Wed Apr 7 2021
Expect to see ceilings lowering into SE ND and thru most of MN
(mainly BJI) tonight into Thursday with IFR cigs in BJI and MVFR
cigs moving into FAR. Some chc of IFR Fargo area late tonight/Thu
AM. Otherwise TVF/GFK likely to remain VFR though brief MVFR cigs
are possible later Thursday as rain moves in. DVL to be VFR thru
the pd. Gusty NE winds tonight will diminish for Thursday.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...Riddle
SHORT TERM...DJR
LONG TERM...AK
AVIATION...Riddle
Area Forecast Discussion
National Weather Service North Platte NE
631 PM CDT Wed Apr 7 2021
.SHORT TERM...(This evening through Thursday night)
Issued at 318 PM CDT Wed Apr 7 2021
The ongoing rain-snow deormation zone operating across wrn and
ncntl Nebraska this afternoon will gradually decay as a strong
upper low deepens across northeast Missouri this evening. The
Missouri low then tilts negative as it moves into the Midwest
Thursday and Thursday night. The models suggest a pronounced area
of wrap-around rain will reach into ncntl Nebraska tonight through
Thursday and end early Thursday evening.
The basic forecast of temperatures, humidity, wind, sky and rain
chances tonight through Thursday night leans on the short term model
blend plus bias correction where appropriate. The gradual clearing
from west to east tonight will stop across Holt county where wrap
around will be underway. This will hold up lows across ern Holt
county. The guidance blend was very close to the short term blend
and lows in the upper 20s to mid 30s are in place overnight. It
would seem much colder lows are likely but temperatures at the 850mb
level rise about 6C overnight from 0C to 6C.
Additional warming continues Thursday with temperatures at the
h850mb level rising to 12C supporting highs in the 60s to around 70,
except across Holt county where the wrap around clouds and perhaps
light rain will occur.
The models are in very good agreement sweeping a powerful Pacific
cold front into western Nebraska late Thursday night or very early
Friday. The rain or snow chances in place across nwrn Nebraska
are post-frontal associated with a cold pool aloft- -25C at
h500mb and -10C at h700mb.
.LONG TERM...(Friday through Wednesday)
Issued at 318 PM CDT Wed Apr 7 2021
A portion of the upper low operating along the coast of British
Columbia this afternoon will drop quickly through wrn and ncntl
Nebraska Friday. We should see an increase in winds to 20-25 mph
with gusts 40 to 45 mph behind the cold front during the day.
Winds aloft increase to 40-50kts at the 850-800mb levels
supporting this forecast. The 700-500mb cold pool aloft and
moisture below should at least support scattered rain and snow
showers. POPs for this forecast are limited to 40 percent and
later forecasts will likely increase chances as warranted.
A brief warm up similar to Thursday is in place for Saturday with
highs in the 60s to around 70 supported by h850mb temperatures
around 12C. A second upper low will drop through the nrn Plains
Sunday. No POP is in place Sunday as the low may track to far
east to affect wrn and ncntl Nebraska.
Isolated to scattered rain or snow showers are in place Tuesday and
Wednesday for what appears to be cold air aloft. Temperatures at
h700mb are steady around -8C Monday through Wednesday and this would
support highs in the 50s. The precipitation would appear to be
diurnally driven with no organized forcing shown in the models, just
a broad trof across the cntl and wrn U.S..
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 631 PM CDT Wed Apr 7 2021
VFR conditions are expected to prevail through the forecast
period. Winds will decrease during the evening, first in northern
Nebraska including KVTN then closer to midnight for southwest
Nebraska including KLBF. However, wind gusts will increase again
tomorrow morning across the area, lasting through the afternoon.
Ceilings will begin to lift this evening and begin to clear in the
early morning hours.
&&
.FIRE WEATHER...
Issued at 318 PM CDT Wed Apr 7 2021
Wetting rain this afternoon and high humidity tonight would seem
to preclude any sort of critical fire weather condition Thursday
afternoon.
The area of concern is western Nebraska south of highway 2 where
wind gusts of 25 to 30 mph should develop and the best guess on
humidity is around 15 percent using the RAP model to 12 percent in
the HRRR. Elevated fire weather conditions driven by low afternoon
RH are expected in the same region Saturday through Monday. Strong
northwest winds may develop Sunday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Meltzer
FIRE WEATHER...CDC
Area Forecast Discussion
National Weather Service New Orleans LA
1100 PM CDT Wed Apr 7 2021
.AVIATION...
