Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/14/24
Area Forecast Discussion
National Weather Service La Crosse WI
1054 PM CDT Tue Aug 13 2024
.KEY MESSAGES...
- Widespread showers/storms likely from late Wednesday
afternoon/evening into Thursday with locally heavy rainfall
possible. This looks to be the highest chance for rain over
the next week with medium to high (40-80%) chances for at
least 1 inch.
- Below to near-normal temperatures are expected over the next
10-days and near-normal in the 10 to 14 day period.
&&
.DISCUSSION...
Issued at 307 PM CDT Tue Aug 13 2024
Tonight into Wednesday...
High pressure will move slowly east of the area. As this occurs,
a developing low pressure over the Central and Northern Plains
will move slowly east toward the area. 925 and 850 mb moisture
transport will gradually increase during the afternoon. This
initial moisture transport will result in a gradual decrease in
cloud heights. There are still some differences in the CAMs on
when showers will move into the area on Wednesday afternoon. The
NAM and FV3 has them moving into the area by early afternoon.
Meanwhile, the ARW, HRRR, and RAP keep much of the area dry
through mid- to late afternoon.
Wednesday night through Thursday night...
The models are in good agreement that the low pressure system
will move slowly east northeast through the area and gradually
deepen. Even though it will be deepening, the 0-6 km shear
primarily remains at 30 knots or less. There is a small window
on Thursday afternoon where the 0-6 km shear does climb up to 40
knots in southwest Wisconsin. However, 0-1 km mixed-layer CAPES
at that time ranges from 500 to 1500 J/kg, so the marginal risk
from SPC looks good. With precipitable water values of around
1.5 inches and warm cloud depths of 3.5 to 4 km, these showers
and storms will be highly efficient rain producers. WPC has the
area under marginal to slight risk for excessive rain for this
time period and that seems reasonable. Most areas will likely
see anywhere from 0.75 to 1.5 inches of rain. The 48-hour HREF
QPF has 2 areas where the ensemble probability-matched mean
climbs into the 2 to 3 inch range. The first area is in
northeast Iowa and there is a secondary area from southwest
Minnesota east northeast into the Twin Cities.
From Friday into Saturday...
The surface low continues to move east northeast into the
northern Great Lakes. This will keep scattered showers and maybe
a few storms as shortwaves rotate around this low. With limited
instability and the best moisture to our east, rainfall totals
generally look on the lighter side.
8-14 Day Period (August 21-27)...
The ensembles continue to show that an omega ridge will likely
remain to our west and northwest from mid to to the latter
portions of August. This will favor near- to below-normal
temperatures and below-normal precipitation. The highest
probabilities for below-normal temperatures will be in the 6 to
10 day period (August 19 to 22).
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1055 PM CDT Tue Aug 13 2024
Predominant VFR conditions expected. Some areas of fog will be
possible overnight in river valleys. Southeast winds will
continue overnight and increase to 10 to 20 knots during the
day Wednesday. Rain chances increase in the mid to late
afternoon Wednesday and remain through the rest of the TAF
period. Along with these showers, there is a 25 to 40% chance
for thunderstorms to occur.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Boyne
AVIATION...Cecava
Area Forecast Discussion
National Weather Service Bismarck ND
1013 PM CDT Tue Aug 13 2024
.KEY MESSAGES...
- Low (20 to 40 percent) for showers with an occasional
thunderstorm through tonight, followed by high chances (60 to
80 percent) on Wednesday. A few storms could become strong.
- Torrential rainfall from slow moving thunderstorms could cause
localized flash flooding on Wednesday. The highest risk is
from south central North Dakota to the James River Valley.
- High temperatures are forecast in the 70s and 80s through
early next week.
&&
.UPDATE...
Issued at 1005 PM CDT Tue Aug 13 2024
Updated pops and sky cover late this evening based on the
latest radar and satellite analysis. Heavy rain has ended over
northern Morton and portions of western Burleigh counties. We
can`t completely rule out additional rain later tonight over
these areas, but at this time it looks like the next round of
potentially heavy rain will be Wednesday. Very high PWATs will
remain over the area, so any storms would have the potential to
produce very high rainfall rates.
UPDATE Issued at 709 PM CDT Tue Aug 13 2024
Thunderstorms continue over south central North Dakota. Strong
moisture flux continues into central ND, and the
Bismarck/Mandan area is right on the nose of the high PWATs
lifting into the state and there may be a slight west to east
inverted trough along the I-94 corridor. This was enough to
provide a focus point for convection and convection continues
to redevelop along this boundary. Fortunately for the Bismarck
Mandan areas, the convection remains north of the Metropolitan
area. We still have a couple Flood Advisories in effect. The
first for the Bismarck Mandan area and although the rain has
stopped, it will still take some time for the excess runoff to
abate. The second Advisory is for portions of Burleigh and
Morton Counties, north of Bismarck and Mandan. The ongoing
convection remains mostly sub-severe, but with very high
rainfall rates it`s not taking long for localized flooding in
poor drainage areas. Reports of 2-4 inches of rain were pretty
common around the Bismarck Mandan area, with some higher reports
to the north. Most of the rain in the Bismarck Mandan area fell
in around 20-40 minutes.
Mesoscale models are still having a hard time resolving this
evenings convection, so we manually adjusted pops east over the
next few hours. Updated text products will be transmitted
shortly.
&&
.DISCUSSION...
Issued at 237 PM CDT Tue Aug 13 2024
For this afternoon, shortwave energy continues bringing a few
showers and thunderstorms through the forecast area. More recent
CAMs continue to suggest more isolated coverage through this
evening. As the wave moves further eastward, it enters a less
favorable environment where instability decreases and effective
shear is progged to be around 35 kts or less. So while another
strong storm or two isn`t out of the question, the more likely
scenario is isolated showers and with an occasional thunderstorm.
Tonight through Wednesday is the more interesting period. In
concurrence with the prior shift, agree that despite a marginal
risk, severe weather potential looks pretty limited. RAP model
projections suggest 0 to 6 km bulk shear limited at 20 kts or less
for most areas most of the time, and often time 15 kts or less in
areas with the best instability. More importantly for tonight
through Wednesday is the potential for heavy rainfall.
High pressure over the Great Lakes Region will help advect Gulf
Stream moisture into the Dakotas on Wednesday, with mixed layer
dewpoints likely in excess of 60 degrees. More robust shortwave
energy, gradually becoming a more organized low, is projected
to approach the area tonight and pass through the day Wednesday.
Simultaneous surface low pressure will deepen with an elongated
center most likely over Nebraska and/or South Dakota. As this
system lifts to the northeast, weak upper flow will lead to the
potential for training thunderstorms. Should this happen, the
potential for very heavy rainfall and localized flooding exists.
