Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/10/24
See below for an aviation forecast discussion for the 00Z TAFs.
&&
.SHORT TERM /THIS EVENING THROUGH TUESDAY NIGHT/...
Issued at 352 PM CDT Mon Sep 9 2024
During this period we will continue to deal with added wildfire
smoke impacts and the continuation of above normal temperatures and
mainly dry conditions. This afternoon, our forecast area remain
underneath mostly sunny skies and temperatures in the 80s to low
90s. Again, we haven`t seen quite the warm up we anticipated, but
there`s still a good 1-3 more hours of peak heating. Vsbl satl
imagery does show a good batch of wildfire smoke movg into the
western and central portions of the Dakotas this afternoon. Based on
obs and model guidance, this area of smoke remains aloft. However, a
much thicker area of smoke, some of which is near sfc remains
poised back to the west across MT and parts of WY. Sfc obs in those
areas indicate low visibilities due to the smoke. And, that is what
will be on our door step so to speak for the day tomorrow.
Upper ridging remains more or less in control of the pattern here
locally with some embedded weak shortwaves across parts of the
Dakotas and Northern High Plains. This upper troughing extends down
to the sfc across the western Dakotas and this feature could deliver
a stray shower or thunderstorm to portions of our western forecast
area later this evening into the early overnight. However, there are
a couple of limiting factors that will likely curtail any activity.
Weak forcing at best will be present as the aforementioned waves
trek east. BUFKIT soundings continue to show very dry air will
remain in place tonight across our western CWA below a 10-15kft
height. But, HREF ensembles and a couple of CAM solutions do paint
in a few spotty areas of precip across central portions of SD and
guidance does continue to indicate some increase in moisture levels
at 500mb. Considering all this, decided to retain inherited low
end(15%) PoPs later this evening into the early overnight. However,
would only anticipate isolated coverage at best with very little
noteworthy precip expected in most areas.
Heading into the overnight hours and Tuesday morning, a low level
jet sets up across our southeast zones, basically across east
central and southeast SD. This will promote some enhanced wind gust
possibilities across portions of the Prairie Coteau through the
early morning hours. We will continue to see an influx of a mild air
mass into the region, so overnight lows will only fall into the
upper 50s to low 60s. The sfc trough will track eastward and through
our eastern zones by the latter half of the day. Sfc winds will turn
west to northwest in the wake of its passage but remain relatively
light. Perhaps the larger and more noticeable impact on weather
conditions Tuesday will be the continued influx of wildfire smoke.
Latest runs from the HRRR vertically integrated smoke product and
near sfc smoke product show a high concentration of smoke across our
forecast area. The near sfc smoke product does indicate the western
half of our forecast area will begin to deal with this by mid to
late morning with the potential for reduced visibilities through the
day. I feel there will be some impact to high temperatures tomorrow,
but confidence remains low enough to not lower readings too much.
Did bump them down to some extent, but sort of waiting to see how
values shake out today with the influence of some smoke already
entering the picture.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 352 PM CDT Mon Sep 9 2024
Overall pattern remains intact through the middle of the week, with
dry air being the dominant feature of the profile. PWAT values
around 0.8 inches will persist and limit chances for rain until the
next disturbance brings potential impacts to the region on Friday.
Abnormally warm 850mb temperatures continue to be a theme the rest
of this week, and ensemble guidance consistently gives values upward
of 20 degrees Celsius, greater than the 90th percentile for this
time of the year.
There is some concern for high winds on Thursday, with a second
round on Friday possible. Deterministic guidance for Thursday
resolves strong southerly flow around 20 knots, but the NBM
deterministic bumps sustained winds up to 30 knots in places.
Ensemble guidance reflects this trend as well, with the probability
of sustained winds exceeding 30mph from the GEFS/GEPS/Euro topping
out around 20%, whereas the NBM resolves probabilities reach greater
than 70%, mainly in the western part of the CWA. Inclined to believe
in the NBM solution at the moment based off model soundings and the
depth of the mixing layer. Gusts to 40 knots or greater may be
produced with this setup. Friday sees a similar wind setup, albeit
with the NBM dropping chances for 30+ mph winds down below 50%
throughout the day.
A longwave trough moves into the Pacific Northwest on Thursday,
where a strong jet streak aloft looks to form over the western
CONUS. This trough looks to move over the ABR CWA this weekend, but
models have consistently shown a weakening of the jet streak as is
progresses northeastward. This is also a lot of uncertainty
remaining in the timing of this system, and recent model runs have
trended towards a slower progression. A band of 60 knot or greater
shear has been consistently forecasted to materialize, but there is
again much uncertainty on where that will set up. Instability is the
main limiting factor for storm development. CAPE is virtually non-
existent, and joint probability of CAPE greater than 500 J/kg and
shear greater than 30 knots is around 20% at best. The best chances
for showers and storms comes in the form of a cold front.
Frontogenesis is much stronger in Canada and North Dakota as the low
pressure system wraps up, and it is not clear how far south the
frontal boundary will extend. Should an extension southward happen,
it does not look to be very strong at the moment. Rainfall amounts
look less than impressive, with NBM PoPs range from 20-40% and
GEPS/Euro Model blends showing less than a 50% chance of rainfall
greater than 0.01 inches. The GEFS is the main outlier, maxing out
at about a 70% chances for measurable rainfall.
Behind the system and frontal passage, winds calm down and slightly
cooler, moister air is set to come in. Temperatures will likely
remain above normal still, and chances for rainfall through the rest
of the forecast period remain low.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 615 PM CDT Mon Sep 9 2024
Terminals KABR,KATY,KPIR,KMBG
VFR conditions are forecast through this forecast period, except
on Tuesday, if near surface wildfire smoke concentrations are
enough to reduce surface visibility at the KPIR/KMBG and possibly
the KABR terminals. Also, there could be an isolated shower or
thunderstorm (very high-based) at/near the KMBG or KPIR terminals
by 06Z tonight.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Dorn
SHORT TERM...Vipond
LONG TERM...BC
AVIATION...Dorn
Area Forecast Discussion
National Weather Service Denver/Boulder CO
840 PM MDT Mon Sep 9 2024
.KEY MESSAGES...
- Warm again Tuesday with isolated showers and storms mainly over
the mountains and Palmer Divide.
- Best chance (20-50%) for showers and thunderstorms will be
Wednesday afternoon and evening.
- Fire weather concerns increasing for Thursday with stronger
southerly winds, near record temperatures, and a drier airmass.
- Mainly dry and calmer weather Friday through the weekend, but an
isolated storm still possible.
&&
.UPDATE...
Issued at 826 PM MDT Mon Sep 9 2024
Current radar shows some weak storms in Larimer and Weld Counties
at this time. Have increased PoPs in these locations to account
for this. Stabilization appears to have helped subside the pesky
virga showers that initiated microbursts across our TAF sites a
little while ago. However, current observations in Logan County
indicate gusty winds up to 40 mph remain associated with lingering
showers across the county. Current forecast is on track. Only
addition made was adding some areas of smoke for the northern
portion of the CWA for the morning hours using guidance from the
HRRR Vertically Integrated Smoke.
&&
.SHORT TERM /Through Tuesday/...
Issued at 252 PM MDT Mon Sep 9 2024
Scattered showers and isolated thunderstorms will continue into
the early hours across the area. Some of the showers will linger
into the late evening hours and possibly after midnight over the
northeast plains. Due to a dry sub-cloud airmass, gusty winds to
50 mph will remain possible into the evening. Skies clear some
overnight, but expect more clouds than we`ve seen recently at
night. This will help to keep overnight lows a little warmer.
For Tuesday, upper level ridging will continue to bring warm
temperatures to the region. Many places across northeast Colorado
should top 90F degrees again. Airmass dries a little, leading to a
decrease in showers and thunderstorm activity. However, still
expect isolated/scattered showers and thunderstorms over the
higher terrain and across the nearby plains. Wind gusts to 50 mph
will be possible under the stronger showers and thunderstorms.
&&
.LONG TERM /Tuesday night through Monday/...
Issued at 252 PM MDT Mon Sep 9 2024
We`ll keep a few showers and storms in the forecast into the
evening hours Tuesday, mainly in/near the higher terrain and
Palmer Divide. Then, the airmass stabilizes late in the evening
with clearing skies expected overnight with near normal low
temperatures.
Wednesday is still shaping up to be the most active convective
weather day. Moisture is forecast to increase slightly, but weak
QG lift is also noted. Thus, convective coverage is expected to
have an uptick into the scattered category for most areas. Low
level moisture is still depleted, however, so look for mostly
gusty winds and light rainfall from the passing showers and storms
that last from afternoon into the evening.