.06Z TAF FORECAST...
For tonight, the main focus will be an approaching cold front and
strong/severe storms expected to press east across the area
through the early morning hours. Have timed approximate arrival
times of impacts to area TAF sites per latest short-range guidance
and observed trends which brings this line across the region
generally from after midnight for far western areas, racing east
to the MS coastline by 10-11Z. Expect a broken line of
thunderstorms to temporarily reduce flight categories with gusty,
erratic downdraft winds the main threat, as well as periods of
reduced VIS from heavy rain. This activity will exit to the east
after 12Z with only a few isolated SHRA remaining across coastal
SE LA and coastal MS, with improving conditions/VFR flight
categories expected thereafter into the day on Thursday. KLG
&&
.EVENING UPDATE... /issued 812 PM CDT Wed Apr 7 2021/
Main focus with the forecast update this evening is with the risk
of strong to severe storms later tonight. Going through a large
suite of short-range CAM guidance confidently illustrates this
activity to persist east across our area later tonight. Analyzing
the pre-storm environment ahead of this line reveals a few
interesting points to monitor for this evening...
1) Observing recent radar trends from KPOE reveals a tail-end
convective plume identifiable also from GOES-16 w/ some nearing -70C
cloud tops over Ft. Polk, LA. This area of convection resides
right at the tail end of a 30-35kt jet which is forecast to press
east tonight. A few WoFS members identify this quite well and
evolves it into a messy line or bow segment entering Pointe Coupee
Parish/Wilkinson Co, MS between 10PM and 11PM. This may be a
localized area to monitor for the potential of a few strong wind
gusts, which could even continue to progress east across our SW MS
counties or along/north of I-10/12 tonight. As far as severity
goes by analyzing vertical wind profile trends, we do see some
uptick of 925mb winds collocated within this messy, broken line
which may locally enhance this line segment, especially if any
mesoscale cold pooling can develop behind this cluster to help
accelerate this line east. Can`t rule out a few severe wind gusts
tonight, especially in the latest D1 00Z SLGT risk area
(along/north of I-10/12), with primarily sub-severe wind gusts
(30-40mph) potential to the south towards the SE LA coastline.
2) The 00Z KLIX observed sounding this evening indicates a few
noticeable differences in the pre-storm environment when visually
comparing a few CAM soundings, mostly in the moisture profile
below 500mb. The magnitude of deep moist return flow in the
mid/lower troposphere is being slightly underplayed by CAM`s, with
perhaps more compressional warming/sinking in the model guidance
owing to a stronger 700mb subsidence/cap inversion. Observed
soundings are much more moist, with this cap steadily eroding due
deep moist ascent in progress. This leads me to believe that the
line to the west may likely fill in towards the LA coastline with
such deep moisture along and ahead of the line (similar to what
HRRR simulated reflectivity trends have shown) by what could be a
blow up of some weak coastal cells, eventually merging into a
broken line as it races east beyond I-55 after midnight. But
again, the severe wind risk will be more limited for far
southern/coastal SE LA areas, with the better risk along/north of
I-10/12.
3) Even though damaging wind gusts will be the main risk tonight,
a few isolated weak tornadoes cannot be ruled out. Model soundings
indicate largely curved low-level hodographs owing to rather
modest SRH (ranging upwards of ~300m2/s2 0-1km SRH to ~400m2/s2
0-3km SRH). If surface winds can remain backed (S to SSE) enough
nearest to the deepest convection, a quick weak spin up can not be
ruled out generally along/north of I-10/12. Will have to watch
observations south of the interstate to determine if a tornado
risk will extend to the coast. If winds shift more SSW to SW ahead
of the line, this will likely cause the line to become more cold-
pool dominant reducing a tornado risk. However, supportive deep-
layer shear exists well to the coast so a spin up or two even
south across SE LA could still be possible.
We will be closely watching it. Overall, we are not anticipating
a signifficant severe weather event, rather more of a sub-severe
line with a few severe wind gusts or a few quick spin ups
possible. This activity will exit to the east by around 11-12Z
with improving conditions/clearing skies Thursday morning with no
significant adjustments necessary for afternoon highs (just
leaning slightly on a warmer bias). Look for more details about
the extended with the AM package early Thursday morning. KLG
PREV DISCUSSION... /issued 321 PM CDT Wed Apr 7 2021/
SHORT TERM (Tonight through Friday)...