The HREF ensemble mean maintains lower amounts generally at an inch
and a half or less. However, with thunderstorm activity and the
aforementioned potential for training; the HREF max may play out in
localized areas. This would mean an area, most likely in the
south central (including the James River Valley) could see 4 to
5 inches of precipitation where any training occurs. One
potential limiting factor to heavy rainfall is a lack of
instability in the eastern half of the state. This is reflected
in some CAMs which show more shower or thundershower activity
rather than an organized thunderstorm complex.
Beyond Wednesday, northwesterly flow aloft prevails through
Friday with occasional shower and thunderstorm chances. Ridging
looks to be prevalent for the weekend and into early next week
with limited precipitation chances. Overall, expect seasonable
to seasonably cool temperatures during a very gradual warming
trend with highs mostly in the 70s and 80s. With cloudy skies
and widespread rain, Wednesday looks to be the coolest day
overall.
One final miscellaneous note is that elevated smoke will
persist over much of the area through tonight, with lesser areal
coverage Wednesday through Wednesday night. A little
near-surface smoke may also begin to filter into the west
especially during the day Wednesday. Any visibility reductions
from smoke should be limited.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 709 PM CDT Tue Aug 13 2024
Currently, showers and thunderstorms will continue to track east
this evening and may impact Jamestown. Later tonight and
Wednesday and Wednesday widespread MVFR to IFR ceilings and
visibilities are expected to develop over central North Dakota,
and may expand as far west as KDIK and KXWA. Numerous showers
and thunderstorms are also expected Wednesday across all of
western and central North Dakota, eventually ending from west to
east later in the day.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...TWH
DISCUSSION...Telken
AVIATION...TWH
Area Forecast Discussion
National Weather Service Hastings NE
658 PM CDT Tue Aug 13 2024
.KEY MESSAGES...
- Cluster of showers and thunderstorms expected tonight, mainly
after 11PM and mainly over south central Nebraska. There is a
Marginal Risk (level 1 of 5) for severe storms, with quarter
size hail 60 MPH wind gusts the main threat.
- Warmer Wednesday with additional chances for thunderstorms,
either over the far E during the afternoon-evening, or from
the west overnight. Marginal risk for severe weather.
- Forecast trends drier or at least more "spotty" with rain
chances late week and into the weekend. Temperatures look to
be near-normal with mid 80s to low 90s for highs.
&&
.DISCUSSION...
Issued at 415 PM CDT Tue Aug 13 2024
As expected, clouds have been slow to clear out today thanks to
low level moisture advection on SErly winds. This has kept
mixing in check and allowed for dew points to rise into the mid
60s to near 70 degrees, which is several degrees higher than
recent days. Should be a quiet and seasonably comfortable
evening with a mix of sun and clouds and continued SErly breeze.
Focus then turns to the potential for convection that develops
along the Front Range this aftn/eve to push E/NE into W portions
of the CWA towards midnight. The arrival has trended a bit
later, but will ultimately depend on how activity evolves over
NE CO and evolves (or maybe doesn`t) into an MCS. Recent HRRR
runs seems to remain aligned with general idea presented by the
12Z HREF that activity will be further N than last night, and
have more instability and slightly more shear to work with. So
the SPC Day 1 Marginal Risk (level 1 of 5) seems quite
reasonable. The one thing working against a more organized
threat locally is the later arrival time atop what should be a
fairly stable BL (i.e. weak mixing this aftn). So also agree
that the higher severe probs (Slight risk) should focus off to
our W/SW. Nonetheless, appears that quarter size hail and 60 MPH
wind gusts will be the main threats with the strongest activity.
While not expecting any hydro issues given recent dry weather,
worth noting that PWATs will be running near +2 std dev tonight
over portions of Neb., so the convection will likely be very
efficient precip producer and put down a quick 1-2" along the
main track, perhaps as high as ~3", in spots. CAMs keep the MCS
moving along, which should limit really high end amounts.
Wednesday sensible weather has shifted around a bit, likely due
to effects from AM convection. In general, the forecast has
trended a bit cooler as the thermal ridge may be "beaten back"
to some extent by the AM outflow. Some hi-res guidance has also
suggested a focus for sfc based convection near a sfc triple
point roughly near the KS/NE border, but perhaps just to our E.
Dew points will be even higher Wed than today and there will be
strong instability in place, so any storms that do form in this
zone could be severe. The updated SPC Day 2 outlook clips our
far E, but agree that the main focus at this time looks to be SE
Neb into NE Kan. The other feature to watch will be a weak cold
front/sfc trough over W Neb. Also expect convection to develop
in this area given steep low-mid level lapse rates and decent
moisture convergence. However, it`s uncertain just how organized
this activity will become amidst otherwise neutral mid to upper
level fields and the aforementioned focus being to our E. It
doesn`t look like there will be a ton to support convection well
past dark, so would think the W 1/3 or 1/4 would be most at
risk. Honestly, the vast majority of our CWA may be sandwiched
in between and not really see a whole lot.
Upper trough deepens and perhaps even closes off for a time over
the Upper MS Valley late week. Some CAMs have hinted at some iso
"pop up" type shwrs/storms over the N/NE Thu aftn under cooler
mid level temps and beneath some weak wrap-around perturbations.
Added some 20% PoPs to account for this. Additional 20-30% PoPs
come on Friday, but confidence on details is low by this point.
Highs will be held in check by the wrap-around NW-N low level
flow, but decent sunshine should still support highs in the 80s
to near 90F (far S/SW).
Upper level pattern really begins to amplify over the weekend
and into early next week with ridging to our W over the Rockies
and troughing from the Great Lakes into the SE CONUS. This
leaves our area and highly meridional NW-NNW upper flow. This
would keep the really hot weather at bay to our SW over S
Rockies/Plains...and really cool weather to our E. So we may be
left in the middle and mostly near-normal. As is typical for
this type of flow, there is a smattering of low-end PoPs in days
5-7, but these are impossible to scrutinize this far out. Worth
noting that with highly amplified upper flow that forecast
changes in temps are certainly possible, even with minor upper
air changes. This is born out in NBM data showing 7-10 deg
spread in 25th - 75th percentiles.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 632 PM CDT Tue Aug 13 2024
For KGRI/KEAR Airports:
There are several aviation concerns mainly tonight into
Wednesday morning with low ceilings and thunderstorms expected.
Thunderstorms to the west of our TAF sites this evening will
gradually track to the east northeast through the overnight
hours. These storms should not enter our TAF sites until after
midnight, maybe as early as midnight to 1 AM in Kearney and then
a bit later than that for KGRI. Some of these thunderstorms
could be strong to severe with the primary threat being strong
wind gusts to over 50 mph. Ceilings will lower just ahead of the
thunderstorms and then remain low (IFR/LIFR) after the storms
pass through about mid morning. The low clouds will eventually
scatter out and lift by Wednesday afternoon with a return of VFR
conditions. Visibility reductions in patchy fog or within the
rain will also be possible late tonight until shortly after
sunrise.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
DISCUSSION...Thies
AVIATION...Wesely
Area Forecast Discussion
National Weather Service Goodland KS
520 PM MDT Tue Aug 13 2024
.KEY MESSAGES...