Thursday will see drier air at all levels, despite the
continuation of weak QG lift. The dry air advection occurs as
stronger south/southwest flow aloft develops in advance of the
ejecting Pacific Northwest/Northern Rockies upper low, essentially
drawing up dry desert air. The main concern will be increasing
fire danger due to gusty winds and near record warmth. High
temperatures will likely soar into the lower to mid 90s across the
plains and I-25 Corridor (Denver`s record is 94F and we should be
very close to that). We`ll address the fire weather concerns in
the Fire Weather section below.
For Friday, the upper level trough to our north shears out,
leaving us in westerly flow aloft. There is still enough pressure
gradient for breezy weather in the mountains, but generally lighter
winds should prevail on the plains in the wake of a backdoor cold
front. That will also bring temperatures down a few degrees, but
still above normal for this time of year. A late day storm is
possible on the far eastern plains where the cap is weaker,
although a farther southward push of the front would effectively
cap things off. We`ll continue some low PoPs over the northeast
plains to account for that.
For Saturday through Monday, we`ll be in lighter and fairly dry
southwest flow aloft. We`ll see a continuation of above normal
temperatures and mainly dry weather. The next changes could start
to enter the picture by Tuesday or more likely Wednesday of next
week, so at least some hopes of seeing more fall-like weather by
then.
&&
.AVIATION /00Z TAFS through 00Z Wednesday/...
Issued at 750 PM MDT Mon Sep 9 2024
Passing virga showers have initiated microbursts at APA and DEN.
Have extended the TEMPO until 3Z to account for this. The past few
radar scans have indicated the environment is beginning to
stabilize, as such, expecting these to diminish as the
stabilization takes hold. There is a low chance these could
continue as more showers make their way off the higher
terrain in the next few hours, but confidence is much higher in
the stability diminishing this threat. Once this takes place,
expecting SSW drainage winds to develop through the overnight
hours.
Tomorrow is expected to see similar conditions to today, with
high-based showers and thunderstorms capable of producing gusty
outflow developing in the afternoon.
&&
.FIRE WEATHER...
Issued at 252 PM MDT Mon Sep 9 2024
Critical fire weather conditions are becoming more likely by
Thursday as stronger south/southwest flow develops. The airmass
will be quite dry, with humidity levels dropping to 10-15% from
Denver metro eastward across a good chunk of the plains. Near
record high temperatures can be expected, and winds will likely
gust into the 30-35 mph over most of the plains east of I-25.
We`ll also have at least elevated if not critical fire weather
conditions in the mountains and foothills with humidity readings
of 15-20%, and similar gusty winds.
It will still be dry and breezy Friday, but less wind than
Thursday. If the front gets delayed, then we could see at least
elevated if not critical conditions develop again.
Lighter winds are expected for the weekend, but temperatures will
remain above normal with low humidity readings.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Bonner
SHORT TERM...Meier
LONG TERM...Barjenbruch
AVIATION...Bonner
FIRE WEATHER...Barjenbruch
New to this forecast discussion is now all of the coastal Kenedy,
Willacy, and Cameron Counties are in a Tropical Storm Watch as the
track for Francine has shifted towards the west.
At the time of writing, Tropical Storm Francine is moving north-
northwest at 5 MPH. Maximum sustained winds are at 60 MPH and a
minimum central pressure of 996 mb. The current location of Francine
is 23.7 N 95.8 W in the southwestern Gulf of Mexico. The current
track forecast does keep the center of Francine off the coast and
most of the stronger winds will be offshore. However, any sort of
shifts in the track could bring more hazards or lessen them, so it is
important to keep up to date on the latest advisories.
As Tropical Storm Francine approaches, the outer bands are expected
to bring moderate to heavy rainfall at times. These rainbands may
have strong winds with wind gusts up to tropical storm strength
possible. Thus, the primary concern with this system is the
potential for flooding. While the current expectations for rainfall
amounts are between 3 to 6 inches, however it is possible that some
areas may receive locally heavier amounts. This would be a likely
scenario should multiple bands go over the same area in a short
amount of time. Considering the elevated PWATs already in the
environment and the tropical moisture that will move into the region
with the system, the environment will be favorable for the heavy
showers to move in. WPC does have most of the coastal regions in a
Marginal Risk to Slight Risk of Excessive rainfall through the
period. The highest QPF values are located in the Lower Rio Grande
Valley.
Another ongoing issue will be the coastal and marine hazards as the
enhanced pressure gradient will drive winds and waves up the along
the coast thus the need for the multiple coastal and marine hazards
mentioned above. Making any sort of beach activity dangerous.
The wind threats are highly subjective and very dependent upon the
actual track of Francine. However as mentioned before, the outer
rainbands could produce some strong gusty winds reaching up to
tropical storm force winds possible. Outside of that, winds are
expected to be breezy out of the north for the duration of the short
term forecast period.
Finally, for the temperatures, highs are expected to be cooler than
normal thanks to all the cloud coverage over the region keeping the
temperatures in the 70s. Low temperatures are also expected to be in
the 70s as well.
&&
.LONG TERM...
(Wednesday through next Monday)
Issued at 407 PM CDT Mon Sep 9 2024
Key Messages:
* Unsettled weather pattern looks to continue with day-to-day
chances for showers and storms
* Temperatures will attempt to trend warmer
* Hazardous marine conditions to start will become more favorable
late week into next weekend
While a large portion of the long term forecast period will feature
unsettled weather, Thursday and Friday currently have much lower
chances in terms of rain as the subsidence from behind Francine
works to hinder the development of showers and thunderstorms.
However, for the rest of the period, showers and thunderstorms are
likely to occur along the sea breeze during the afternoon periods.
As for the temperatures, the high temperatures are expected to
increase back up to the 90s, while the low temperatures will remain
mostly in the 70s, but a few places could get into the low 80s. With
the higher temperatures, heat indices are also expected to increase
as well and Special Weather Statements for elevated heat indices are
possible for the later part of the long term forecast period.
&&
.AVIATION...
(00Z TAFS)
Issued at 615 PM CDT Mon Sep 9 2024
While mostly expecting MVFR conditions for the large majority of
the TAF cycle at all TAF sites, there will be periods where IFR
conditions will occur due to the rainbands associated with
Tropical Storm Francine. These rainbands are likely to bring heavy
downpours that will reduce visibilities and bring lower ceilings
to the area as well. Tried to use the HRRR to base the timing for
the convective elements. Northerly winds are expected to persist
through the period as well. The rainbands could bring some
elevated winds to the airports as well.
&&
.MARINE...
Issued at 407 PM CDT Mon Sep 9 2024
Tonight through Tuesday Night...Adverse to hazardous marine
conditions are expected through Tuesday night, as Tropical Storm
Francine moves through the coastal waters. The enhanced pressure
gradient over the region will result in stronger northerly winds
over the waters. The rainbands of Francine will bring moderate to
heavy rainfall and could generate wind gusts up to tropical storm
force as well. Currently Tropical Storm Warnings are in effect for
the offshore Gulf waters and the southern nearshore waters.
Meanwhile, Tropical Storm Watches are in effect for the Laguna Madre
and northern Gulf waters.
Wednesday through Next Monday...The start of the period will still
have lingering adverse to hazardous conditions over the waters, but
should improve quickly as Francine leaves the area. At which point
the winds should be light to moderate with low seas. Isolated to
scattered showers and thunderstorms will be present through next
Monday, which could also generate locally elevated winds and seas.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE 75 84 75 91 / 90 80 50 30
HARLINGEN 72 84 73 92 / 80 80 40 30
MCALLEN 74 89 76 96 / 60 60 30 20
RIO GRANDE CITY 74 90 73 95 / 30 30 20 20
SOUTH PADRE ISLAND 79 84 78 87 / 90 90 70 40
BAYVIEW/PORT ISABEL 75 84 73 89 / 90 90 60 30
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Tropical Storm Watch for TXZ351-354-355-451-454-455.
Flood Watch through Wednesday morning for TXZ251-254-255-351-354-
355-451-454-455.
Coastal Flood Advisory until 7 PM CDT Tuesday for TXZ451-454-455.
High Rip Current Risk through Tuesday evening for TXZ451-454-455.
High Surf Advisory until 7 PM CDT Tuesday for TXZ451-454-455.
GM...Tropical Storm Watch for GMZ130-132-135-155.
Tropical Storm Warning for GMZ150-170-175.
&&
$$
SHORT TERM...64-Katz
LONG TERM....64-Katz
AVIATION...64-Katz
Area Forecast Discussion
National Weather Service Des Moines IA
640 PM CDT Mon Sep 9 2024
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
- Thunderstorms with very low precipitation amounts possible
tonight into Tuesday morning. A few may fest near the IA-MN
state line in the afternoon.
- Wind gusts up to 30 mph possible in the north Tuesday
afternoon.
- Smoke to remain aloft through at least Wednesday.
-Uncertain extended forecast dependent on behavior of large-
scale features.
&&
.DISCUSSION...
