Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/31/24
Area Forecast Discussion
National Weather Service La Crosse WI
1047 PM CDT Tue Jul 30 2024
.KEY MESSAGES...
- Periodic storm chances continue through Thursday. Confidence
in timing/location of storms remains lower, but the higher
chances for storms look to be Wednesday night into Thursday
(60-80%). A few severe storms, including locally heavy rain,
are possible.
- Very warm, humid conditions will continue through late week.
Peak heat indices in the 90s to locally near 100 expected
Wednesday.
&&
.UPDATE...
Issued at 800 PM CDT Tue Jul 30 2024
Based on latest observational and guidance trends, have greatly
reduced the coverage and magnitude of the precipitation
forecast for tonight. Late afternoon storms that developed over
north-central Wisconsin are gradually decaying with the loss of
daytime heating and increasing subsidence/loss of shear in the
wake of a upper level shortwave axis that is now moving into the
UP of Michigan.
Meanwhile, to the south, the airmass over central and eastern
Iowa is still recovering in the wake of today`s MCS, though a
mid-level ACCAS field over western Iowa would indicate that
destabilization is starting to take place. The skies are devoid
of any low to mid-level clouds northeast of a Sioux City to Des
Moines line and with neutral to even rising height tendencies
tonight, there is little to indicate that the instability will
surge northward overnight.
The last 6 hours of HRRR runs have latched onto this idea with
a new MCS developing around midnight in central Iowa and
tracking ESE. This would once again place the forecast area
within general subsidence and minimal risk for storms north of
Highway 18. Therefore, have coordinated a scaling back of the
PoPs into Wednesday morning with confidence in the afternoon
pattern hinging on how the overnight storms behave.
&&
.DISCUSSION...
Issued at 241 PM CDT Tue Jul 30 2024
This Evening-Wednesday:
A lower predictability weather pattern continues through mid-week
with weak large-scale forcing, some capping, and mesoscale
boundaries/waves providing lift for storms regionally. Early
afternoon radar loops showed decaying showers across southern
Minnesota as low- level moisture transport weakened and boundary
layer stabilization occurred in the wake of convection sliding
south across southeast Iowa. Additional storms were occurring
with a MCV passing east across northern Wisconsin. Although RAP
soundings maintain some inhibition through the afternoon,
relatively lower CIN is indicated across parts of central/north-
central Wisconsin. A few storms could not be ruled out late this
afternoon/evening, especially across north-central/central
Wisconsin, but this evolution/coverage is uncertain. With
effective shear increasing to 30-40 kts and MLCAPE reaching
1500-2500 J/kg, a conditional risk for a strong/severe storm
with wind/hail and localized heavy rain exists if storms form
(20-30% chance).
Another weak wave ejecting from the northern plains may result
in additional showers/storms overnight/early Wednesday across
parts of the region. There is some uncertainty in how this
convection evolves (timing and location), but right now the
higher chances look to be south of I-90 with the axis of
strongest moisture transport generally favored across Iowa.
Beyond these storms, there is not a clear signal for additional
daytime storms through much of the day on Wednesday as
transient shortwave ridging builds into the area. Assuming
little interference from storms, a hot/humid day is expected
with heat indices into the 90s for most, perhaps near 100 in a
few areas. Early morning fog is possible again late tonight,
particularly in valleys, if skies remain clear overnight in some
areas.
Wednesday Night-Thursday:
A pronounced mid-level trough will approach from the northern plains
Wednesday night, slowly progressing across the Upper Mississippi
Valley Thursday. Areas of showers/storms may develop from the
west Wednesday night ahead of the wave with shower/storm chances
persisting through Thursday when forcing from the wave is
maximized. High precipitable water values nearing 2" and deep
warm cloud depths will favor locally heavy rainfall, especially
with slower-moving storms. Some potential would exist for severe
storms Wednesday evening/night if MCS development occurs
Wednesday afternoon to the west and is maintained eastward into
the area. Additional showers/storms are likely beneath the
trough on Thursday, but weak deep layer shear may be a limiting
factor for organized stronger storms.
Friday-Tuesday:
A typical summertime pattern will persist late this week into early
next week with a large mid/upper ridge centered over the Rockies and
northwest flow aloft along its eastern periphery extending into the
Upper Midwest. A modestly drier, more seasonable airmass is
expected, especially by late weekend into early next week.
Predictability of shower/storm chances in this regime is low,
influenced by any waves sliding southeast along the edge of the
ridge. Overall, the signal for rain among EPS members is
minimized over the weekend with 20-40% shower/storm chances
early next week.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1045 PM CDT Tue Jul 30 2024
IFR to LIFR fog may develop along and east of the Mississippi
River valley after 07-09Z tonight, though the thickness and
coverage of the fog will be driven by the the degree of high
clouds overnight. The fog/low ceilings lift by 13-14Z with VFR
conditions through the late afternoon. The risk for showers and
thunderstorms increases from west to east after 22Z, with the
greatest risk for storms occurring overnight and into early
Thursday morning. Winds during the period will be around 5-10
kts from the south to southeast, except around thunderstorms.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
UPDATE...Skow
DISCUSSION...JM
AVIATION...Skow
Area Forecast Discussion
National Weather Service Des Moines IA
642 PM CDT Tue Jul 30 2024
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
- Low confidence in details, but the overall pattern continues
to support several rounds of thunderstorms into Wednesday
night with severe weather and heavy rains possible.
- Excessive heat is expected to build into central and southern
IA Wednesday, but that is conditional on overnight and early
Wed convective trends
- Seasonal heat and humidity, but drier, less active weather to
end the week and the weekend
&&
.DISCUSSION...
Issued at 347 PM CDT Tue Jul 30 2024
Our weather looks to remain active through at least Wednesday
night with IA on the northern fringe of southern Plains upper
level ridging, and the southern edge of the westerlies and PV
trough axis which currently extends from UT into NE. A mainly
wind producing MCS and its associated mesohigh pushed outflow
out of the state and into MO where it is currently reinforcing
the synoptic scale warm front. This has led to the cancellation
of all previous Heat Advisories. However elevated convection
continues to fester southeast of the Des Moines metro, likely
driven by baroclinicity and warm advection toward 700 mb. Model
guidance has been doing very poorly with details on convective
timing and location, including incorrectly not expecting much at
all at the moment. This leads more to nowcast tools and pattern
recognition to try and pin down trends into tonight. The
current elevated convection is likely giving a clue to where the
elevated boundary will fire again tonight with lingering mid
based clouds over northeast NE as well. While it doesnt appear
to be strong, the latest RAP guidance suggests 0-2km moisture
convergence will linger essentially along the NW-SE axis that
is currently active. 850mb moisture continues to pool upstream
across NE, and while it will not be strong (20-30kts), it should
be sufficient for typical nocturnal/warm advection development
upstream through the MO Valley later this evening. There does
not seem to be much potential for surface based development
anytime soon with the lack of cumulus development upstream.
Much like the recent past a forward propagating wind producing
MCS seems to be the most likely scenario later tonight, per the
SPC Enhanced Risk. For instance, the 18z HRRR sounding at
Carroll for late this evening is somewhat alarming with 3-4K
J/kg MUCAPEs, 1200 J/kg DCAPEs, and 50kts of effective shear in
an elongated hodograph. Heavy rains are also in play. While the
12Z HREF and its members dont` seem to have much utility it
trying to pin down details, most members suggest some form of an
MCS with heavy rain potential and 24hr localized probability
matched mean noting the potential for isolated 2-5. Thus have
issue a Flood Watch for excessive rain/flash flooding in a NW-SE
axis, relatively lined up with where heavy rains have fallen
over the past few days. More hydro details in the Hydrology
section below.
Looking ahead into tomorrow confidence remains low. The general
synoptic pattern begins changing with a bit more amplitude and
a transition to southwest flow. This may be more conducive for
the warm front and thermal ridge building into IA, and would
result in 105-110F heat indices building into the state.
However this is somewhat conditional as what occurred today is
still in play with the potential for an overnight MCS surging
outflow southward. The heat index forecasts tomorrow are tough
to ignore, so have played a middle ground and issued a Heat
Advisory for Wednesday afternoon. An upgrade to an Excessive
Heat Warning and cancellation are both unfortunately in play as
well depending on overnight convective trends. The forecast into
the evening becomes a little more straight-forward with
synoptic scale forcing helping to drive convection along and
ahead of the approaching cold front. With extreme instability
and more than sufficient effective shear, an Enhanced Risk of
severe weather seems appropriate per SPC.
The weather should turn less active into Thursday, although
chances for showers and a few storms will linger north and east
as the current ID/MT upper wave deepens into the Upper MS
Valley. For the end of the week and into the weekend, our
current southern Plains ridge builds into the Rockies with
surface high pressure and weak northwest flow in place Friday
into Saturday.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 642 PM CDT Tue Jul 30 2024
VFR conditions remain across the terminals this evening, with
mainly high clouds over portions of central into southern Iowa.
The main concern is the remaining potential for showers and
storms, which look to arrive into the region later this evening
into Wednesday morning. Uncertainty remains on the higher end at
this time in terms of exact timing and coverage, though given
recent trends would expect most activity to impact mainly KDSM
and KOTM, but will continue to keep a close eye on how
conditions evolve over the next several hours. Would expect
periods of lowered ceilings and reduced visibilities at times
with any storms that move through the area. Additional shower
and storm activity is possible into the afternoon to evening
Wednesday, though will depend on the outcome of the previous
activity.
&&
.HYDROLOGY...