- Another round of strong to severe storms this evening
currently favoring north of I-70; all hazards are possible,
including flooding.
- 90 degree high temperatures look to return for most of the
next week.
&&
.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 1159 AM MDT Tue Aug 13 2024
Dense cloud cover is persisting throughout most of the Tri-
State area, but southwesterly winds are slowly clearing it out.
Central portions of the CWA can expect some direct sunlight in
the afternoon, but the far northeastern CWA will likely remain
cloudy all day.
Jumping right into the severe thunderstorm threat today, it
appears we will have two separate forcing mechanisms firing off
the storms that will eventually merge into one. Nearly all CAMs
are showing a very similar development this evening with timing
and specific parameters being slightly different between the
models. As a result, confidence is fairly high regarding the
early storm track.
The area that looks to fire off first will be in the
south-central or southwestern CWA, starting around 0-1Z. The
850mb LLJ looks to spark a few (2-5) isolated storms that will
move to the northeast. Looking at 16Z HRRR and 12Z NAMNEST
sounding for the south-central CWA at 2Z, all hazards will be
possible. Effective inflow layer, 0-1 km, and 0-3km shear are
around 25 kts and EBWD is around 45 kts. PWATS are 1.5+ inches
and MLCAPE is around 2650 J/kg. If these storms are able to form
free of any competing updrafts and not cluster together, hail
up to 2 inches would be possible, as would a tornado or two.
The hail threat will be severely limited by the 16,000-18,000
foot moist melting layer, but that increases the potential for
torrential rainfall. Storm motion looks to be around 35+ kts
and these look to be isolated cells or clusters, so the threat
for training storms causing flash flooding is low. These storms
will likely (90% confidence) be ingested by the the second wave
of storms from the east around 4Z.
The second wave of storms will be more widespread and look to
form to the west of the CWA and move east-northeast into the
CWA. These storms will be forced by a lee low ejecting off of
the Rockies. These storms will be in more of a linear
formation. These storms look to enter the western CWA around
1-2Z, absorb the first storms around 4Z, and proceed across the
northern half of the CWA. The storms look to last all night, but
the best time for severe weather to occur from this second wave
will be between 3-7Z. As far as hazards, 70 MPH winds, 1 inch
hail, and a brief QLCS tornado will all be possible. A sounding
from the 16Z HRRR and 12Z NAMNEST in northern Yuma county for 3Z
show around 1,600 J/kg of MLCAPE, PWATS near 1.6 inches, and
EBWD around 30 kts. 0-3 shear looks to be around 20-25 kts from
the south, which is nearly parallel to the orientation of the
storm, lowering confidence on the QLCS tornado potential. The
motion of these storms is concerning for flooding reasons. While
the system as a whole will be progressing to the east-
northeast, the downshear motion will be from the southwest, the
orientation of the line itself. This causes a setup for training
storms to occur, potentially leading to flash flooding. Much
like the first wave of storms, the melting height looks to be
above 15,000 feet and very moist, allowing very efficient hail
melting and warm weather precipitation processes to occur,
increasing the potential for flooding.
Following the storms, the winds are expected to be light and
variable, which will allow fog to form, much like the past few
days. Currently, the northeastern 1/3 of the CWA looks to get
to worst fog, likely dropping down to less than a mile of
visibility. This fog will limit overnight cooling and keep
temperatures in the 60s across the CWA.
Tomorrow morning, as stratus and fog linger throughout much of
the CWA, a mid-level ridge will begin moving into the area.
This will work to lift the fog and stratus from west to east
throughout the day. High temperatures will warm into the upper
80s.
Tomorrow afternoon and early evening, another shortwave will
eject off the Rockies and give us another wave of storms across
the CWA. We could see some severe weather with these storms,
with wind being the primary threat and hail as a secondary
threat. Storms look to enter the northwestern CWA around 0Z and
move southeast through the CWA, exiting around 14Z. Low
temperatures tomorrow night look to cool into the mid 50s to
lower 60s.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 1159 AM MDT Tue Aug 13 2024
The upper level ridge is forecast to build over the Southern CONUS
during this period, eventually building over the forecast area by
the weekend. During this timeframe numerous upper level short wave
troughs will move around the ridge and over the forecast area. While
the weather pattern will be active, confidence for severe weather
goes down as the center of the ridge moves over the forecast area.
However this does not mean severe weather will not occur, just that
confidence is low for it to occur. As the ridge center moves closer
to the forecast area precipitation chances fall into the weekend due
to the storm track being pushed north of the forecast area.
GEFS and ECMWF ensembles both show a better potential for
precipitation Friday than any other day for this timeframe. The
ECMWF is more over Southwest Kansas while the GEFS is along the
KS/NE border. Based on the current GFS and ECMWF model run the
ECMWF ensemble seems to be the most representative with the location
of the precipitation chances.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 515 PM MDT Tue Aug 13 2024
KGLD...VFR conditions are expected through about 01z with winds
from the southeast around 12kts. From 02z-14z, sub VFR
conditions are expected. There is a threat for thunderstorms
impacting the terminal from 02z-08z with reduced visibilities
due to heavy rainfall and stratus that moves in. Winds generally
variable at speeds under 10kts. After 15z, VFR conditions are
forecast with winds from the west to northwest at speeds up to
11kts.
KMCK...VFR conditions are expected through 04z with winds from
the southeast up to 10kts. From 05z-15z, sub VFR conditions are
expected due to thunderstorms and stratus over the terminal.
After 16z, VFR conditions return with winds from the west up to
10kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
SHORT TERM...CA
LONG TERM...JTL
AVIATION...99
Area Forecast Discussion
National Weather Service Gray ME
1045 PM EDT Tue Aug 13 2024
.SYNOPSIS...
A tranquil evening is expected tonight as high pressure holds
over the area. Mostly clear skies are expected across NH and ME
tonight before some valley fog develops across portions of
western NH tomorrow morning. Scattered thunderstorms develop
tomorrow and Thursday afternoon. Some storms tomorrow may
contain small hail and gusty winds. Friday looks to be more
pleasant with storms mainly staying contained in N NH and NW
ME. After Friday, more unsettled weather is possible through
this weekend and potentially even into early next week as well.
Hurricane Ernesto passes offshore late this weekend and early
next week, bringing an increasing swell and dangerous rip
currents by late this weekend and early next week.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
946 PM Update...
The last of the isolated showers will continue to dissipate over
the northern mountains late this evening. This will leave the
region with dry condition, albeit, patchy fog will develop,
especially in the Connecticut River Valley.