Issued at 239 PM CDT Mon Sep 9 2024
Southerly flow continued to build in today ahead of a shortwave
arriving off of the Northern Plains. Some upper level smoke
continued to move east across the state with more collocated
with the shortwave further west. The nocturnal jet picks up
tonight and will generate some cloudiness and perhaps some light
showers in the north and west through the morning hours. A few
CAMs keep showers near the IA-MN border going through Tuesday
afternoon. This is plausible given the jet-driven convergence
continues here, have kept chances lower in this timeframe due to
less moisture convergence there compared to overnight. Overall,
this system remains moisture starved; moisture from the Gulf of
Mexico is being redirected to Tropical Storm Francine instead.
Soundings illustrate this well with almost all moisture focused
above 700mb. There exists some instability aloft, generally
under 1000J/kg, which will be enough to generate some
thunderstorms as the shortwave progresses across northern Iowa.
Storms are not expected to be severe, but some gusty winds may
accompany them as there will be plenty of dry air entrainment to
accelerate parcels as they descend. Rainfall amounts are
expected to be under 5 hundredths of an inch. The low level dry
air will attribute to efficient boundary-layer mixing Tuesday
afternoon, making for breezy conditions and gusts up to 30mph in
the north.
Upper level ridging will build in behind the departing wave and
boost temperatures further into the 80s. A limiting factor to peak
temperatures will be the continued presence of smoke aloft. The
final hours of the extended RAP and HRRR smoke vertically integrated
smoke runs coat almost the entire state in smoke Wednesday morning.
H250 winds (30,000ft in the air where the smoke is located) are
minimized Wednesday as the ridge axis centers overhead. Therefore,
smoke is not anticipated to move much through at least Wednesday. In
collaboration with neighboring offices, have coated the area in 30%
sky cover for the day Tuesday and Wednesday and have also lowered
highs a few degrees below NBM guidance to account for solar
insulation caused from the smoke.
The forecast becomes more uncertain over the second half of the week
for two reasons: Francine and the Pacific trough. Francine will move
inland up the Mississippi river at least through Friday, eventually
turning east. Depending on its proximity to the state, some
cloudiness and cooled temperatures will be in store for at least
southeast Iowa this weekend. Meanwhile, the Pacific longwave trough
will take on a more cold season appearance, developing a closed low
by the time it reaches the Northern Rockies on Thursday. Mid-range
guidance tilts the trough negatively, phasing it back towards
Canada, and does this across the Dakotas. NBM PoPs keeps Iowa dry
from both features Friday and Saturday. Trends will be monitored as
deviations from either feature could mean rain for the state either
of those days. What can be said is high temperatures will be stunted
with low temperatures potentially undershooting current forecasts
due to the presence of low level dry air between systems.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 640 PM CDT Mon Sep 9 2024
Confidence remains high in VFR conditions prevailing through the
period. While ceilings and visibility are not concerns, there
is high level smoke from western US wildfires passing over the
state and have included initial FEW300 lines for this. A weak
system will bring clouds with SCT/BKN150 ceilings, but rain
chances are too low and isolated to even consider including a
mention. Finally, southerly winds will remain breezy overnight
with gusts up to around 20 knots during the day Tuesday.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Jimenez
AVIATION...Ansorge
Area Forecast Discussion
National Weather Service Quad Cities IA IL
619 PM CDT Mon Sep 9 2024
.KEY MESSAGES...
- Upper level wildfire smoke will linger through midweek. Not
anticipating impacts at the surface.
- Quiet pattern into late week with summer-like daytime warmth
and pleasant nights.
- Tropical remnants could be close enough this weekend to bring
some rain chances, however confidence remains low.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 303 PM CDT Mon Sep 9 2024
Surface to mid level ridging persists tonight. Dry air, light
winds and mostly clear skies will lead to good radiational
cooling. As a result, low temperatures are likely to be below
"deterministic" NBM (MinT guidance) and a blend of NBM
10th-25th percentile, especially south of I-80 being in closer
proximity to the ridge and reservoir of anomalously dry air
situated immediately south (12z SGF RAOB PWAT of 0.34 or 29% of
normal). Overall, this lends to lows generally in the upper
40s and lower 50s with a few mid 40s in the cool drainage sites
particularly south.
Tuesday, models are in reasonable agreement on shuttling a
couple of waves through a broad longwave upper ridge. The
first is a rather pronounced vort max in the 12z-18z timeframe
passing to our north across portions of Minnesota and
Wisconsin. That region would be most favored for any showers
attendant to the DCVA, but a few trailing showers could extended
down into north-central Iowa within a ribbon of elevated
theta-e advection waning as they shift eastward. A secondary low
amplitude wave in behind this is expected to again pass to our
north for Tuesday night. A weak branch of the LLJ and weak
theta-e advection could foster some elevated echoes/returns on
radar across our north/northwest service area, but a deeply
mixed troposphere above 600 hPa and pronounced drying should
evaporate any rain thus have kept out any precipitation mention.
Otherwise, on Tuesday we`re looking at another increase in upper
level wildfire smoke as the day progresses per satellite and the
HRRR vertically integrated smoke product. This will lead to
milky/hazy sunshine. Given the time of year now and thicker
smoke potential I`ve knocked down highs a bit favoring the NBM
50th percentile, which gives widespread highs around 80/lower
80s.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 303 PM CDT Mon Sep 9 2024
The long range remains rather quiet initially as ridging builds across
the Central Plains and into the Midwest and with the pattern
possibly becoming more active towards the middle to end of the
period as the remnants of Tropical Storm Francine work northward
into the mid-Mississippi Valley. In addition, a return to
summer temperature is expected in the long term as well. Lets
break it all down:
Wednesday-Saturday
A generally quiet pattern exists for our area through the start of the
period as ridging begins to build back in earnest Wednesday and
Thursday. In response to the ridge, temperatures will begin to
rise into the 80s across much of the area with some potential
(40-50%) of temperatures exceeding 90 on Thursday, especially in
the Southern CWA. While heat will return, much drier conditions
are expected in conjunction with this warm up with dew points
only topping out in the 40s to 50s. Guidance does continue to
suggest the continuity of upper level candida wildfire smoke
through midweek. While this may create a hazy appearance to the
sky, little in the way of effects to air quality at the surface
is expected.
An upper trough is also forecast to come ashore in the Pacific
Northwest during the timeframe and translate eastward into the
Northern U.S. Rockies. This will help to evict the primary ridge
axis and center of high pressure to the north and east of the
Midwest and Great Lakes Region. Tropical Storm Francine in the
Gulf of Mexico is currently forecast to make landfall around
late-evening on Wednesday between Lake Charles, LA and
Lafayette, LA and track north, along the Mississippi River,
arriving to the Mid-Mississippi Valley/Southern Illinois region
by Saturday Morning. Uncertainty remains prominent around the
northern progression of Francines remnants through the day on
Saturday with blocking high pressure to the Northwest making the
difference between the center of the post-tropical low settling
in Northern Illinois or Southern Illinois. Current NBM guidance
favors the Southern scenario, with only a ~20% chance of QPF,
and mainly for the Illinois side of the river. A system that
tracks further North before weakening would likely present a
much more formidable chance of precipitation for our CWA.
Sunday & Monday
After the tropical system diminishes, broad ridging returns to the
eastern half of the CONUS which will keep the pattern mostly
inactive with above normal temperatures.
Beyond Monday, a pattern shift looks in order as troughing
approaches from the West. CPC 8-14 day forecasts suggest
continued above average temperatures and near normal
precipitation chances.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 617 PM CDT Mon Sep 9 2024
A quiet night of aviation weather is expected tonight, and
another quiet day is expected Tuesday. South winds will be under
10 kts most of the period, but could be near the 8-12 range in
the afternoon hours Tuesday. For now, the smoke aloft remains
well above 10000 ft, and visibility is very good.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...McClure
LONG TERM...McClure
AVIATION...Ervin
Area Forecast Discussion
National Weather Service Goodland KS
618 PM MDT Mon Sep 9 2024
.KEY MESSAGES...
- Continuing to watch for fire weather concerns Wednesday
through Friday with breezy to gusty winds. Strongest winds and
highest fire concerns will be Thursday
- Above normal temperatures are forecast to continue through
the rest of the week.
&&
.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 153 PM MDT Mon Sep 9 2024
A transition to more zonal upper level flow although some
slight northwesterly flow remains as the ridge across the
western CONUS remains. At the surface a trough is draped across
the area. East of the trough (Highway 25 on east) wind gusts of
25-30 mph remain possible along with a sustained wind around
15-20 mph. There does remain some potential for locally near
critical to critical fire weather conditions to develop but
seems to be more spotty than what it was appearing to be when
looking at data 24 hours ago. The 200- 230 degree wind that was
mentioned in yesterdays discussion is occurring so far as
temperatures have been quick to warm into the low 90s across the
majority of the area. As the surface trough continues to move
through the area thinking is that winds will lose their SW
direction and become more southerly losing the "furnace wind"
feature so am opting to leave temperatures alone for now;
wouldn`t be surprised if a rogue triple digit temperature is
recorded in Hitchcock, Thomas, Rawlins county vicinity.