Issued at 347 PM CDT Tue Jul 30 2024
Once again flash flooding will be possible from this afternoon into
at least Wednesday. In spite of maturing crops (which usually limit
flash flood potential this time of year), recent heavy rainfall has
led to elevated soil moisture values (and thus elevated flash flood
concerns) across much of the CWA. Right now the NASA SPoRT 4-inch
soil moisture as well as CREST and SAC-SMA upper-level soil moisture
parameters all agree on elevated soil moisture values roughly north
of a line from Sioux City to Winterset to Centerville. While soil
moisture values are elevated across much of the CWA north of this
line, the most elevated values are roughly within a 75-mile band
north of that line. In this area the soil moisture values are
elevated such that flash flooding concern is significantly higher
than normal.
With this aforementioned 75-mile wide band, it will take
significantly less rainfall than typical for this time of year to
produce flash flooding. Flash flood guidance values within this
region are as low as 1.7 inches over three hours which could easily
be achieved and exceeded with the potential rainfall through
Wednesday. Even outside this 75-mile band if the rain is heavy
enough then flash flooding would be possible elsewhere across the
CWA especially within a 125-mile band north of the aforementioned
line. Of course urban flooding will be a concern as well regardless
of location with the heavy rainfall amounts that are possible.
In terms of potential river flooding, it would be heavily dependent
on the amount, location and timing of the heavy rainfall. Although
the rivers in the area of most concern through Wednesday have
recovered significantly from the high stages associated with the
flooding last month into the early part of this month, much of the
Des Moines, Skunk and Cedar/Iowa River basins are still reporting
above (76 to 90th percentile) to much above normal (greater than
90th percentile) flows for this time of year. Right now the most
likely scenario according to QPF hydrograph ensemble and HEFS
guidance is that there would be minor to moderate rises on area
rivers with isolated moderate to significant rises possible in
isolated areas.
Make sure to stay up to date on the latest forecasts and river
information, avoid flooded areas and rivers, and never drive around
barricades or through flooded areas.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM to 7 PM CDT Wednesday for IAZ033>035-
044>048-057>061-070>075-081>086-092>097.
Flood Watch through Wednesday morning for IAZ034>036-045>049-
058>062-072>075-085-086-097.
&&
$$
DISCUSSION...Small
AVIATION...Bury
HYDROLOGY...Zogg
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1154 PM EDT Tue Jul 30 2024
.KEY MESSAGES...
- Warm and humid conditions will persist through Friday.
- There is a chance of thunderstorms each day this week. Strong to
severe thunderstorms will be possible both Wednesday and Thursday.
&&
.AVIATION...
Conditions overnight marked by a moist near surface environment and
diminishing gradient flow within the backdrop of weak surface
ridging. Assuming higher level cloud cover from ongoing convection
upstream remains sufficiently thin, this environment will support
some degree of fog formation late tonight. Forecast will maintain a
conservative outlook with visibility restriction holding at 3-5
miles, but a brief dip below this level remains plausible at one or
more terminals early Wednesday morning. A moist and unstable
environment may encourage a low coverage of convection late
Wednesday, but confidence in occurrence remains very low attm.
For DTW/D21 Convection...Conditions may prove favorable for a low
coverage of thunderstorms to develop over the airspace late
Wednesday afternoon and evening.
DTW THRESHOLD PROBABILITIES...
* Low for thunderstorms late Wednesday afternoon and evening
* Low for ceiling 5000 ft or less Wednesday afternoon and evening.
&&
.PREV DISCUSSION...
Issued at 356 PM EDT Tue Jul 30 2024
DISCUSSION...
An upper-level shortwave and associated MCV now resides over western
Ontario, where broad mid-level subsidence has filled in within its
wake across western Michigan. For the remainder of the afternoon and
evening hours, shortwave ridging will briefly fill in over MI, in
response to a secondary shortwave that is located over northern
Wisconsin. This will maintain dry conditions for most locations,
outside of the exiting activity near the eastern Thumb and Metro
region. Will retain low PoPs (15%) through portions of the Tri-
Cities and Flint region this evening to account for weak low level
convergence that holds this evenig.The main response with this will
likely just be some increasing cumulus with the tail-end of daytime
heating, but cannot rule out stray showers. A weak cap along with
the building subsidence and expansive dry layer aloft are major
inhibiting factors for any meaningful precipitation chances.
Overnight, the continuation of dry weather is expected, with
clearing trends leading to the chance for fog development. The
aforementioned shortwave/MCV over northern Wisconsin is riding along
the instability and will outpace the instability reservoir, with
expectation that convection will dwindle as it paces into northern
lower Michigan. A secondary complex is expected to initiate over
NE/IA, where a large reservoir of CAPE resides. The nocturnal jet
will likely fuel a MCS that will track into IL/IN. The integrity of
this system will be challenged leading into the mid to late morning
hours once the intensity of the nocturnal llj wanes and orientation
of the jet turns a more unfavorable W-E. Nearly all hi-res models
outside of the NAM12 track this system south of the state line, so
impacts from this direct system itself are low but will be worth
monitoring overnight. Any type of impacts across SE MI would likely
be sourced from two MCS derived outflow boundaries or land/lake
differential heating boundaries to lake breezes. Hi-res models
provide an assortment of plausible scenarios pertaining to the
above, which is not atypical in this high dew point/weaker forcing
scenario.
Instability will build towards 1,500 J/kg through tomorrow afternoon
and evening while deep layer shear approaches 30 knots. Storm
relative hodographs showcase weak 0-1 km shear but subtle elongation
between 1-3 km with a good degree of streamwiseness, w.r.t the rap
output. This will support the marginal chance to see strong to
severe storm development for all of SE MI. Storm modes can range
between isolated pulse, multicluster, or possibly small linear with
bowing segments given the unidirectional flow in the low to mid
levels. Wind gusts to 60-70 mph will be the primary threat, with
hail to an inch as a secondary threat. Steep low level lapse rates
and DCAPE aoa 1000 help support wind as the primary threat. But
again, this is a conditional, lower confidence setup, and thus will
retain about a 40% PoP chance, noting the possibility of strong
storm intensification. Any precipitation chances will dwindle
through Thursday morning as another shortwave ridge builds into the
Great Lakes. Otherwise, highs in the mid to upper 80s are expected
through the afternoon, and with dewpoints approaching or hitting 70,
it will feel very humid outside.
Thursday evening into Friday morning will feature another chance for
showers and thunderstorms, specifically from an MCS that is expected
to develop from a passing shortwave across the northern Plains. This
system retains a chance to impact portions of the southern Great
Lakes, but the exact evolution of the system remains dampened this
far out. Still, southwest flow across the Plains and western Midwest
will fuel convection chances, supporting a moisture rich airmass
that extends into Michigan. This will again support a marginal
chance for severe weather where damaging wind gusts would be the
primary concern. Hot conditions with highs in the upper 80s are
again expected Thursday afternoon.
MARINE...
Remnant showers and a few rumbles of thunder persist this afternoon
with the departure of a low pressure system into Southern Ontario.
Gusts largely hold below 15 knots the rest of today and weaken
overnight with light winds backing westerly in the wake of the low.
Unsettled conditions return as early as Wednesday afternoon with the
potential for convective outflows to initiate a few storms before
low pressure approaches from The Plains. Some differences in model
track remain, therefore the storm/precip coverage over Lake Huron
carries less certainty than western Lake Erie and the connecting
waterways. Isolated strong storms are possible with some of this
activity which presents an opportunity for localized wind/wave
concerns.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
AVIATION.....MR
DISCUSSION...AM
MARINE.......KGK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1100 PM CDT Tue Jul 30 2024
.KEY MESSAGES...
- Dangerous heat expected through Thursday.
- A few chances for severe thunderstorms, mainly for northern
portions of MO through Wednesday.
&&
.DISCUSSION...
Issued at 329 PM CDT Tue Jul 30 2024
In the upper levels, there is broad ridging over the southern CONUS
with troughing in the Great Lakes and Northeast. At the surface,
there are two lows: one to the north over IA and one over western
KS. These lows and their associated frontal boundaries will provide
multiple chances for showers and storms through Wednesday. Since
Monday, an 850-mb thermal ridge has set up to the west over the
Great Plains, indicative of the excessive heat encompassing much of
the central U.S. early this week. An excessive heat warning remains
in effect through Wednesday evening for the entire CWA. Heat indices
may exceed 110 degrees F across the area during the afternoon hours;
however, the presence of storms may locally mitigate excessive heat,
at least temporarily.
Overnight into Wednesday morning, a vorticity maximum will progress
eastward through the northern and central Plains. Convection-
allowing models are depicting convection developing in the vicinity
of this perturbation as it progresses through the central U.S.
However, exactly when and where storms develop is highly uncertain,
with CAMs in unusually poor agreement spatially and temporally
through tomorrow. For example, comparison of the 18z HRRR and NAM
Nest is enlightening. The NAM Nest simulates convection in central
Nebraska moving east-southeastward into northwest Missouri tonight,
whereas the HRRR dissipates these storms before coming close to our
region. Meanwhile, more storms develop in Iowa tonight, but the HRRR
and NAM Nest have timing disagreement of 4-6 hours and very
different evolutions overall, providing little confidence to
thunderstorm coverage/timing anywhere in our region through
Wednesday morning. Meanwhile, another stronger perturbation moves
through the region by tomorrow evening, with another round of
convection expected to develop in the central Plains. CAMs depict
such convection moving into our CWA by tomorrow evening, although
large discrepancies remain on overall timing and severity.