822 PM Update... Quick update to raise pops over northern
areas. A few showers may make its way across the international
border and into Maine over the next hour or two before
dissipating. This is supported by the latest HRRR and NamNest
solution.
Update...
Mainly clear skies continue this evening across the region with
with some cloudiness lingering across the northern higher
terrain. Patchy fog will develop once again tonight, mainly in
the Connecticut River Valley and mainly after midnight.
Otherwise, little in the way of changes to the near term portion
of the forecast.
Prev Disc...
Skies generally clear out of the region this evening, allowing
for a tranquil evening ahead. With a crisp and calm night ahead,
the CT river valley could see some valley fog tomorrow morning.
Some lighter patchy fog is possible elsewhere but light winds
will likely keep western and central Maine mixed, preventing the
formation of fog out there.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
Tomorrow, an upper-level low positioned over eastern Maine may
bring some scattered thunderstorms tomorrow afternoon. Chances
of seeing a thunderstorm are higher across central ME and the
Midcoast, but everyone has a chance of seeing a storm. These
will likely be garden variety thunderstorms, with heavy
downpours, small hail, and perhaps a few strong wind gusts as
well. Storms will move from north to south tomorrow afternoon.
Tomorrow night, storms clear the area before fog possibly
develops early Thursday morning.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Overview...
A series of troughs move through the Northeast late this week
and through the weekend, bringing multiple chances for showers
and storms, as well as near average to seasonably cool
temperatures. Tropical storm Ernesto is expected to strengthen
into a Hurricane and pass offshore this weekend and early next
week, bringing an increasing swell and dangerous rip currents
starting this weekend.
Details...
A cutoff low deepens across Atlantic Canada on Thursday, with
multiple shortwave troughs rotating around it starting on
Thursday. With this feature, increasing clouds, showers, and
storms develop during the afternoon on Thursday, with the
greatest coverage across the higher terrain. These gradually die
off after dark. A weak shortwave ridge moves through on Friday,
bringing a brighter and relatively drier day. However, with the
cutoff low and cold pool aloft still nearby, some scattered
showers are still possible Friday afternoon, especially across
northern and eastern areas.
By Saturday, the next trough begins to dig in through the Great
Lakes. This brings an increasing chance of showers late in the
day, especially across western and northern areas. These
continue to spread eastward overnight as low pressure develops
through the Great Lakes and slowly drifts eastward. A ridge
develops and remains nearly stationary across Atlantic Canada
over the weekend. This slows and nearly stalls the system in the
Great Lakes from making much eastward progress, allowing
eastern areas to stand a better chance at remaining drier. This
pattern continues through Monday, with another reinforcing
shortwave transiting the trough going into Tuesday.
While all this is going on across the Northeast, Ernesto is
expected to become a hurricane and pass offshore this weekend
and early next week, likely passing close to Bermuda this
weekend. An increasing swell from the system is expected to
begin arriving by Saturday, with waves gradually building
through Monday, and then slowly lowering from Tuesday through
midweek next week. There remains some question as to how much
the trough across the Northeast will interact with Ernesto and
affect its track. While it`s expected to remain offshore, this
interaction will determine how close Ernesto will pass by to
New England, and the angle that it will be tracking while
offshore. These factors impact how large the waves will build
to, and the strength of the rip currents. Regardless, the long
period swell begins to arrive by Saturday, likely starting as a
2ft swell with a 16 second period, and then gradually build
through Monday. To how large remains in question and dependent
on the track distance and direction, which will be the main
question to solve over the next few days. Regardless, rip
currents begin to strengthen by Saturday and remain a concern
through at least midweek next week.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Short Term...
VFR expected the remainder of this evening. Some fog is
expected along the CT river, lower CIGs at LEB and HIE. Confidence
is high in LIFR CIGs due to fog at LEB. Low stratus likely at HIE,
lowering HIE to IFR early tomorrow morning. Otherwise tomorrow
starts as a VFR day, but thunderstorms could bring restrictions
tomorrow afternoon with higher confidence in these lower CIGs at AUG
and RKD. More patchy fog is possible Thursday morning with low CIGs
possible across all TAF sites.
Long Term...Mainly VFR conditions are expected, but periods of
MVFR ceilings and showers are likely at times from Thursday
through early next week, especially across interior terminals
during the afternoon and evening. Nighttime valley fog is also
likely at LEB and HIE each night.
&&
.MARINE...
Short Term...
Southwesterly flow at 7-12kts with 1-3 ft seas expected this
afternoon. Winds shift to the northwest at 7-12kts by tomorrow
morning with no change in seas. Scattered thunderstorms possible
tomorrow afternoon, especially in Penobscot Bay. Outside of
convectively driven wind gusts, wind speeds should generally calm
through the afternoon. No SCAs are expected through Thursday morning.
Long Term...Weak pressure patterns prevail as broad high
pressure gives way to broad low pressure late this week through
the weekend. Hurricane Ernesto likely passes east of the Gulf of
Maine late this weekend and early next week, bringing an
increasing southeasterly swell starting by Saturday. The swell
may build to greater than 5ft by Sunday.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
Cannon/Clair
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
912 PM CDT Tue Aug 13 2024
.KEY MESSAGES...
- A couple periods of thunderstorms are expected later this week,
one Thursday morning and the other in the evening/nighttime
hours of Thursday. The latter one has the better chances for any
strong to severe storms.
- The storms also have some potential to produce heavy rainfall
amounts, though details on exact placement are a bit murky at
the moment.
- After a short period of more typical mid-August temperatures,
late week and early next week will see a modest cooldown.
&&
.UPDATE...
Issued at 859 PM CDT Tue Aug 13 2024
Would still like to see a few of the other 00z solutions (NSSL
WRF, ARW, etc) before jumping to conclusions, but feeling more
confident that Wednesday and Wednesday evening will remain
relatively rain-free across our western counties, such that we can
trim the slight chance PoPs to below 10-15%. Otherwise, the
latest 00z HRRR exhibits a very underwhelming convective event for
central Illinois during the late Wednesday night into Thursday
morning time period, with only a few elevated thunderstorm
clusters. The main show will occur late Thursday afternoon into
Thursday night as we become increasingly unstable ahead of a cold
front. Most 00z hi-res guidance barely begins to resolve that
period, so we remain lean on timings/locations for now, and will
thus maintain broad likely thunder mention.
MJA
&&
.SHORT TERM... (Through Late Wednesday Afternoon)
Issued at 256 PM CDT Tue Aug 13 2024
Latest surface map shows high pressure centered near northern Lake
Michigan. Some diurnal cumulus has formed across the forecast
area, with some delay where the earlier mid-level clouds had hung
on the longest. The MCS continues to roll across southern Missouri
but has been weakening, and a bit of thinning of the high clouds
has occurred along its periphery. A general decrease in cloud
cover will begin in earnest after sunset, and skies over our area
should be mostly clear by mid evening.
