Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/09/20
Area Forecast Discussion
National Weather Service Denver/Boulder CO
853 PM MDT Tue Sep 8 2020
.UPDATE...
Issued at 837 PM MDT Tue Sep 8 2020
No significant adjustments to the grids at this time. Of note, we
tied the record low of 31 for this date at DIA this evening. It
also ties the record for the earliest coldest temperature in
Denver. It look a little longer for the rain/drizzle to turn over
to snow this afternoon, but light to moderate snow finally settled
in by this evening as the better mid and upper level moisture
filled from the southwest. Bands of heavier snow along the urban
corridor, generally in the 1/2 to 1 inch per hour range. So far,
here at NWS Boulder we have picked up 3.6 inches of snow. Latest
HRRR shows the snow west of Denver and north of I-70 tapering off
by midnight, but it should continue overnight for zones 34/37 with
favorable southeasterly winds in the mid levels. The focus east
of I25 will shift more to the Palmer Divide and eastern plains
late tonight into Wednesday morning. No changes to any of the
ongoing highlights.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 332 PM MDT Tue Sep 8 2020
A mix of light rain, drizzle and light snow has been spread across
northeast Colorado through this afternoon as moist northeast flow
has continued into the region. Over the mountains, precipitation
has been enhanced by upper dynamic forcing associated with a
cutoff upper level low that has developed over east-central Utah.
The upper level dynamic forcing and elevated instability moving
northward out of New Mexico has produced an area of moderate
intensity precipitation over the San Juan Mountains and other
central Colorado mountain ranges this afternoon. The northern
fringes of this upper lift will extend over the north central
mountains and I-25 corridor through this evening. This should
enhance snowfall over north central and northeast Colorado well
into tonight. Light to moderate snow is expected in the mountains
and over the Palmer Divide with lesser amounts of snow over the
I-25 urban corridor and adjacent plains. Will be maintaining the
Winter Storm Warning and Winter Weather Advisories that were
previously in effect for tonight. In addition, a Freeze Warning
will continue on the plains. Low temperatures on the plains should
be in the mid to upper 20s. Additional snow accumulations in the
Front Range mountains and foothills should be 5 to 10 inches. The
Palmer Divide should see 4 to 8 inches of snow, and other plains
locations will see 2 to 5 inches of snow.
After midnight, all of the ingredients for snowfall should begin
diminishing and snowfall rates should begin to come down. The
Denver metro area may still see some lingering snow over the
morning commute, but little additional accumulation is expected.
Scattered snow showers will also be possible over the mountains.
Weak upslope flow over the plains will hold low level moisture in
place leading to only partially clearing skies by late in the
afternoon. Temperatures will be much cooler than normal, only
reaching the upper 30s and lower 40s on the plains, due to the
lack of sunshine.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 332 PM MDT Tue Sep 8 2020
Models are in very good agreement that the cutoff low will weaken
and move northward near the UT-CO border on Wednesday night and
Thursday morning. The greatest forcing for ascent will remain well
south of the area and there will be less coverage of showers.
On Thursday, the low should advance further north into eastern
WY. A small jet streak embedded with the low along with increasing
mid-level lapse rates, especially over the mountains, will
contribute to a higher coverage of showers by afternoon.
Isolated storms and another brief period of snow accumulation in
the mountains are also possible.
Friday, the low should move east across the Central Plains. As it
does, flow aloft will turn to northwesterly. Friday afternoon may
see isolated showers, mainly in the high terrain, but otherwise no
active weather is expected for a while. Saturday, will see more
ridging and significant clearing, and Sunday the area will be
close to the ridge axis. This will lead to dry weather, but more
seasonable temperatures.
Monday, long range models agree that another upper level trough
should begin to move onshore in the Pacific Northwest. Tuesday, this
trough may clip the area as it moves east towards the Great
Plains. We`ll likely return to above normal temperatures during
this period with a continuation of warm westerly flow aloft.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 837 PM MDT Tue Sep 8 2020
Ceilings and visibilities will be in the IFR/MVFR categories
overnight along with light snowfall. Mainly light snow, but
localized bands of moderate snowfall with rates 1/2 to 1" per hour
possible this evening. Overall, snow accumulations of 2 to 4
inches are expected overnight on elevated and grassy surfaces.
Accumulation on pavement should be much lower due to heat stored
from this past weekend, more slush vs snow. Snow is expected to
taper off Wednesday morning with a gradual improvement in cloud
heights and surface visibilities through the late morning and
afternoon hours.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Freeze Warning until noon MDT Wednesday for COZ038>051.
Winter Storm Warning until noon MDT Wednesday for COZ033>037-041.
Winter Weather Advisory until 6 AM MDT Wednesday for COZ031.
Winter Weather Advisory until noon MDT Wednesday for COZ038>040-
042-043-045-046.
&&
$$
UPDATE...Cooper
SHORT TERM...Dankers
LONG TERM...Direnzo
AVIATION...Cooper
Area Forecast Discussion
National Weather Service Boston/Norton MA
1029 PM EDT Tue Sep 8 2020
.SYNOPSIS...
Increasing humidity, along with warm temperatures are in the
forecast for the next couple of days. A cold front will bring
scattered showers and a few thunderstorms Thursday into
Thursday with the focus for this activity near and south of the
Massachusetts Turnpike. High pressure brings dry and cooler
weather Friday and Saturday. Another cold front approaches
Sunday into early Monday bringing another round of showers. Dry
weather with cool nights and mild days follow the rest of Monday
into Tuesday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
1015 PM Update...
Adjusted the forecast to bring down visibilities a bit more
across the interior. Uncertain on how far west the Dense Fog
Advisory will need to be extended, but will save this for the
next update when fog expands a bit more. RAP low level RH values
are doing well so far, but will need to continue to monitor for
future updates. Combined this with the GLAMP guidance to bring
down visibilities. Added a bit more drizzle to the forecast,
mainly across areas where visibilities are anticipated to be at
or less than 1 mile. Rest of the forecast is on track.
735 PM Update...
* Areas of dense fog develop through the overnight hours
Areas of low clouds and fog were already making their way onto
the Cape/Islands early this evening, faster than what most of
the guidance was indicating. Given light southerly winds with
dewpoints in the 60s coupled with increasing longer nights this
time of year, areas of fog and low clouds will continue to
expand northwest overnight. We think the low clouds and fog may
end up more extensive than much of the guidance indicates based
on pattern recognition. This is especially true with decoupling
winds; so expect to see areas of dense fog develop and spotty
drizzle too.
We already issued a dense fog advisory for the Cape and Islands
through 8 am Wednesday. This will likely need to be expanded
overnight. Previous discussion follows.
The synoptic situation is largely unchanged from 24 hours ago,
so what we saw last night is likely what we will see overnight.
Given the moderately moist low levels and light winds, another
round of fog/stratus is pretty much a given. Of course, the
devil is in the details...how dense the fog will get? how far
inland will the clouds make it? You get the idea. Didn`t make
any significant changes to the forecast we had. Fog should be
most widespread across coastal areas/eastern MA/CT River Valley,
and thinking that the thicker fog will be across SE MA, Cape
and Islands. Heck, like this morning, there may even be some
light drizzle in those areas as well. Lows overnight will
generally be in the 60s, but some upper 50s are possible.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
as of 230pm...