As of now, SPC has a northwestern corner of MO clipped in a slight
risk for severe thunderstorms tomorrow. MUCAPE values ranging from
3,000-4,000 J/kg and lapse rates approaching 8 degrees C/km suggest
plenty of instability. The limiting factor for these storms seems to
be the shear. Shear over our area ranges from 15-25 knots which
suggest storms may remain somewhat disorganized and pulse-like
in nature. Current model guidance suggests most of the
convection remaining north of I-70, but as alluded to above,
confidence is rather low. Damaging winds and small hail seem to
be the primary hazards.
For Thursday, a surface low to our northeast dips farther south
shifting our winds to the north. This will result in a welcomed
decrease in temperatures across the region, along with a prolonged
period of dry weather. However, expect temperatures to still remain
a few degrees above seasonal norms. High temperatures heading
through the weekend are expected to stay around the low to mid
90s.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1055 PM CDT Tue Jul 30 2024
Clear conditions and southerly winds currently prevailing at all
terminals. Gusts between 20-25 knots anticipated at all terminals by
the afternoon tomorrow, as well as the development of diurnal cu.
Winds will remain southerly as gusts fall off during the evening,
with lower ceilings ahead of an oncoming boundary from the
northwest. Winds expected to briefly turn towards the northwest with
the passage of this boundary, with ceilings possibly lowering to
MVFR. There is greater confidence that this boundary will bring
prevailing weather to all terminals, but keeping this mention out of
the TAFs for now, as overall performance of CAMs has remained poor
the past several days. Specific details such as placement, timing,
and intensity may become clearer with later forecast periods.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Excessive Heat Warning until 7 PM CDT Thursday for MOZ028-029-
037-043-053.
Excessive Heat Warning until 7 PM CDT Wednesday for MOZ001>008-
011>017-020>025-030>033-038>040-044>046-054.
Heat Advisory from 7 PM Wednesday to 7 PM CDT Thursday for
MOZ020>022-030>033-038>040-044>046-054.
KS...Excessive Heat Warning until 7 PM CDT Thursday for KSZ025-057-
060-103>105.
Excessive Heat Warning until 7 PM CDT Wednesday for KSZ102.
&&
$$
DISCUSSION...Collier
AVIATION...SPG/Blair
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
544 PM MDT Tue Jul 30 2024
...New AVIATION...
.SYNOPSIS...
Issued at 154 PM MDT Tue Jul 30 2024
Daily afternoon and evening shower and thunderstorm chances will
continue through the week, scattered in coverage over the
mountains and isolated over the desert lowlands. Temperatures will
remain above the seasonal average through the week with highs
topping out in low 100s for the El Paso Metro.
&&
.DISCUSSION...
Issued at 154 PM MDT Tue Jul 30 2024
Overall, no major changes in the forecast from previous forecast
packages with daily afternoon/evening scattered mountain and
isolated lowlands shower/storm chances.
Current water vapor satellite imagery overlayed with 500mb RAP
analysis shows the aforementioned (from over the past few days) high
pressure aloft now over eastern TX and the Red River Valley
vicinity. Typically, this would be good placement for the high in
terms of increased shower/storm coverage across the forecast
area. However, looking at the surface analysis, the corresponding
surface high is fairly displaced towards the SE from the upper
level high. The associated moist surface and low-level flow from
Gulf will remain over the eastern half of TX. That said, moisture
still remains in place across the region, giving us daily
shower/storm chances each afternoon. Afternoon high temperatures
for today and tomorrow will be in the upper 90s to low 100s across
the desert lowlands, 100-103 for the El Paso metro.
By the Thursday/Friday timeframe, the upper level high over east TX
will quickly retrograde back to the NW, centering in the CO/UT
vicinity. Guidance shows this strengthening upper level high
becoming stationary through the long term period, anchoring itself
over the Intermountain West. Expect a continuation of daily
shower/storm chances through the period, scattered mountain and
isolated lowland in terms of coverage. High temperatures through the
period remain above the seasonal average, hovering around the 100
degree mark across the lowlands and low 100s for El Paso.
&&
.AVIATION...
(00Z TAFS)
Issued at 529 PM MDT Tue Jul 30 2024
VFR conditions expected through much of the period with limited
thunderstorm activity this afternoon with low chances of storms
near TAF sites. Otherwise, mild southwest breezes will continue
this afternoon, calming overnight to AOB 10KT. Expect scattered
mountain and isolated lowland thunderstorms popping up again
tomorrow afternoon. Lingering mid and high level clouds expected
over much of the area during the overnight hours.
&&
.FIRE WEATHER...
Issued at 154 PM MDT Tue Jul 30 2024
Fire weather concerns remain LOW through the period. Recent
monsoonal moisture surges and rainfall have helped, as ERC values
below 50th percentile at most sites. Weather wise, scattered shower
and storm chances remain in the forecast for the remainder of today
and through the work week, with the focus and better coverage over
the mountains. Gusty outflow winds, lightning, and wetting rains
will be the primary impacts.
Temperatures through the period will continue running above the
seasonal average with Min RH values each in the 20-40 percent range
of the high terrain and 17-30 percent range over the lowlands. Winds
will be light and generally diurnal/terrain driven in terms of
direction.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 103 80 103 78 / 10 30 20 30
Sierra Blanca 97 72 95 69 / 20 30 40 40
Las Cruces 102 75 101 73 / 10 30 20 20
Alamogordo 100 73 99 72 / 10 10 20 20
Cloudcroft 78 57 75 55 / 40 20 60 20
Truth or Consequences 98 73 98 72 / 20 20 20 10
Silver City 92 67 88 65 / 40 20 60 20
Deming 100 73 98 71 / 10 20 20 20
Lordsburg 97 71 93 70 / 20 20 50 20
West El Paso Metro 101 77 99 76 / 10 30 20 30
Dell City 103 74 101 72 / 10 20 20 20
Fort Hancock 103 75 101 73 / 20 40 40 40
Loma Linda 95 72 93 69 / 10 30 30 30
Fabens 101 77 102 74 / 10 30 30 40
Santa Teresa 100 76 98 74 / 10 30 30 30
White Sands HQ 101 77 100 75 / 10 20 30 20
Jornada Range 100 72 98 72 / 10 20 20 20
Hatch 102 72 100 71 / 20 20 20 20
Columbus 99 76 95 73 / 10 30 30 20
Orogrande 99 73 98 71 / 10 20 20 20
Mayhill 89 62 87 60 / 40 10 50 20
Mescalero 89 62 88 59 / 40 20 50 20
Timberon 88 60 85 57 / 30 20 40 20
Winston 91 61 90 61 / 50 20 50 20
Hillsboro 97 69 95 69 / 30 30 40 20
Spaceport 99 70 98 69 / 20 20 20 20
Lake Roberts 92 62 88 60 / 50 30 70 20
Hurley 95 67 93 65 / 30 20 50 20
Cliff 98 66 98 66 / 40 20 60 20
Mule Creek 94 68 91 67 / 40 20 60 30
Faywood 95 69 92 66 / 30 20 40 20
Animas 96 71 92 70 / 30 40 50 30
Hachita 96 70 92 69 / 20 40 40 30
Antelope Wells 95 69 89 68 / 40 50 60 30
Cloverdale 90 66 83 65 / 40 50 70 40
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
TX...None.
NM...None.
&&
$$
FORECASTER...37-Slusher
Area Forecast Discussion
National Weather Service Grand Rapids MI
803 PM EDT Tue Jul 30 2024
.KEY MESSAGES...
- Low chance of storms through Wednesday night
- Showers/storms Thu/Fri, hot and humid, then drier and a bit
cooler
&&
.DISCUSSION...
Issued at 338 PM EDT Tue Jul 30 2024
- Low chance of storms through Wednesday night
To start, we have a few isolated showers re-firing near/east of
U.S. 127 related to last night`s shortwave which is still nearby
(combined with diurnal heating/1500-2000 Capes). Will carry a 20
pop for a shower or storm through sunset for Clare/Mt Pleasant
down to LAN/JXN.
Unfortunately this remains a low confidence forecast in terms of
convective potential/coverage and timing over the next 36 hrs in
very warm/unstable environment. CAMs continue to struggle with
convective trends in our area, although the main corridor of
better shear/instability continues to be focused just to our
southwest.
Will carry 20-40 pops late tonight into Wednesday/Wednesday night
given the potential for any weak shortwaves and/or upstream
convective remnants/MCVs to drift through the area, although HRRR
forecasts remain dry.
- Showers/storms Thu/Fri, hot and humid, then drier and a bit cooler
Not much change to the going forecast. Quasi zonal flow will keep
the short wave train rolling through Thursday and Friday. The last
wave in the train will roll through later Thursday into Friday and
is the largest of the last several. Pops will ramp up Thursday
afternoon and evening, the diminish a bit with the loss of heating,
then ramp up again Friday afternoon before finally moving east
Friday night.
Chances for severe wx aren`t zero, but not particularly high either.
Models do show pockets of higher shear scattered throughout their
solutions. Heavy rainfall remains possible with well over 2 inches
of precipitable water available Thursday through Friday. Thus, any
storms that develop will be prolific rainfall producers and capable
of producing localized flooding.
Thursday will be hot and humid with highs near 90 and dewpoints in
the mid 70s; pretty oppressive. Given the clouds and rain, Friday
won`t be as oppressive. Conditions will improve Friday night through
the weekend as the short wave moves out and somewhat drier air moves
in. Highs will fall into the lower to mid 80s by early next week.