Morning high-res models trended slower with the eastward
progression of the line of showers/storms that is expected to form
over the central Plains overnight, and most show the line fizzling
as it comes into western Illinois. PoP`s have been trimmed back
some and generally limited to the far western CWA. Otherwise, a
general increase in clouds is expected tomorrow, though a fair
amount of sunshine is expected. While temperatures will be
comparable to today, southeast winds will result in a general
uptick in dew points and make it feel a bit more uncomfortable.
Geelhart
.LONG TERM... (Wednesday Night through Next Tuesday)
Issued at 256 PM CDT Tue Aug 13 2024
Wednesday Night-Friday:
-----------------------
Main focus in this period will be with a pair of convective
clusters moving across the region. Morning models continue to show
the first cluster developing across the mid-Missouri Valley
Wednesday evening, moving southeast. HREF guidance has trended
more southeast with its movement overnight, with several of the
individual members bringing the line into the Illinois River
Valley toward 5-6 am Thursday. The highest PoP`s have been
reoriented as a result, favoring the 4 am to noon period.
Precipitable water values are forecast to increase to 2+ inches
during this period, with NBM probabilities of rainfall amounts
over an inch increasing around 60% near/north of I-72 by mid
morning Thursday. While a few stronger wind gusts can`t be ruled
out as the line arrives around sunrise, it should generally be in
a weaker state as it passes through.
Some model discrepancies were noted with the second round late
afternoon and evening, notably the NAM focusing the west-east band
of heavier rain south of I-72. Only a handful of GFS ensemble
members come close to the amount of rain shown by the NAM, but
focus it more northwest, and the European ensembles are generally
lighter. This will probably be one of those situations where
guidance fluctuates until better mesoscale details (not available
this far out) start to get incorporated. In terms of the severe
threat, surface based CAPE`s over 3000 J/kg will be favorable for
convection as it refires later in the afternoon, though shear
levels ahead of the line will be a bit more marginal. Damaging
winds appear to be the main threat.
On Friday, much of the activity will be out of the area. However,
as an upper low swings across the Great Lakes, some wraparound
showers can`t be ruled out, primarily near and north of I-74.
Saturday-Tuesday:
-----------------
Longer range appears to be relatively quiet at this point. The
departure of the upper low over the Great Lakes may be slowed a
tad late week, depending on tropical activity across the western
Atlantic. In general, the upper ridge will amplify again across
the Rockies, with broad troughing setting up over the eastern U.S.
This will keep us in more of a northwest flow, with temperatures a
few degrees below seasonal normals, and humidity levels not
expected to be oppressive.
Geelhart
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 606 PM CDT Tue Aug 13 2024
VFR conditions and light/variable winds will persist tonight as
surface high pressure remains centered over the Great Lakes
region. By Wednesday afternoon, surface winds are expected to
become southeasterly and increase as high pressure begins to
depart. Some mid-level cloudiness will also return on Wednesday as
a cluster of thunderstorms passes southwest of the regional
terminals.
MJA
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1054 PM EDT Tue Aug 13 2024
.KEY MESSAGES...
- Temperatures gradually rise to near normal levels by Wednesday and
remain there through Friday.
- Humidity and the possibility of showers and thunderstorms will
increase late in the week.
&&
.UPDATE...
Issued at 1053 PM EDT TUE AUG 13 2024
Hourly grids were updated based on recent observations and trends.
The thin mid level clouds that had been in place across northern
portions of the area have diminished in areal extent, but some
still remain in the vicinity of the Mountain Parkway or in spots
from KIOB toward KSJS and KPBX per recent observations and
satellite imagery. Otherwise, cirrus is streaming overhead with
the thickest of this crossing the southwest at this time. In most
locations where there mid level deck was not present, temperatures
were in the 60s at this time. However, some ridgetop and more open
terrain locations were nearer to the 70 degree mark.
Hourly grids were freshened up based on recent observations and
trends. Overall, min T for valley locations that had experienced
the thin mid level deck was increased a couple of degrees, with
little or no change in min T elsewhere at this point.
UPDATE Issued at 801 PM EDT TUE AUG 13 2024
A rather thin mid level deck has been quite persistent across the
north late this afternoon and evening, with this deck having
drifted to as far south as near a KJKL to KSJS line. Model
guidance such as the RAP keeps the layer between about 850mb and
700mb with higher rh compared to rh above and below those levels
for much of the night. Weak flow in that layer of around 5KT or
so is also forecast. There is uncertainty as to how long this deck
may persist, but it could affect some areas for much of the
night. Other areas would be left with more significant breaks or
just high clouds. This leads to a lower than average confidence in
overnight lows and the areal extent of ridge/valley temperature
splits. At this point, sky cover was increased in the current general
footprint of this cloud deck through near midnight, but trends
will be monitored. Otherwise, hourly grids were freshened up
based on recent observations.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 355 PM EDT TUE AUG 13 2024
Seeing a general northwest flow pattern aloft through the period.
Subtle short wave features continue to weaken and drift off to the
east through the short term as well, resulting in neutral to rising
heights across the lower/mid Ohio Valley through the period. At the
surface, Great Lakes high pressure will shift eastward to the east
coast, veering our north-northeasterly gradient winds increasingly
out of the east-southeast over the next 24 to 36 hours.
Sensible weather features a continued warming of our daily high
temperatures back up to near normal levels by tomorrow. However,
with drier air mixing down during the daylight hours and a minor
advection of drier air into eastern Kentucky from the northeast,
minimum afternoon surface dew points are expected to fall into the
50s. As a result, overnight lows will be cool and pleasant,
generally in the 50s tonight and tomorrow night. Western valleys
will likely not cool as much tomorrow night as southerly return
flow begins to kick in. Thermal belt temps will also be a bit
warmer tomorrow night. But overall, we will still see overnight
lows averaging a few degrees below our normal low-mid 60s. The
lower overnight temperatures will be aided by a gradual decrease
in cloud cover over eastern Kentucky as well. Otherwise, our
weather will be dry and generally uneventful through the short
term. With less cloud cover overall, conditions will be more
favorable for the development of some radiation fog within the
valleys. However, with cross over temps being so low, expect the
most impactful valley fog (lower visibilities) to remain closer to
water sources.
.LONG TERM...(Thursday through Tuesday)
Issued at 355 PM EDT TUE AUG 13 2024
The large scale upper flow pattern to begin the extended will
feature a large trough of low pressure off the east coast of Maine,
with another trough moving steadily through the Great Lakes to end
the week and eventually into New England over the upcoming weekend.