12z short term models still indicate the idea that deeper
moisture off to our south will nudge northward later in the day
into Wednesday night. Models show an axis of precipitable water
values that close in on 2 inches. At the surface, we will see
this in the form of dewpoints of 70F or a little higher,
especially closer to the south coast. Don`t see a lot of
forcing, but with that amount of deep moisture, it doesn`t take
much for scattered showers to develop. So have blended in some
of the hi-res models to drive the hourly PoP grids, which
basically gives us a 20-30% chance of showers Wednesday night
across the southern half of the forecast area -- with highest
along the south coast and adjacent coastal waters. Some signals
of a little bit of instability in the models, primarily from the
high dewpoints, so have gone ahead and included a slight chance
of thunderstorms mainly along the immediate south coast and
offshore. QPF is rather tricky. Given the high precipitable
water values, local downpours of 1/2" are possible. But since
the chance of precipitation is rather low, the areal average QPF
ends up less than 0.10". High temperatures Wednesday will again
top out well into the 80s across inland areas, 70s but with an
increasingly humid feel nearer the coast. Wednesday night is
looking to be fairly muggy in most areas due to those increasing
dewpoints with lows in the 65-70F range. You`ll need to go to
the higher elevations of NW MA to experience lows in the lower
60s.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Highlights...
* Humid Thu/Thu night with scattered showers & a few t-storms
with the best chance near and south of the MA Turnpike
* Much less humid and also cooler Fri/Sat with dry weather
* A period of showers is possible sometime Sun into early Mon with
a cold front
* Dry weather follows the rest of Mon into Tue with cool nights and
mild days
Details...
Thursday...
It will be warm and quite humid on Thu ahead of an approaching cold
front. This front will bring the potential for a round of scattered
showers and a few thunderstorms Thu/Thu night with the focus near
and south of the MA Turnpike. The guidance indicates that we may see
around 1000 J/KG of Cape develops ahead of the front, so a few
thunderstorms are certainly possible. Some guidance also suggests
the showers may linger well into Thu night towards the south coast.
So while Thu into Thu night will not be a complete washout, the
threat for showers and a few t-storms exists with the focus near and
south of MA Turnpike.
High temps on Thu should be mainly in the 80 to 85 degree range, but
it will be humid with dewpoints well into the 60s to near 70.
Friday and Saturday...
High pressure will build to our north behind the cold front Fri into
Sat. This coupled with a wave of low pressure to our south will
generate a northeast flow of much less humid & cooler airmass to the
region. Dry weather expected over this time too, other than the low
risk for a few lingering showers across southeast New England early
on Fri.
NE winds will hold high temps in the middle to upper 60s along
portions of the coastal plain and especially the Cape/Islands on Fri
and Sat. Elsewhere, high temps should reach the lower to middle 70s,
but with plenty of sunshine and low humidity. Low temperatures late
Friday night into early Saturday morning will bottom out well down
into the 40s to the lower 50s.
Sunday through Tuesday...
High pressure moves east of our region on Sun as a cold front
approaches from the west. This will likely bring a return to a bit
of humidity and another round of showers sometime Sunday into early
Mon. This will be followed by another large high pressure system the
rest of Mon into Tue, bringing dry weather with cool nights and mild
afternoons.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Through 00z Thursday...overall moderate confidence in TAFs.
IFR-LIFR conditions will overspread much of the region through the
overnight hours in low clouds and fog. This process was already
occurring across the Cape and Islands and will occur in many
areas from southeast to northwest through 08z. Fog/stratus
should lift at most TAF locations by 14z tomorrow, but areas
near the south coast and especially Cape/Islands may see low
clouds and fog flirting with the area into the afternoon.
KBOS Terminal...Moderate confidence in TAF. Sea breeze should
shift back to the south 01-02z, with another sea breeze
developing tomorrow 14-16z. Highest uncertainty is with how low
the ceilings and visibility drops late tonight, as BOS may end
up being on the edge of the most widespread IFR conditions.
Although currently an MVFR forecast, there is a possibility for
another round of IFR conditions as we saw early today.
KBDL Terminal...Moderate confidence in TAF. Uncertainty exists
in exact timing of fog/stratus development overnight. Expected
to drop to IFR, but LIFR is possible. Improvement should occur
by mid to late Wednesday morning.
Outlook /Thursday through Sunday/...
Thursday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA, isolated TSRA, patchy FG.
Thursday Night: Mainly VFR, with areas MVFR possible. Breezy.
Chance SHRA, isolated TSRA.
Friday: Mainly VFR, with local MVFR possible. Breezy.
Friday Night through Saturday: VFR.
Sunday: Mainly MVFR, with areas IFR possible. Breezy. Chance
SHRA.
&&
.MARINE...
With a ridge of high pressure across the region, winds will
remain rather light for the next couple of days. Biggest concern
will be the fog that will become most widespread during the
overnight and early morning hours. Visibilities of less than
1/2nm will be most common around and south of Cape Cod. A slight
chance for thunderstorms will also be possible for Wednesday
night.
Outlook /Thursday through Sunday/...
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers, isolated thunderstorms, patchy fog.
Local visibility 1 to 3 nm.
Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas. Chance of rain showers,
isolated thunderstorms.
Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Areas of rough seas.
Friday Night through Saturday: Moderate risk for Small Craft
Advisory winds with gusts up to 25 kt. Seas up to 5 ft.
Saturday Night: Winds less than 25 kt. Seas up to 5 ft. Chance
of rain showers.
Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. Chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Dense Fog Advisory until 8 AM EDT Wednesday for MAZ022>024.
RI...Dense Fog Advisory until 8 AM EDT Wednesday for RIZ008.
MARINE...None.
&&
$$
SYNOPSIS...Frank/Nash
NEAR TERM...Frank/BL/Nash
SHORT TERM...Nash
LONG TERM...Frank
AVIATION...Frank/Nash
MARINE...Frank/Nash
Area Forecast Discussion
National Weather Service State College PA
1108 PM EDT Tue Sep 8 2020
.SYNOPSIS...
A nearly stationary frontal boundary will remain stretched along
the south shores of Lakes Ontario and Erie over the next few
days as a strong upper level ridge expands westward into the
Mid Atlantic region.
A weak cold front will push south of the area by Friday. Most
of the time will feature dry conditions, but a few showers will
be possible late Wednesday night into Thursday. Most of the
activity is expected to be across the southeast portion of the
Keystone state.
An upper level trough and associated front are likely to push
into Pennsylvania by late in the weekend. This system will bring
the potential for some showers and perhaps a thunderstorm on
Sunday.
&&
.NEAR TERM /UNTIL 8 AM WEDNESDAY MORNING/...
A cirrus and cirrostratus layer will continue to stream north
across the eastern two thirds of PA overnight while skies stay
mainly clear across the NW Mtns.
Weak ridge of sfc high pressure will remain over the area
keeping winds light. Some patchy fog is possible late, mainly
across the southeast.
Lows will be mainly in the 60s.
&&
.SHORT TERM /8 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
Weak high pressure will keep mainly dry conditions across the
area on Wednesday, with plenty of sunshine and warm temperatures
again. Warmest readings likely to be near IPT, given it is a bit
drier there, and the southeast areas may have some fog early on.
Not seeing much support for high dewpoints across the southeast
early on, so cut down on the chance of showers across the
southeast some. Sfc based CAPE will be rather minimal and only
400-600 j/kg at the upper end per the latest RAP guidance, so we
should see primarily MDT cu across the SE and NW zones will the
flattest clouds across the central counties of PA.
Higher chance of rain late Wednesday night into Thursday, mainly
across the far east, as dewpoints forecast to climb closer to
the upper 60s and lower 70s after the day on Wednesday.
As was the case today, any showers and storms with the front
to the north likely to be on the cool side of the front, unlike
the situation on Labor Day.