Into this evening, RAP 700-500mb moisture continues to suggest
moisture in the profile. Looking at how everything evolved
yesterday, thinking is that roughly the same amount of coverage
is possible as convective temperatures should help overcome the
weak forcing in place for convective initation to occur;
convective temperatures look to be in the upper 80s to lows 90s.
The favored area looks to be along/near the Highway 385
corridor from Idalia down towards Cheyenne Wells before
wandering across the state line towards sunset. Similar to
yesterday, there is just not much to work with in the atmosphere
but given again steep lapse rates, high DCAPE and inverted v
soundings wind gusts up to 50 mph would be the most likely
hazards. Any storms from late this afternoon/early evening will
dissipate around sunset as heating ends. An additional area of
showers and storms may move into northern Yuma/Dundy counties
early this evening as well with winds around 50 mph as the main
threat, these as well should dissipate as diurnal heating ends.
Tonight, similar to the past couple nights a fairly stout LLJ
looks to develop causing overnight winds to be around 15 mph
sustained. As a result of this and the SSW wind component have
upper overnight lows a bit with upper 50s across eastern
Colorado to the mid 60s across the east currently forecasted.
Have also introduced some slight chance pops across the east
after 09Z tonight as the continued LLJ should help promote
additional lift in an area of high mid level moisture for a few
showers/ perhaps an embedded storm to develop. These should they
occur will end just after sunrise as the LLJ erodes.
Tuesday, continues to show that the area will be in transition
to a more active synoptic pattern. The above normal temperatures
will continue with highs in the 90s. Winds however will not be
as breezy as they are currently forecasted to remain around
10-15 mph for the duration of the day with the breeziest across
Decatur, Norton, Graham and Gove counties. Continued moisture in
the mid levels and weak subtle 700 mb short wave looks to
continue the trend of spotty low chance showers and storms. At
this time the relative favored areas for storms looks to be near
the KS/CO state line. Sounding continue to show a fairly weak
convective environment similar to the previous days as wind
gusts around 50 mph would again be the primary hazard.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 153 PM MDT Mon Sep 9 2024
The extended period continues to show strong signals of
temperatures remaining well above normal with highs in the 90s
and gusty winds. I am noticing a bit of a slower moving system
and quicker turn to the north which may impact the coverage and
potential strength of the winds. Nevertheless gusty to strong
southerly winds remain forecasted with fire weather conditions
developing especially across eastern Colorado.
Wednesday, will see a upper level trough begin to take shape
across the western CONUS. The low level wind field will also
begin to increase as well which will begin the first of multiple
days of fire weather concerns as winds will begin to ramp up
during the late morning hours with gusts of 25-35 mph currently
forecasted.
Thursday will see the trough begin to deepen which will tighten
the pressure gradient across the area as southerly winds are
currently forecasted to gust 35-45 mph across the area there is
potential as well for gusts across eastern Colorado to reach the
50 mph range. Near critical to critical fire weather conditions
remain a concern for areas along and west of Highway 25. Per
phone calls with some of our fire partners have reiterated that
fact that fuels are either ready to burn or are quickly drying
out. This continues to create a concern for fire spread for the
entire area irregardless if the critical fire thresholds are
met. The tropical system in the Gulf of Mexico may throw a
caveat into the forecast as southeast winds will be present
especially along and east of Highway 25. The exact track of the
tropical system as well may lead to some cloud cover concerns
that may impact temperatures and winds. Overall the highest
confidence for very high to extreme fire weather concerns will
be along and west of Highway 27.
Into Friday the trough will push to the north as winds wont be
as intense as Thursday but will still be gusty around 30-40 mph
resulting in another day of fire concerns. However if the
potential slower track of the trough continues then winds may
need to be increased as well. Still can`t completely rule out
some shower and thunderstorm potential as the trough ejects to
the north. If this were to occur then locales north of
Interstate 70 would be favored. At this time severe weather is
not anticipated.
This weekend does again appear to another transition
synoptically wise as another trough begins to form across the
western CONUS. The above normal temperatures at this time do
appear to continue, although perhaps not as warm with highs in
the 80s to low 90s. Some storm potential is possible as well,
especially Sunday as a wave from the developing trough moves
across the area; will go with silent pops for now due to the
slightly more delayed nature of this weeks trough.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 600 PM MDT Mon Sep 9 2024
GLD: VFR conditions will rule through the TAF period. A
nocturnal low-level jet anticipated to develop this evening and
overnight may result in a period of south southwesterly LLWS,
mainly between ~04-10Z. Expect southerly winds at 12-15 knots
this evening (occasional gusts to 20-25 knots possible until
03-04Z), veering slightly to the SSW overnight and becoming
light/variable a few hours after sunrise. Light and variable
winds may persist through the majority of the day.. eventually
shifting to the SE-SSE at 10-15 knots near the end of the TAF
period (~00Z Wed).
MCK: VFR conditions will rule through the TAF period. A
nocturnal low-level jet anticipated to develop this evening and
overnight may result in a period of south southwesterly LLWS,
mainly between ~04-10Z. Expect S winds at 10-15 knots this
evening and overnight.. possibly veering to the SSW for a few
hours on either side of sunrise. Otherwise, 10-15 knot S winds
are anticipated to prevail through the TAF period.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
SHORT TERM...Trigg
LONG TERM...Trigg
AVIATION...Vincent
Area Forecast Discussion
National Weather Service Grand Rapids MI
1030 PM EDT Mon Sep 9 2024
.KEY MESSAGES...
- Areas of Fog Tonight
- Warming Trend Continues Tomorrow
- Warm and Dry to end the Week
- Low Confidence in Weekend Rain
&&
.UPDATE...
Issued at 1030 PM EDT Mon Sep 9 2024
No changes needed to the going forecast. The fog threat still
looks strong overnight, with latest HRRR soundings and model
visibility guidance supportive of strong low level inversions and
shallow fog formation. Some of the fog could become dense but
confidence in extent/placement of vsbys less than 1/2 mile is too
low at this time to issue a Dense Fog Advisory.
The Beach Hazards Statement expired at 5 PM and waves continue to
subside with buoys now showing 1-2 ft.
&&
.DISCUSSION...
Issued at 336 PM EDT Mon Sep 9 2024
- Areas of Fog Tonight
Nearing daytime highs currently and dew points are mid 50s to
around 60, which will set the crossover temperature. Surface
pressure gradient is expected to weaken tonight under a ridge
extending north from the Ohio valley high. Under mostly clear
skies, nearly calm surface winds, and winds below 925 mb likely to
fall below 15 knots after midnight, forecast low temperatures
around 50 degrees should be far enough below the crossover
temperature to support fog development prior to sunrise. Short
term model guidance suggests areas of fog east of M-66 including
the US-127 vicinity, and patchy fog in the US-131 vicinity.
- Warming Trend Continues Tomorrow
A broad upper-level ridge moves over the region on Tuesday with
jet streaks moving far away. High pressure centered over the mid-
Atlantic states will turn our low-level flow more from the
southwest, advecting warmer air our way. 850 mb temperatures on
Tuesday a couple degrees C warmer than Monday should support highs
near to a little above 80, though the Lake Michigan shoreline may
stay cooler.
There is a chance of sprinkles Tuesday night, mainly in central
Michigan and to the north. Subtle H5 shortwave trough/vorticity
presently over South Dakota / Nebraska propagates through the
broad ridge toward northern Michigan. Altostratus or altocumulus
at/above 10,000 feet or 700 mb with slightly unstable lapse rates
for moist parcels may result in some precipitation being produced.
However, very dry air beneath should evaporate most of it.
- Warm and Dry to end the Week
Upper ridging will keep conditons quiet through the end of the week.
Deep layer subsidence will keep the column dry warranting overnight
lows in the 50s while southerly return flow pushes daytime high
temps into the 80s. Temperatures peak Thursday in the upper 80s.
- Low Confidence in Weekend Rain
Tropical storm Francine will attempt to move northwards into the
region but will interact with upper level ridging to form a rex
blocking pattern: an upper level high located directly north of a
closed low. A plume of moisture associated with the tropical system
will nose into Illinois and far southwest lower Michigan presenting
low rain chances into the weekend.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 728 PM EDT Mon Sep 9 2024
Not much change in forecast overnight. Fog remains the main
concern overnight with visibilities potentially below a mile,
especially at the central TAF sites of LAN and JXN. Expecting 2-5
miles at AZO, BTL, and GRR. Winds are already slackening and will
go near calm after sunset. Fog will begin to develop after 04Z
with restrictions mainly between 8-13z Tuesday morning. Conditions
will improve fairly quickly after sunrise. Winds tomorrow will be
mainly from the south to southwest.
&&
.MARINE...
Issued at 336 PM EDT Mon Sep 9 2024
As of 2 PM, winds have dropped below 10 knots north of Saugatuck,
but remain gusty over 20 knots at St Joseph. The wave heights at the
buoys are slowly going down but remain a hazard for small craft and
swimmers. Planning on letting the small craft advisory and beach
hazards statement expire at 5 PM, however, a moderate swim risk
and 2 to 4 foot waves are expected to continue through sunset
this evening from Muskegon to St Joseph. Water temperatures
reported this morning at several beaches were still in the 50s.
After today, minimal marine concerns for the next few days given the
dry and quiet pattern. A southerly breeze Tuesday night into
Wednesday may make the waters a bit choppy north of Grand Haven.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
UPDATE...Meade
DISCUSSION...CAS/Thielke
AVIATION...Ceru
MARINE...CAS
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
808 PM CDT Mon Sep 9 2024
.KEY MESSAGES...
- Large diurnal temperature swings are expected the next couple
days, with cool mornings rebounding to near or above normal
highs.
- An extended period of rain chances will begin Thursday night, as
the remnants of Hurricane Francine approach from the southwest.
Chances of over an inch of rain are highest south of I-70
(50-80% for the event).
&&
.UPDATE...
Issued at 808 PM CDT Mon Sep 9 2024
High pressure centered near southeast IL will be the dominant
influence on central/SE IL weather tonight, providing clear skies
(except for smoke aloft) and light winds. With the moderating air
mass over the area, highs were several degrees higher today (upper
70s) than yesterday (lower 70s), and dewpoints as of peak
temperatures were well into the 40s over most of the area. This
should limit lows for tonight to no lower than mid 40s. Given
24-hour change of temperatures of plus 4-6 degrees and yesterday`s
lows mostly mid 40s, upper 40s look to be more likely for tonight,
however. Have nudged tonight`s lows down a degree or two, but
otherwise this afternoon`s forecast package looks in good shape
with these features.
37
&&
.SHORT TERM... (Through Wednesday Night)
Issued at 234 PM CDT Mon Sep 9 2024
Main forecast challenge in the short term is with the smoke
coverage. Early morning HRRR runs show a fairly substantial smoke
layer moving in from the west Tuesday and Tuesday night, with
greatest impacts north of the I-80 corridor. However, with high
pressure drifting eastward out of the Midwest, the circulation
will keep some of the existing smoke across the region as well.
Sky grids have generally been set with a floor of 15-20%, though
little in the way of actual cloudiness is expected until some
diurnal cumulus develops west of I-55 Wednesday afternoon.
Otherwise, the dry air will result in large diurnal temperature
swings through Wednesday. Though much of the forecast area will
likely dip to around 50 degrees tonight, temperatures should
rebound well into the 80s. Good mixing of the air will continue,
with dew points mainly in the 40s. Despite a south/southeast flow
mid week, Gulf moisture will be cut off, preventing a significant
rise in dew points, so upper 40s/lower 50s dews are expected on
Wednesday as well.
Geelhart
.LONG TERM... (Thursday through Next Monday)
Issued at 234 PM CDT Mon Sep 9 2024
Forecast challenge in this period is with the impacts of now-
Tropical Storm Francine in the Midwest late week.
Latest guidance from NHC brings in the storm as a hurricane across
the southern Louisiana coast by Wednesday evening, with its
remnants reaching the southern tip of Illinois by Saturday
morning. This position is about midway between the operational GFS
and European models, with the Canadian model significantly
further north and shearing out faster. Cluster analysis from the
morning ensembles would support this position as well.
With a rex block pattern developing (upper level high pressure
north of the tropical low), the northern extent of the associated
rain shield will likely struggle to get much past I-72 until the
high slides eastward later in the weekend. As such, highest PoP`s
will be south of I-72, with some potential for the northern CWA to
be dry later into Friday. In terms of rainfall amounts, LREF
probabilities of total rainfall over 1 inch are about 50-80% south
of I-70, and about 30-50% between I-72 and I-70. Given the area
south of I-70 is running less than 25% of normal rainfall over the
last month, and the fact the rain will be falling over an
extended period (rain chances into early next week), flooding is
not anticipated at this time.
With the remnant low meandering across the region late this week,
temperatures will be kept down the most across the south half of
the forecast area. Highs Friday may struggle to reach 70 near
I-70, while getting close to 80 near Galesburg and Peoria. By
Sunday, lower 80s return west of the Illinois River, but mid-upper
70s are expected across eastern Illinois.
Geelhart
&&
.AVIATION... (For the 00z TAFs through 00z Tuesday Evening)
Issued at 605 PM CDT Mon Sep 9 2024
VFR conditions expected the next 24 hours, with a layer of smoke
expected to remain elevated through the period. Winds light and
variable to SSW around 5 kts overnight, becoming S 8-10 kts by
15Z.
37
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service North Platte NE
701 PM CDT Mon Sep 9 2024
.KEY MESSAGES...
- Continued hot, hazy, and generally dry through midweek with just
some isolated precip chances (20%)
- Winds strengthen Wednesday into Thursday ahead of a cool front,
greatly increasing fire weather concerns
- Temperatures head back toward normal with greater precip potential
(30-40%) to wrap up the week
&&
.SYNOPSIS...
Issued at 403 PM CDT Mon Sep 9 2024
With the northerly stream straddling the Canadian border, a summery
setup has set back in across the Great Plains with widespread highs
in the 90s. A somewhat split pattern at H5 results in quasi-zonal
flow there. Toward the surface, high pressure is centered over the
Mississippi Valley while a low is stationed near the Black Hills. A
couple weak troughs/boundaries stretch out from the low and cut
through the panhandle and north central Neb. The western trough
presents a marked wind shift and dew point cutoff, while some
moisture convergence takes place along the eastern trough.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 403 PM CDT Mon Sep 9 2024
This evening into tonight... Despite the hot and dry setup, the
surface troughs in concert with a subtle mid-level shortwave may be
enough to fire off a couple showers or storms. Weak radar echoes and
agitated cumulus via IR/vis satellite have already been noted over
the western panhandle as of 20z. SPC/RAP mesoanalysis indicates a
ribbon of greater low level moisture streaming northward across
eastern Neb ahead of the one surface trough. Included schc PoP for
each of these areas through 06z. Thinking the overall dry nature of
the low levels will keep activity isolated at most, and not all CAMS
are sold on convective development. Generally used the more
aggressive solutions for timing and placement. Also brushed the far
eastern zones with schc PoP overnight to account for possible
activity along the low level jet. Guidance again does not suggest
much, but a similar setup this morning resulted in scattered showers
in the far southwest. Coordinated with neighboring offices to go
with a "persistence" PoP forecast through daybreak or so. The low
level jet appears rather impressive with 45-50kt flow from the
southwest and the nose directed at the Upper Midwest. Also included
haze across the Sandhills to account for mid/upper level atmospheric
smoke. Used HRRR integrated smoke for guidance. As for min temps,
values were a bit tricky to iron out. Observations seem to have
undercut guidance the last couple mornings, and all MOS guidance lie
near the bottom of the NBM envelope. Used a blend of MAV/MET and
NBM25, which gave upper 50s panhandle to lower 60s west central to
mid 60s north central.
Tomorrow... Basically rinse and repeat, with zonal flow aloft,
surface high still near the Great Lakes and low near the Black
Hills, and negligible temp advection at H85. Maintained forecast
highs in the lower/mid 90s across the area, which drives humidity
values down below 20% along and west of Hwy 83. Winds should remain
light enough to preclude any serious fire weather threat. Also
maintained schc (20%) PoP in north central ahead of the slowly
advancing surface trough. Again, guidance hints at some development,
but many solutions must overestimate the dry layer. Included haze
mention for the Sandhills for continued thick atmospheric smoke, but
unclear how much will be mixed to the surface for visby impacts.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 403 PM CDT Mon Sep 9 2024
Heading into midweek, a deeper surface low emerges onto the northern
High Plains and pulls a cool front toward the central Plains. A
powerful shortwave also accompanies a digging upper trough and
closed low over the Western US. A tightening surface gradient and
increased H85 flow off the southern Plains will promote
strengthening winds Wednesday into Thursday. Will really need to
watch for red flag potential Wed as remnant very dry air holds
across the west. Slightly better moisture arrives Thursday, possibly
entrained from the incoming tropical cyclone. However, winds
increase further as most guidance show sustained 25+ kts and gusts
35+ kts. More aggressive members of the NBM suggest high wind
potential (50 kts). Nevertheless, NAEFS and ECM EFI both highlight
an anomalous pattern. NAEFS indicates H85 winds reaching 99%ile of
climo, while ECM suggests near surface speeds hitting 0.9/1 EFI and
1 SoT for Thu. Precip potential increases late Friday into Saturday
with a secondary frontal passage, but amounts appear up in the air.
Longer range guidance suggests temps backing off from early week
heat, but still holding near or slightly above average into the
weekend.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 701 PM CDT Mon Sep 9 2024
VFR conditions will persist through Saturday evening at both
terminals. A dry forecast with clear skies will continue across the
region. Winds are expected to remain below 10 knots through Tuesday
afternoon.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Snively
SHORT TERM...Snively
LONG TERM...Snively
AVIATION...Kulik
Area Forecast Discussion
National Weather Service Louisville KY
829 PM EDT Mon Sep 9 2024
...Forecast Update...
.KEY MESSAGES...
* Hazy skies today due to smoke aloft. Much warmer this afternoon
after a chilly start to the day.
* Smoky skies are expected to continue into Tuesday.
* Confidence is increasing for showery weather late this week into
the weekend as a tropical system moves from the Gulf of Mexico
into the Mississippi Valley.
&&
.UPDATE...
Issued at 829 PM EDT Mon Sep 9 2024
Looking for a clear and quiet night across the area with high
pressure in control. Temps won`t be as cool as last night, however
morning lows will still be chilly in the upper 40s and low 50s for
most spots. Forecast is on track, no changes planned.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 300 PM EDT Mon Sep 9 2024
RAP 500 MB analysis and water vapor imagery showed a trough over the
northeast portion of the CONUS with a ridge of high pressure
building across the southwest. Mid level smoke from western
wildfires is obscuring the traditional sky clear blue color with a
sensible gray color, but otherwise is not impacting ground level.
Temperatures across the region were in the upper 60s to lower 70s
during the early afternoon.
The trough of low pressure that brought cooler than average
temperatures will continue to move to the east as the high pressure
builds across the desert southwest. Before heat associated with the
ridge returns, low temperatures tonight will be mainly in the mid to
upper 50s (between 5 and 10 degrees below normal). A few spots
tonight may reach the upper 40s. Height rises are expected to spread
across the entire country and into Canada headed into Tuesday which
will bring a return to above normal high temperatures. Highs in the
mid to upper 80s with clear skies with the possibility of continued
mid level smoky gray color due to smoke.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 300 PM EDT Mon Sep 9 2024
Warm and dry weather continues through Wednesday night as a blocking
upper ridge remains parked over the Great Lakes. Dry ground
conditions and unseasonably low dewpoints will support wide diurnal
ranges, with lows near or slightly below normal, but highs well
above normal and even touching 90 in many locations on Wednesday.
Showery weather develops on Thursday, expanding south to north late
in the day as a decaying tropical low lifts north into the Lower
Mississippi Valley. The rainy pattern will continue at least through
Saturday, if not into Sunday but the best chances for precip will be
Friday into Friday night. Confidence is moderate to high that we
will see 1-2 inch rainfall totals through Friday night, especially
along and west of Interstate 65. With the low center near the
Missouri Bootheel on Friday, we`ll also have to watch the potential
for rotating storms, but there remains quite a bit of uncertainty
about the dynamics by that time.
Forecast confidence really decreases over the weekend, as the post-
tropical low spins down and its track becomes more uncertain.
Blocking ridge over the Great Lakes strengthens by that point, which
could either cause the low to stall out over the Mid-Mississippi
Valley or guide it farther west. Will hang on to precip chances into
Sunday, potentially dropping another inch or more of rain,
especially along and west of I-65. Abundant cloud cover and
scattered to numerous showers will limit diurnal temp ranges over
the weekend.
&&
.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 725 PM EDT Mon Sep 9 2024
VFR weather expected with light and variable surface winds. Any
prevailing wind direction will most likely be out of a general east
component, but low confidence given the light, erratic nature. High
pressure is centered over the lower Ohio Valley, leading to mainly
clear skies and light and variable winds through the next 24 to 30
hours. Skies will continue to be hazy due to increasing
concentrations of smoke in the mid-levels (especially 7-14 kft AGL).
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...BJS
SHORT TERM...MCK
LONG TERM...MCK
AVIATION...BJS
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
606 PM CDT Mon Sep 9 2024
.KEY MESSAGES...
- Warming trend with summer-like daytime temperatures through
the work week.
- Persistent stretch of dry conditions will yield an increased
threat for grass and brush fire starts, especially south and
western locales.
- Rain chances increase by the weekend, as the remnants of
Tropical Storm Francine move into the region.
&&
.DISCUSSION...
Issued at 200 PM CDT Mon Sep 9 2024
Through Tuesday night:
Delightful September weather continues across the Midwest with cool
mornings and above normal daily highs expected to continue for
several days. There will be increased fire weather risk through
mid week mainly due to low humidity.
Water vapor satellite imagery depicts upper level flow out of the
northwest across the lower Great Lakes, with very dry conditions
through the atmospheric column over a large portion of the
continental United States. This is consistent with upper air
radiosondes which have precipitable water values across the region at
or below 25th percentile readings for early-mid September. Upper
level flow will shift westerly as a seasonally strong ridge axis
across the plains meanders eastward and begins to flatten. The other
interesting features on the satellite analysis include: 1) a weak
upper low in the northern/central Plains and then 2) the tropical
disturbance across the western Gulf which will influence our local
weather this weekend. The local area is currently under the
influence of high pressure at the surface with seasonal temperatures
in the upper 70s and low humidity.
The main weather phenomenon of interest will be both increasingly
dry conditions, which may contribute to an increased brush fire
risk. Forecast soundings depict continued subsidence and an even
further drying of the lower atmospheric column on Tuesday, and this
will continue into midweek as temperatures continue to inch upward,
in spite of a slow increase in deep layer moisture. With
surface high pressure in place, any influence from the weak
upper low across the plains may be some increased high clouds,
with any light precipitation heading north of the area. Low
level flow will be out of the southwest, and thus temperatures
will increase through the 80s, whereas normal highs are
generally in the upper 70s. With these high temperatures and
dewpoints mixing down into the 40s for most areas tomorrow,
relative humidity readings will dip to as low as 20 percent in
some locations, and this is quite dry. Fortunately wind gusts
should remain under 20 mph as the pressure gradient over the
area will remain fairly weak except toward the Rockford area.
A secondary feature of note will be the advection of smoke aloft
back into the lower Great Lakes mainly from a more concentrated of
smoke noted extending from MN southward to Arkansas. Winds both in
the mid and upper levels will shift more westerly as the upper ridge
axis flattens. Therefore some of the smoke will advect back toward
the lower Great Lakes later Tuesday into Tuesday night. Cross
section analysis from the HRRR seems to be biased a bit low in terms
of how close to the surface smoke will extend, but the HRRR
depiction of an increased smoke concentration aloft late Tuesday is
reasonable.
KMD
Wednesday through Monday:
Main long-term forecast concerns continue to focus on warm, dry
weather mid-week with potential increased brush fire risk, then
rain trends with the remnant circulation of what is now
Tropical Storm Francine in the western Gulf of Mexico.
Medium-range guidance/ensembles develop upper-level ridging
across the Midwest/western Great Lakes Wednesday into Thursday,
to the northeast of the remnant circulation of TS Francine which
combines with a weak upper low currently over Mexico. This is
expected to maintain dry weather and well above average warmth
across the forecast area mid-week, with daytime highs in the
mid-upper 80s (near 90 in our warmest metro locations).
Subsidence and dry easterly low-level flow is expected to
maintain low dew points and relative humidities during this
period, especially during the midday and afternoon hours of best
mixing and warmest surface temps. Have maintained the trend
from earlier shifts, blending lower NBM 10th percentile and
ensemble MOS guidance both Wednesday and Thursday, yielding
afternoon RH values around 25 percent. While winds will not be
particularly strong, combined with our antecedent dry conditions
this will likely present an elevated risk of grass and brush
fires through Thursday.
Attention then focuses on the eventual approach of the remnants
of TS Francine from Friday through the weekend. GFS/ECMWF
ensembles are in decent agreement in bringing the mid-level
circulation across the lower Mississippi Valley Thursday, and
eventually into the lower Missouri/Ohio/Tennessee Valley regions
where it then is progged to wobble slowly east Friday through
Monday. NBM pops continue to appear a bit too high/too far north
especially in the Friday through early Saturday period based on
current guidance (the GEM/CMC ensemble are more phased with
short wave energy emerging from the central Rockies and are
significantly farther N/NW with the circulation). Have generally
lowered NBM pops for the Friday through Saturday AM period to
match our going forecast, which could still eventually end up
being too high. With decreasing confidence in location/track of
the slow-moving circulation later Saturday into Monday,
maintained NBM chance pops through that period. Increasing cloud
cover and easterly low-level winds Fri-Mon along with loss of
upper ridging overhead should support more typical temperatures
by the late week/weekend period.
Ratzer
&&
.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 605 PM CDT Mon Sep 9 2024
There are no aviation concerns through the TAF period. West
winds at press time will back modestly toward the southwest
overnight and remain so through tomorrow. Pockets of upper-level
wildfire smoke will occasionally meander over the terminals, as
well.
Borchardt
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1044 PM CDT Mon Sep 9 2024
.KEY MESSAGES...
- Near to slightly above normal temperatures return Tuesday through
Wednesday.
- There are strengthening signals that remnants of a tropical
system over the Western Gulf will bring beneficial rain to the
area late this week with the highest potential over southeast
Missouri into southwest Illinois.
&&
.SHORT TERM... (Through Late Tuesday Night)
Issued at 243 PM CDT Mon Sep 9 2024
Surface high pressure remains in control with its broad influence
extending from the mid-Atlantic Region westward through the mid-
Mississippi Valley. Midwest regional surface analysis shows light
and variable surface winds gradually turning out of the south-
southeast from eastern Missouri into the eastern Plains. Despite
that a strong warm air advection feature doesn`t quite jump out at
us tonight into Tuesday, mid-level ridging shifts east far enough
for return flow to draw warmer temperatures into the region.
Sensible changes will be more notable Tuesday, when 850mb
temperatures subtly rise around 5C from west to east. With the lack
of strong moisture advection, dewpoints remain in comfortable
territory (40s/50s).
The other item to address is the presence of Canadian wildfire
smoke. This was clearly evident Monday morning with the milky,
orange sunrise. HRRR doesn`t show much in the way of near-surface
particulate. However, mid-level and upper level trends show
particulate increasing tonight into early Tuesday and it remains
suspended aloft. Some of the higher concentrations wrap around the
western side of the departing mid-level ridge. So, while smoke
initially get pushed south, it is redirected back northward around
the western side of the mid-level riding pattern. Aside from
inhibiting diurnal maximums by a degree or two, the only other
impact will be the potential for a couple of picturesque
sunrises/sunsets.
Running ahead of the warm-up, tonight`s temperatures will be the
last of the cool(er), fall-like air (for now) with lows in the mid-
40s to low-50s. Highs Tuesday reach well into the 80s with Tuesday
night`s lows ranging from the mid-50s to near 60 degrees.
Maples
&&
.LONG TERM... (Wednesday through Next Monday)
Issued at 243 PM CDT Mon Sep 9 2024
Surface and mid-level ridging is expected to have enough influence
to stave off any precipitation potential through Wednesday. This
is favored to be the height of the warmth with nearly uniform high
temperatures ranging from the upper 80s to low-90s.
The focus shifts to what is likely to be the bigger story - remnants
of the tropical system (Francine). The main challenge the last
several days has been the track of the system with most global
guidance moving its remnant through the Tennessee Valley. Now that
the system has a formidable representation in the Western Gulf,
better sampling has given guidance a little more to work with and
the latest trends look promising. GEFS 500mb spaghetti plots have
latched onto track nearly parallel to the Mississippi River with
the surface/mid-level blocking to the east. EPS is about 50 miles
further east, but it, too, has also trended westward. Despite that
some extended ensemble guidance will not get wholesale update
until 00z tonight, 06z ensemble runs of the ECMWF and GFS do show
a number (over 50%) of members with 1-2 inches at KFAM and 1+ inch
amounts extending northeast through KSTL. Though the amount drop
off to the north and west, event KCOU lands in 0.50-0.75 inch
amounts with measurable precipitation reaching as far north as
KUIN. LREF guidance from 00z last night (Sunday evening) show at
least 50% probabilities for 1 inch in the generally swath along
and southeast of I-44 and south of I-70. Given the last trends, I
wouldn`t be too surprised to see these numbers nudge upward.
Fortunately, CAPE values look all but negligible (low and
unimpactful) with little support for convective development.
All that being said, the other challenge will temperatures Thursday
into the weekend. Much of the guidance is keying in on a Thursday
arrival. The northward transport of mid/upper level moisture and
consequential cloud cover and/or rainfall will keep temperatures
cooler (70s) to the south of I-70 and warmer to the north (80s). The
highest uncertainty lies somewhere in between, including KSTL, where
an earlier/later arrival will play on cool/warmer temperatures. It
does seem more reasonable that temperatures will remain cooler
Friday as the system rotates over overhead with likely (60% or
higher) probabilities for rainfall along and east of the Mississippi
River.
Guidance diverges beyond Friday as the blocking pattern to the east
keeps the weaker version of the system rotating somewhere
overhead. Exactly how this plays out could lead to additional,
light precipitation amounts, but confidence is low at this
distance in time.
Maples
&&
.AVIATION... (For the 06z TAFs through 06z Tuesday Night)
Issued at 1043 PM CDT Mon Sep 9 2024
Light winds overnight become light southeasterly during the day on
Tuesday. The sky will be clear aside from some high level smoke
denoted in the TAF by a high level cloud layer. This smoke is not
expected to impact any terminals.
Kimble
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
610 PM CDT Mon Sep 9 2024
.KEY MESSAGES...
- Elevated smoke moves in this evening and is expected to last
thru at least Wednesday.
- Summer-like temperatures through the end of the week.
- Small chance of showers in southern MN Tuesday morning but
additional chances for rain wait until next weekend.
&&
.DISCUSSION...
Issued at 256 PM CDT Mon Sep 9 2024
Sunny skies and light southerly winds have allowed for a beautiful
day with temperatures warming into the low to mid 80s this
afternoon. The clear skies will not last much longer, though, as the
RAP and HRRR show elevated wildfire smoke moving in from the west
this evening. Smoke should cover the entirety of our CWA by Tuesday
afternoon, creating a thick haze. At the moment, the RAP and HRRR
show nearly all of the smoke remaining elevated, which is fortunate
because forecast smoke concentrations are quite high. A bit of
uncertainty in this outcome does exist Tuesday morning as forecast
models show a frontal boundary and weak upper-level trough passing
through southern MN. Forecast guidance favors isolated showers and
light QPF developing from elevated instability and lift, despite
forecast soundings showing dry low-levels. Have added 20% PoPs for
our southern MN counties Tuesday morning. Where this comes into
uncertainty with smoke is sometimes precipitation can transport
smoke aloft down to the surface. So, there is a small chance parts
of southern MN could see more near surface smoke if said showers
occur. The low chances for precip should move east of our area by
Tuesday evening, resulting in the rest of the work week being dry.
Highs will range in the 80s through Friday as temperatures continue
above normal. Have slightly decreased Tuesday and Wednesday`s highs
to remove mentions of 90s in western MN due to expected thick smoke.
Lows each night are forecast in the mid 50s to lower 60s.
Chances for rain don`t return until next weekend as long-range
guidance shows a closed but weakening upper-level low crossing east
of the Rockies. Models differ in both the speed of the low and how
quickly it decays as it moves through the Northern Plains, resulting
in smearing of 20-30% PoPs Saturday through Sunday. Regardless,
would figure to see at least one good shot of precip during the
weekend, especially if Tropical Storm Francine moves nearby
into the Midwest. Temperatures should cool slightly for the
weekend, with highs in the upper 70s to lower 80s. But a real
cooldown isn`t looking likely (evidenced by the CPC 6-10 and
8-14 Day Temperature Outlooks) as highs should remain above
normal/more summer-like through mid-September.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 610 PM CDT Mon Sep 9 2024
VFR through the period with winds calmer tonight, higher in
parts of western MN like RWF. Elevated smoke through the period
with increasing clouds by the morning. Some showers are possible
in southern Minnesota as well on Tuesday. Best chances at MKT
and maybe as far north as MSP. Chances overall too low for
inclusion in the TAF. Winds will pick up again tomorrow during
the day as the diurnal winds continue.
KMSP... As mentioned above MSP has a slight chance for rain
tomorrow, but too low for inclusion in the TAF.
/OUTLOOK FOR KMSP/
WED-THU...VFR. Wind S 10-15 kts.
FRI...VFR. Wind SE 10-15 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...CTG
AVIATION...NDC
Area Forecast Discussion
National Weather Service Pueblo CO
544 PM MDT Mon Sep 9 2024
.KEY MESSAGES...
- Isolated showers/thunderstorms this evening, mainly mountains.
- Hot again Tuesday, with a modest upturn in convective
coverage/strength.
- Isolated to scattered showers and thunderstorms across the
higher terrain through Wednesday, then fairly dry for the
remainder of the extended period.
- Enhanced fire danger possible on Thursday for portions of the
plains.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 235 PM MDT Mon Sep 9 2024
Currently...Isolated showers/thunderstorms over the mountains again
this afternoon, though with surface dewpoints and instability
slightly less than yesterday, storm strength has been rather weak
and have seen only a handful of lightning strikes as of 2 pm across
the region. Temps were running well above seasonal averages, with
70s/80s over interior valleys and 80s/90s along I-25 and across the
southeast plains (KLAA was a toasty 97f and KSPD 94f at 2pm).