Humid conditions will remain as dewpoints in the lower to mid 60s
will remain entrenched over the region.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 803 PM EDT Tue Jul 30 2024
Clear skies persist across the area this evening, then higher
level cloud cover from storms to the east filters overhead late
tonight. A moist and stable environment will support radiational
fog development prior to sunrise Wednesday morning should upper
level cloud cover remain thin enough, with visibility mainly down
to 3 to 5 miles. Pockets of convection may develop Wednesday
afternoon but confidence remains low. Overall mainly VFR expected
with pockets of MVFR fog just prior to sunrise Wednesday morning.
&&
.MARINE...
Issued at 338 PM EDT Tue Jul 30 2024
In general, relatively tranquil conditions expected to continue
on Lk MI the next few days in terms of winds/waves. However the
very warm and humid air mass could support some fog patches at
times as well as a few bouts of thunderstorm activity. Any storms
could lead to times of briefly increased winds/waves, although the
timing/coverage of potential thunderstorm events is currently low
confidence.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Meade/04
AVIATION...Thielke
MARINE...Meade
Area Forecast Discussion
National Weather Service Huntsville AL
835 PM CDT Tue Jul 30 2024
...New NEAR TERM...
.NEAR TERM...
(Tonight)
Issued at 834 PM CDT Tue Jul 30 2024
Luckily, the MCS that brought many strong to severe thunderstorms
to central and eastern TN into central Georgia earlier this
afternoon and early this evening moved just east of northern AL
and our southern middle Tennessee counties.
A weak convergence boundary extends NNW west from that activity
just east of the I-65 corridor. Only isolated to scattered showers
(mainly isolated) have occurred along this boundary this evening.
However, upstream of our area a second convective complex has
formed over southwestern Kentucky that is moving southeast towards
the area. Additional scattered strong to severe thunderstorms
have already developed in north central Tennessee ahead of this
activity. HRRR and RAP14 seem to show an increase in 700 mb
forcing pushing into southern middle Tennessee between 3Z and 6Z.
Expect this is likely with that complex of convection moving
southeast at this time.
The storm complex will be moving into an unstable airmass even
into the 10 PM to midnight period based on current dewpoints and
model forecast CAPE. Given forecast shear of 25 to 35 knots
possibly clipping areas near and east of the I-65 corridor when
this convection moves into southern middle Tennessee, think a
strong to severe thunderstorm potential could continue later
between 11 PM and 4 AM as this activity moves into southern middle
Tennessee and into northern Alabama. Damaging winds and frequent
lighting would be the main threats, but small hail could occur. A
watch severe thunderstorm watch will be issued shortly that will
be in effect through 2 AM. This watch may be extended if the
convective storms hold their intensity overnight. Thus, have
increase Pop to between 30 and 60 percent toward midnight into the
3 or 4 AM timeframe near and east of the I-65 corridor. There is
some question how far west this activity will extend at this time.
&&
.SHORT TERM...
(Wednesday through Thursday)
Issued at 110 PM CDT Tue Jul 30 2024
On Wednesday, the upr ridge will expand farther eastward into the
OH/TN Valley regions. This will lead to an increased risk for hot
temperatures and dangerous heat indices as a high dew point air
mass remains in the region. Heat indices are likely to exceed 105
F in most locations on Wed afternoon. The same can be said for
Thursday as the ridge and low-lvl temps increase perhaps a bit
further ahead of a short wave beginning to dig into the Midwest
from the norther. The expansion of the ridge will tend to
encapsulate the region in a more westerly upr flow regime, more
effectively pushing NW flow and chances for showers and
thunderstorms mainly to our east. Due to uncertainty with the
specific extension of the ridging and potential for outflows from
convection, we have retained slight chance/chance POPs in the east
for both days. Due to increased confidence in meeting heat
advisory criteria, a Heat Advisory has been issued for all
counties for tomorrow and into Thursday.
&&
.LONG TERM...
(Thursday night through Monday)
Issued at 200 AM CDT Tue Jul 30 2024
Friday looks to be the last day of heat indices near or exceeding
Heat Advisory criteria as high pressure begins to retrograde to the
west. This will place us under the influences of NW flow, a more
favorable pattern for additional rain and storms. Low PoPs are
introduced Friday afternoon and maintained through the weekend as a
trough swings through the Ohio Valley. Diurnal heating will be able
to take advantage of the favorable pattern allowing for scattered
showers and storms each afternoon. While there are no significant
severe signals right now, this weekend will need to be monitored
through the week for MCS potential given the favorable pattern.
Models indicate high pressure building back east through the day on
Monday with flow transitioning to the NNE.
&&
.AVIATION...
(00Z TAFS)
Issued at 711 PM CDT Tue Jul 30 2024
Winds around 6 knots from the west will become light and variable
this evening after 02Z or 03Z. Uncertainty still exists towards
midnight whether a complex of showers/storms may approach KHSV
arnd 31/06Z, but will not formally include for now. Did include a
tempo group for BKN VFR CIGS between 5Z and 9Z at both terminals.
May have to add prob30 group or temp group for -TSRA activity if
the convective complex develops upstream and maintains itself SE
in future updates. If so, would more likely be at KHSV and some
MVFR to IFR CIGS or VSBYS could be possible.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory from noon Wednesday to 7 PM CDT Thursday for
ALZ001>010-016.
TN...Heat Advisory from noon Wednesday to 7 PM CDT Thursday for
TNZ076-096-097.
&&
$$
NEAR TERM...KTW
SHORT TERM....KDW
LONG TERM....RAD
AVIATION...KTW
Area Forecast Discussion
National Weather Service Northern Indiana
737 PM EDT Tue Jul 30 2024
.KEY MESSAGES...
- Low confidence in the next 24 to 36 hours in regards to timing,
coverage, intensity, and track of thunderstorms.
- Better chances for showers and thunderstorms Thursday through Saturday.
Thursday afternoon and evening looks like it will be the best
chance for strong to severe storms.
- Very hot and humid midweek with highs in the upper 80s to low
90s and dewpoints in the mid to upper 70s. Peak afternoon heat
indices may be as high as the upper 90s Wednesday and
Thursday, but this is highly dependent on coverage of showers
and storms.
&&
.DISCUSSION...
Issued at 209 PM EDT Tue Jul 30 2024
The weak trough that moved through the area last night continues to
slowly move off to the east with a stationary boundary just south of
the CWA. Subsidence behind the trough should limit any convection
today from developing into more organized showers and thunderstorms.
The partly cloudy skies and high dew points should allow high
temperatures today to reach well into the 80s with heat indices well
into the 90s. This hot and humid pattern will persist until at least
Thursday. With highs in the upper 80s to low 90s, dewpoints in the
mid to upper 70s, and heat indices in the 90s, conditions will
remain just below headline criteria on Wednesday and Thursday.
Forecast heat indices are a bit lower than previous forecasts; they
are now in the mid to upper 90s as opposed to the lower 100s due to
increasing confidence in showers and storms Wednesday and Thursday.
Today, the axis of highest wind shear exists from about southern MN
to southern IL. As currently seen on visible satellite imagery in
Iowa and southern Illinois, storm complexes should form and drift
southeastward along this corridor, and they should remain well
southwest of our CWA today. Some scattered showers and storms cannot
be totally ruled out through this evening with high humidity and
decent CAPE, but better chances for more organized rain chances will
likely have to wait until Wednesday morning/afternoon.
In general, this forecast is quite complicated and filled with
uncertainty. Mesoscale models often struggle at resolving short term
trends and development of MCSs and how these complexes affect
instability in the atmosphere. Regardless, over the next couple of
days, there appear to be two distinct, but subtle, mid-level trough
features that rotate southeastward along the periphery of the large
ridge to our southwest. By tonight, a weak shortwave trough should
begin progressing through Nebraska and Iowa. Several of the models,
such as the HRRR, suggest that this new mid-level feature could be
the catalyst for another organized MCS behind our ongoing complexes
of storms in Iowa and Illinois. This trough and its associated rain
chances should generally move east to east-southeast towards Indiana
by late Wednesday morning. However, models disagree heavily on
timing, location, and strength. The HRRR keeps this new feature
mostly south of the CWA while the GFS keeps it farther north over
most of the CWA. It is likely that this feature will be weakening as
it moves closer to us, which is denoted by the low, Day 2 Marginal
Risk (level 1 of 5) from SPC. There seems to exist the
possibility of additional storm formation along remnant outflow
boundaries later on Wednesday in localized areas of increased
convergence, which should keep rain chances elevated through
most of the day. The main risks on Wednesday should be limited
to localized damaging winds and heavy rainfall. Our second
feature arrives as a more robust trough that dips into the upper
midwest late Wednesday/early Thursday.
The greatest chances for severe weather comes on
Thursday/Thursday night as a deepening, positively tilted upper
level trough and associated surface cold front move through.
Dewpoints in the mid to potentially even upper 70s will result
in ample instability Thursday afternoon and evening. 12Z
soundings from the GFS and NAM depict a high CAPE, low shear
environment Thursday, with only 20-25 kts of 0- 6 km and MLCAPE
of 3000 to 5000 J/kg. Moderately steep low and mid level lapse
rates of 6 to 7 C/km and upwards of 1000 J/kg of DCAPE should
support a favorable environment for severe weather. Damaging
wind gusts appear to be the main threat at the time, but I
wouldn`t rule out some hail or a tornado or two. LCLs below
1000m and low level 0-1 km SRH of 100 to 150 m2/s2 could lend to
a brief tornado or two occurring, especially if it is embedded
in QLCS or cluster of storms. Despite these favorable parameter,
severe weather is not 100% certain Thursday as early morning
convection and lingering cloud cover could stunt diurnal
heating and destabilization later in the day. SPC currently has
a Slight Risk (level 2 of 5) for Thursday, which seems warranted
given the uncertainty that remains.