Highs will range from the mid 80s to around 90 degrees.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Latest GEFS and EC are in good agreement depicting a stationary
front off the east coast, which will continue to pool moisture
from the Carolinas to the northeast into the southern part of PA
Wednesday night.
A fast-moving and fairly flat shortwave racing east over the
aforementioned llvl stationary front may lead to a few showers
Wednesday night, and isolated to scattered showers and T-storms
Thursday afternoon.
PoPs are highest in southeastern PA topping out around 40-45%.
A cold front will sag southeast through the northwest mountains
during the day Thursday, but mid- level ridging/subsidence and a
deep mid level layer of dry air will limit convection to little
more than isolated showers as the front passes through.
Temperatures will dip by a few degrees on Friday (to near
normal) accompanied by ample sunshine and northerly winds. An
approaching upper trough and surface low pressure system will
move in from the Ohio Valley region for the second half of the
weekend as southerly flow ushers in mild and breezy conditions
for Saturday and Sunday. A surge of moisture will also bring an
increased likelihood of showers and thunderstorms on Sunday,
with likely PoPs forecast in northwest PA and only chance PoPs
in the southeast.
The start of next week appears more tranquil, as a cold front
and surface high pressure ushers in near normal temperatures for
a couple of days. A few lingering showers are possible Monday
but the trend will be drier heading into the middle of next
week.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Weak stationary boundary will linger off to our NW, but high
pressure over Central PA will keep mainly clear skies and VFR
conditions ongoing through Wednesday with just some patchy
morning river valley fog possible. Winds will remain light from
the S/SE with a thin cirrus veil overhead.
Outlook...
Thu...Widely scattered showers/tstms and low cigs, restrictions
possible.
Fri-Sat...Mainly VFR conditions expected.
Sun...Lower conditions possible with a chance of showers.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert/Martin
NEAR TERM...Lambert/Martin
SHORT TERM...Martin
LONG TERM...Lambert/Banghoff
AVIATION...Martin/RXR
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1153 PM EDT Tue Sep 8 2020
.AVIATION...
Low level moisture overriding frontal boundary will maintain low
cigs into Wednesday. Scattered showers and a few storms will also
lift northeast through the area overnight as a pocket of unstable
elevated air is pulled through the area as main upper disturbance
lifts to the north of the area. In the wake of this activity, minor
vsby restrictions in br/-dz should set in late tonight into early
Wed morning.
For DTW...low ceilings will persist through the forecast period with
some breaks/lifting of cigs late Wednesday. Any shower activity
looks to be rather spotty and mainly north/northwest of terminal
overnight.
.DTW THRESHOLD PROBABILITIES...
* High for ceiling 5000 ft or less through Wednesday.
&&
.PREV DISCUSSION...
Issued at 407 PM EDT Tue Sep 8 2020
DISCUSSION...
A deep stationary baroclinic zone is gradually sloped over Lower
Michigan and the Northern Great Lakes this afternoon. The frontal
zone will serve as a conduit, bringing active weather to at least
portions of the region throughout the next 36 to 42 hours. Main
driver for the weather will be episodic waxing/waning of
ageostrophic forcing along the frontal zone due to changes in
Ontario/Quebec +145 jet streak. The northern Great Lakes and Lower
Michigan will remain in an area of preferred right entrance region
dynamics.
The next significant warm advection surge will funnel through the
Saginaw Valley late this afternoon and early evening in response to
upper level high retrograding to Ohio and polar vorticity anomaly
swinging through Northwest Ontario. For forecast details, on late
afternoon and early evening refer to the Update Discussion earlier
today. The main item of uncertainty tonight is on coverage of
convection, particularly for the central and southern cwa. A portion
of NWP solutions suggest a decent coverage across portions of the
southern or central cwa in the 01-6Z timeframe. HRRR has been
advertising the potential with the ARW offering a more robust
solution with a greater coverage. Prefer to err on a more bullish
solution given the impressive frontal boundary in place and amount
of available moisture to interact with the front. Introduction of
drier air aloft from northward migrating frontal zone will provide
for steeper lapse rates and MUCAPE development this evening. Latest
forecast soundings suggest as much as 1000 J/kg will be available
for a time. Low level stability will limit the potential for any
strong thunderstorm risk. Potential exists for some localized
heavier rainfall due to cell training, but high uncertainty exists
given the low QPF in model solutions.
For Wednesday, most active weather appears to remain more centered
over portions of northern Lower Michigan and northern Great Lakes as
very deep anticyclonic flow lifts directly into the cwa. A good
signal exists for differential AVA through the area. Models show
opaque cloud holding within the baroclinic zone with saturation
trapped within the strongly stratified 2.0 to 4.0 kft agl layer.
Lowered high temperatures a little despite the ridging.
Very strong surface based ridging will then develop over the state
on Thursday in response to geopotential height rises. Some
uncertainty exists with end timing of precipitation, as could see
remnant showers hanging on over the Thumb through Thursday morning.
Current forecast reads more optimistic/dry. No real cold advection
to speak of as stationary boundary lifts northward as a warm front,
therefore and increase in geostrophic/gradient winds is relatively
non-existent. That will set the stage for pleasant end of the week
weather with very chilly Friday and Saturday mornings.
MARINE...
A stationary front draped across western Lake Erie will remain
stalled in the area for the next few days. Disturbances tracking
along the front will bring periodic chances for showers and some
thunderstorms through Thursday with the next round moving in this
evening and overnight. The best coverage of showers tonight will be
across Saginaw Bay and central to northern Lake Huron. Stout
northeast winds will persist on the northern side of the front and
Small Craft Advisories continue across the Thumb and Saginaw Bay
shorelines due to the long fetch and onshore wave action. Gusts will
approach or exceed 25 kt at times, especially across the bay. Marine
conditions then begin to improve on Thursday as high pressure builds
into the Great Lakes.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Lakeshore Flood Advisory until 8 PM EDT Wednesday for MIZ048-049-
054-055-063.
Lake Huron...Small Craft Advisory until 11 AM EDT Thursday for LHZ421-422-
441>443.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....DG
DISCUSSION...CB
MARINE.......CB
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Grand Rapids MI
917 PM EDT Tue Sep 8 2020
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 211 PM EDT Tue Sep 8 2020
- Showers and a Few Storms Tonight, Light Showers Wednesday
- Dry Thursday and Friday, Rain Possible Saturday into Sunday
&&
.UPDATE...
Issued at 917 PM EDT Tue Sep 8 2020
Highest pops/most persistent rain showers tonight will be near
and north of a Muskegon to Clare line where the 850 mb front warm
front is located. South of that line showers should be more
scattered to isolated.
The highest risk of a tstm overnight will be near and east of an
AZO to LAN line where RAP guidance shows 500-1000 J/KG Capes
persisting through 12Z.
The storms currently entering NW Indiana from the southwest
should be arriving along the I-94 corridor toward midnight if
they hold together. Main threat with these elevated storms (and
any others overnight) would be periods of locally heavy rainfall
and a few cloud to ground lightning strikes.
&&
.DISCUSSION...(This evening through next Tuesday)
Issued at 211 PM EDT Tue Sep 8 2020
-- Showers and a Few Storms Tonight, Light Showers Wednesday --
This evening will be the last threat for thunderstorms until later
Saturday. Otherwise, occasional showers will progress through the
region tonight into Wednesday before ending Wednesday night.
Chilly early September weather has settled in north of a warm front
positioned across north central Indiana and Ohio. Temperatures
haven`t move much today out of the 50s to around 60 north of I-94,
which corresponds to 20 degrees below normal for most locations.
Coupled with on and off rain and a northeast breeze, and one could
say it is rather raw outside. Even so, much of our region has been
in either a D0 (abnormally dry) or D1 (moderate drought) recently,
so the cool and wet weather will help ease the situation.
Periods of showers and thunderstorms will continue riding north of
the warm front this evening and tonight, with no severe weather
expected given their elevated nature. HREF MUCAPE does suggest
some thunderstorm potential across southern Lake Michigan and
especially near and south of I-96 this evening and tonight. This is
where 250-1000 J/kg of elevated instability is shown. Otherwise,
general rain showers are expected.
Periodic light showers or sprinkles are possible Wednesday with
cloudy skies continuing. There will likely be prolonged periods
without rain during the day, however. Expect any leftover showers to
exit the region Wednesday night.
-- Dry Thursday and Friday, Rain Possible Saturday into Sunday --
Medium range guidance is in fairly good agreement that an upper
low centered across the SW U.S. will move toward the Great Lakes
by this weekend. The low will become cutoff from the northern
stream flow across the northern U.S. and spin for a couple days
across the Four Corners region before migrating northeast and
getting reabsorbed in the westerlies. The precise timing of
phasing such as this can be tricky to pinpoint several days out,
but ensemble guidance has good consensus on bringing the chance
for rain into the region particularly Saturday evening into Sunday
morning. Amounts do not look heavy given the progressive nature of
the system. ECM mean surface based CAPE looks pretty weak Saturday
but maybe just enough to warrant some lightning potential. Mid
level winds look strong at 50 kts but we probably won`t have
enough instability to realize those strong wind gusts in any
deeper convection.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 802 PM EDT Tue Sep 8 2020
Southwest Lwr MI is on the north side of a stationary frontal
boundary so expect low cloudiness and scattered showers/drizzle
to persist tonight and Wednesday. An isolated tstm cannot be ruled
out either.
A mix of IFR and MVFR cigs this evening will trend down overnight
into early Wednesday to more widespread IFR with some areas of
LIFR as well. On Wednesday cigs are expected to gradually lift to
mostly MVFR category by 18Z. Northeast sfc winds around 10-15 kts
will continue.
&&
.MARINE...
Issued at 211 PM EDT Tue Sep 8 2020
Persistent offshore winds will continue through the week and as a
result the highest wave action will be across the western half of
Lake Michigan. For our nearshore waters, the highest wave action
is expected into this evening and Wednesday with 2 to 4 footers
likely. Looking ahead, adverse conditions to small craft are
possible on Sunday behind a front when winds swing around to the
NW and build higher wave action.
&&
.HYDROLOGY...
Issued at 211 PM EDT Tue Sep 8 2020
Rainfall over the last 24-48 hours has put a dent in the D0/D1
drought status across much of the region. River levels were very
low to begin with and are able to take the runoff with little
problem, but Sycamore Creek near Holt will crest near bankfull
tonight and the Grand River at Ionia is expected to go above
bankfull Thursday given a projected 6 foot rise from its current
stage reading as of this afternoon. This crest will translate west
toward Kent and Ottawa counties by the end of the week and
weekend but no flooding will occur.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...Meade
SYNOPSIS...Hoving
DISCUSSION...Hoving
AVIATION...Meade
HYDROLOGY...Hoving
MARINE...Hoving
Area Forecast Discussion
National Weather Service Wichita KS
910 PM CDT Tue Sep 8 2020
.UPDATE...
Issued at 909 PM CDT Tue Sep 8 2020
Main synoptic boundary has dropped south into ern OK, at this time,
but the mid level baroclinic zone continues over the eastern half of
KS. Over the top of the boundary, 850h moisture transport axis
continues to lead to showers and embedded thunderstorms moving N-NE
into SE KS at this time, with a more diffuse area of moisture
transport across the rest of the forecast area leading to widely
scattered showers and patchy drizzle. Current forecast continues to
look on track, with the SE KS area of moisture transport expected to
continue with more numerous showers and a few thunderstorms at least
until 08-09z. But think as the night progresses, think showers will
become the main precip type, as the elevated instability begins to
wane or drop further south, so less thunder. The showers could still
pose a localized flooding threat for portions of SE KS, given the
training of the showers and high precipitable water rates for
efficient rainfall producers.
The rest of the area will continue to see a more widely scattered
shower and patchy drizzle chance, as low layers stay fairly
saturated. Could see a slight uptick in the shower coverage
overnight, as RAP bufkit soundings suggest that column will become
more deeply saturated after 06-09z, which would change the drizzle
over to more of a rain.
Will send out a quick update, mainly just to freshen the wording.
Ketcham
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 308 PM CDT Tue Sep 8 2020
Unseasonably cold air will continue to ooze southward tonight into
Wednesday with occasional post-frontal drizzle/rain and even bouts
of convection. Moderate cape/weak shear within higher PWAT axis
along the front will support strong/marginally severe storms and
heavy rainfall rates until early this evening across southeast
Kansas. Meanwhile, elevated instability within frontogenetic zone
further northwest across central Kansas may support scattered
convection tonight as well. Otherwise, it looks like record lows
and cool highs are in jeopardy for Wednesday across most of the
area. The closed upper low will be slow to evolve Wednesday into
Thursday across the Four Corners region before lifting out
Thursday night. This will keep the area unseasonably cool with
periods of rain and chances for convection.
Darmofal
.LONG TERM...(Friday through Tuesday)
Issued at 308 PM CDT Tue Sep 8 2020
The upper low will will continue to lift northeastward across the
northern Plains and Upper Midwest Friday through Saturday with
upper ridging trying to build in across portions of mid-America by
early next week. This is expected to result in a warming trend
and return to a drier regime with temperatures trending close to
seasonal climo.
KED
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 643 PM CDT Tue Sep 8 2020
Expect widespread IFR cigs and MVFR vsbys as shallow cold air on the
north side of a cold front has led to lots of low clouds. Also
seeing patchy drizzle develop, as the cloud deck continues to lower
and saturation increases in the lowest layers of the atmosphere. The
only exception will be over SE KS where proximity to the main
synoptic frontal boundary may lead to MVFR cigs and possible VCTS
due to convection developing along or over the top of the main
synoptic front.
As the evening progresses moisture transport over the top of the
shallow cold air will lead to the drizzle and rain increasing for
most locations, with a gradual lowering of the cigs to LIFR in some
locations with MVFR vsbys due to the DZ/RA. Kept the aviation
conditions very pessimistic for the overnight into Wed, with IFR
prevailing as the moisture transport continues over the top of the
shallow cold air, for off and on, RA/DZ for the daytime hours on
Wed.
Ketcham
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 49 54 52 62 / 90 80 80 60
Hutchinson 46 51 47 59 / 90 90 80 50
Newton 46 52 50 60 / 90 80 80 60
ElDorado 50 56 52 62 / 80 80 70 60
Winfield-KWLD 53 59 55 65 / 80 80 70 60
Russell 42 47 44 56 / 100 90 80 40
Great Bend 42 47 45 55 / 100 90 80 40
Salina 45 50 47 59 / 90 90 80 50
McPherson 46 50 47 58 / 90 90 80 50
Coffeyville 60 73 60 73 / 80 40 40 50
Chanute 56 67 58 71 / 80 50 40 50
Iola 55 65 56 70 / 80 50 40 50
Parsons-KPPF 58 71 59 72 / 80 50 40 50
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Ketcham
SHORT TERM...KED
LONG TERM...KED
AVIATION...Ketcham
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1033 PM EDT Tue Sep 8 2020
.SYNOPSIS...
A southerly flow around high pressure will bring dry weather and
above normal temperatures through Thursday. Seasonal temperatures
return for Friday after a weak cold front drops through the Ohio
Valley. Showers and thunderstorms will be possible Saturday and
Sunday along the next cold front.
&&
.Update...
A frontal boundary has settled across northwest portions of the
forecast area with nearly all of the area seeing mostly clear
skies at the current time. Within northeast flow north of the
front, low level stratus is beginning to move southwestward into
the northern fringes tonight. Near this front, the potential
for thickening fog is increasing through the overnight hours
and will continue into the morning. Visibility guidance (HRRR,
SREF, NBM, RAP forecasting sounding) all show locations around
the boundary becoming the focus for areas of fog and perhaps
dense fog. Have added this mention into the near term forecast
update. Further south, radiation fog remains a concerns,
especially for river valleys, but there is uncertainty as to
how severe fog will get outside of valleys toward morning. Have
kept patchy fog from the previous forecast but this may need to
be adjusted through the overnight as light southeasterly winds
persist south of the front. The greatest threat for thickening
fog is likely across the north where recent rains have provided
a fresh source of low level moisture.
Otherwise, no major changes made to the forecast. Temperatures
drop into the low to mid 60s by morning with fog the biggest
hazard for the morning commute.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
High pressure at the surface and aloft is centered along the Mid
Atlantic Coast, with a nearly stationary boundary situated to the
northwest. The warm and humid airmass over the Ohio Valley is
exhibiting a lack of forcing and deep moisture, with FEW to SCT
cumulus forming in a shallow layer around 4000 ft, dissipating
at sunset. This weather regime should keep precip from
developing through tonight.
Under mainly clear skies and light winds, patchy fog may develop
later tonight in humid near surface conditions. We can expect above
normal overnight lows in the lower to middle 60s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Dry weather is forecast to linger through the short term.
Though high pressure to the east will weaken by Wednesday night
under a moistening southeast flow, it appears that dry air and a
lack of forcing will persist over the ILN area, resulting in no
precipitation. Abundant sunshine fortified by warm advection
will allow above normal temperatures to continue, with forecast
highs ranging from the lower 80s northwest, the upper 80s DAY
CMH and CVG, up to the lower 90s southeast.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Region will find itself on the south side of a stationary front at
the beginning of the period. The front will stretch from the eastern
Great Lakes back into the central plains. The front will remain near
stationary until the weekend. This will lead to dry conditions for
Thursday and Friday. Highs will range from the mid 70s in West
Central Ohio to the upper 80s in the lower Scioto Valley. Increasing
clouds on Friday will knock a few degrees off the highs for Friday.
On Saturday, a strong H5 s/w will swing out of the northern plains
into the western Great Lakes. Moisture that has pooled in the deep
south will be pulled north on Saturday and will begin to interact
with the upper level lift. Showers and thunderstorms are expected
Saturday through Saturday night as the s/w swings across the region.
A cold front is forecast to push through the region on Sunday,
shunting the rain chances off to the east. The highest PoPs are
forecast in the southeast quarter of the fa on Sunday.
High pressure will build for Monday, bringing highs in the 70s.
The high pressure moves quickly off to the east and by Tuesday the
region is already on the backside. Highs will be in the 75 to 80
degrees range.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
VFR will continue through this evening under high pressure at
the surface and aloft.
Went a little more aggressive with the potential for FOG at LUK
late tonight into Wednesday morning. Climatologically, light
southerly winds and current dewpoint depressions point toward a
favorable setup for valley fog in the area.
Additionally, trends in fog development near a stalled surface
boundary across northern Ohio will have to be monitored closely
as the southern extent of the fog may creep close to
DAY/CMH/LCK/ILN. For now, have kept mention of BR in 00Z TAF as
ground fog should gradually build till morning. At this time,
there is low confidence as to the ultimate severity of the fog.
OUTLOOK...No significant weather expected.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Coniglio
NEAR TERM...Coniglio/McGinnis
SHORT TERM...Coniglio
LONG TERM...Sites
AVIATION...Coniglio/McGinnis
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1123 PM EDT Tue Sep 8 2020
.UPDATE...
Issued at 1123 PM EDT TUE SEP 8 2020
Went ahead and updated the forecast to remove the evening wording
from the forecast. Temperatures remain on track, so no need to
update these. Fog is beginning to form a bit earlier than expected
and earlier than the past few nights, so did beef up the fog
wording a bit more for the rest of tonight in the valleys. This
also means having it start sooner as well. Changes have been saved
and sent.
UPDATE Issued at 740 PM EDT TUE SEP 8 2020
Forecast is in good shape this evening with the only change to
bump up dewpoints through the rest of the evening as they have
come up much faster. Otherwise, everything remains on track.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 354 PM EDT TUE SEP 8 2020
We see surface high pressure parked off to the east and this
combined with mid and upper level ridging will lead to mostly dry
and warm weather through the period. Tonight we will see a bit
more moisture return given the placement of the high and this will
lead to an increase in mainly river valley fog. Another night of
ridge/valley temperature splits are on order.
The question remains just how warm we will get on Wednesday, as
we have been cooler today than forecast and we see a similar setup
for tomorrow. Given this ran very close to what we had going, but
concerned it could still be a little lower if similar 850 mb
temperatures are the influence. Also, another factor for cooler
highs today could be some upper level smoke present based off of
the HRRR smoke product and a hazy look when looking in the sky
this afternoon. However this is not forecast to be a factor for
Wednesday based of the 12Z HRRR smoke product. There is some
indication in the CAMS for a few PoPs in the far southeast toward
the VA border by Wednesday afternoon, but the surface trough
would tend to lean further east with convection and the more
favorable downslope flow out of the east seems less conducive for
development as well. Given this have kept the forecast dry, but
do have a 10-14 PoP in the this area given the CAMs and increased
moisture. None the less expect at least a little more cumulus
throughout the region and even some high clouds sneaking in from
the east coast disturbance.
Wednesday night, we will see skies become mostly clear, as
cumulus relents through the early evening. Another night of mainly
river valley fog seems reasonable, as we continue to see moisture
on the increase. Outside of this we will continue to see some
ridge/valley temperature splits going into early Thursday morning.
.LONG TERM...(Thursday through Tuesday)
Issued at 447 PM EDT TUE SEP 8 2020
Eastern Kentucky will continue to bask in a warm early fall
weather pattern Thursday and Friday as temps reach well into the
80s each day under partly to mostly sunny skies. There is a small
chance for shower or storms each afternoon over far southeast
Kentucky, but even there many places should remain dry. A warm
front brings better chances for a few showers and storms on
Saturday. Additional shower chances continue Sunday into Monday as
a a couple of cold fronts affect the region.
Model agreement is generally good through the long-term period.
The latest model suite analysis for 12z Thursday continues to
show an anomalous ~ 598 dam high SE of Nova Scotia with broad
ridging extending SW across most of the eastern CONUS south of
the Great Lakes. A col develops in this ridging over eastern
Kentucky and central Appalachians on Thursday and persists into
early Friday as a weak cool front bleeds southward across the
area, eventually stalling near/south of the TN Valley. The upper
level col disappears on Friday as surface high pressure nudges in
from the north. Meanwhile, the upper level ridging gradually
erodes through the day as a broad upper level trough deepens over
central Canada and captures a filling cutoff low over the Great
Plains. Some shortwave energy, rotating around this low, lifts
over the Mid- Mississippi Valley late Friday, initiating a low
pressure wave along the stalled front near the TN valley. That
surface wave accelerates toward the Great Lakes on Saturday
lifting a warm front across east Kentucky. A trailing cold front
follows Saturday night/Sunday morning. During the day Sunday, a
broad shortwave trough - the last vestige of the cutoff low -
passes over the Great Lakes dropping another cold front toward
the Ohio Valley. The fronts progress south of the Ohio River is
in question as the best upper level forcing is sheared away
toward Canadian Maritimes.
The sensible weather will feature continued warm temperatures and
mostly sunny skies on Thursday. There will be a threat for
isolated to widely scattered showers and storms across southeast
KY during the afternoon/evening hours ahead of/along the weak
cold front. Thursdays highs are forecast to remain on the warm
side of normal - in the mid 80s for most but pushing upper 80s
near the TN border. Northeasterly winds usher in a slightly cooler
air mass behind the front for Friday knocking down highs into the
low 80s over northeast KY to the mid 80s further south. A subtle
surface trough could again trigger a few afternoon/evening
showers and storms closer to the Virginia border. Temperatures and
humidity levels rebound slightly on Saturday as the warm front
lifts through the area with some scattered showers and storms.
The rain chances continue for Sunday into Monday as a couple of
cold fronts pass through the region. High temperatures are
forecast to reach the mid 80s on Saturday cooling off into the
upper 70s to low 80s by Monday. Night lows are expected to range
through the 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 740 PM EDT TUE SEP 8 2020
Mainly VFR conditions will be seen through the period, outside of
a period of river valley fog late tonight. Light winds will be
seen through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...DJ
LONG TERM...GEERTSON
AVIATION...KAS
Area Forecast Discussion
National Weather Service North Platte NE
625 PM CDT Tue Sep 8 2020
.SHORT TERM...(This evening through Wednesday night)
Issued at 327 PM CDT Tue Sep 8 2020
Another round of rain and snow is likely tonight. The trigger or
forcing is currently moving east through wrn Colorado and should
lift through wrn and ncntl Nebraska late tonight. The strength of
the forcing across wrn Nebraska could be sufficient for a period of
accumulating snow across the wrn Sandhills at elevations near of
above 4000 ft. The RAP model is keying on regeneration of strong
midlevel frontogensis and periods of strong lift in the DGZ across
wrn Nebraska. If the model is correct than periods of rain mixed
with snow at times should develop along and west of highway 83
tonight.
The upper level energy energy across srn Colorado this afternoon is
producing thunder and satellite indicates a robust deformation zone
underway. The HRRR echo tops product suggests 25kft tops across swrn
and ncntl Nebraska tonight and the NAM shows a few hundred J/KG of
elevated CAPE in this area also. The forecast tonight will carry an
isolated thunderstorm chance.
The forcing should exit wrn and ncntl Nebraska late Wednesday
morning with a chance of showers in the afternoon. Periods of light
rain are possible Wednesday night associated with weak forcing and
continued moist, warm air advection operating on aloft on the front
side of a stalled upper level low across the Four-Corners region of
the wrn U.S..
The temperature forecast leans on the warmer deterministic based
short term model blend for lows in the 30s tonight and Wednesday
night and highs in the 40s Wednesday. This is probably the best
strategy given the expected overcast skies tonight through Wednesday
night dictated by all models. The cloud cover will negate any sort
of radiational cooling. Sensible heating from the relatively warm
ground should be the dominate force to hold overnight temperatures
above freezing.
.LONG TERM...(Thursday through Tuesday)
Issued at 327 PM CDT Tue Sep 8 2020
Dry weather is possible Thursday as the models indicate no
substantial forcing for rain. However, the southerly 850mb-500mb
flow is moist. This moisture will be running over a sfc high
pressure ridge and the models suggest overcast skies.
The last rain chances for this storm system appear to be Thursday
night into Friday morning and Friday night as the upper low lifts
through the central and northern Plains. Most of this rain will
affect north central and areas to the east. Thunderstorms are in
place Friday night as lapse rates will steepen in response to warm
air advection. Mild, near normal temperatures and dry weather return
Saturday through Tuesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 625 PM CDT Tue Sep 8 2020
Low ceilings and gusty winds will continue through the evening
regionwide, then conditions slowly begin to improve across
northwest Nebraska overnight (including KVTN). Meanwhile,
precipitation becomes more steady with perhaps a rumble of
thunder across the southwest (including KLBF). A brief transition
to rain-snow mix is possible around sunrise. Expect generally MVFR
through the forecast period.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Snively
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
953 PM CDT Tue Sep 8 2020
.UPDATE...
Issued at 934 PM CDT Tue Sep 8 2020
Scattered to widespread thunderstorms continue to develop along
the front in mid-Missouri with a few storms showing signatures
indicating they may be producing small hail. These storms are
largely being forced by low level convergence along the front and
are tapping into a pool of up to 1000 J/kg of elevated
instability. As we head later into the early morning hours, this
low-level convergence and instability is expected to gradually
tail off, decreasing precip chances across much of the area. That
said, lower end precip chances will persist across NE MO and
west-central IL where deeper forcing can be found along elevated
portions of the front.
Hazards associated with current storms appear to be fairly low-
end threats for damaging winds, hail, and flooding. The severe
threat continues to fall by the hour with diminishing instability,
and since these storms are largely elevated, they will have a
difficult time mixing strong winds to the surface. As for
flooding, several areas have seen multiple rounds heavy rain this
afternoon and evening. Fortunately this rain has been spread
across several hours, and rain rates limited to about an inch an
hour have kept things from getting out of control.
BSH
&&
.SHORT TERM... (Through Late Wednesday Afternoon)
Issued at 309 PM CDT Tue Sep 8 2020
Primary concern for the rest of this afternoon into the evening is
convective trends. Scattered storms have already formed and will be
ongoing for the remainder of the afternoon into the evening. A few
of the storms will likely be strong to severe as a decent amount of
MLCAPE has built up this afternoon. Latest SPC mesoanalysis shows
2500+ J/Kg MLCAPE just south of the cold front, just north of I-44
in Missouri and I-70 in Illinois, though effective shear is pretty
weak. Respectable DCAPE values in excess of 1000 J/Kg in this
environment is supportive of pulse severe storms with microbursts.
The RAP shows the instability weakening considerably after sunset
(though MUCAPE remains stout enough for thunder through the night.
Convection allowing models suggest the thunderstorm coverage should
decrease significantly through late evening and will be generally
confined to northern portions of the area by early Wednesday morning.
The cold front will continue to drift south, though deterministic
guidance keeps the coolest air bottled up across northern Missouri
and west central Illinois. This will translate into a warm and
humid day again across east central and southeast Missouri into
southwest Illinois. There may be some lingering convection on
Wednesday morning north of the front in northeast Missouri and west
central Illinois...though the low level forcing is weak, and the
primary area of moisture convergence is well north of the forecast
area over central Iowa.
Carney
.LONG TERM... (Wednesday Night through Next Tuesday)
Issued at 309 PM CDT Tue Sep 8 2020
Guidance is in general agreement that the mid Mississippi Valley
will see somewhat cooler and drier weather for Thursday and Friday,
although the details are a bit sketchy. The GFS is more aggressive
in driving the cold front south into the lower Mississippi Valley
than other models, and it looks like it`s trying to keep more low
clouds around than the EC or NAM. This translates into 2m
temperatures that only get to the mid 60s to low 70s on the GFS
while the NAM and EC get back into the low 80s along and south of I-
70...keeping the cooler temperatures in the mid 60s and 70s bottled
up in northern Missouri and west central Illinois. Ensemble
guidance is leaning more toward the warmer solutions which does lend
confidence to the EC/NAM for Thursday into Friday.
the large cut off low over the Four Corners Region begins lifting
and filling in on Friday, and by 00Z Saturday the GFS and ECMWF have
it moving east across the Great Plains as a (mostly) open wave. The
resulting surface low drags another cold front into the Mid
Mississippi Valley Saturday afternoon. Southerly flow ahead of the
front will should be enough to get most of, if not the entire area
into the 80s again, with some scattered convection most likely in
the afternoon and evening.
The airmass behind the front doesn`t look particularly cold at this
juncture, however deterministic guidance does show a large and
persistent high pressure system building into the Midwest and Great
Lakes behind the front Sunday and Monday. The high produces cool
and dry northerly flow both days which keep highs in the mid and
upper 70s with little chance of precip. Tuesday may be a little
warmer as the high drifts east and the flow turns back around to the
east/southeast.
Carney
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 621 PM CDT Tue Sep 8 2020
Initial concern is with the ongoing convection across the area. The
best chance for thunder has pushed southeast of UIN and COU. Further
southeast, storms have really filled in just to the west of the
metro terminals. I anticipate storms to gradually diminish
over the next few hours, but SUS and STL are so close to these
heavier storms that it`s likely they will see a heavier storms
pass overhead. Therefore I`ve gone ahead and included a tempo
group with TSRA at those terminals. Confidence is lower that these
storms will reach CPS, so have stuck with VCTS for the time being.
As the best shower and storms chances retreat to the northeast,
confidence is high that MVFR and eventually IFR cigs will slide
further SE, reaching the metro terminals later this evening.
Ceilings will gradually lift and scatter out after sunrise
tomorrow morning, though some uncertainty remains with regards as
to just how long the reduced cigs will hang on.
BSH
&&
.PRELIMINARY POINT TEMPS/POPS...
Saint Louis 66 86 65 80 / 70 10 5 5
Quincy 55 71 58 73 / 50 20 10 20
Columbia 58 79 60 75 / 70 10 10 20
Jefferson City 61 80 62 78 / 90 10 10 20
Salem 64 88 64 83 / 20 10 0 5
Farmington 63 85 64 83 / 20 10 0 5
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Midland/Odessa TX
631 PM CDT Tue Sep 8 2020
.DISCUSSION...
&&
.AVIATION...
Cold front currently moving through the area... as of 2325z front
at INK and north of MAF moving south at about 14kts. North wind
with gusts to 35kts with fropa... bldu as low as 1sm. Have
thunderstorms over SE NM and Upper Trans Pecos moving east with
additional showers and storms developing behind the front across
Northern Permian Basin. Have storms mentioned in all TAFs and
expect will transition to light rain overnight with development of
IFR cigs.
&&
.PREV DISCUSSION... /issued 450 PM CDT Tue Sep 8 2020/
UPDATE...
Updated NPW for high wind and issuing new ZFP.
DISCUSSION...
Have already received an observation from GDP with gusts to 60
mph, have updated NPW to begin High Wind Warning for GDP and Wind
Advisory for Culberson County now. Expect high wind there to
continue on and off through Wednesday night.
PREV DISCUSSION... /issued 245 PM CDT Tue Sep 8 2020/
DISCUSSION...
WV imagery shows the upper trough now over eastern UT. Models dig
this to the UT/AZ border by 00Z Thu, before ejecting the trough to
the upper MS Valley by 18Z Sat. At the sfc, the cold front is just
NW of KLUB as per area radars, and appears to be slowing as diurnal
heating takes place. Hourly analysis throughout the morning has the
HRRR and Nam Nest performing best on the placement/timing of the
front, as would be expected over the lwr res models. That said,
fropa at KMAF looks to be 02-03Z this evening, although that timing
gets defenestrated if convection comes into the mix. Speaking of,
the latest HRRR develops convection along a weak dryline up against
the higher terrain 19-20Z, w/development along the front 20-21Z,
putting everything east of the Pecos, as well as the Stockton
Plateau/lwr Trans Pecos, in a warm sector w/dewpoints mostly in the
60s. Forecast NAM soundings to the north of KMAF at 21Z show
mlcapes in excess of 3000J/kg w/no cap. Models are in good
agreement w/steep mid-lvl lapse rates of 7+C/km from KMAF west ahead
of the front, as well as dcapes over 1000 J/kg. Convection
along/behind the front should quickly become elevated, and a few
severe storms this afternoon/evening are not out of the question.
Supplementing this will be a 40kt LLJ set to develop over the lwr
Trans Pecos ahead of the front, as well as the right entrance region
of the upper jet. One other possibility tonight that`s been absent
from these parts for quite awhile will be heavy rainfall. PWATs are
running about 2 std devs above normal, and K indices ahead of the
front in excess of 35 suggest a potential for heavy rainfall, which
is also noted in fairly impressive model QPFs.
Temps w/this front continue to frustrate, mainly because the GFS
decided to go off on its own, which has messed up the blends quite a
bit. Looking at post-frontal temps up north, the GFS can be
discounted for now, and the NAM is the favored model for this event.
That said, many targets of opportunity have arisen over the next
couple of days, and we`ll undercut NBM numbers quite a bit. This
should result in record-breaking cold highs Wed afternoon.
Temps should stay cool through until at least Friday, when skies
begin clearing and sfc flow veers around to the SE. Long range
models still develop a weak upper trough between ridges over Texas,
which will keep a chances of convection in play each day, and temps
below normal for once.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 52 56 50 60 / 80 80 70 70
Carlsbad 44 57 45 66 / 70 30 20 20
Dryden 60 69 56 67 / 60 70 70 70
Fort Stockton 53 61 49 62 / 80 50 50 50
Guadalupe Pass 44 58 43 65 / 70 30 20 20
Hobbs 44 53 44 62 / 90 50 40 30
Marfa 46 65 43 66 / 70 40 40 40
Midland Intl Airport 52 57 49 61 / 80 60 60 60
Odessa 52 58 48 62 / 80 60 50 50
Wink 51 61 49 64 / 80 50 40 30
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...Wind Advisory until 8 AM CDT Thursday for Eastern Culberson
County-Van Horn and Highway 54 Corridor.
High Wind Warning until 7 AM MDT Thursday for Guadalupe and
Delaware Mountains.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
833 PM EDT Tue Sep 8 2020
.SHORT TERM...(This evening through Wednesday)
Issued at 338 PM EDT TUE SEP 8 2020
Water vapor imagery and RAP analysis show a positively tilted mid-
upper level trough extending from Quebec to the Great Basin. At the
sfc, cold front that passed across Upper MI Sun night is now setup
from the Lower Great Lakes to the Southern Plains. Large sfc high
pres is centered over MT with one ridge extending e to the northern
Great Lakes and a second one nne to nw Manitoba. Closer to home,
clouds and rain have spread into Upper Mi this afternoon from
convection which initiated earlier this morning over WI and southern
MN. Strengthening fgen along the mid-level front in response to
upper divergence in the right entrance region of 120+ kt upper jet
extending from the eastern Dakotas into Quebec will continue to
support rain showers over the southeast half of Upper Mi into this
evening.
Tonight, Expect pcpn band to diminish and shift farther s and e this
evening and overnight, however, there is some question as to how
much the mid and high clouds will thin out across the nw fcst area
late tonight as satellite imagery still shows considerable mid-high
clouds upstream over MN and SD. If this cloud cover stays intact and
doesn`t thin out much later tonight, that should prohibit formation
of widespread frost. For now, will maintain mention of patchy frost
in the grids over the western interior with a few lows getting down
in the 33-35F range and will brief the evening shift to monitor
upstream cloud trends in case adjustment in temp fcst may be needed.