What will likely be Hurricane Ernesto will be churning northward off
the southeastern CONUS toward Bermuda. Broad ridging aloft will be
in place along the Rocky Mountains, across the four corners region,
and into the desert southwest and southwestern CONUS and southern
Plains. Another trough aloft, based on the latest GFS, will be
pushing onshore. The pattern in the east will shift eastward, with a
cold front moving through the Ohio and Tennessee Valleys Thursday
night and Friday. This front will bring showers and storms to
eastern Kentucky beginning Thursday evening, with scattered activity
slowly spreading into the area overnight. By Friday morning, the
front should finally begin to make a concerted push through the
area, with numerous showers and storms expected across the area by
early Friday afternoon. The rain will linger through Saturday night,
as the front stalls out over the area. We should see additional
rounds of showers and storms Saturday night through Sunday, after
the front has moved away and its parent upper trough spins its way
by to our north. The GFS and WPC analysis were in pretty good
agreement with regards to timing and evolution of the upper trough
and surface front.
The first few days of the period will see temperatures at or just
above normal before the front arrives. After the front has gone, we
should see a cooler air mass filtering into the region, which will
lead to daytime temperatures a few degrees below normal heading into
the first of the upcoming work week. The only weather hazard in the
extended will the normal danger from lightning during thunderstorm
activity.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 750 PM EDT TUE AUG 13 2024
VFR flight conditions will prevail through the period at the TAF
sites. A mid level deck will affect more northern locations such
as KJKL, KSJS, and KSYM initially. Confidence in how long this
persists is not high, but it appears that it may linger for much
of the first 6 hours of the period at least. Elsewhere, mainly
just passing cirrus is anticipated and a few valley locations
immediately near larger bodies of water may experience valley fog
between about 06Z and 13Z with reductions to MVFR. However, fog
is not expected to impact any of the TAF locations. Winds will be
light and variable through the period, averaging between northeast
and east.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...RAY
LONG TERM...AR
AVIATION...JP
Area Forecast Discussion
National Weather Service Lake Charles LA
1005 PM CDT Tue Aug 13 2024
...New UPDATE...
.UPDATE...
Issued at 950 PM CDT Tue Aug 13 2024
Isolated to widely scattered afternoon convection has dissipated,
and quiet albeit warm and muggy conditions are expected
overnight. Another hot day will be on tap for Wednesday, with heat
index values of 108 to 113 degrees common across the area. Made
some small adjustment to Td values for Wednesday afternoon, in the
typical more humid areas near the Atchafalaya Basin and Vermilion
Bay where guidance tends to run a degree or two too high. This
keeps apparent temperatures well above advisory criteria, and a
few spots could hit Excessive Heat Warning criteria of greater
than 113 degrees briefly. This, however, does not warrant issuance
of a warning as these higher readings will be short-lived and
isolated.
Updated text products to reflect these changes as well as to
remove today`s Heat Advisory headline.
24
&&
.SHORT TERM...
(Tonight through Thursday night)
Wx map shows weak surface high pressure ridge over the Eastern
U.S. and Gulf, keeping light south to southwest winds across the
region. Temperatures range from the lower to mid 90s, expecting
mid to upper 90s before the afternoon is over. Dewpoints remain in
the mid to upper 70s, with maximum heat index values 108 to 113
expected this afternoon. Heat Advisory continues through 8 PM.
Radar showing earlier scattered showers and thunderstorms across
the coastal parishes/counties and adjacent coastal waters have
diminished greatly. Latest HRRR guidance shows coverage as well.
Thus, lowered PoPs for this afternoon by about 10% into the
20-40% range. For tonight, mostly clear skies and warm. Low
temperatures in the mid to upper mid 70s north of I-10, near
80/lower 80s I-10 south.
For Wednesday through Thursday night, the mid to upper level
ridge will continue to be centered right over Louisiana and Texas,
continuing the above normal temperatures. Afternoon high temperatures
in the mid to upper 90s along and south of the I-10 corridor,
upper 90s to near 100 further north. Maximum heat index values 108
to 113 expected, possibly higher in some locations. All areas, as
well as our neighboring offices, have issued a Heat Advisory from
late Wednesday morning through the early evening hours. Wednesday
morning low temperatures in the mid to upper mid 70s north of
I-10, near 80/lower 80s I-10 south. Later Thursday morning into
the afternoon hours, preliminary forecast numbers will be very
similar to Wednesday, and chances for another Heat Advisory across
the entire area remain high.
With the influence of the upper level ridge and the limited mid
level moisture, only isolated afternoon showers and thunderstorms
along the I-10 corridor southward can be expected, with even less
chances further north.
08/DML
&&
.LONG TERM...
(Friday through next Monday)
Ridging aloft will remain anchored from the southern Rockies to the
southern Plains throughout the long term period, with the CWA
remaining generally on the southeastern edge of the ridge. With
little day to day changes in the synoptic pattern expected through
the weekend into early next week, a rather repetitive hot and dry
forecast will persist. Temperature wise, we will continue to see
highs in the mid 90s to near 100 degrees, while overnight lows will
generally fall into the mid 70s to low 80s. In addition, heat
indices will likely continue to flirt with or exceed heat advisory
criteria each day, especially along the I-49 corridor and across
lower Acadiana.
Otherwise, minimal rain chances are expected to continue, with NBM
painting POPs around 15-40% each afternoon. With the influence of
the ridge being weaker on our eastern edge, lower Acadiana will
likely see the best rain chances each afternoon. Any showers that do
form will be solely driven by the seabreeze and daytime heating, and
will have to overcome the cap in place aloft, which should keep
coverage isolated to widely scattered at best.
17
&&
.AVIATION...
(00Z TAFS)
Issued at 654 PM CDT Tue Aug 13 2024
Generally VFR conditions and only isolated thunderstorms are
ongoing at this hour. Convection is already showing sign of
winding down and should be over by 01Z. Low clouds will clear out
and only light cirrus aloft will prevail overnight. This little
cloud cover should stop most fog from developing.
Expect similar conditions tomorrow after 15Z with the diurnal
cycle bringing about more showers and thunderstorms in the
afternoon. Convection will be isolated to scattered in nature with
local impacts of gusty winds, heavy rainfall and frequent
lightning.
11/Calhoun
&&
.MARINE...
Light south to southwest winds and low seas expected to continue
through the week. Isolated to scattered showers and thunderstorms
is expected through much of the week as well, with the best rain
chances through the morning hours.
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 76 99 76 99 / 10 10 0 10
LCH 79 94 78 95 / 10 20 0 20
LFT 79 98 79 98 / 10 20 0 20
BPT 78 94 78 95 / 10 10 0 20
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory from 11 AM to 8 PM CDT Wednesday for LAZ027>033-
044-045-055-073-074-141>143-152>154-241>243-252>254.