Tonight into Thursday morning, an upper level trough is expected
to move through the area, enhancing rain chances. Southerly
surface winds ahead of the system will help to enhance the warm
air advection and moisture advection into the area. Upper level
divergence ahead of the system will help to enhance lifting in the
environment as well. As the system moves through, the dynamic
forcing will be enough when combined with other parameters to
provide a favorable environment for strong to severe storms. A
Slight Risk of Severe Weather is in effect for our northern most
area for tonight and overnight. And a Marginal Risk of Severe
Weather is out for the rest of our area. The main threats from
this system will be gusty winds (up to 60mph or greater) and frequent
lightning. A few tornadoes and hail cannot be ruled out either.
Localized heavy rainfall will be possible as well inside of
thunderstorm development. The main timing of these threats will
be from 10pm through 6am for most of our area.
Thursday and Friday, after the system moves through the area
Thursday morning, zonal flow will dominate the upper level
pattern. Southerly surface winds will help to enhance warm air
advection and moisture advection for the area. Upper level
divergence will help to enhance lifting for the atmosphere as well
these days. As a result, showers and storms will be possible
throughout the area, primarily during peak daytime heating hours
both of these days. Frequent lightning will be possible with these
showers along with locally heavy rainfall. MSW
LONG TERM (Saturday through Wednesday)...
Saturday into Sunday, another upper level low pressure system will
make its way through the area. Southerly surface winds ahead of
the system will continue to enhance warm air advection and
moisture advection into the area. Upper level divergence will act
to enhance the lifting in the environment as the system moves
through the area. Looking at the shear, the speed shear looks like
it will be favorable for severe weather development, but the
directional shear may be limited, looking at the models. The best
directional shear / helicity will be in the Southwest Mississippi
counties and northern Southeast LA Parishes. Another interesting
note and potential limiting factor for severe weather development
is the timing of the parameters, however. Looking at some of the
model consensus, the timing of the best helicity and directional
shear may not line up with the best lifting and upper level
divergence. This will be something important to monitor as we get
closer to the event. Overall, the main threats from this system
based on the parameters will be gusty winds, frequent lightning,
and the potential for a few tornadoes. Locally heavy rainfall
inside thunderstorm development will be possible as well.
Monday through Wednesday, zonal flow will dominate the upper
level pattern. Easterly surface winds will allow for some
enhancement (or maintaining status quo) of moisture advection and
warm air advection into the area. Upper level divergence will act
to enhance the lifting in the environment primarily Tuesday and
Wednesday. As a result of these conditions, showers and storms
will be possible across the area Monday through Wednesday, mainly
during daytime heating hours during these days. The main impacts
from these storms would be frequent lightning and locally heavy
rainfall inside thunderstorm development. Overall, these storms
will be scattered in coverage and overall rainfall totals are
expected to be low in general. In addition to the scattered
showers, maximum temperatures are expected be higher than normal
for this time of year with most locations forecast to be in the
upper 70s to low 80s for this time period. MSW
MARINE...
Winds will be moderate (<15 knots) and southerly tonight through
Saturday morning. Saturday morning through Sunday morning, winds
will be southerly and strong (15-20 knots). Sunday, winds will be
shifting from southerly to northerly to easterly and will be
moderate (<15 knots). Winds will be easterly and moderate (<15
knots) Monday through Thursday morning. Wave heights will
correspond to the wind speeds. MSW
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 61 83 64 82 / 90 10 10 40
BTR 62 85 66 85 / 90 10 10 30
ASD 65 83 65 82 / 90 30 10 50
MSY 67 83 69 83 / 90 40 10 40
GPT 66 81 66 79 / 80 50 30 50
PQL 65 80 64 79 / 70 60 30 60
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Louisville KY
906 PM EDT Wed Apr 7 2021
.Forecast Update...
Issued at 905 PM EDT Wed Apr 7 2021
Current radar image shows returns associated with this evening
convection dissipating and exiting out of our CWA as of 01z. We will
get a break for a couple of hours before our next wave of
rain/storms arrive associated with a line of showers/thunderstorms
across western IL and entering far western KY. These showers/storms
will reach our far western CWA around midnight and continue to push
eastward overnight and into tomorrow morning. Due to the
overnight/early morning timing, some of this activity will weaken so
not anticipating strong storms like we saw this afternoon. The rest
of the forecast looks to be on track through the overnight and into
tomorrow.