The severe threat diminishes but showers and storms will linger into
Friday and Saturday as the trough closes off. Quiet, dry conditions
return Sunday through at least early next week as an area of high
pressure sinks south over the Great Lakes region from central
Canada. Highs will still be warm in the mid 80s but it will be
noticeably less humid with dewpoints in the low 60s.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 735 PM EDT Tue Jul 30 2024
Fairly stable flow off Lake MI and a cap as well as large scale
subsidence today kept shower/storm potential low and this will
likely remain the case in the first 12 hours of this TAF
period. West winds allow a more unstable airmass into the area
overnight into Wednesday, but the ridge axis also begins moving
closer to the area allowing for more instability, but less
forcing outside of convectively enhanced boundaries/waves. There
is still plenty of uncertainty with short term models and their
handling of the convective complexes, but have enough
confidence to hold off thunderstorm chances until at least mid
to late morning and perhaps even into the afternoon.
As far as fog chances go, cross-over temperatures will likely
struggle to be met with the increased theta-e advection overnight.
One note is that there could be some haze with MVFR reductions with
the increased low level moisture and light winds, but do not have
the confidence to put it in there with this issuance.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Johnson
AVIATION...Roller
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
841 PM CDT Tue Jul 30 2024
.KEY MESSAGES...
- Periods of thunderstorms expected, especially late tonight
into Wednesday morning, Wednesday night into Thursday morning,
and Thursday afternoon into the evening, some of which could
be strong to severe with damaging winds, large hail and
locally heavy rainfall.
- Very warm to hot and humid conditions continuing through
Thursday outside of cloud cover and precip. influence, then
cooler (and at times showery) Friday, and cooler near the
lake this weekend.
&&
.UPDATE...
Issued at 841 PM CDT Tue Jul 30 2024
Regional satellite imagery depicts a relatively quiet scene in the
general area in the wake of several clusters of thunderstorms that
rolled from central Iowa and into Kentucky throughout the day. The
00Z DVN RAOB shows a classic "worked over" airmass, with a notable
dry pocket from the surface to nearly 500 mb and only modest MUCAPE
near 1000 J/kg, driven largely by steep mid-level lapse rates of
around 8 K/km from around 850 to 200mb. Looking well upstream of our
area, two clusters of thunderstorms are evident across the Plains:
the first along the Nebraska and South Dakota border, and the other
in central South Dakota. CAM guidance favors one or both clusters
growing upscale and racing through Iowa overnight, and charging into
west-central Illinois after daybreak tomorrow morning. The
HRRR/HRDPS have been more or less locked in on such a forecast
scenario for the past 4 to 6 runs, allowing for cautious forecast
confidence.
The fly in the ointment is an area of expansive ACCAS festering
across southwestern and south-central Iowa. Based on RAP-analyzed
moisture fields and observed cloud bases from 5000 to 8000 ft, the
ACCAS appears to be rooted in a layer of moisture between 925 and
700 mb which is being transported northeasterly via broad
southwesterly flow. However, with the moisture pocket "between obs"
(that is, between the 00Z OAX and DVN RAOBs), it`s difficult to
fully ascertain the integrity and depth of the moisture. With that
said, the appreciably large area and increasing depth to cumulus
towers does give me concern that convection is right on the cusp of
taking off (that is, "activating" the EML), indeed, much earlier
than originally forecasted.
Although northeasterly transport winds and continued evaporation via
early failed attempts to initiate convection will help erode the
pocket of dry air sampled by the 00Z DVN RAOB, it is difficult to
fully discern just how far northeast the pocket of ACCAS will reach
before convection actually takes off (assuming it does). Based on
prior experience, we`re probably still 2-4 hours before sustained
convection can take hold. Extrapolating the position of the ACCAS
field would place explosive thunderstorm development somewhere
between Des Moines and the Quad Cities by around midnight, which
would then be poised to surge east-southeastward along an outflow-
reinforced stationary front draped from southern Iowa through
central Illinois. The 18Z HRRR actually looks pretty reasonable in
that regard, with thunderstorms erupting near the Quad Cities and
shifting southeastward into central Illinois toward or just after
midnight. Whatever does develop from the ACCAS field would then be
poised to "set the stage" before the MCS that develops out of the
aforementioned Nebraska and South Dakota convection after daybreak.
Taken altogether, confidence is cautiously increasing that the
highest chances for showers and storms tonight and tomorrow morning
should be across our western and southern forecast zones, generally
from Mendota, IL to Fowler, IN and points southward. With this in
mind, did make modest adjustments to PoPs to feature the highest
values (40-50%) in those areas. Now, if the ACCAS field fails
to convect, the results of upscale growth of the northern Plains
convection would be prone to potentially impacting a larger
portion of our area tomorrow morning, perhaps as far north as
I-88 or even the Wisconsin state line. Needless to say, the
forecast will be adjusted as trends evolve overnight.
One final thing - we do see the thunderstorms near Green Bay, which
appear to now be moving southward toward Illinois. Since the storms
are semi-discrete (that is, not contributing to or being forced by a
surface cold pool), they will be prone to succumbing to increasing
MLCIN. Accordingly, we favor them weakening within the next few
hours. Nevertheless, trends will be watched for signs of upscale
growth, which in that case, would mean chances for storms in far
northern IL would increase (after midnight).
Updated products will be sent soon.
Borchardt
&&
.DISCUSSION...
Issued at 325 PM CDT Tue Jul 30 2024
Through Wednesday:
Convectively reinforced stationary front remains from near the
KS/NE border south of Omaha, arcing southeast across northern
Missouri to near Litchfield IL (south of Springfield) to near
Evansville IN. Morning central IL MCS has tracked well off to
the southeast into Kentucky, while another loosely-organized MCS
was currently following a similar path across west-central IL.
Additional likely-elevated convection was occurring across
central IA, atop the cold pool from this second MCS. Combination
of strongest deep shear and low-level instability (~40 kts
effective shear and ~4000 J/kg MLCAPE) was located along and
south of the aforementioned frontal boundary, though slightly-
elevated convection north of the boundary across western IL will
likely continue to track east-southeast and affect southern
parts of the cwa mainly south of the I-80 corridor through late
afternoon. Can`t completely rule out a risk for some isolated
gusty winds with these storms, though the greatest risk of
severe weather is expected to remain south of the forecast area
in closer proximity to the surface front and associated higher
shear/instability parameters.
Though CAM guidance continues to show considerable spread in
convection coverage tonight into Wednesday, some consensus (and
HREF ensemble output) suggests a lull in coverage this evening
behind early-evening activity across our south. Re-intensification
of a southwesterly low level jet across western IA (in
association with a minor-amplitude short wave emerging from
western NE/SD) is expected to increase warm/moist advection
atop a lingering cold pool and eventual northward-lifting warm
front across parts of IA and western IL again from midnight
onward. This activity would likely spill into northern IL toward
morning as the wave continues to progress eastward and the low
level jet veers. There remains considerable spread in northward
placement of this convection in CAM guidance however, based on
where the effective low-level boundary sets up as well as with
some of the timing details (later HRRR runs develop storms along
the boundary into central IL as early as midnight, but are
slower bringing IA convection into the cwa Wednesday morning).
Thus lower confidence remains in the details.
Overall, have gone with high-chance (50-55%) pops across
northern IL during the pre/post dawn hours, with lower chance
pops settling mainly across our south/southeast counties later
Wednesday morning/afternoon where the combined outflow/frontal
zone is expected to reside. Severe/locally heavy rainfall
potential will exist with these storms, especially across our
western/southern counties closer to the frontal zone and its
associated greater instability/shear corridor. Damaging winds
and locally heavy rainfall continue to be the greatest threats,
though increasing low level shear would support a QLCS tornado
potential for storms which are more surface-based near the
boundary. Convective coverage then looks to be fairly low
especially across our far northern IL counties Wednesday
afternoon, in the wake of the morning MCS. Have maintained
higher chance (30-40%) for our far south/southeast areas, closer
to the outflow/frontal boundary.
Otherwise, warm and humid conditions are expected to continue
Wednesday, with highs near/around 90 and peak heat index values
in the 95-100F range during the afternoon. Some slight lake
breeze cooling is possible along the immediate Lake Michigan
shore.
Ratzer
Wednesday Night through Tuesday:
The convective forecast remains quite uncertain through tomorrow
(Wednesday) night, but then confidence is increasing in higher
t-storm coverage late Thursday afternoon and into the early
evening hours.
Early Wednesday evening, a warm front, possibly merged with
retreating outflow from earlier day convection, will be in the
process of lifting north. An initially capped but potentially
highly unstable environment will reside near and south of the
boundary. With the capping not all that strong, but forcing
lacking, best chance of isolated to widely scattered
thunderstorms (20-30% PoPs) developing in the ~7-10pm timeframe
would be primarily south of I-88. As the low level jet and warm
advection/isentropic ascent ramps up in the late evening and early
overnight, footprint of scattered storms may expand (40-50% PoPs),
with the possible exception of far northeast Illinois.
The signal for a (potentially organized) MCS remains for late
Wednesday night into Thursday morning among most of the guidance,
though its evolution and timing remain highly uncertain. A
weakening MCS missing part of the area to a robust MCS with strong
to severe wind gusts and a flash flooding threat for an
appreciable chunk of the area give an idea on a plausible range of
outcomes (and of course in between the above scenarios). Have
PoPs and thunder chances peaking at around 50%. MUCAPE of 2-4k
J/kg, a shallow near surface stable layer, steepening mid-level lapse
rates are factors that may support convective maintenance/intensity
at a less diurnally favorable time. On the other hand, the less
favorable timing and marginal deep layer effective shear (20-30
kt) could result in steady weakening as the possible/probable MCS
moves into our area.