TX...Heat Advisory from 11 AM to 8 PM CDT Wednesday for TXZ180-201-
259>262-515-516-615-616.
GM...None.
&&
$$
SHORT TERM...08
LONG TERM....17
AVIATION...11
Area Forecast Discussion
National Weather Service Marquette MI
731 PM EDT Tue Aug 13 2024
.KEY MESSAGES...
- 15-25% chance of lake breeze showers, ~15% chance of thunder today
- Patchy fog potential overnight, 20-40% chance of dense fog in
the interior
- Wet period later this week with showers and maybe some
thunderstorms developing Thursday, continuing Friday, then
lingering, but diminishing on Saturday.
&&
.UPDATE...
Issued at 637 PM EDT Tue Aug 13 2024
Scattered showers and thunderstorms are wrapping up across the
western UP, and though some additional weak convection has fired
along the Superior lake boundary in the eastern UP over the past
hour, this is also quickly dying out. Expect clearing skies over the
next couple of hours, followed by a quiet night.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 114 PM EDT Tue Aug 13 2024
GOES-16 Channel 10 Low Level Water Vapor imagery shows mostly dry
conditions at the low levels for virtually all of the eastern half
of the CONUS except for a MCS traveling through MO. RAP
analysis shows broad high pressure over the eastern CONUS from
1016-1020 mb supported by ridging aloft over the central CONUS.
This has resulted in clear skies to start the morning over the
UP. Fairly typical summer weather should result today with high
temperatures in the upper 70s with a few typical warm spots
hitting the low 80s.
The main question of the afternoon forecast is whether or not
thunderstorms will form. Northwesterly flow aloft has advected in
some cooler air aloft to steepen lapse rates, allowing for SBCAPE to
grow to 500-1000 J/kg this afternoon and evening. Moisture may be
somewhat lacking though as efficient mixing will allow surface RHs
to fall as low as 35 percent inland today. CAMs show fairly typical
Great Lakes lake breezes today, so the battle will be between the
broad inhibition of the high pressure or the lift from the lake
breezes to see if any parcels can capitalize on the instability.
However, with flow below 20 kt nearly up to the EL, even if the
instability is realized, any showers or isolated thunderstorms that
do form will just be pulse thunderstorms as there is virtually no
shear to work with to organize and maintain said updrafts.
A quiet night is expected as any showers that do form will cease by
00Z. Another threat for patchy fog tonight as GLAMP gridded guidance
shows sub-mile visibility for much of the UP and the HREF shows 20-
40% probability of 0.5 mile or less visibility by 12Z Wednesday, but
given the inconsistency in fog with similar setups in previous
evenings, will continue to only put fog in the forecast and not go
with any headlines.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 243 PM EDT Tue Aug 13 2024
Upper air pattern consists of a broad 500 mb ridge across the
southern half of the U.S. poking up into the Great Lakes with
troughing in the eastern U.S. and on the west coast 12z Wed. There
is also a shortwave in the northern plains 12z Wed which heads into
the northern Mississippi Valley 12z Thu. This closes off a 500 mb
low Thu night which slowly moves into the upper Great Lakes on Fri.
850-500 mb q-vector convergence and deeper moisture move into the
area on Thu and remain into Fri. This will bring in the next chance
for rain and could be widespread through Friday. Overall, did not
make too many changes to the going forecast.
In the extended, the GFS and ECMWF show a 500 mb ridge across the
southern Rockies into the plains 12z Sat with a trough over the
Great Lakes region. Ridging then builds into northern Rockies 12z
Sun with troughing in the lower Great Lakes and then the ridge moves
back into the northern plains by 12z Mon as troughing digs into the
ern U.S. Troughing then tries to drop into the upper Great Lakes 12z
Tue with a closed low. Temperatures are below normal for this
forecast period. Backdoor cold front hangs around the area as well,
but does look mostly dry.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 730 PM EDT Tue Aug 13 2024
Lake-breeze induced showers are waning across the U.P. as
instability diminishes with sunset. Quiet weather and VFR conditions
are expected for the remainder of the TAF period, however, patchy
fog is possible at all sites before sunrise. Given the fickle nature
of overnight fog the previous nights, have only included a brief
TEMPO of fog and accompanied visibility reduction for all sites in
the 09-12z timeframe. Patchy fog will burn off in the morning sun.
The only forecast concerns for the remainder of the period are
showers and thunderstorms along lake breeze development in the
afternoon, but opted to leave coverage out of the TAFs for now since
confidence on timing and exact location is low.
.
&&
.MARINE...
Issued at 243 PM EDT Tue Aug 13 2024
Light winds less than 20 knots remain through Wednesday night.
Thu/Fri, low pressure will develop e and ne into WI, bringing
increasing easterly winds to Lake Superior. Expect winds to
occasionally gust to 20-25kt, particularly Thu aftn and Thu night.
Exact track of the sfc low will determine whether these stronger
wind gusts continue on Fri. As the low departs, n to nw winds may
gust to 20-25kt late Fri into Sat, mainly across the e half of Lake
Superior. Winds then drop below 20 knots on Sunday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
UPDATE...
SHORT TERM...GS
LONG TERM...07
AVIATION...BW
MARINE...07
Area Forecast Discussion
National Weather Service Reno NV
1208 PM PDT Tue Aug 13 2024
.SYNOPSIS...
* Plan on typical late day breezes through the end of the work week
with localized fire weather concerns.
* Cooler temperatures persist this week along with some low chances
(8-10%) for showers along the OR border Wednesday-Thursday.
* More widespread, stronger winds may kick up this weekend as a
stronger low approaches the West coast.
&&
.DISCUSSION...
Temperatures are running about 5 to 8 degrees cooler regionwide
today which is a welcome reprieve from the hotter mid-August highs!
These cooler conditions will continue with valley temperatures in
the mid-80s to low-90s, 70s in the Sierra valleys, and 60s in the
higher elevations. One caution will be that some overnight lows in
Sierra valley communities may drop into the 30s with pockets of
freezing temperatures possible (15-25% chance this weekend). There
will still be smoke/haze in the vicinity through the week with
ongoing fires nearby. Generally, HRRR simulations keep much of the
smoke aloft aka "up high" to where we shouldn`t see much of a
degradation in air quality in the valley areas.
Ensemble cluster analysis continues to highlight a general trough
just off the PacNW and West coast through the upcoming week. This
will keep the temperatures cooler, but also promote some enhanced
breezes here and there through the forecast. Primarily typical
breezes are forecast each day with west to southwest winds 10-20
mph and gusts up to 30 mph. The stronger wind days appear to be
tabled until the weekend as a closed low approaches the West
Coast. While we may experience short duration, localized critical
fire conditions through the week, the period to watch will be over
the weekend with the stronger upper level support and
strengthening surface pressure gradients. The increasing south-
southwest flow projected across the Sierra and western Nevada for
Sat-Sun could result in impacts to aviation, lake recreation, and
fire weather.
Blended guidance continues to highlight a 10-30% chance of
showers and a few thunderstorms for the far northern portions of
the region Wednesday evening through Thursday evening as an upper
level trough swings through the Pac NW. For now, the best
instability and shear associated with the trough passage will
remain north into OR, but still can`t rule out a handful of
showers and storms for far northern Washoe and Lassen counties,
including the Surprise Valley.
-Edan
&&
.AVIATION...
VFR conditions continue through the period. Main hazard continues
to be gusty winds. West to southwest winds with speeds 10-15 kts
and gusts to around 25 kts return from 18-04Z. LLWS and turbulence
is still likely in areas along and adjacent the Sierra this morning,
especially south of Lake Tahoe towards KMMH through 15Z.
Slantwise visibility may be slightly degraded later this afternoon
due to smoke/haze from the Gold complex near Verdi/Mogul, but latest
simulations are fairly sparse with the smoke output.
-Crespo/Edan
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
Area Forecast Discussion
National Weather Service Tucson AZ
118 PM MST Tue Aug 13 2024
.SYNOPSIS...
Isolated thunderstorms can be expected the rest of today, mainly
east of Tucson. Atmosphere dries out for the next few days, before
monsoonal activity picks up once again this weekend.
&&
.DISCUSSION...
Some convective activity has sporadically started to pop up across
the CWA early this afternoon. Nothing thus far have been severe in
nature, but that will likely change as the afternoon goes on.
The environment today is such that ample moisture is available and
DCAPE values are AOA 1100 J/kg, with the steering flow at mid
levels having a westerly component. This should keep storms
moving at a nice clip towards the east, and likely keep the main
activity east and south of the Tucson Metro area.
The last few runs of the U of A WRF HRRR have backed off on storm
coverage and intensity, but it`s not capturing the current
situation very well, so will take this with a grain of salt.
Something to keep an eye on today will be the interactions between
particular storm cells, and how they may enhance rainfall rates.
Terrain will play a factor as well, depending on whether storms
set up in a favorable place to create some localized flash
flooding.
After today, the upper level high will move east through the end
of the week, which should provide us with a few down days before
the monsoon ramps up again this coming weekend. This pattern shift
will also bring high temperatures up a few degrees above normal
from Wednesday into the weekend.
&&
.AVIATION...
Chances for SHRA and TS at all terminals this afternoon and
evening, with localized MVFR conditions possible. Visibility
restrictions, gusts to 45 kts, heavy rain, and mountain
obscurations likely with any thunderstorm. Wind outside of
thunderstorms will be less than 12 kts and favor a west to
southwesterly direction. Aviation discussion not updated for TAF
amendments.
&&
.FIRE WEATHER...
Isolated to scattered thunderstorms expected again this afternoon
and evening. A downturn in thunderstorm chances is likely
tomorrow and Thursday, with moisture and thunderstorms returning
by the weekend. Temperatures warm a few degrees above normal the
second half of the week. This trend brings minimum relative
humidities down to around 15 to 25 percent in the valleys. Outside
of thunderstorm outflow winds, 20-foot winds will generally be 15
mph or less, with afternoon/early evening gusts to 20-25 mph and
light winds overnight.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Public...Singer
Aviation...Singer
Fire Weather....Singer
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
538 PM MDT Tue Aug 13 2024
.KEY MESSAGES...
- Strong to severe storms are possible tonight and Wednesday, but
offset timing of the key ingredients will limit the severe potential.
- An upper ridge begins to rebuild toward the end of this week,
persisting into next week, bringing warmer and mostly dry
conditions; however, small chances of daily showers/storms will
remain.
&&
.DISCUSSION...(This Evening Through Tuesday)
Issued at 128 PM MDT Tue Aug 13 2024
The latest water vapor images and 500-mb RAP model analysis
showed a ridge across the central CONUS with an upper low over
WA/OR. Southwest flow aloft was fairly moist with above-average
PWATs streaming toward the CWA. Short-wave troughs were embedded
in the flow, with a more notable one over western WY. The visible
and DCP satellite images showed considerable clouds across the
CWA, especially west-central through south-central SD. Although
MLCAPE was 500-1500 J/kg in this area, the MLCIN also was
respectable at -50 to -200 J/kg. Most of the shower/thunderstorm
activity from earlier today has dissipated/moved east of the CWA.
Otherwise, a weak cool front was over northwestern MT with a warm
front/trough extending southeast across eastern WY.
The timing of the aforementioned wave over western WY will not be
ideal for thunderstorms during peak heating today. The best Q-vec
convergence isn`t until 06-18z. Most of the CAMs have caught on to
this and have delayed the onset of the stronger convection until
around 00z. The threat of severe storms remains somewhat in question
given the poor timing and modest midlevel lapse rates. At the same
time, there is sufficient MLCAPE and 0-6km shear for a few
supercells to develop across southwestern into central SD late this
afternoon and evening. This is consistent with the 12z HREF guidance
as well. In addition, storms will be slow moving, which when
combined with PWATs of around 175 percent of average could lead to
some locally heavy rainfall. This would be more likely later in the
evening when the LLJ increases along with low-level warm advection.
The short-wave trough will be crossing the CWA on Wednesday, again
resulting in rather poor timing relative to peak heating. 0-6km
shear also will be weaker on Wednesday versus today. At the same
time, this will drag a weak cool front across the CWA after midnight
tonight -- reaching KRAP early in the morning and KICR late in the
afternoon. This could favor the stronger storms to be mostly in
that area. PWATs will be lower tomorrow in the wake of the short-
wave trough. Another short- wave is progged to cross the CWA
tomorrow night with additional chances of showers and storms. This
short-wave trough will exit the area Thursday, with a drier
period late Thursday through most of Friday, but then another
short-wave by late Friday that could bring additional chances of
thunderstorms. Midlevel lapse rates might be steeper at that time,
fostering a better chance of robust updrafts.
The upper ridge begins to rebuild towards the end of the week, and a
gradual warming (and perhaps drying) trend will recommence through
the weekend. Although we expect mostly dry conditions, some short-
wave troughs moving through the ridge will continue to keep small
chances for showers/storms around. Cluster analyses and spaghetti
plots depict upper ridging over the central CONUS persisting through
much of next week.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Wednesday Evening)
Issued At 537 PM MDT Tue Aug 13 2024
Isolated showers and thunderstorms can be expected this evening
with local MVFR/IFR visibility in the stronger storms. Outside of
storms, VFR conditions will prevail.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION/KEY MESSAGES...Bunkers
AVIATION...15