&&
.Short Term...(This evening through Thursday)
Issued at 315 PM EDT Wed Apr 7 2021
KLVX radar is showing showers and storms pop up within the last hour
over west-central KY and southwest IN as expected. Some
thunderstorms could produce small hail this afternoon, but overall
severe threat appears low given the limited amount of wind shear.
By 00z this evening, some lingering showers and storms will be
possible across our southern IN counties in a region where the
environment could be possibly holding onto some sfc based
instability and higher moisture content. RAP/HRRR model soundings
show SBCAPE values could be over 1000 J/kg and PWATs well above
1.2". RAP does show some sfc based CIN develop after 02z due to a
developing low level inversion, so expect us to see a break from any
activity between then and 05-06z.
Precip shield will move in from the west late tonight/early Thu AM
ahead of the cold front boundary attached to the deep low. Guidance
continues to suggest the precip shield will be weakening,
potentially limiting QPF amounts for our region. By 12z, the western
edge of the weakening north-south oriented line of showers should be
near the I-65 corridor and continuing eastward. With a LLJ working
overhead, expect to see sfc winds increase for Thursday morning and
afternoon hours, with gusts of 20-30 mph not out of the question.
The LLJ will continue to help advect deep Gulf moisture into the
region, which correlates to the highest QPF amounts east of the I-65
corridor in the range of 0.75-1.0" storm total. To the west, a dry
slot could be working into western KY, helping to clear out skies
and increase heating by the late morning to early afternoon hours
over our CWA.
SPC has expanded the Day 2 Convective Outlook Marginal risk to
include our eastern CWA. HREF ensemble shows more cellular structure
possible to develop on the back edge of the precip shield where best
destabilization looks to occur ahead of the cold front and within a
region of clearing sky cover. Model soundings show cool temps aloft
that support an uncapped environment, and with sfc temps warming to
the low 70s and dewpoints near 60.
HREF/HRRR both indicate some marginal instability will be nosing
into our eastern CWA by the afternoon, with highest instability over
our Lake Cumberland region. Even with the deep cyclone set to
occlude by tomorrow, 850mb jet will continue to hold steady over the
region with winds of 30-40kts expected from our region the Great
Lakes. Per SPC, this low level jet should provide sufficient flow
for an isolated damaging wind threat despite marginal instability.
.Long Term...(Thursday night through Wednesday)
Issued at 222 PM EDT Wed Apr 7 2021
Most shower and storm activity associated with a large, occluded
upper level low (ULL) will be winding down by Thursday evening and
push east of the region by midnight. Most guidance forecasts the ULL
to lift north overnight Thursday into Friday with weak ridging
building in from the south into the lower Ohio Valley. This may
promote enough subsidence aloft that we stay dry for most of the day
Friday, though a few models hint at convection developing during the
day. Not seeing much in the way of lifting mechanisms to support
convection, and with weak capping in place, any activity should be
largely isolated.
A weak wave coming out of the southern Plains will likely phase with
a stronger shortwave trough diving into the Midwest on Saturday.
This will result in a deepening low pressure system as it moves
toward the lower Ohio Valley region. Models vary on the overall
phasing and evolution of the systems, but in general it looks like
we will see widespread precipitation on Saturday. Instability will
be very limited, but given the dynamic forcing with this system,
we`ll likely have some embedded thunderstorms within the main
precipitation shield.
Precipitation could linger Sunday morning across northern parts of
the region due to wrap-around moisture associated with an occluded
low pressure. Otherwise, upper level ridging building in from the
west along with high pressure nosing in from the southwest will
transition us to drier conditions. Weather beyond Monday remains
quite uncertain due to large model spread in the handling and
evolution of various shortwave troughs that swing through the north-
central U.S. At this time, won`t deviate much from current blended
forecasts and hold on to small PoPs.
&&
.Aviation...(00Z TAF Issuance)
Issued at 725 PM EDT Wed Apr 7 2021
Impacts: Mostly VFR conditions through the evening and overnight
with MVFR ceilings possible for SDF/HNB/BWG by tomorrow morning.
Returning to VFR later in the afternoon. Rain showers after midnight
into the first half of the day with the possibility of thunder
around SDF mid morning to around midday. Winds will also be gusty
out of the south with gusts 20 to 25 kts through most of the
forecast period.
Discussion: As of writing this discussion there were rain and
thunder around SDF but moving out. Some rain could linger to the
start of the TAF cycle for SDF, while the rest of the TAF sites
remain dry with VFR. Conditions remain VFR for most of the evening
and overnight until about 12-14Z for HNB/SDF/BWG where we could see
MVFR CIG for a couple of hours as a cold front works into the
region. Expect CIG to lift back to VFR levels and rain diminish just
past midday and into the afternoon. Winds will also be gusty out of
the south for most of the period with gusts of 20-25kts.
Confidence: Moderate for timing and location of storm chances as
well as ceiling timing. High for gusty winds.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...BTN
Short Term...CJP
Long Term...DM
Aviation...BTN
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Morristown TN
958 PM EDT Wed Apr 7 2021
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
The forecast timing of the onset of showers will be adjusted
slightly later with this update. There is good agreement among the
high-res rapid refresh models that showers will begin to reach our
SW counties around 09Z, so will drop PoPs before that time. All
other parameters appear on track this evening.
The potential for severe storms on Thursday is looking a little
more concerning with the latest model runs, particularly in the
afternoon when models show redevelopment occurring. MLCAPE values
in the NAM rise to 1500 J/kg while wet bulb 0 heights drop below
10 kft. Deep layer shear is supportive of discrete supercells.
Recent HRRR runs are pointing in that direction as well. The main
threats in this environment appear to be primarily large hail with
damaging wind gusts as a secondary threat given the dry air aloft
that builds in during the afternoon.
DGS
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR conditions will persist through the night. Toward morning,
showers are expected to spread into the area from the SW, bringing
MVFR cigs to CHA in the morning, with a chance of MVFR vis with
thunderstorms. These should spread into TYS late in the morning,
although cigs are expected to stay higher due to a southerly
downslope flow off the mountains. The downslope flow will help
weaken showers and keep cigs VFR at TRI in the afternoon.
DGS
&&
.PREV DISCUSSION...
/ISSUED 330 PM EDT Wed Apr 7 2021/
SHORT TERM...(Tonight and Thursday)...
This afternoon mid to upper level ridging is beginning to shift east
of the forecast area as a low pressure at the surface approaches the
Mississippi Valley and a mid to upper level low lies over the
central Plains states. A cold front was moving into the western part
of Arkansas with a line of showers and thunderstorms developing
along and ahead of the cold front at mid afternoon. A few showers
were occurring across middle TN and the Cumberland Plateau at this
hour. At mid afternoon temperatures were about 10 degrees above
normal in the mid 70s to lower 80s. Skies were most sunny east and
partly cloudy west. Expect a mostly clear evening after clouds
gradually decrease west. isolated showers and a possible
thunderstorm possible plateau counties next few hours before
dissipating before sunset. Overnight moisture will continue to
increase ahead of the cold front moving into the Lower Mississippi
Valley. Temperatures will be mild with lows dropping into the 50s to
near 60. The line of storms are expected to weaken as they move away
from the upper level support over Missouri late tonight moving into
middle Tennessee. The steady precipitation with this system may
become more scattered as it moves onto the plateau late tonight.
Rain showers and a few thunderstorms are possible before sunrise
Thursday or about 12Z. The stacked low will then move slowly north
to northeast toward the Great Lakes Thursday. Showers and
thunderstorms will increase during the day as heating increases. The
convection should weaken in the morning and then strengthen during
the afternoon. Some strong storms possible later in the day with
gusty winds and marginally severe hail, especially if significant
heating occurs. Temperatures will stay mild in the 70s, possibly
closer to 80 across the eastern valley near the mountains with
enough early clearing.
TD
LONG TERM...(Thursday night through Wednesday)...
We start the period with a large stacked low pressure system
drifting north across the upper Mississippi Valley/western Great
Lakes region. This system will drag a weak front though our area
Thursday night. Will carry a few showers/possibly some thunder for
the first part of the night, but forcing looks to be minimal and
PoPs will be no higher than low chance. We will be in southwest flow
aloft behind the front, with no significant cooling.
We should be between systems on Friday, and the model soundings
indicate northern sections may be capped with little or no
convection. Soundings look a bit more favorable for convection
south. Models have been inconsistent and given the uncertainty will
keep low chance PoPs for showers/thunderstorms all areas on Friday
with highest PoPs south.
Much higher confidence for a round of precipitation Saturday, as
models in decent agreement that a strong short wave will move
southeast out of the northern Plains into the Mississippi Valley
before lifting northeast into the eastern Great Lakes region.
Surface low pressure will develop to our west and track northeast,
dragging a cold front through our area Saturday night. The low
level jet will increase out of the south Friday night into Saturday,
bringing significant moisture. Downslope flow may inhibit
precipitation early on Friday night/early Saturday in the
northern/central valley areas, and while direction is still
uncertain it looks marginal for some mountain wave enhancement of
the winds for late Friday night and/or Saturday. This will bear
watching as it gets closer. Right now it looks like the rain begins
moving in late Friday night and continues into Saturday, and
convective energy looks to be quite low so will go no more than
chance thunder despite likely/categorical PoPs. There will be
considerable shear present with this system, so we will need to
monitor for any signs of an increase in available convective energy
which would lead to the possibility of strong/severe storms.
Drier air will move in behind the front late Saturday night into
Sunday with surface high pressure building in from the southwest and
heights rising as a ridge aloft begins to build in. Monday will be
dry and warm, but there remains significant uncertainty for the
Tuesday/Wednesday time frame as models show considerable spread.
Right now another short wave and moisture starved front looks to
move through sometime in that time frame, and will carry low PoPs
both days for showers.
LW
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
Area Forecast Discussion
National Weather Service Nashville TN
810 PM CDT Wed Apr 7 2021
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
A broad area of showers and thunderstorms is progressing eastward
across West Tennessee and eastern Arkansas, along and ahead of a
surface boundary that will eventually come through Middle
Tennessee later tonight and tomorrow morning. Expect this activity
to weaken the farther east it goes, but some strong to severe
storms are still possible in our area, mainly west of I-65. The
HRRR brings the leading edge of this activity across the Tennessee
River between 03-04Z, and into Nashville Metro between 06-07Z,
with considerable weakening thereafter. The 00Z sounding from OHX
does show some instability, but is also somewhat dry and lacking
in significant low-level wind shear. The surface-based CAPE is
700 J/kg and the LI is -2. PWAT is 0.98" and the 0-3 km storm-
relative helicity is 78. Hourly grids are holding up well thus
far and see no need for a forecast update at this time.
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR conditions will continue for a few more hours, but showers
and a few thunderstorms will approach from the west by 03-04Z and
bring MVFR cigs/vis to BNA/MQY/CKV. CSV will see reduced flying
categories, too, but not until after 07Z. VFR should return for
all terminals by 18Z Thursday.
South to southwest winds will continue to be gusty through the
period.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......08
AVIATION........Unger
Area Forecast Discussion
National Weather Service Paducah KY
600 PM CDT Wed Apr 7 2021
.UPDATE...
Issued at 558 PM CDT Wed Apr 7 2021
Aviation update.
&&
.SHORT TERM...(Tonight through Friday night)
Issued at 239 PM CDT Wed Apr 7 2021
Convective activity will quickly wane after 00-02z tonight has
instability decreases to basically nothing. This will leave a
solid shield of light to moderate rain that will pass through
much of southern IL, west Kentucky, and southwest IN late tonight
through early Thursday morning. Some light showers may linger into
the post-daybreak morning hours in our extreme east/northeast
counties, and isolated light wraparound rain showers are possible
during the afternoon hours Thursday, with the best chances along
I-64. There will also be considerable cloud cover with high
temperatures in the middle to upper 60s.
We`ll rapidly warm up and dry out for a brief period Friday as H5
ridging builds over the region. High temperatures will rebound
into the middle to upper 70s. However, precipitation looks to
return Friday night into Saturday morning as a disturbance passes
somewhere near the lower Ohio Valley. There is still considerable
model uncertainty regarding the forecast evolution of this system,
so confidence is low regarding the placement and amounts of
rainfall.
.LONG TERM...(Saturday through Tuesday)
Issued at 239 PM CDT Wed Apr 7 2021
Forecast confidence is fairly high through the weekend and then
plummets as we head into and through next week.
A compact storm system over eastern Kansas at 12Z Saturday will push
east across Missouri through the day and then lift northeast
Saturday night. In response a surface low will develop and lift
northeast across our region during the day. Widespread showers and
some thunderstorms are expected through the day with the heaviest
rain, 1/2" to 3/4", generally over the eastern half of the region.
The greatest coverage is expected in the morning with more scattered
coverage in the afternoon. At this time severe weather seems
extremely unlikely. As the storm system lifts northeast away from
our region we should be dry Saturday night through Sunday.
Looking at next week, the flow aloft becomes rather chaotic with
numerous upper lows/troughs flying around and interacting with one
another. This creates a low confidence forecast for the week. The
12Z ECMWF continues to be the wet model and is similar to its 00Z
run. It brings a cold front through the area under west northwest
flow aloft late Monday, and generates some light QPF over far
southern portions of the region behind it into Monday evening.
Meanwhile, the GFS has upper ridging over the area. The forecast is
dry for now.
The 12Z ECMWF continues its wet trend Tuesday night through
Wednesday, with a prolonged period of rain as a large positively-
tilted trough pushes east into the region. The surface system is
well to our south, and this looks like a frontogenetical/isentropic
lift situation for our region. Unfortunately, the GFS and CMC are
dry with upper ridging over the region.
The upper pattern becomes rather amplified and blocky next week, and
the details seem to hinge on how progressive or not the flow is in
the northeast. The ECMWF is more progressive which allows it bring
the system in here by mid-week, while the GFS/CMC are not
progressive which holds the ridge over us and the next storm system
well to our west. This is a very low confidence situation, but we
will have slight chance PoPs for showers Tuesday night through
Wednesday.
As for temperatures, we will be a bit above normal Saturday through
Monday, and then after a cold front moves through late Monday,
readings will drop down near normal Tuesday and Wednesday. Of
course, if we end up wet Wednesday, temperatures may be cooler.
&&
.AVIATION...
Issued at 558 PM CDT Wed Apr 7 2021
Timing of showers and thunderstorms into and through the WFO PAH
TAF sites modeled fairly well with the HREF and HRRR numerical
guidance. MVFR ceiling and visibility conditions will occur within
one to six hours prior to cold front/wind shift line tonight,
with a gradual return to VFR conditions within another six to
twelve hours.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...Smith
SHORT TERM...DWS
LONG TERM...DRS
AVIATION...Smith
Area Forecast Discussion
National Weather Service Blacksburg VA
827 PM EDT Wed Apr 7 2021
.SYNOPSIS...
Weak stationary front will backdoor into the area tonight into
Thursday, bringing an uptick in moisture. A complex low
pressure systems will bring periods of showers and scattered
thunderstorms to the area Thursday afternoon through Saturday
and will push a cold front across the eastern United States
Sunday.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 800 PM EDT Wednesday...
Main change this hour was to increase temperatures as on average
current readings are about 5-degrees warmer than advertised.
Dewpoints also a bit lower. Adjustments were made through 06Z,
but still plan to reach minimum temperatures advertised by
morning due to dryness of air mass. Also, made winds a bit more
northeast to east overnight/early Thursday and increased speeds
a bit as shown by NAMNest and HRRR. Fairly good wedge progged to
spread in from the east by morning and then be reinforced "in
situ" as rain showers move in from the southwest tomorrow
afternoon.
As of 1235 PM EDT Wednesday...
Warm but increasing threat of showers and a few storms Thursday
afternoon.
Increasing cumulus field this afternoon across the mountains
although still more sun than clouds keeps impact of solar
insolation near full strength to bring temperatures into the 70s
and lower 80s.
Tonight, front across the Virginia tidewater heads west and may
see some increase in the cloud cover toward Lynchburg as winds
turn east, but rain threat is nil.
Thursday, the front starts to head back across the Virginia
piedmont as a warm front, while a cold front enters the
Ohio/Tennessee Valley. Model consensus shows an initial wave of
showers/few thunderstorms moving across the area Thursday but
overall coverage looks scattered but could be a better zone of
development from the Greenbrier Valley/Alleghanys southeast to
the foothills of VA and New River Valley. For now keeping pops
under 60 percent, with highest chance in this corridor from
Lewisburg to Roanoke/Blacksburg/Rocky Mount, with lower threats
in the upper TN Valley/NC mountains and east of Buckingham VA
south into NC.
Mild lows tonight in the upper 40s to lower 50s, except some
lower 40s in the deeper valleys like Burkes Garden.
Cloud cover will keep temperatures a few degrees lower than
today but still about 6 to 10 degrees above normal.
Confidence in this forecast is moderate to high.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 200 PM EDT Wednesday...
Scattered showers and a slight chance of thunder with warm
temperatures as the weekend begins...
Increased moisture advection on Thursday will increase shower
chances across the area for Thursday night overnight into Friday. A
cutoff low situated to our west tracks northwards Thursday night,
bringing a cold front across the Gulf states. Southerly flow ahead
of this front will cause that moisture advection. Limited
instability will prevent widespread thunderstorms late Thursday, but
enough forcing from a stationary boundary and some elevated CAPE
warrants a slight chance remain in the grids until just after
midnight.
Friday sees more interaction with the stationary boundary in the
area sliding a bit further south. Not expecting strong interaction
as a high off the New England coast and the high cloud cover from
Thursday onward will suppress surface temperatures and instability
Friday. For Saturday there is good agreement in the guidance for a
cold front to pass over the Mid-Atlantic late on Saturday. The front
will bring much better dynamic setup than Thursday or Friday`s
events, so have isolated thunder in the forecast for a few
hours given the limited instability.
Overall have kept temperatures a few degrees under guidance with the
continuous cloud cover throughout the period. That said, highs will
still be in the 60s and 70s, a few degrees above normal for early
April. Lows will categorically be in the 50s through Saturday.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 200 PM EDT Wednesday...
Conditions dry out to start next week...
After the front and associated precipitation moves out east Sunday
morning, upper ridging and broad surface high pressure will keep our
pattern pretty inactive. The next chance at showers will be
overnight Wednesday at earliest, as the leading edge of a deep
positively tilted trough approaches the Mid-Atlantic. This break in
rain will probably encourage some good prescribed burn conditions in
the middle of the week. Increased post frontal winds on Sunday and
Monday help dry out fuels, before calmer winds and modest RH`s in
the midweek.
Temperatures will rebound a bit from the weekend, highs staying
healthily above normal for this early in the spring.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 800 PM EDT Wednesday...
Generally VFR conditions expected through the TAF valid period.
Extensive high cloud cover expected through the forecast period
as a result of widespread strong convection currently aligned
along the MS river and moving east overnight. Some mid-level
moisture also noted resulting in areas of SCT-BKN080-100.
Overnight, VFR conditions will remain in place with surface air
mass dry and dewpoints in the 30s/40s and temperatures in the
50s and 60s.
Overnight, a backdoor front will move into the area from the
east. Winds will veer overnight to the northeast and then more
toward the east/southeast during the day Thursday. NAMNest and
HRRR show fairly healthy winds Thursday and the potential for
gusts of 20-25kts around BLF and 15-20kts in the LYH/DAN/ROA
area. Overnight, wind speeds should remain mostly less than
8kts.
By Thursday afternoon, a closed upper low in the Midwest will
begin to shift east into the OH Valley. This will allow a warm
front to lift north through our area by afternoon with elevated
convection likely along this warm front in the 18Z-22Z time
frame. This has been indicated in the western TAF sites
(BLF/LWB/BCB) with PROB30 for TSRA. Elsewhere, convection
appears to marginal to include in the TAF at this time.
Potential for MVFR conditions will be limited to the PROB30
groups at this time.
/Confidence Levels in Forecast Parameters/
Ceilings - Moderate to High,
Visibilities - High,
Winds - Moderate to High,
Thunder Chances - Low.
Extended Aviation Discussion...
MVFR or worse ceilings/visibility are expected to evolve across
the region Thursday night into Friday as the wedge of cool
easterly flow dominates the area. Meanwhile, aloft weak
disturbances will track across the area from a broad area of low
pressure aloft in the OH Valley. This will keep cloudy, damp,
wet, drizzly and perhaps at times foggy conditions in place into
the early part of the weekend. Additional shower and
thunderstorm chances are expected over the weekend as a stronger
upper-level low pressure area moves toward the region from the
southwest Sunday. Conditions should improve somewhat early next
week as the upper low weakens and moves north of the area.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS/WP
NEAR TERM...RAB/WP
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...RAB