Min temps over the east half will generally be in the lower to mid
40s. Given uncertainty, will end up issuing a SPS for some patchy
frost west tonight and then a better chance for widespread frost Wed
night.
Wednesday, the mid-level front, rather than the surface front, will
be the focus for weather over our area. Models indicate another fgen
band developing with fgen maximized around 700 mb. This band will
lift northeastward across the central and eastern UP resulting in a
band of steady rain developing by late morning and persisting
through the evening. Still looks like there will be a sharp cutoff
to the northwest of this band. Many of the 12Z models trending
slightly se with axis of better pcpn and higher (categorical to
likely) PoP grids. In updated PoP grids, will keep the Keweenaw
virtually dry and only have chance POPs west of a line from roughly
Marquette to Watersmeet. Expect a quarter inch or more of QPF across
south central where axis of heavier pcpn with the fgen band is
expected. With 850 mb temps still progged to be around or just below
0 C and thick cloud cover and pcpn expected, still expecting near-
record cold highs across the area Wednesday in the low 50s. Under
more persistent rain temps will likely struggle to even get out of
the 40s.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 335 PM EDT TUE SEP 8 2020
Little change to the longterm forecast from the past few days as the
cooler pattern continues as a blocked pattern maintains its grip
across much of the CONUS. Temperatures look to remain anywhere from
5 to 10 degrees blo normal, perhaps reaching back up towards normal
Monday into Tuesday next week...but both deterministic and ensemble
GEM, GFS, and EC modeled 500mb height tendencies at the start of
next week suggest that "warm-up" won`t last too long.
Heights are rising as high pressure is moving into the region on
Wednesday night. The high pressure will create the combination of
calmer winds and clearing skies across the area through the night,
leading to the chance for widespread frost development, a SPS has
been issued to cover that. Taking the fcst verbatim at this point, a
freeze watch/warning would be warranted for portions of the interior
west, with lows falling into the mid to upper 20s, but have opted
for the SPS with the frost potential tonight to keep things simple.
There is some chance that clouds hang on a little bit, and the
eastward extent of the clearing is still up for debate yet. The
other question is how much rain falls during the day Wednesday and
does that lead to fog development, and with that, freezing fog?
Adjusted MOS guidance seems to bite a little bit more on this
chance, as well as steep inversions in model soundings(see NAM). For
now, will stick with widespread frost wording and not dive into the
fog/freezing fog potential. By mid-morning Thursday, high pressure
will be into the area with dry weather expected through Friday.
Highs near 60 on Thursday and mid 60s on Friday, with some patchy
frost Thursday night.
The next chance for precipitation is with the advertised cutoff low
currently over the intermountain west. Models have the shrtwv moving
through the Great Lakes region Saturday evening, bringing widespread
rain across the UP. Behind this wave, an associated cold front
passes over the UP, bringing a cooldown with breezy conditions on
Sunday.
Heights rise as a ridge moves into the central CONUS on Monday,
bringing a warmup to start the week. Look for highs to be near
normal Monday and maybe a touch abv normal Tuesday, in the low
70s...yes this is now abv normal! Models show some discrepancies in
the deterministic, but ensembles suggest another cooldown in the
latter part of next week, but nothing looks too cold at this point.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 832 PM EDT TUE SEP 8 2020
VFR conditions are expected through the forecast period at KIWD and
KCMX. Upslope northeast flow with added Lake Superior moisture will
support a period of MVFR cigs this evening and likely again by later
Wednesday afternoon as rain chances increase. Even with some
improvement expected overnight, cigs should remain at or
near MVFR.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 338 PM EDT TUE SEP 8 2020
A quieter period of weather is shaping up for Lake Superior for the
next several days as a high pres ridge shifts se, reaching Lake
Superior Wed aftn and then lingering across the Great Lakes region
Thu/Fri. Winds should be mostly under 20kt. There may be a period of
somewhat stronger winds across western Lake Superior on Thu as sw
winds increase on the nw edge of the high pres ridge over the Great
Lakes. Otherwise, the next potential of stronger winds will occur on
Sat as a low pres trough approaches and crosses Lake Superior. There
may be some 20-30kt southerly winds ahead of the trough, mainly
across eastern Lake Superior, and then possibly 20-30kt nw winds in
its wake late Sat night into Sun.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...JAW
AVIATION...JLB
MARINE...Voss
Area Forecast Discussion
National Weather Service Tucson AZ
219 PM MST Tue Sep 8 2020
.SYNOPSIS...A strong storm system over Utah will bring gusty winds,
much cooler temperatures and scattered showers and thunderstorms into
Wednesday. Temperatures will slowly warm to near normal by the
weekend with a slight chance of afternoon thunderstorms near the New
Mexico border.
&&
.DISCUSSION...As of 2 pm the cold front has moved just south of
Prescott and continues to plow southward. A line of convection has
developed right along the front with one severe thunderstorm warning
thus far. Other than that convection has been very limited and the
wind has been a bit tamer than forecast. Both likely the result of
the heavy smoke laying across the region impacting the heating and
resultant mixing. Latest HRRR runs indicating that convection still a
decent bet as far SW as Tucson when the front rolls through this
evening so have left pops in the forecast for the overnight period
with a little adjustment. Weak mid-level cold advection is currently
taking place and that will translate to stronger mid and low level
cold advection this evening behind the frontal passage. The result
will be cooler overnight temps and highs on Wednesday around 8-10
degrees cooler than this afternoon. With the upper low parking itself
over Arizona/Utah border through Wednesday night there remains a
threat of showers and afternoon/early evening thunderstorms east of
Tucson through Wednesday night.
At this time the upper low looks to slowly fill and move Thursday
into Friday. Left a slight chance of showers and storms for the far
eastern areas Thursday as enough moisture and instability should
remain, especially if the low is a bit slower, to allow for that.
Afternoon temperatures only a couple of degrees warmer Thursday and
remaining about 5 degrees cooler than average.
Friday through the weekend ridging will follow the departure of the
upper low with a rebound in temperatures as a result. The ridge not
looking quite as pronounced as earlier with a low level easterly flow
undercutting the ridge. This easterly flow may bring enough moisture
for a few showers and mountain storms far eastern areas each
afternoon through the weekend. Temperatures running within a couple
of degrees of normal Friday into early next week.
&&
.AVIATION...Valid through 10/00Z.
SCT-BKN 10-15k ft MSL. A slight chance of -TSRA/-SHRA KTUS eastward
into Wednesday. SFC wind SWLY/WLY 15-25 kts with gusts up to 35 kts
easing to 10-15 kts after 09/05Z. SW winds increasing again after
09/17Z to 10-20 kts through the afternoon. Aviation discussion not
updated for TAF amendments.
&&
.FIRE WEATHER...An unseasonably deep storm system over southern Utah
will maintain breezy conditions this evening and again Wednesday
afternoon with a chance of some showers and a few thunderstorms from
Tucson eastward. Much cooler temperatures will also move in resulting
in below normal highs Wednesday and Thursday. A slight chance of
residual showers and thunderstorms are possible for eastern areas
Thursday but otherwise, mostly dry and gradually warming temperatures
are expected Thursday into Friday with generally light winds. This
weekend, will be warm with a slight chance of showers and
thunderstorms east of Tucson each afternoon through Monday. Winds
will be light Saturday with an easterly breeze developing Sunday into
Monday.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Public...Cerniglia
Aviation...Rasmussen
Fire Weather....Rasmussen
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