Thursday PM`s evolution will undoubtedly be affected by what
plays out Wednesday night into Thursday morning, including extent
of remnant showers, cloud cover, and placement of effective air
mass related to outflow boundaries. Maintained chance PoPs around
30% in the morning, with any lingering early AM storms probably
diminishing by the mid to late morning. From Thursday afternoon
into the evening, a robust mid-level short-wave will dig
southeast across the upper MS Valley, with its weak surface low
reflection dragging its trailing cold front through the area.
Stronger large scale forcing, frontal convergence, and erosion
of capping of strongly unstable air mass (3-4k J/kg of MLCAPE),
suggest a favorable window for numerous thunderstorms in roughly
the 4pm-9pm timeframe, some of which may be strong to severe.
Deep layer shear will once again be marginal at 15-25 kt, though
the large instability (including DCAPE) and steep low and mid-
level lapse rates will likely support a damaging wind gust and
marginally severe hail threat. While low-level wind profiles
are generally unfavorable for an appreciable tornado threat,
such high dew points (mid-upper 70s) suggest very low LCLs and
forecast 0-3km CAPE may be enough for outflow boundary
interaction related "funny business".
The short-wave trough will become a closed low by early Friday
over the interior central or eastern CWA. Convective coverage
should steadily diminish in the late evening and overnight as
instability quickly wanes. Friday will likely be showery,
especially in the morning, due to the proximity of the upper
low, with embedded thunder most favored in far interior
sections, especially south of I-80. Shower activity may wind
down in the afternoon from north-northeast to south-southwest
with cooler and slightly drier air working its way inland from
the lake. Thus, for interests in downtown Chicago, the afternoon
forecast appears to be trending more favorably. Temperatures
will top out in the lower 80s inland, and upper 70s near the
lake due to onshore flow.
A quieter weekend then remains in store, albeit with still above
normal temps (mid-upper 80s) and humid conditions away from Lake
Michigan. Looking at lower 80s along the immediate lakeshore.
With northwest flow aloft around the ever-present strong h5
ridging over the interior West, can`t rule out a threat for
storms into the WI state line area toward Sunday evening, though
most areas should be dry. The pattern may turn periodically more
active again next week, and still very warm/hot and humid until
a possible stronger cold front passage beyond Tuesday.
Castro
&&
.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 639 PM CDT Tue Jul 30 2024
Current radar imagery depicts a lake breeze situated just east
of KMDW and KORD with an outflow boundary to the southwest of
KDPA. The lake breeze is slowly advancing west-southwest towards
KMDW and KORD while the outflow boundary is advancing to the
east-northeast towards the Chicago terminals. Current thinking
is that the lake breeze will stall out and not reach the
terminals before the outflow boundary intercepts it and kicks it
back to the east. However, cannot rule the possibility that the
lake breeze crosses KMDW and/or KORD before the outflow
boundary can push it to the east. Have handled this scenario
playing out with a TEMPO for KMDW through 02Z as this looks like
the terminal with a higher chance to see the lake breeze move
through given current radar imagery.
The next area of concern for the TAF period comes early
Wednesday morning as convection is expected near the
terminals. Most guidance suggests this convection being
primarily south of the terminals, however, cannot rule out the
possibility of reduced visibility and heavy rain at any of the
terminals. There also remains a possibility that storms may
form late this evening on the edge of a highly unstable airmass
that is advancing towards the area and persist through much of
the night. Although this scenario does exist, it is not the
favored solution overnight tonight.
Following the potential for morning convection, tomorrow will
have relatively few concerns with light southwesterly winds
and clearing skies. Towards the end of the 30 hour TAF period
for KORD and KMDW, there is another chance for convection,
however, confidence is too low at the current time to include a
PROB30.
Carothers
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1104 PM CDT Tue Jul 30 2024
.KEY MESSAGES...
- Hot and humid Wednesday, with widespread heat indices in the
mid to upper 90s. Heat index values will approach the low 100s
in southwestern Minnesota.
- Damaging line of thunderstorms possible Wednesday afternoon
and evening. Confidence is highest in the threat of destructive
winds across western Minnesota.
- Heat sticks around this weekend, but temperatures are forecast
to trend cooler (low to mid 80s) for much of next week.
&&
.DISCUSSION...
Issued at 251 PM CDT Tue Jul 30 2024
Tuesday afternoon radar imagery is much improved as compared to
this morning, when rain and thunderstorms were ongoing across
southwestern Minnesota and portions of western Wisconsin.
Regional radar display shows the active "ring of fire" pattern
driving multiple organized MCS`s from northwest to southeast
across the Midwest, generally developing and tracking along the
12c isotherm at 700mb which is well to the south of our forecast
area. With this in mind, we expect the skies over south central
Minnesota and western Wisconsin to remain quiet for the rest of
the day and into the overnight hours. RAP forecast guidance
illustrates that the low-level jet will strengthen across south
central Iowa tonight, so it`s plausible that isolated to
scattered convection may develop on the nose of the jet and move
into southern Minnesota. We have included low end PopS to
account for this, though the lack of excitement across the CAM
suite adds confidence that the dry theme should win out for most
locations.
The forecast is set to turn in a more active direction to close July
tomorrow, with heat, humidity, and severe storms all in the cards.
Air temperatures are forecast to warm into the upper 80s/low 90s and
combine with tropical dew points in the low to mid 70s to produce
widespread heat indices in the upper 90s tomorrow afternoon.
Locations in southwestern Minnesota will likely experience a few
hours of heat indices in the low 100s. The combination of heat and
humidity will create extreme instability, which may fuel strong to
severe thunderstorms during the afternoon and evening hours.
Wednesday is a little different compared to the past few days, as
there will be more pronounced forcing from the advance of an upper-
level shortwave trough. Add the ~4000+ J/kg of MLCAPE, a stout
EML aloft (mid-level lapse rates of 8.0-9.0 deg/km), and the
approach of the upper level forcing together and the setup bears
watching for severe thunderstorms capable of producing damaging
winds in excess of 70-80+ mph, along with large hail. There are
a number of solutions on the table from the 12z HREF reflectivity
stamps, but the general idea of a forward propagating MCS developing
to the west in the Dakotas is captured across the CAM suite.
Where and when convection initiates is in flux at this distance,
however we will lean heavily on the northward extent of the
theta-e boundary/instability axis for the tracks that an
organized MCS may travel along tomorrow. Even if the higher end
scenario of a damaging MCS does not materialize, the forcing
aloft should be enough for strong convection to blossom across
the region. Given the progressive nature of the forcing, the
concern for training thunderstorms and a hydro threat will serve
as a secondary concern, however it cannot totally be ignored
given that PWATs are forecast to climb towards the daily max of
sounding climatology. The new SPC Day 2 Outlook reflects the
growing concern for a damaging wind threat across the southern
half of Minnesota, as the Slight Risk has been expanded north to
include most of the area. SPC has introduced an Enhanced Risk
across far southwestern Minnesota, northeast Nebraska, and
western Iowa, which includes a sliver of southern Martin county.
The outlook also includes hatching for significant wind
potential across southwestern Minnesota, where confidence in
damaging wind is the highest. A Marginal Risk remains in place
across western Wisconsin. Confidence is highest in impacts
across western Minnesota, with uncertainty in the eastern extent
of the threat as supported by SPC`s outlook.
In summary, the combination of an extreme thermodynamic environment
and approach of the shortwave will create a favorable setup for
severe weather Wednesday afternoon and evening. The placement of
boundaries from any nocturnal convection and a stationary front tied
to a surface low in Nebraska will be key in determining where the
threat will be the greatest. This is where the highest uncertainty
exists in the forecast at this time, with several guidance members
supporting highest threat further to the southwest near the surface
low (NE/IA). However, there are members such as the RAP, which have
consistently advertised that the theta-e boundary will lift as far
north as I-94, which would open the door for a significant threat
over much of the Slight Risk area in Minnesota. Should the pieces
come together, pattern recognition supports the threat for a forward
propagating MCS with significant damaging wind (80+ mph), large
hail, an a few brief tornadoes possible.
The shortwave will slide east Thursday, however renewed convection
appears likely in far eastern Minnesota and western Wisconsin. We
have included likely PoPs (60-70%) across the eastern portion of the
area. Northwest flow will bring cooler temperatures (low 80s) for
highs Thursday afternoon. The amplification of a ~600 dm ridge over
western CONUS will allow for temperatures to creep back into the
upper 80s and low 90s Friday and Saturday, before large scale
northwest flow takes over and drops highs back into the low to mid
80s from the end of the weekend into next week. Dry weather is
expected through much of the weekend. A few disturbances slide
across the Upper Midwest amid the northwesterly flow next week,
which may bring the chance for isolated to scattered showers and
storms.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1048 PM CDT Tue Jul 30 2024
Areas of patchy mist/fog are still expected early Wednesday
morning through sunrise, mainly in western WI and the river
valleys in central MN. CAMs suggest IFR conditions are most
likely at EAU before fog clears. A line or cluster of
thunderstorms is still expected to move west to east late
tomorrow afternoon into the evening. Thus, have kept PROB30s for
-TSRA across MN and have included them at WI terminals for the
evening hours. One or two CAMs do suggest the possibility of a
morning to early afternoon line of storms moving west to east
across the area. Then, another line of storms would follow
through Wednesday evening. However, forecast confidence is
much lower for this solution so have opted not to include it in
the TAF.