For the remainder of the afternoon and tonight, mainly isolated
thunderstorms will continue over the mountains and interior valleys,
though most activity will produce more wind than rain given surface
dewpoints in the 30s and CAPE only a few hundred J/KG. Suppose some
outflow winds and sprinkles are possible through the I-25 corridor
from 4-7 pm, with most CAMs showing activity dying out east of the
Interstate. Showers/storms end toward sunset, with clearing skies
and decreasing winds overnight into Tue morning.
On Tuesday, upper ridge flattens and low levels slightly moisten
with weak short wave energy drifting across the area by afternoon.
As a result, should see a a modest upturn in storm strength and
coverage, with again mountains and interior valleys favored for
storms, though a few CAMs drift some storms eastward along the
Palmer Divide by late afternoon. Best coverage of storms initially
would appear to be over the ern San Juans/srn Sangres, though HRRR
shows some stronger storms over the Pikes Peak region after 23z. Max
temps will continue to run above seasonal averages, with readings
within a couple degf of Monday`s numbers.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 235 PM MDT Mon Sep 9 2024
Tuesday night through Wednesday...A trough of low pressure off the
Pacific NW coast deepens Tue, then moves onshore across WA and OR on
Wed. West to southwest flow aloft begins to increase into Wed,
drawing some Pacific moisture across the Desert SW and Four Corners
regions into the western half of CO. A weak shortwave in the upper
flow will spark increased convection chances across the higher
terrain both days, with scattered to likely pcpn chances for the
Continental Divide and the central mts, and scattered convection for
the remaining high terrain. Low temps Tue night will drop into the
40s for the high valleys, and 50s for the plains. Maximum temps for
Wed will climb into the 70s for the high valleys, and mid 80s to
lower 90s for the plains.
Thursday and Friday...Pacific NW upper low will push across ID on
Thu, then up across MT into Canada on Fri. This pattern produces a
fairly strong trough over the western third of the country on Thu,
which then transitions to more zonal flow on Fri. Both scenarios
keeps warm temps in place for the forecast area into the weekend,
but the stronger southwest flow aloft for Thu will produce stronger
downslope flow, which means dry and gusty conditions leading to
enhanced fire danger. Plan on the absence of pcpn chances both days,
with elevated fire danger for portions of the plains on Thu. As for
temps, expect highs in the 70s to near 80F for the high valleys, and
mid 80s to mid 90s for the plains.
Saturday and Sunday...Long range models indicate that another trough
begins to develop just off the West Coast over the weekend, while an
upper disturbance out ahead of it pushes across the Four Corners. At
this point, timing and strength are still a question, but there is a
hint that this feature will bring a chance of some showers to at
least the higher terrain both days, as well as enhanced cloud cover
that will cool max temps a couple of degrees. As always, stay tuned.
Moore
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 537 PM MDT Mon Sep 9 2024
VFR conditions expected at COS, PUB and ALS over the next 24
hours. Convection this afternoon remains tied to the higher
terrain, however, an outflow boundry will move across PUB
bringing brief westerly winds to the termainl shortly after
00Z. Otherwise, convective clouds to slowly clear overnight
with generally light diurnal wind regimes. A better coverage
of showers and storms is expected across the region tomorrow
afternoon, with the best chances of seeing shra/tsra at the
terminals being at ALS aft 20Z. Could see shra/tsra approaching
COS late in this taf period.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...PETERSEN
LONG TERM...MOORE
AVIATION...MW
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
831 PM EDT Mon Sep 9 2024
...New UPDATE, AVIATION...
.UPDATE...
Issued at 830 PM EDT Mon Sep 9 2024
It was a slow start to the convection today thanks to the abundant
clouds this morning which delayed heating and the sea breezes.
However, once the sun came out we saw the sea breezes move inland
with scattered to numerous showers and thunderstorms developing.
This convection will wind down this evening and should end around
or shortly after midnight over land with partly to mostly cloudy
skies overnight. Northeast to east low level flow and moist
conditions will favor the development of some low clouds again
later tonight into Tuesday morning similar to this morning. This
along with the east to northeast flow should keep most of the
convection from developing in our area until mid to late afternoon
into the evening hours with showers and thunderstorms moving west
southwestward back toward the west coast. Current forecast looks
on track with no changes planned at this time.
&&
.AVIATION...
(00Z TAFS)
Issued at 830 PM EDT Mon Sep 9 2024
Scattered convection will wind down by midnight with VFR
conditions expected for most of the area overnight. However, areas
of low clouds causing some MVFR/IFR conditions are expected later
tonight into Tuesday morning. VFR conditions should return by
afternoon, but then more numerous showers and thunderstorms are
expected to develop after 19Z which could cause some more
MVFR/local IFR conditions. Northeast to east winds at 4 to 8 knots
overnight will continue through Tuesday morning, then shift to
more northwest to west at SRQ, PGD, FMY, and RSW during the
afternoon before the northeast winds return late in the day.
&&
.DISCUSSION...
Issued at 208 PM EDT Mon Sep 9 2024
The synoptic pattern shows broad upper ridging and surface high
pressure well to the north sitting over the Ohio River Valley and
mid-Atlantic states. A stationary frontal boundary remains stretched
from west to east across northern Florida, while high pressure
ridges across southern Florida. Cloudy conditions along the
stationary boundary will persist through the day. Not a whole lot of
change in this pattern is expected through at least Thursday
morning. Most of the region will remain predominately on the south
side of that stationary frontal boundary keeping west central and
southwest Florida in a warm and moist environment. PWAT values will
remain quite high ranging between 2.0 - 2.4 inches over the region.
This will continue to support scattered to numerous showers and
storms each day through Thursday.
The latest HRRR guidance for today has the bulk of the showers and
storms developing early afternoon along the east coast and interior
and traversing slowly westward during the late afternoon/evening on
an east-southeast wind flow. As we have seen over the past few days,
some of these storms could cause some localized flooding impacts
over already saturated soils. All of west central and southwest
Florida remains in a Marginal Risk of Excessive Rainfall each day
through the middle of the week. Daytime highs will top out in the
mid 80`s along the Nature Coast to low 90`s over central and
southwest Florida, with heat indices reaching 95-105 degrees each
day.
The tropics are becoming active with Tropical Storm Francine located
in the southwest Gulf of Mexico. This storm is forecast to
strengthen to a hurricane by Tuesday evening as it moves northward
through the western Gulf of Mexico toward Louisiana. There are also
2 other areas in the central Atlantic that has a 60 percent of
development over the next 7 days. The good news is that neither of
these systems pose a threat to the Florida peninsula at this time.
By Thursday morning, Tropical Storm Francine will have made landfall
over Louisiana and will continue moving northward over Mississippi.
This will allow the upper ridging and surface high pressure over
southern Florida to shift slightly northward, which in turn will
shift the stationary boundary slightly northward as well. Models are
hinting at some slightly drier air over the region for the latter
part of the forecast period with PWATs ranging between 1.8 - 2.1
inches. This is still adequate for scattered showers and storms each
day over the weekend, but not as numerous as we have seen over the
past week.
&&
.MARINE...
Issued at 208 PM EDT Mon Sep 9 2024
High pressure will hold north of Florida through the rest of the
week as a stationary frontal boundary remains stretched across the
northern Gulf of Mexico through at least midweek before lifting
north by the latter part of the week. This pattern will keep a
predominant east and southeast flow in place with wind speeds
remaining around 15 knots or less. Tropical Storm Francine is
forecast to move north through the western Gulf of Mexico through
the first half of the week, potentially increasing swells over the
eastern Gulf by Wednesday.
&&
.FIRE WEATHER...
Issued at 208 PM EDT Mon Sep 9 2024
A stationary frontal boundary remains stretched across northern
Florida with high pressure over south Florida. This pattern will
favor warm and humid weather through the week. Scattered to numerous
showers and storms can be expected each day through the period. No
fire weather concerns are expected.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 76 88 75 88 / 40 70 40 70
FMY 76 92 76 91 / 50 80 40 70
GIF 75 89 75 89 / 50 80 30 70
SRQ 76 90 75 90 / 50 70 40 70
BKV 74 89 74 88 / 30 70 30 70
SPG 79 89 78 90 / 50 70 40 60
&&
Sea Breeze Thunderstorm Regime For Tuesday: 2
Sea Breeze Thunderstorm Regime For Wednesday: 6
For additional information on sea breeze regimes, go to:
https://www.weather.gov/tbw/ThunderstormClimatology
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION...Close
DISCUSSION/MARINE/FIRE WEATHER...Wynn
DECISION SUPPORT/UPPER AIR/CLIMATE...Giarratana/Ulevicius