KMSP...Kept PROB30 for -TSRA Wednesday evening with likely
showers prevailing after 07Z Thursday. There is a possibility of
a thunderstorm during the early morning hours Thursday so have
also included a PROB30 for this scenario.
/OUTLOOK FOR KMSP/
THU...VFR. Chc MVFR/-TSRA. Wind NW 5-10 kts.
FRI...VFR. Wind N 5-10 kts.
SAT...VFR. Wind W 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...Strus
AVIATION...CTG
Area Forecast Discussion
National Weather Service Marquette MI
655 PM EDT Tue Jul 30 2024
.KEY MESSAGES...
- Afternoon showers and non-severe storms taper off into the
evening.
- Patchy fog possible tonight (50% chance).
- Warmer than normal temperatures throughout the work week, best
chances (40-60%) for 90 degree highs on Wednesday.
- Isolated to scattered showers graze mainly the WI/MI state
line and the south central U.P. late Wednesday night through
Thursday.
- High pressure to bring pleasant summer weather for much of the
weekend with a trend toward cooler and less humid conditions.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 227 PM EDT Tue Jul 30 2024
Water vapor imagery and RAP analyses show a shortwave ejecting out
of the Arrowhead of MN, which is touching off scattered showers and
storms over far western Lake Superior and the western UP. Weak
synoptic forcing and limited shear preclude any organized strong
convection, but with daytime heating, we`ve destabilized quite
nicely; several hundred to around 1000j/kg of CAPE is analyzed over
the western half of the UP, and higher across the eastern UP where
skies have remained mostly sunny so far. So, would not be surprised
by the occasional stronger storm with small hail and gusty winds.
In fact, storms across NW WI and the western UP have put down gusts
near and in excess of 30mph at times.
Meanwhile, a cumulus field as popped across the eastern UP, but is
quickly eroding behind the lake breezes moving inland from Superior
and Lake Michigan. Some agitated cu is already apparent across
Chippewa and Mackinac counties, with weak radar returns developing
there as well. So, convection may soon develop along the converging
lake breezes, with a similar threat for some stronger wind gusts and
small hail present into the late afternoon.
Once diurnal heating wanes in the evening, showers should decrease
and another quiet overnight is expected with some redevelopment of
fog, especially over areas that experienced precipitation during the
day. Otherwise, expect another fairly mild night as temperatures
drop back to around 60F for most of the interior UP, and in the
lower to mid 60s near the lakeshores.
&&
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
Issued at 435 PM EDT Tue Jul 30 2024
With a warm airmass of 850mb temps fluxing between 17-21C overhead
the next few days, above normal temps continue through the work week
and into the weekend. The best chances for 90 degree or higher max
temps are on Wednesday (~40-60%), but MOS guidance hints at
additional, less widespread, 90s later in the week. This will also
keep overnight temps mild in the upper 50s to 60s. Wednesday likely
stays dry, but chances for showers and storms increase on Thursday
with on and off slight chances then into Friday. A cold front late
this weekend brings another round of possible showers and storms.
From there, precip looks to come from shortwaves riding through the
area.
Starting Wednesday, a warm airmass results in likely our hottest
overall day across the UP with highs in the 80s to low 90s. With
weak sfc ridging extending overhead, a cap noted in model soundings,
and a shortwave staying to our south, dry weather is expected. Given
SBCAPE of 500-1500 in the afternoon, some diurnal cu development is
possible. Lows overnight are expected in the 60s.
Meanwhile, a shortwave trough over the northern Rockies tracks east
to MN by Thursday morning. An associated sfc low around 1000 mb
organizes over NE, moving east-northeast into IA/southern MN. On
Thursday, the trough takes a southeast drift over the western Great
Lakes bringing the sfc low eastward with it. There still is some
uncertainty with the exact sfc low track with the GFS still being
the more northern solution, but the recent guidance has trended the
track further south and there is better agreement on it tracking
along the southern edge of the Great Lakes Basin. For the overall
event, the best chances for showers and thunderstorms are Thursday
afternoon and evening from resulting PVA and peak diurnal heating.
Instability is there with SBCAPE ~1000-2000 J/kg, also mid level
lapse rates do increase to around 7C/km during this period. That
said, severe weather is unlikely as 0-6km bulk shear stays well
below 20 kts so storms will struggle to stay organized. As the low
continues through the basin, slight chances for showers and storms
continue into Friday, but a more drier pattern is favored. Highs are
expected in the upper 70s to 80s Thursday and Friday with lows in
the upper 50s to 60s.
Moving onto the weekend. The shortwave trough and sfc low depart
eastward from the region. A drier period under brief ridging then
continues until Saturday night when a weak sfc trough and
accompanying cold front drop southeast across the region. This
brings a round of showers and storms through the area. Although bulk
shear is finally elevated to around 30-40 kts with mid level lapse
rates nearing 7C/km, instability will be limited with only a few
hundred J/kg of SBCAPE (max of 1000 J/kg) so severe weather isn`t
anticipated. Dry weather returns Sunday evening as high pressure
passes overhead on Monday. There is some spread on timing/track, but
the next expected showers and storms look to accompany a shortwave
early next week. Otherwise, cooler northwest flow behind the cold
front Saturday night likely brings temperatures back down near
normal for the start of the next week.
&&
.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 655 PM EDT Tue Jul 30 2024
CMX should remain VFR through the period. At SAW and IWD, VFR
conditions will give way to MVFR or IFR fog later tonight which
burns back off Wed morning.
&&
.MARINE...
Issued at 435 PM EDT Tue Jul 30 2024
Winds hold mainly below 15 kts through the rest of the work week as
a generally weak surface pattern continues with stability over the
lake. Next chance of showers won`t be until Wednesday night
continuing through Thursday, but confidence remains low (PoPs ~15-
30%). However, if rainfall does occur marine fog formation will be a
possibility given high dew points lingering over the area.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Dense Fog Advisory until 8 AM EDT Wednesday for LSZ245-248>251-
265>267.
Lake Michigan...
None.
&&
$$
SHORT TERM...LC
LONG TERM...Jablonski
AVIATION...07
MARINE...Jablonski
Area Forecast Discussion
National Weather Service Tallahassee FL
901 PM EDT Tue Jul 30 2024
...New UPDATE...
.UPDATE...
Issued at 901 PM EDT Tue Jul 30 2024
The previous forecast appears to be on track, and no major changes
were made.
&&
.NEAR TERM...
(Through Wednesday)
Issued at 318 PM EDT Tue Jul 30 2024
Northwest to northerly flow will continue on the downwind side of an
upper high spinning over the ArkLaTex. Some mid level dry air will
continue through the column, tamping PWATs through much of the area
below 2 inches, and opening the door for strong gusty winds in
convection into the evening hours and once again on Wednesday. The
HRRR is advertising a complex of storms developing late this
afternoon and evening with the east coast seabreeze in south central
Georgia moving southwest this evening into the northern Gulf of
Mexico. Did keep rain chances elevated for this feature into the
evening hours and will watch this area if it develops for the next
shift.
Another hot day in store for Wednesday with highs in the mid 90s
with heat index values above advisory levels once again with
readings of 108-112F. A heat advisory will be issued for the daytime
hours. Much of the convection may be pinned once again to the
Florida counties under northerly flow with more isolated airmass
convection into the southeast Alabama and southwest Georgia areas.
&&
.SHORT TERM...
(Wednesday night through Thursday night)
Issued at 318 PM EDT Tue Jul 30 2024
The second half of the week will feature hotter temperatures as
highs push into the middle to upper 90s Thursday afternoon.
Overnight lows won`t cool off all that much with temperatures
settling in the middle to upper 70s. Rain chances won`t be as high
as recent days, but will still remain in the forecast, primarily
along the sea breeze, Thursday afternoon.
The region will be on the eastern edge of a building 597dm H5 ridge
to start the period. Being on the eastern edge of the ridge means
there remains a chance for a thunderstorm complex to sag south
around the edge of it. However, the best chance for rain will remain
primarily in Florida along the seabreeze.
&&
.LONG TERM...
(Friday through Monday)
Issued at 318 PM EDT Tue Jul 30 2024
The H5 ridge will begin to retrograde to the west as a robust
shortwave trough moves through the Upper Midwest and the Great
Lakes. As a result, rain chances will increase slightly for the
weekend as temperatures nudge down a degree or two, but still remain
in the middle 90s, this weekend into early next week.
It`s also worth mentioning that a tropical wave currently well out
in the Atlantic Ocean will trudge towards the Turks and Caicos
and near the Bahamas Friday into Friday night. After that, there
is a large degree of uncertainty as to whether the tropical wave
develops and passes east of the Florida Peninsula or remains
rather weak and manages to make it into the Gulf of Mexico. This
could impact our forecast in that if it stays in the Atlantic, we
could be a bit drier and warmer than currently forecast next
week. The inverse would be true if the wave moves into the Gulf of
Mexico. There`s still a lot of time to monitor this system, so be
sure to stay updated with the latest forecast as we head into the
weekend and early next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 753 PM EDT Tue Jul 30 2024
Convection had mostly dwindled down this evening outside of
isolated activity invof DHN, so VCTS is maintained for another
couple hrs. Quiet wx is expected tonight except perhaps ABY where
an upstream storm complex may sag just south enough to impact the
site. Therefore, intro`d thunder from 6-8Z to acct. Low cigs/vsbys
may infringe on DHN/ABY/VLD in the early morning hrs. Good
convective coverage tmrw yields aftn VCTS at all terminals with
PROB30s for TSRA from 18Z to end of this TAF cycle.
&&
.MARINE...
Issued at 318 PM EDT Tue Jul 30 2024
Overall, mostly favorable marine conditions are anticipated through
the rest of the week and into the weekend. Light and variable winds
are expected with seas around 1 to 2 feet. Showers and thunderstorms
are possible each evening and morning over the waters and should
diminish during the day. These storms may feature gusty and erratic
winds with waterspouts possible.
&&
.FIRE WEATHER...
Issued at 318 PM EDT Tue Jul 30 2024
There are minimal fire weather concerns for the next few days with
daily chances of showers and thunderstorms. Gusty and erratic winds
with frequent lightning are expected within or near any storms.
Outside of thunderstorms, afternoon high temperatures will reach the
mid to upper 90s with heat indices approaching or exceeding 110F.
&&
.HYDROLOGY...
Issued at 318 PM EDT Tue Jul 30 2024
Precipitable water values (PWATs) nudge closer to 2", that`s still
enough to produce torrential rain within any of the stronger
thunderstorms. That said, the coverage of showers and thunderstorms
is forecast to be lower than we`ve seen the past several days and
primarily confined along the seabreeze. Nuisance and localized flash
flooding will remain possible within any of the stronger storms
through the remainder of the week and into the weekend.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 76 95 76 96 / 30 60 10 50
Panama City 79 93 79 93 / 20 60 10 30
Dothan 77 96 76 97 / 20 50 0 30
Albany 77 95 76 97 / 20 40 10 30
Valdosta 76 96 76 97 / 30 50 10 40
Cross City 75 94 76 94 / 40 60 10 60
Apalachicola 79 91 80 91 / 20 60 10 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory from 11 AM EDT /10 AM CDT/ to 8 PM EDT /7 PM CDT/
Wednesday for FLZ007>019-026>029-034-108-112-114-115-118-
127-128-134.
GA...Heat Advisory from 11 AM to 8 PM EDT Wednesday for GAZ120>131-
142>148-155>161.
AL...Heat Advisory from 10 AM to 7 PM CDT Wednesday for ALZ065>069.
GM...None.
&&
$$
NEAR TERM...Scholl
SHORT TERM...Reese
LONG TERM....Reese
AVIATION...IG3
MARINE...Reese
FIRE WEATHER...Scholl
HYDROLOGY...Reese
Area Forecast Discussion
National Weather Service Great Falls MT
806 PM MDT Tue Jul 30 2024
.SYNOPSIS...
Scattered showers and thunderstorms diminish and end by late this
evening. High pressure then builds in for the second half of the
work week and brings a return to dry and hot conditions.
&&
.UPDATE...
The only adjustments of note were to the location and timing of
fog and haze/smoke based on updated model guidance. Overall, the
previous fog forecast remains on track with valleys in
southwestern Montana having the highest chance for fog development
overnight. The latest model guidance did expand the coverage area
slightly and extend the time by a couple hours. Overall,
widespread dense fog is not expected so no products are needed at
this time.
The latest run of the HRRR smoke put a little more haze and smoke
into central Montana for tomorrow afternoon based on expected
activity from the wildfires near Lincoln. While the specifics may
change based on fire behavior tomorrow, it is safe to expect hazy
skies over portions of the Little Belts and Big Belts as well as
lower elevations of Lewis and Clark, Cascade, Judith Basin, and
Meagher counties. Near-surface impacts are expected to be minimal
outside of the immediate areas surrounding the fires. -thor
&&
.AVIATION...
31/00Z TAF Period
VFR conditions will predominately prevail through the 3100/0100 TAF
period; however, showers and even an isolated thunderstorm or two
will continues to drift east and southeast across portions of North
Central through Southwest Montana through the evening hours. Brief
heavy rain associated with these showers and storms may temporally
bring CIGS/VIS to low-VFR, but MVFR conditions are not anticipated.
Showers and thunderstorms will gradually exit the region through 03-
06z Wednesday, with clearing skies thereafter. There is the potential
for valley fog to develop through the morning hours on Wednesday
across Southwest and Central Montana; however, probabilistic data for
this fog developing remains below a 10% chance. - Moldan
Refer to weather.gov/zlc for more detailed regional aviation weather
and hazard information.
&&
.PREV DISCUSSION...
/ISSUED 509 PM MDT Tue Jul 30 2024/
A passing trough will continue to bring variable clouds, showers,
and a few isolated thunderstorms through this evening. Diurnal
destabilization has been on the slower side so far this afternoon,
resulting in less storm coverage than earlier expected,
especially in the southwest, but ML CAPE approaching 500 J/kg in
an uncapped environment should result in increasing shower and
storm development as the afternoon progresses. Still not expecting
storms to become very strong aside from localized erratic, gusty
winds, occasional lightning, and brief downpours. This activity is
expected to taper off this evening through midnight with partial
to full clearing taking place during the overnight hours.
Lingering moisture combined with light winds may result in some
patchy fog development late tonight into early Wednesday, mostly
for the central and southwest valleys.
Ridging aloft builds in for the second half of the work week for
a return to hot and dry conditions. Temperatures will warm well
into the 90s to near 100 Thursday through Saturday. Ensembles show
a series of shortwaves and weak surface fronts dampening the
ridge Friday and through the weekend, introducing breeziness and
isolated to scattered shower and thunderstorm activity. Initially,
the continued hot temperatures and a dry sub- cloud layer look to
increase the chances for drier thunderstorms with stronger gusty
and erratic winds before slightly cooler temperatures and higher
humidities bring more wet storms Sunday into early next week. The
lack of a defined westerly flow aloft is not very favorable for
widespread stronger winds outside of thunderstorms, but seasonably
breezy conditions are expected. - RCG
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 54 87 55 93 / 30 0 0 0
CTB 53 85 52 91 / 20 0 0 0
HLN 54 88 57 96 / 50 0 0 0
BZN 47 86 51 94 / 50 0 0 0
WYS 37 76 40 85 / 60 0 0 0
DLN 44 82 48 89 / 60 0 0 0
HVR 57 90 58 95 / 20 0 0 0
LWT 50 83 53 90 / 40 0 0 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls
Area Forecast Discussion
National Weather Service Las Vegas NV
727 PM PDT Tue Jul 30 2024
.SYNOPSIS...Dry, breezy, and seasonal weather is on tap for the
region today. Ridging will begin to build over the region tomorrow,
opening the door for the return of monsoonal moisture during the
second half of the week. This increase in moisture will bring
increased chances for isolated to scattered showers and
thunderstorms to the region beginning Thursday. Temperatures will
heat up over the weekend as the ridge remains in place overhead
going into next week.
&&
.UPDATE...The Nixon Fire in Riverside County did not get
as active this afternoon, so less concern of a dense smoke layer
aloft coming toward Las Vegas tonight. The Borel and Trout Fires in
the southern Sierra Nevada, northeast of Bakersfield quieter as
well. Actually off satellite, there was a wind shift with smoke from
those fire drifting to the southeast. Just due to proximity, parts of
Inyo County continue to report moderate air quality.
Will update the smoke/haze grids this evening from the latest 00Z
HRRR smoke forecast. Otherwise, no change.
&&
.PREV DISCUSSION...139 PM PDT Tue Jul 30 2024
.DISCUSSION...through Monday.
Current satellite and water vapor imagery show a shortwave trough
the Pacific Northwest/northern Intermountain West and an area of
high pressure over the south-central US, and an inverted trough over
the Baja Peninsula, which leaves us in an area of dry southwesterly
flow aloft. This southwesterly flow will continue to transport smoke
from the Trout, Borel, and Nixon fires into the western portions of
our forecast area. Outside of smokey/hazy skies, today`s weather
will be relatively benign with dry conditions, seasonal
temperatures, and some afternoon breezes.
An upper-level ridge will begin to build into the area tomorrow. As
this ridge pushes in, we will also see the aforementioned inverted
trough begin to lift to the north. This will increase southerly flow
aloft, opening the door for the return of monsoonal moisture.
Chances for isolated showers and thunderstorms will return to the
region on Thursday, becoming more widespread on Friday. With
precipitable water values around 140% to 190% of normal on Thursday
and Friday, flash flooding will be a potential concern with any
storms that develop. With the ridge of high pressure remaining
overhead into early next week, this monsoonal moisture will continue
to be recycled each day, helping to fuel afternoon convection.
Temperatures will remain in the normal to slightly above normal
range through the end of the week, with additional warming over the
weekend as the ridge remains in place. As such, we will see
Moderate HeatRisk expand across much of the area with pockets of
Major HeatRisk in the Lower Colorado River Valley towards the end
of the forecast period.
&&
.AVIATION...For Harry Reid...South-southwest winds with gusts
around 20 knots will continue into the early evening before
diminishing. The south-southwest winds should remain under 10 kts
during the overnight hours. Winds will be mainly diurnally driven on
Wednesday. There is a low probability (< 20%) that outflow winds
from storms in Arizona work their way into the Las Vegas Valley
Wednesday evening and will favor the eastern corridors of Peach
Springs and Mormon Mesa.
For the rest of southern Nevada, northwest Arizona and southeast
California...Breezy south to southwest winds with gusts to around
20kts will continue at most regional TAF sites until sunset. Smoke
from wildfires burning in Kern County, CA, will continue to affect
Inyo County. Slantwise visibilities may be reduced. Otherwise, no
operationally significant cloud cover is expected through Wednesday
afternoon. Convection in southern Arizona may provide outflow winds
and mid and high level clouds into the lower Colorado River Valley
(KEED and KIFP) Wednesday evening.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
DISCUSSION...Stessman
AVIATION...Czyzyk
For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter