Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/07/24
Area Forecast Discussion
National Weather Service Amarillo TX
627 PM CDT Tue Aug 6 2024
...New AVIATION...
.SHORT TERM...
(This evening through Wednesday night)
Issued at 220 PM CDT Tue Aug 6 2024
A strong upper-level ridge is stationed overhead which will lead to
widespread highs in the upper-90s to mid-100s. The ridge will shift
westward and weaken some tonight and through tomorrow leading to
weak northwest flow aloft as a weak shortwave trough rounds the top
of the ridge. Some thunderstorms may develop tomorrow afternoon in
the higher terrain of northern New Mexico/southern Colorado and
track into the northwestern combined Panhandles. Gusty winds will be
possible with any shower or thunderstorm.
The main story for tomorrow will be widespread 100+ degree
temperatures. Latest NBM came in up to a few degrees cooler than
previous runs. Taking a deeper look, the HRRR and NAM NEST have some
high clouds lingering across a portion of the area which are
leftover from convection that`s expected to develop along the
Rockies today. Still, there are several counties reaching or
exceeding 105 degrees (Heat Advisory criteria), and a couple
locations approaching 110 degrees (Excessive Heat Warning criteria).
Will opt to issue a Heat Advisory for Palo Duro Canyon as that has
the highest confidence of reaching at least 105 degrees, but will
hold off on issuing elsewhere for now given uncertainty in where the
clouds may linger, and which counties could hit 105 degrees.
Vanden Bosch
&&
.LONG TERM...
(Thursday through next Monday)
Issued at 220 PM CDT Tue Aug 6 2024
The upper-level ridge will be in place over the Four Corner states
as a robust upper-level shortwave trough is moves across the Upper
Midwest. An associated cold front will surge south through the
Plains Thursday afternoon as the shortwave moves eastward. Timing of
the cold front varies by model which is leading to a wide range in
potential high temperatures; as much as a 20-30 degree spread
between the NBM 5th and 95th percentile in the central and northern
combined Panhandles.
Pooled up moisture will be present behind the front with PWATs above
the 90th percentile. The Four Corners ridge will stay in place, or
slightly shift west and east, while a large upper-level trough is
stationed over the Great Lakes. This leads to northwesterly flow
aloft with embedded shortwave potential and daily chances for rain
as thunderstorms develop on the higher terrain and move
eastward/southeastward. It`ll be hard to pinpoint which days, if
any, will be more favorable than others for strong to severe storms
due to the potential for lingering cloud cover to limit
destabilization. Given the high PWATs, thunderstorms will be capable
of producing heavy rain that may lead to flash flooding.
Temperatures will be seasonably cool across the Panhandles Friday,
but triple digits are forecast to return by Sunday for the southern
Panhandles.
Vanden Bosch
&&
.AVIATION...
(00Z TAFS)
Issued at 620 PM CDT Tue Aug 6 2024
VFR conditions continue through the 00Z period. Winds at the
surface should remain light and variable through the rest of the
day, and then shift to being southerly and breezy again tomorrow
afternoon. Isolated areas of low level wind shear may be present
in the vicinity of the DHT and GUY terminals tonight, but this is
a low confidence outcome; and as such, no mentions were made in
the TAFs.
Rangel
&&
.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX 71 104 71 96 / 0 0 0 10
Beaver OK 68 104 69 88 / 0 0 10 10
Boise City OK 65 101 66 85 / 0 10 20 20
Borger TX 73 109 73 98 / 0 0 10 10
Boys Ranch TX 68 105 69 96 / 0 0 10 10
Canyon TX 67 103 68 97 / 0 0 0 10
Clarendon TX 71 104 71 102 / 0 0 0 0
Dalhart TX 63 102 66 88 / 0 0 10 10
Guymon OK 66 102 66 86 / 0 0 20 10
Hereford TX 66 103 67 98 / 0 0 0 0
Lipscomb TX 70 106 73 95 / 0 0 10 10
Pampa TX 71 104 71 96 / 0 0 10 10
Shamrock TX 70 105 71 104 / 0 0 0 10
Wellington TX 70 106 73 106 / 0 0 0 0
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 8 PM CDT this evening for TXZ007-008-012-013-
018-317.
Heat Advisory from 1 PM to 8 PM CDT Wednesday for TXZ317.
OK...None.
&&
$$
SHORT TERM...52
LONG TERM....52
AVIATION...55
Area Forecast Discussion
National Weather Service Cheyenne WY
201 PM MDT Tue Aug 6 2024
.KEY MESSAGES...
- Thunderstorm possible Today (20-30%) and Wednesday (40-60%)
with a few strong to marginally severe storms possible.
- Active weather pattern continues into late this week with
below normal temperatures for early August. Expecting a
gradual warmup through the weekend returning to near normal
temps.
&&
.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 107 PM MDT Tue Aug 6 2024
Surface high pressure continues to build across the Great Plains,
with a stationary boundary positioned from north to south along
central to east Wyoming. Observations throughout the morning
have seen increased dewpoints in the mid-50s along the I-25
corridor and into the low-60s in eastern Wyoming/Nebraska
Panhandle. HiRes model guidance is still pinging enhanced
convergence along the stationary boundary, supporting convective
development in the afternoon hours. Best MLCAPE still looks to
be positioned along a narrow band along the Wyoming/Nebraska
Border, reaching around 1000+ J/kg in the early afternoon. Some
concerns for higher MLCAPE values building across Dawes county
in the late afternoon, with the HRRR being the most interested
in placing stronger cells developing long the main line of CAPE
and pushing east into the Nebraska Panhandle. Nevertheless,
capping concerns remain for today, with ample CIN across the
majority of the Panhandle. As a result, most storms will largely
depend on the assistance from the shortwave disturbances
pulsing within the overlaying ridge. Regardless, will need to
monitor for Dawes County for any storms digging through, and
across the northern zones where outflows are able to initiate
storm development. Nevertheless, severe weather chances exist
this afternoon, with a Marginal Risk of severe thunderstorms
from east Wyoming and extending into the Nebraska Panhandle.
Into tomorrow, another round of active weather is expected, with
increased confidence for our zone to have stronger storms. Mid
to upper level winds will continue to increase, with an upper
level jet across the northern Rockies digging to the south /
southeast, ultimately increasing shear totals across the area.
Forecast soundings are also pointing at a more impactful system
with better MUCAPE values hovering around on the north side of
1200 J/kg, effective bulk wind difference at 50 to 60kts, and
PWATs around 0.86 to 1.04 inches. With the forecast sounding
remaining quite moist into tomorrow and some good storm
dynamics, would suggested heavy rainfall for tomorrow with
increasing cloud cover into the overnight hours and additional
precipitation across the CWA. Will continue to support high
storm coverage tomorrow, with 50%+ POPs across the majority of
the CWA.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 107 PM MDT Tue Aug 6 2024
Northeast upslope flow over much of the CWA for Thursday with
surface boundary roughly laying along a line from Denver to
Laramie to Rawlins. Moisture at lower levels fairly high at 90
percent or higher and dewpoints in the mid to upper 50s across
much of the CWA east of the front. ECMWF/NAM/SREF all in good
agreement with fairly widespread precipitation over the CWA.
GFS on the other hand is the driest with showers mainly confined
to the Laramie Range. Decided to follow the consensus models
with widespread precipitation (60-90%) across much of the
forecast area. Does not look like storms will be severe as
afternoon high temperatures only in the mid to upper 60s. PWATs
range from .75 inch over Carbon County to 1.04 inches in the
southern Panhandle. Confidence pretty high on fairly widespread
precipitation occurring.
With the upsloping easterly winds...do believe that aviation
issues will occur...especially east of the Laramie Range where
GFS sounding are showing possibility of stratus and fog being
widespread in the Panhandle to the I-25 Corridor along the
Laramie Range. Great opportunities for forecasting
widespread/persistent IFR conditions Thursday morning and again
Thursday evening.
That higher moisture sticks with us Friday with PWATS increasing
another .25 to .5 inches above what we see Thursday. This
moisture remains over the area through the weekend. Look for
daily chances for widespread afternoon and evening showers and
thunderstorms through Sunday. Aviation concerns will continue
each evening as well.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1128 AM MDT Tue Aug 6 2024
Some concern this afternoon for the 18Z TAFs. KCYS...KAIA and
KBFF all show some thunderstorms tracking over their airfields
according to HRRR guidance. Followed this guidance on timing.
Storms ending fairly early this evening with decreased heating.
Will continue to monitor airfields.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...MRD
LONG TERM...GCC
AVIATION...GCC
Area Forecast Discussion
National Weather Service Dodge City KS
500 PM CDT Tue Aug 6 2024
...Updated Aviation...
.KEY MESSAGES...
- Last very hot day for the foreseeable future tomorrow
afternoon with 104 to possibly isolated 106F highs across
mainly far west central Kansas (Syracuse to Scott City
corridor in particular).
- Significant cold front leading to long-term pattern change
late Wednesday Night/early Thursday morning.
- Latest indications are Friday Night through Monday Night
period will be the best 4-day window of multiple thunderstorm
episodes leading to widespread 1"+ rainfall (point location
probabilities increased to 40-50% across much of western and
central Kansas).
&&
.DISCUSSION...
Issued at 352 PM CDT Tue Aug 6 2024
This afternoon`s water vapor loop and RAP objective analysis showed
our summer subtropical high centered from Arizona-Utah border east
across the Texas Panhandle to western Oklahoma. The upper ridge axis
was quite formidable resulting in erosion of much of the cloud cover
south of far west central Kansas. The passage of a weak shortwave
trough across the Upper Midwest region yesterday resulted in a cold
front passage across southwest Kansas earlier this morning. The cold
front did result in a bit of a pullback in temperature and an
increase in low level dewpoints, but overall impacts were negligible
at best.
The mentioned cold front was already undergoing significant
frontolysis as it moved into the region of subtropical high
influence. Winds north of the front will continue to veer around
from the east to southeast tonight, generally 10 to 15 mph, with
winds becoming south-southeast if not due south through the day
Wednesday. The advertised hot day for Wednesday is still on track.
Much of the guidance is similar to each other, especially out west
(west of U283) where NBM 25-75th percentile spread is only 3 degF.
This is largely due to the fact that most of the models are fairly
locked in the thermal ridge and deep mixing expanding at least out
to U283. Thus, confidence in high forecast is fairly high, and the
official grids will lean more toward the hotter 75th percentile of
around 103 to 104F in western locations like Syracuse, Garden City,
and Scott City. Farther east, especially Hays down to Pratt, there
is greater uncertainty as models do differ more on how far east
mixing out of hottest temperatures will reach as the eastern
counties will still see trajectories from the residual surface high.
That will be it for the heat, as the major pattern change is on its
way and still very much on track. In fact, today`s model runs,
especially the ECMWF and its 50-member ensemble system, have really
ramped up the precipitation signal from over the past couple of
days. Some models have trended much cooler for daytime temperatures
as the result of more precipitation in the model, but not every
model/ensemble system is on the same page, and as such, NBM 25-75th
percentile spreads on high temperature for Friday, Saturday, and
Sunday are in the 8-12 degF range across much of western
Kansas...with 25th percentile NBM temperatures of low-mid 70s across
much of western Kansas both Friday and Saturday. The official
forecast follows fairly closely the cooler 25th percentile.
The 12Z run of the 100-member Grand Ensemble was still rolling in at
the time of this writing (mid-afternoon), but the 00Z run was still
showing a good 5-day precipitation signal (August 8-13) with 25-75th
percentile precipitation of around one-half inch to a little over an
inch and a half (Dodge City). The ECMWF EPS continued to be the
wettest ensemble system for much of DDC. In fact, the new 12Z ECMWF
EPS is doubling down on Total QPF for DDC of over two inches by
August 16/00Z (from an ensemble system mean of 1.5" on the previous
ECMWF EPS run).
As mentioned in previous discussions, the devil will be in the
details, and there will be some areas that will see well in excess
of two inches when this cool/wet pattern eventually comes to an end
and other areas missing out with less than an inch. There will also
be an attendant severe weather risk, but severe weather risk for
each day/night will be contingent upon air mass recovery to develop
CAPE and how much westerly mid-upper level wind can reach down into
western Kansas to provide enough vertical wind shear for organized
severe convection.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 500 PM CDT Tue Aug 6 2024
Excellent flying weather will continue through this TAF period,
with VFR/SKC and light winds. Light SE winds will prevail
through 12z Wed. After 15z Wed, south winds will increase
modestly at all airports, gusting 22-24 kts.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Umscheid
AVIATION...Turner
Area Forecast Discussion
National Weather Service Green Bay WI
1026 PM CDT Tue Aug 6 2024
Updated aviation portion for 06Z TAF issuance
.KEY MESSAGES...
- Patchy ground fog could lead to rapid reductions of visibilities
over parts of north- central and central Wisconsin late
tonight into early Wednesday morning.
- Water levels on some rivers and creeks and in ditches will be
on the rise for the next few days due to recent heavy rain.
- High waves and dangerous currents on Lake Michigan south of
Sturgeon Bay will result in conditions hazardous to swimmers
and boaters.
- On and off chances for showers and thunderstorms return late
Wednesday night and continue through Friday. Risk of severe
weather is low.
&&
.DISCUSSION...
Issued at 242 PM CDT Tue Aug 6 2024
Short Term...Tonight and Wednesday
The latest RAP analysis and satellite/radar imagery show low
pressure moving east over northern Indiana and northeast Ohio
while a large high pressure system is moving into the northern
Mississippi Valley and Lake Superior. Fair weather cumulus turned
out to be a little more robust today thanks to unstable conditions
over the Great Lakes. Northeast winds of 15 to 25 kts are
generating 3-5 ft waves on Lake Michigan per the buoys. As the
high pressure moves into the region, focus of the forecast
revolves around fog potential and marine hazards.
Fog Potential: High pressure will continue to shift southeast and
become centered over the Upper Peninsula and northwest Wisconsin.
With arrival of the surface high, winds are expected to become
light and variable and skies will become clear over north-central
Wisconsin. These conditions will be favorable for ground fog
development after midnight. Expanded the lower visibilities and
patchy fog in this forecast cycle. Will also add a mention of
reduced visibilities to the HWO.
The Fox Valley and far northeast WI will have a lower chance of
fog due to more wind in the boundary layer.
Marine Hazards: Gusty northeast winds will slowly subside this
evening as directions veer slightly. With onshore flow continuing,
waves will be slow to subside so will continue the Beach Hazards
and Small Craft Advisory through 4 am.
Wednesday: High pressure will shift to the northeast as height
falls and associated cold front move into the northern Mississippi
Valley in the afternoon. After the morning fog burns off, clear
skies will give way to increasing mid and high clouds in the
afternoon. Temperatures will be warmer with highs in the middle to
upper 70s.
Long Term...Wednesday Night Through Tuesday
Precipitation returns to the forecast early in the extended
period as an upper trough moves along the Canadian border to our
north. This will also bring a seasonally cool airmass to the
region.
Wednesday night through Friday...The cold front accompanying the
upper trough will be the primary driver for the showers Wednesday
night through Thursday morning, crossing the region by around
early Thursday afternoon. Thunder potential this early will be
relatively minimal, which in turn keeps qpf fairly light. Models
do retain some additional post frontal precipitation, as there is
some suggestion that surface instability will be on the increase
again Thursday evening. Kept some minimal pops in for this, but
would largely suspect the now much drier and cooler airmass will
struggle to produce additional precipitation Thursday.
As we get into Thursday night to Friday, the upper trough is
expected to close off and remain well between Manitoba and
Ontario, which may yet bring enough wrap around forcing and
moisture for some additional showers across the northwoods and
along the Upper Peninsula border but areas further south have
trended drier. Diurnal instability and decent shear could still
produce some rumbles of thunder Friday afternoon within any
showers, but no severe or strong storms are expected at this time.
Temperatures during this period will cool from the lower to upper
70s on Thursday to the middle 60s to lower 70s on Friday.
Rest of the forecast...The general upper pattern keeps the upper
trough near the Great Lakes for the early portions of the weekend,
so wouldn`t be surprised to see a few sprinkles work their way
back into the forecast, but most of the weekend to early next week
are dry currently. Temperatures remain on the cooler side during
this period, ranging from the middle 60s to lower 70s on Saturday,
but will moderate back to the upper 70s to lower 80s early next
week.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1022 PM CDT Tue Aug 6 2024
High pressure will bring VFR conditions to the region through
most of the TAF period. The exception will be over NC/C WI, where
patchy ground fog should drop vsbys to IFR/LIFR overnight into
early Wednesday morning. Will carry a TEMPO group for fog at RHI,
AUW and CWA. SCT cumulus clouds will develop during the daytime
on Wednesday, and increasing mid-level clouds should arrive at the
western TAF sites later in the afternoon. An approaching frontal
boundary may bring scattered showers to RHI, AUW and CWA toward
the end of the TAF period.
Light winds are expected through the night. Light SE-SW winds
will develop on Wednesday.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement until 4 AM CDT Wednesday for WIZ040-050.
&&
$$
DISCUSSION.....MPC/Uhlmann
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Louisville KY
944 PM EDT Tue Aug 6 2024
.KEY MESSAGES...
* Hot and dry today with heat indices near 100 degrees in some
locations. Slightly cooler temperatures return Wednesday.
* Mainly dry weather through most of this week. Some patchy
morning fog possible.
* Very pleasant weekend with cooler temperatures and lower
humidity.
&&
.UPDATE...
Issued at 944 PM EDT Tue Aug 6 2024
Cold front continues to drop southward through Indiana this evening.
Just ahead of the front, scattered showers and a few storms have
developed. The heaviest convection has remained northeast of us
across central OH. Ongoing convection looks to continue southward
and may get into our northern row of southern IN counties in a few
hours before diminishing. For now, will keep some slight chance
PoPs going across our northern row of southern IN counties and our
row of northern Bluegrass counties where stronger convection coming
out of southern OH could brush our Bluegrass region.
&&
.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 258 PM EDT Tue Aug 6 2024
Things are pretty quiet across the area at the moment as we remain
situated between a surface low and trailing cold front over the
lower Great Lakes and Debby to our SE. Hot and humid conditions
continue through the afternoon with high temps peaking in the low
and mid 90s and max heat indices topping out in the 96 to 101 degree
range.
The main focus for the short term has been on the cold frontal
boundary sinking into our northern CWA later tonight. Forecast
models continue to suggest that a few isolated showers or storms
could survive into our northern tier of counties after sunset, so
have an isolated pop mention there. That being said, the recent runs
of the HRRR have initialized pretty well and it suggests convection
will fizzle before reaching our northern tier. Overall, quite a bit
working against convection surviving including: mid level cap, past
peak heating, and overall drier air in place here.
After some patchy morning fog possible, the cold front slowly slides
through on Wednesday, with a few showers and storm possibly
developing over east central KY on Wednesday. Confidence is low, but
some slow moving heavy rainers can`t be ruled out. Overall cooler
tomorrow with the front passing. Highs mostly in the low to mid 80s.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 258 PM EDT Tue Aug 6 2024
===== Wednesday Night - Thursday =====
Zonal flow aloft and a post-frontal regime will promote dry weather
for Wednesday night. We should have slightly improving skycover as
drier air sets in, with temperatures in the 60s and low 70s
overnight.
Dry weather will continue for Thursday, though with the tropical
system sitting over the Carolinas, could see cloud cover spread out
and increase in coverage across our eastern half of the forecast
area by Thursday afternoon. It should not impact temperatures
though, which are progged to reach the upper 80s and lower 90s.
Dewpoints will be somewhat muggy, which could end up translating
heat indices to the upper 90s, and perhaps a few isolated instances
of 100 degrees.
===== Friday - Monday =====
On Friday, the remnants of Debbie will begin to finally move on
from the Carolinas after dumping incredible amounts of rainfall. The
system should shift slightly northward before getting pushed east by
an incoming secondary cold front. While this frontal boundary will
lack moisture this far west, it will eventually run into better
moisture, possibly as far west as I-75. We`ll have a slight chance
of an isolated shower along our I-75 corridor, but outside of that,
the rest of the forecast area should remain dry. The overall best
chances for Kentucky remain well to our east. Temps will range in
the 80s on Friday.
With this second dry cold front, we will get a reinforcing shot of
cooler air into the region. Temps on Saturday morning will be in the
upper 50s and low 60s, around 10 degrees below normal. Saturday`s
highs will be in the upper 70s and low 80s, along with dewpoints in
the 50s. The same forecast is expected for Sunday. It will be a
fantastic weekend weather-wise, and it`s not often we get to
forecast 50s in August.
Dry weather will continue for Monday, with highs still in the low
80s. The below normal temps may continue for Tuesday too, but slight
rain chances may make a return.
&&
.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 714 PM EDT Tue Aug 6 2024
Surface cold front to the north of the region will continue to move
southward this evening and into the overnight hours. A few storms
may accompany the front, mainly in the area between I-70 and I-64.
Overall coverage still looks sparse enough to leave out of KHNB. The
front will sink toward the Ohio River by dawn and we`ll see a bit of
low-mid level cloud develop. Guidance seems to be hinting at some
IFR/MVFR cigs around frontal passage, so plan to add some lower
clouds into this forecast. Winds this evening will be out of the
west/northwest but shift to the southwest later this evening. Behind
the front, look for winds to quickly shift to the northwest.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Air Quality Alert until midnight EDT tonight for KYZ029>031.
IN...Air Quality Alert until midnight EDT /11 PM CDT/ tonight for
INZ076>079-083-084-089>092.
&&
$$
UPDATE.......MJ
SHORT TERM...BJS
LONG TERM....CJP
AVIATION.....MJ
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
803 PM CDT Tue Aug 6 2024
.KEY MESSAGES...
- Dangerous swimming conditions at southern Lake Michigan
beaches will continue through Wednesday afternoon.
- Dry and cooler weather will continue through early next week.
&&
.UPDATE...
Issued at 803 PM CDT Tue Aug 6 2024
Only adjustment to the going forecast this evening was to
maintain a mention of showers for an additional hour or two
before tapering to sprinkles after mid-evening before ending.
Otherwise, forecast remains in good shape into Wednesday. Breezy
northeast surface winds will maintain high waves and dangerous
swimming conditions for Lake Michigan beaches into Wednesday.
Surface low pressure was analyzed over southeastern Indiana
early this evening, with a cold front trailing off to the
southwest across southern Illinois. This low will continue to
move southeast across the Ohio Valley tonight, in association
with a mid-level short wave trough propagating east-southeast
across the region. Breezy and cooler conditions were in place
across the western Great Lakes region to the north and northwest
of the departing surface low. Spotty light showers and
sprinkles were noted in local radar data across northeast
Illinois and adjacent northwest Indiana, a product of breezy,
convergent low-level northeast winds within relatively shallow
(< 8 kft) wrap-around moisture on the back side of the low. RAP
soundings indicate some of these are likely lake-assisted, given
Lake Michigan surface water temperatures in the mid-70s
juxtaposed below relatively cool (<10C) 800 mb temps. Gradual
low-level dry advection late this evening and overnight should
allow these showers/sprinkles to dissipate however, with a
gradual decrease in cloud cover especially north of I-80. Clouds
will likely linger into Wednesday morning across our southern
counties, with a minimal though perhaps non-zero chance of a few
sprinkles as well.
Going forecast has off this handled nicely, and with the
exception of hanging onto low-chance PoPs for showers another
hour or so this evening, no other changes are warranted.
Ratzer
&&
.DISCUSSION...
Issued at 145 PM CDT Tue Aug 6 2024
Through Wednesday Night:
There remains a small chance for a thunderstorm across northwest
IN through mid afternoon. Current activity has been developing
just east of cwa and expect this trend to continue over the next
hour or so. Any thunderstorms that do develop in northwest IN
would likely not have enough time to become strong before
exiting the cwa. After the thunder potential ends, there will
remain a chance of showers or sprinkles into this evening. There
may also be a chance of a few showers across the southern cwa
overnight into Wednesday morning but confidence is too low to
include mention at this time.
A few breaks may develop in the clouds this afternoon,
especially across northern IL. This may allow temps to recover
back into the lower 70s but temps generally around 70 can be
expected through sunset, while temps will fall into the 70s in
the far southern cwa as the cold front exits the area this
afternoon. Low temps tonight will likely be in the upper 50s to
lower 60s for most locations, perhaps warmer in Chicago and near
Lake Michigan. With mostly sunny skies expected Wednesday, highs
may reach 80 for most locations, cooler near the lake.
Northeast winds will continue in the 25-30 mph range over
southern Lake Michigan into tonight, which will allow high
waves in the 6-10 ft range and create dangerous swimming
conditions at Lake Michigan beaches. The winds will gradually
diminish on Wednesday with waves slowly subsiding. Current end
time for the beach hazard statement, which is 3pm Wednesday, may
need refinement, but looks ok for now. cms
Thursday through Tuesday:
The extended forecast period features dry conditions, cooler
temperatures, and comfortable humidity levels as upper level
troughing/closed upper low sets up across the Great Lakes region
late in the week. Temperatures will be the warmest on Thursday
away from the lake with highs in the lower 80s in the afternoon
before a cold front then pushes across the region. The
associated mid-level vort max and surface low remain largely to
the north along with any precipitation chances. Expansive
surface high pressure then sets up across the region in its wake
keeping the area dry into early next week with below normal
temperatures with highs in the 70s.
Petr
&&
.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 614 PM CDT Tue Aug 6 2024
MVFR ceilings are expected to gradually erode and lift this
evening as drier air advects in from the northeast. A few
sprinkles cannot be ruled out during this time. VFR conditions
are then expected overnight through the remainder of the period.
NE winds will persist through the period, with gusts over 20
knots this evening and possibly again through much of the day
Wednesday.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Beach Hazards Statement through Wednesday afternoon for ILZ006-
ILZ103-ILZ104.
IN...Beach Hazards Statement through Wednesday afternoon for INZ001-
INZ002.
LM...Small Craft Advisory until 3 PM CDT Wednesday for the IL and
IN nearshore waters.
&&
$$
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Area Forecast Discussion
National Weather Service Pendleton OR
449 PM PDT Tue Aug 6 2024
.AVIATION...00Z TAFs...VFR conditions are currently forecast for
all sites through the period. However, northwest winds are advecting
a plume of smoke eastward into central Oregon. This plume may
drop BDN/RDM`s VSBYs to MVFR this evening and overnight by 02-03Z
(50% chance). Confidence in timing/magnitude was too low to
include in the 00Z TAFs, and will be handled with amendments, if
needed. Elsewhere, smoke from area wildfires will likely (70-90%
chance) produce haze, but confidence in VSBY reductions below 6SM
is low enough (<50% confidence) to preclude a mention in the 00Z
TAFs.
Winds will diminish in magnitude this evening for all sites such
that sustained speeds of 10 kts or less are forecast through the
remainder of the period.
Aside from haze and smoke aloft, mostly clear skies are forecast.
Confidence in smoke producing an opaque layer at BDN/RDM was too
low to include in the 00Z TAFs. Plunkett/86
&&
.PREV DISCUSSION... /issued 249 PM PDT Tue Aug 6 2024/
SHORT TERM...Tonight through Thursday...Areas of showers and
thunderstorms have been noted across our northern and eastern
border, in both the Columbia Basin and across the Wallowas
respectively. CAMs show that this activity should continue to be
possible for another couple of hours or so before fully departing
our region to the northeast, which will allow the Red Flag Warning
to expire at that time.
Beyond this, the short term forecast will be largely quiet on
Wednesday and Thursday. With a deep upper low moving across Canada
and a deep upper high over the Four Corners, our region will
remain between strong systems. For Wednesday, surface level flow
is expected to veer to a northeasterly to easterly direction, a
bit out of the ordinary which will also impact some operations for
ongoing fires across the region, but speeds should be 10 mph or
less; and by Thursday, winds strengthen a bit more but overall
speeds will still remain on the low side, at around 10-15 mph.
Temperatures should regulate better than the past week and drop
closer to but still slightly above normal, with highs for our
population centers in the low to mid 90`s. The NBM thankfully
struggles to produce anything warmer, with probabilities for
temperatures 100+ at less than 10%. Highs may also struggle in
some locations thanks to smoke and haze as the HRRR indicates the
shifting of the winds should produce a bit more smoke and haze for
our region. Goatley/87
LONG TERM...Friday through Tuesday...Models are in good agreement
in having a trough influencing weather over the Pacific Northwest
with relatively small differences as to the depth and placement of
the trough. The weather pattern will favor a slow cooling trend from
near normal to a couple of degrees below normal by early next week.
The Extreme Forecast Index indicates little in the way of unusual
weather.
Friday starts out with a large ridge over the desert southwest while
a shortwave moves south along the British Columbia coast and
develops a trough over our area. The trough will be centered just
offshore and this will develop a southwest flow over the area as the
ridge breaks down. This will enable a slight chance of showers and
thunderstorms over the washington Cascades and eastern Oregon
mountains. The NBM is indicating a 15-25 percent chance of
thunderstorms in those area as well as a 10-15 percent chance over
Bend and Redmond. Have held off on a slight chance of thunderstorms
in central Oregon, but wouldn`t be surprised if it gets added as we
approach Friday. Rain amounts look to be just a few hundredths of an
inch. Temperatures will be similar to Thursday, perhaps a degree or
so cooler, with highs in the upper 80s to mid 90s in the lower
elevations and in the upper 70s and 80s in the mountains.
On Saturday, model clusters show the trough remaining more or less
in place while the ridge is flattened southward. There are few
noticeable differences between the clusters, so confidence is high.
This will cool us another degree or two from Friday. A continued
southwest flow will keep instability over the Washington Cascades and
the higher terrain of northeast Oregon and a slight chance of
showers and thunderstorms is expected there, though with less
coverage than on Friday.
By Sunday, model clusters show the ridge flattening further. Another
wave or closed low is over the central British Columbia coast and
the flow becomes more westerly. this limits the chances for showers
and thunderstorms and the NBM shows only about a 10 percent chance of
thunderstorms along the higher terrain from John Day and the Grande
Ronde Valley into Wallowa county. Temperatures will drop another
degree or two to the mid 80s to lower 90s while the mountains are in
the mid 70s to mid 80s.
Monday and Tuesday, models keep the trough axis along the coast but
instability looks more limited, so have a dry forecast. Temperatures
cool a degree or two each day, ending up in the mid 80s to around 90
in the lower elevations and in the mid 70s to lower 80s in the
mountains by Tuesday. By Tuesday, the GFS has a fairly strong closed
low over southern British Columbia while the ECMWF and Canadian have
a weaker wave. The GFS develops a tighter pressure gradient than the
other two models and in response, the NBM has 15 to 25 mph winds
through the Cascade gaps and 10 to 20 mph in the rest of the
Columbia basin. The NBM shows a 50-60 percent chance of 20 mph winds
in the Columbia Gorge, Simcoe Highlands and the Kittitas Valley and
15 percent or less elsewhere. However, the chance of 25 mph winds
are 34 percent in Ellensburg and under 15 percent everywhere else.
Perry/83
AVIATION (Previous Discussion)...18Z TAFs...VFR conditions are
expected for the next 24 hours. Smoke and haze from area wildfires
will continue to affect VSBY and local MVFR conditions are
possible at BDN, RDM and YKM during the overnight and early
morning hours. Have used 6SM HZ at those sites to indicate that
possibility. Currently there are unstable conditions over the
eastern mountains and will continue through this afternoon. There
is a small chance for a cell to pass near PSC, ALW or PDT through
mid afternoon but the probability was too low to include in the
TAFs. Winds are increasing and DLS will have northwest winds of 20
kts gusting to 30 kts through 04Z before decreasing this evening
and overnight. Other TAF sites will have west to northwest winds
of 10-15 kts gusting to 25 kts through 03Z before decreasing and
shifting to normal night time directions. Perry/83
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 56 91 59 92 / 0 0 0 0
ALW 62 95 62 96 / 0 0 0 0
PSC 64 96 67 96 / 0 0 0 0
YKM 58 94 61 95 / 0 0 0 0
HRI 61 96 63 96 / 0 0 0 0
ELN 61 95 61 94 / 0 0 0 0
RDM 49 91 56 91 / 0 0 0 0
LGD 53 90 56 91 / 0 0 0 0
GCD 53 92 58 93 / 0 0 0 0
DLS 61 98 69 98 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 5 PM PDT this afternoon for ORZ643-645.
WA...Red Flag Warning until 5 PM PDT this afternoon for WAZ692-693.
&&
$$
SHORT TERM...87
LONG TERM....83
AVIATION...86
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
902 PM PDT Tue Aug 6 2024
Aviation Discussion Updated...
.SYNOPSIS...Very warm and dry weather continues through the
week. Skies will be hazy due to north/northeast ongoing wildfires
within the region. The coast will remain mild with onshore flow
and marine stratus. Upper level troughing returns late in the
week, however little to no precipitation is expected due to the
dry air mass. There is potential for a cooling trend early next
week.
&&
.SHORT TERM...Zonal flow aloft will persist through Wednesday and
will support warmer temperatures on Wednesday. Expect
temperatures to be 8-10 degrees warming throughout the
Willamette Valley with highs peaking in the upper 80s to low
90s. There is a 10-20% chance that highs make it to 95 within
the valley. Northerly winds persist tomorrow and will likely
advect some wildfire smoke southward, mainly east of the Coast
Range. This will generally make the sky look hazy and may
obscure objects that are far away. More concentrated areas of
smoke are expected within closer proximity to ongoing wildfires.
Upper level flow will shift to the southwest as ridging centered
over the Great Basin region builds northward into the PNW. This will
support hot temps on Thursday with highs in the mid to upper
90s through the Willamette Valley. There is a 10-30% chance
that highs make it to the triple digit mark. There is a moderate
HeatRisk for most of the Willamette Valley and localized areas
of major HeatRisk around the Portland metro. This will impact
individuals sensitive to heat and especially those without
effective cooling and/or adequate hydration. Highs along the
coast will top out in the upper 60s to mid 70s. Models indicate
that a weak thermal trough may develop west of the Cascades on
Thursday which would support weak offshore flow for a portion
of the area. The main concern with this pattern would be intense
wildfire growth. Winds aren`t expected to be particularly
strong at 5-10 mph with gusts around 15 mph but, air from the
east will be much drier and would impact RH values. Easterly
winds would also be more efficient in advecting wildfire smoke
from the Gifford Pinchot National Forest around Mt Adams and
farther north near Seattle. The HRRR indicates plumes of smoke
could approach the Portland metro Thursday afternoon, supporting
another hot and hazy day across the area.
A short wave trough is expected to move across the PNW Thursday
night into Friday and will help bring temperatures back down into
the upper 80s to low 90s within the Willamette Valley.
Unfortunately, no substantial precipitation is expected with
this system given the very dry airmass in place. NBM
probabilities for measurable precipitation (0.01 inch or more)
in a 48-hour period ending 5 AM Sunday are low but non- zero:
10-20% for higher terrain and about 5% for interior lowland
valleys. -Batz
.LONG TERM...On Monday, about 75% of ensemble members continue
to show broad troughing over the western United States. However,
they all begin to show 500 mb heights falling to near average.
While precipitation still remains unlikely, we could experience
a slight cool down in temperatures for the early to middle part
of next week. -Alviz
&&
.AVIATION...Mostly VFR throughout the airspace, with the exception
of MVFR conditions at KAST due to marine stratus currently pushing
into the coast from the north. Coastal marine stratus is expected
to redevelop along the entire coast by 04-08z Wed, lowering
CIGs to MVFR for all coastal terminals until 18-20Z Wednesday,
improving to VFR thereafter. IFR cigs will also be possible
(30-50%) beginning 11-12Z Wednesday, but it looks it will be
predominantly MVFR. Otherwise, northwesterly winds will increase
to around 12-15 kt with gusts up to 25 kt along the coast and 5-10
kt with gusts up to 20 kt inland by 18-20Z Wednesday. Inland
terminals will remain VFR through the TAF period, with a 10-30%
chance of marine stratus pushing into the Columbia River and
imposing MVFR conditions for an hour or two around KPDX and KTTD.
Wildfires burning across the WA, OR and CA as well as local
wildfires located in the Central OR Cascades (east of KEUG) as
well as within the Columbia River Gorge (east of KPDX and KTTD)
could result in some slant range visibility issues at times.
PDX AND APPROACHES...VFR conditions expected throughout the
period. Sustained northwesterly winds around 10 kt with gusts up
to 20 kt possible Wednesday afternoon and evening.
/Sala
&&
.MARINE...Generally north to northwesterly winds expected through
the rest of the week. Winds increasing on Wednesday afternoon,
with some marginal Small Craft Advisory Winds possible Wednesday
evening and overnight. Have issued a Small Craft Advisory from
Wednesday afternoon to Wednesday night due to the expected winds
looking sufficient in intensity and duration. Seas 3-6 ft
primarily composed of short period 4-6 second wind driven waves,
and fresh swell with periods around 8 to 10 seconds. /Sala/Liu
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory from noon to 11 PM PDT Wednesday for PZZ252-
253-272-273.
&&
$$
www.weather.gov/portland
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Area Forecast Discussion
National Weather Service Phoenix AZ
455 PM MST Tue Aug 6 2024
.UPDATE...Updated 00z Aviation Discussion.
&&
.SYNOPSIS...
Strong to severe thunderstorms will be possible going through the
rest of this afternoon into the evening, primarily across south-
central Arizona. The primary concern with thunderstorms will be
damaging winds, which could lead to dense blowing dust. Locally
heavy rainfall will also be possible, which could lead some
instances of flash flooding. Chances for scattered showers and a
few storms will persist over much of the area on Wednesday before
retreating to mainly over higher terrain areas late week as some
drier air works into the area. Excessive heat conditions will
continue today across southeast California before coming to an end
this evening. Temperatures are expected to be closer to seasonal
normals during the middle of the week before heating back up into
the weekend.
&&
.DISCUSSION...
Strong to severe thunderstorms will be the primary forecast concern
today with damaging winds being the primary threat. Latest afternoon
WV imagery and objective analysis showed a defined inverted trough
near the far southern border of AZ/NM and into northern Mexico and
is beginning to help force thunderstorm development across southeast
Arizona. Elsewhere, convection is already firing along the Mogollon
Rim near Flagstaff with a few isolated thunderstorms developing
further south closer to Cibecue. Meanwhile, visible satellite
imagery showed mostly clear skies across the south-central Arizona
lower deserts, allowing for plenty of insolation to help further
destabilize the environment.
The ingredients needed for strong/severe thunderstorms are present
given the moist and unstable environment that is currently in place.
This morning`s 12Z PHX sounding recorded a PWAT value of 1.78",
while current dew points are in the lower 60s across much of south-
central Arizona. This moisture and the abundant insolation will help
push MUCAPE values upwards of 1000-1500 J/kg, while forecast
soundings indicate DCAPE values upwards of 1500-2000 J/kg. The
favorable thermodynamics will be supportive of robust thunderstorm
development capable of producing strong to severe downbursts. The
12Z HREF indicates upwards of a 70% chance for outflow winds to
exceed 35 mph across south-central Arizona and a 10% chance to
exceed 58 mph. Given the favorable environment for strong/severe
downbursts, the SPC has highlighted much of south-central and
southwest Arizona in a Slight risk for straight-line damaging winds.
Given the potential for strong outflows, dense blowing dust will
also be a concern. Thus, a Blowing Dust Advisory is in effect for
nearly all of the lower deserts of Arizona.
There is still some forecast uncertainty with how things will evolve
going through this evening. Convection thus far remains limited east
of Gila County this afternoon and could impact future development
further west. If more widespread robust convection develops further
south along the Rim, favorable 15-25 kt easterly steering flow will
help move these thunderstorms toward the west into southern Gila
County and toward the Valley floor. EBWD values around 30 kts may
also support organization of thunderstorm development. Uncertainties
related to thunderstorms surviving into the lower deserts is
expressed in the 12Z HREF paintball plots which shows a limited
number of members with thunderstorms into the Valley this evening.
However, given the favorable environment, limited CIN and some
support from the IT to the south, outflows coming off the high
terrain should support additional thunderstorm development into the
Valley. Additional convection across southeast Arizona may also send
a northward propagating outflow into south-central which could lead
to boundary collisions that support more robust development. The
20Z HRRR seems to have a better handle on what could develop over
the Phoenix area this evening with at least some isolated to
scattered thunderstorms possible, which could become strong to
severe. Stay tuned for the latest forecast updates this evening
as things evolve. The better storm motion should limit the
residence time of thunderstorms over a given area and thus limit
more widespread flash flooding concerns. However, locally heavy
rainfall could lead to some instances of flash flooding this
evening with a WPC Slight risk of excessive rainfall for southern
portions of Maricopa County into Pinal County.
Temperature wise today, areas of Major HeatRisk are focused across
southeast California. The hot temperatures combined with dew
points into the lower 70s has helped boost heat indices in excess
of 120 degrees across parts of the Imperial Valley so far this
afternoon. An Excessive Heat Warning remains in effect for areas
along and west of the Lower Colorado River Valley through this
evening.
.PREVIOUS DISCUSSION...
Wednesday may still present a decent chance of showers and storms
for any areas that don`t get completely worked over today as
monsoon moisture levels will remain quite high and the remnants of
the inverted trough should still be present, but positioned a bit
farther west than today. For now, the best areas of focus for
storm potential on Wednesday should be over the eastern Arizona
high terrain and over southwest Arizona and southeast California.
Starting Thursday, drier air will begin to work into the area
while the subtropical high starts to have more of an influence
over eastern portions of the region. NBM PoPs from Thursday into
the weekend generally favor higher terrain areas with only a
10-20% chance over the south-central Arizona lower deserts.
Temperatures starting Wednesday look to drop off a good 5-8
degrees largely due to the expected expansive rain-cooled air
pushing through much of the area later today. Considerable cloud-
cover should also be a contributing factor to the near normal
forecast highs on Wednesday. Starting Thursday, temperatures will
begin to warm over the western deserts as drier air begins to
filter in from the southwest, but readings are still expected to
be near normal. As the subtropical high begins to expand back
into the region and strengthen Friday into the coming weekend, we
will see a return of above normal temperatures and even some
potential for Major HeatRisk over the weekend.
&&
.AVIATION...Updated at 0000Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The main aviation concerns for the forecast period will be
potentially multiple outflows that could move through the metro
this evening. Currently, convection to the north along the Rim is
showing less potential of a strong northerly outflow reaching the
metro, so that is reflected in the TAF`s with a downgrade to
TEMPO`s between 01-03z. Should the outflow reach any terminals,
the anticipated direction is from the northwest. A stronger
southerly outflow looks more potent later between 04-06z, that
could result in blowing dust impacts and strong south to southwest
winds moving through the metro. This outflow is expected to bring
the best chances for thunderstorm chances across the metro between
04-06z as well. However, that potential is also lower, as all
TEMPO TSRA impacts have been removed from all terminals. After the
main outflow and thunderstorm potential, winds are expected to
resume their normal diurnal tendencies late tonight and tomorrow.
Southeast California/Southwest Arizona including KIPL and KBLH:
The main aviation impacts is outflows bringing reduced
visibilities in blowing dust and/or haze through this evening. An
outflow has moved through KIPL within the last hour, with evidence
of haze across the area. This outflow is expected to reach KBLH
within the next couple of hours, also resulting in hazy
conditions. Once these conditions settle within the next several
hours, a second outflow from the east is possible, with another
round of gusty winds and blowing dust advertised with a TEMPO
between 05-09z tonight. After these outflows move through the
region, winds will resume their normal diurnal tendencies through
tomorrow afternoon.
&&
.FIRE WEATHER...
The increased moisture through midweek will combine with a
disturbance passing across the southern portion of the region.
This will result in rather good thunderstorm chances today across
south-central Arizona with some potential for severe storms.
There is also a high probability of strong outflow winds today
sweeping through south-central Arizona late afternoon/early
evening into southwest Arizona mid to late evening potentially
affecting ongoing wildfires. The chances for showers and storms
will continue on Wednesday, but coverage and strength should be
much more limited. Beyond Wednesday, the chances for precipitation
will somewhat shift back over eastern Arizona as some drier air
filters into the western deserts. MinRHs will improve to 25-30%
on Wednesday before lowering to around 20-25% across the western
districts Thursday. Overnight Max RHs will be around 45-70% before
beginning to drop off Wednesday night. After excessive heat
across the western deserts today, temperatures will cool down
closer to normal for a couple of days before warming back to above
normal by the weekend.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST this evening for AZZ530-
532.
Blowing Dust Advisory until 10 PM MST this evening for
AZZ530>533-535-536.
Blowing Dust Advisory until 8 PM MST this evening for AZZ534-
537>540-542>544-546-548-550-551-553-554-559.
CA...Excessive Heat Warning until 8 PM PDT this evening for
CAZ560>570.
Blowing Dust Advisory until 10 PM PDT this evening for CAZ569.
&&
$$
DISCUSSION...Smith
PREVIOUS DISCUSSION...Kuhlman
AVIATION...Young
FIRE WEATHER...Smith/Kuhlman
Area Forecast Discussion
National Weather Service San Diego CA
137 PM PDT Tue Aug 6 2024
.SYNOPSIS...
Chances for showers and storms will continue this afternoon into
Wednesday across the mountains and deserts. Other areas will see
slightly cooler weather by the middle of the week as onshore flow
increases and the marine layer becomes a bit deeper. Thursday and
Friday look to be drier as high pressure over the southwestern
part of the country moves closer to our area. Slight warming and
increase in monsoonal moisture will occur by the weekend. Early
next week looks to be dry and cooler as a weak trough begins to
influence our weather pattern.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (Through Friday)...
High pressure over the desert southwest continues to suppress our
marine layer. Areas of foggy conditions continue at the beaches
with slow improvements of clearing expected by this afternoon. The
marine layer will build slightly over the next couple of days,
improving visibility near the coast. This will also help increase
onshore flow, which will also help with temperatures over the
next few days. Inland areas will still be warm with moderate to
locally high heat risk Wednesday through Friday, but not as hot as
we have seen.
In terms of the monsoon, adequate moisture is in place with
southerly flow as cumulus rise over the mountains. Isolated
showers and storms are expected again this afternoon, especially
across the San Diego and Riverside Co mountains. High clouds
coming over the area may inhibit some of these storms building to
their utmost potential today. An easterly wave pushing across
northern Mexico overnight into Wednesday morning. This feature may
allow for elevated storms to produce rainfall in areas across the
lower deserts and southern mountains. This confidence on this
scenario is still quite low, depending on the exact track of the
easterly wave. As of now, the HRRR produces a more southerly
track, which would keep our area mostly dry tonight and Wednesday
morning. If higher clouds are able to dissolve in the morning to
allow for some daytime heating to affirm its grip, mountains and
deserts may see another better chance to see more storms by
Wednesday afternoon. Monsoonal moisture will decrease by Thursday
and Friday, keeping the area mainly dry.
&&
.LONG TERM (This Weekend into Early Next Week)...
Monsoonal moisture and humidity will return by the weekend as the
large area of high pressure retrogrades back into New Mexico and
Texas. This will bring hotter and more humid weather across the
region, where the peak of the heat will occur on Saturday. The
highs on this day will be close to those of today. Slightly cooler
with less chances for higher terrain storms will occur by Sunday.
This is also when models begin to indicate a weak trough forming
off the California coast. Model clusters agree on this trough
strengthening by early next week. This will create a drying
pattern with cooler weather overall with a deeper marine layer.
&&
.AVIATION...
062028Z...Coast/Valleys...SCT-BKN low clouds with bases 600-800 ft
MSL along portions of the coast. Tops around 1500 feet. Localized
VIS reductions down to 1-3SM possible for higher coastal terrain and
valleys.
Later this afternoon and tonight low clouds are expected to become
more widespread in coverage with better chances for low clouds at
coastal TAF sites. CIGs expected to develop 05z-10Z Wed. Bases are
expected to be slightly higher, 800-1200 ft MSL. Tops around 1800
feet. Confidence in arrival time of low clouds at KSAN of around 05Z
Tue night is moderate.
Mountains/Deserts...15-20 percent chance of TSRA over the mountains
21Z Tue-00Z Wed with SCT-BKN Cu based around 12000 ft MSL. Gusty and
erratic winds and localized VIS reductions near any storms. Mod
up/downdrafts near mountains. Areas of high clouds with bases AOA
20000 ft MSL expected Tue PM into Wed, with unrestricted VIS.
&&
.MARINE...
No hazardous marine conditions are expected through Sunday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning until 11 PM PDT this evening for Apple
and Lucerne Valleys-Coachella Valley-San Bernardino and
Riverside County Valleys-The Inland Empire-San Diego County
Deserts-San Gorgonio Pass Near Banning.
Heat Advisory until 11 PM PDT this evening for Orange County
Inland Areas-Riverside County Mountains-San Bernardino
County Mountains-San Diego County Mountains-San Diego
County Valleys-Santa Ana Mountains and Foothills.
PZ...None.
&&
$$
PUBLIC...APR
AVIATION/MARINE...Small
Area Forecast Discussion
National Weather Service Las Vegas NV
708 PM PDT Tue Aug 6 2024
.SYNOPSIS...Excessive Heat will continue through this evening
with marginal risk of severe thunderstorms in southern Mohave County
and the lower Colorado River Valley late this afternoon and evening.
A modest increase in monsoonal moisture Wednesday and beyond will
result in moderating temperatures, through still above normal, along
with thunderstorm activity spreading into the eastern Mojave Desert
through the weekend.
&&
.UPDATE...Increasing confidence for gusty outflow winds to impact
southern Mohave County through 10 PM tonight.
Thunderstorms continue this evening in eastern Mohave County. With
PWATs over 1 inch, modest instability, and slow storm motion- heavy
rain has been reported with area thunderstorms. Numerous
accumulation amounts of 0.50-1.00 inch were reported in area gages
and almost 2 inches fell from a storm near Peach Spring, AZ earlier
this evening. In addition to heavy rain, gusty wind have also been
reported with thunderstorms in the past few hours. Gusts over 50 MPH
were reported on Highway 93 in Arizona near the Kaiser Bridge, and
earlier Fort Rock, AZ gusted over 40 MPH due to thunderstorms.
Current radar trends and area observations are closer to the models
that showed thunderstorm activity continuing and an outflow pushing
through southern Mohave County the rest of this evening.
Mesoanalysis shows there is still sufficient most-unstable CAPE
through southern MOhave County so additional thunderstorm activity
is possible given the continued instability. The best chance for
thunderstorm development and heavy rain will be the next 2-3 hours
east of Kingman and Highway-93. Thunderstorms should lose their
intensity and dissipate as they push west of Kingman as instability
wanes after sunset.
Downdraft CAPE in areas south of I-40 remains fairly high this hour,
1500-2000 J/Kg, the potential for strong outflows over 40 MPH with
storms is high. The latest HRRR shows outflow winds sweeping through
southern Mohave County in the next few hours, with wind gusts to
around 40 MPH reaching Lake Havasu CIty and the Colorado River
Valley between 8PM-10PM. Some models show these outflow winds
impacting areas further north, including parts of Lake Mohave and
Lake Mead. Confidence for sudden gusty winds that far north is lower
given the lack of instability and the inconsistencies amongst models
for wind in that area. Will need to watch it the storms currently
around Peach Springs produces and outflow that pushes west as this
could indicate the winds may impact Golden Valley, Lake Mead, and
Lake Mohave. Anyone with outdoor plans or who is driving in the next
3 to 4 hours in southern Mohave County should be prepared for
thunderstorm impacts including lightning, strong winds, blowing
dust, and heavy rain. Boaters should also remain vigilant for
thunderstorms and impacts. Remember- storms do not need to be
occurring at your location for you to be impacted by outflow winds
or flash flooding.
By midnight, thunderstorms activity will be passed and the area
should be dry for the rest of the night. The risk for gusty winds
will also dissipate by midnight, though lingering southerly breezes
up the Colorado River Valley are possible. OUtside of the area of
thunderstorms, expect dry conditions with mostly clear skies.
Temperatures tonight will be cooler than the past few nights. The
Excessive Heat Warning is set to expire at 9PM and with cooler
temperatures expected in the next 24 hours, will likely let the heat
product do on time. Any changes to the evening and overnight
forecast were for thunderstorm chances to update with the latest
trends and increase precipitation potential in southern Mohave
County.
-Nickerson-
&&
&&
.PREVIOUS DISCUSSION...150 PM PDT Tue Aug 6 2024
.SHORT TERM...Through Wednesday night.
Another hot day across the region as high pressure remains the
dominant weather feature over the Desert Southwest. Excessive heat
warnings remain in effect until 9pm this evening with several
locations at or near record highs once again. Although high pressure
will remain in place Wednesday and even shift slightly further west
in response to an inverted trough moving westward across northern
Mexico, it does begin to weaken. This slight weakening of the high
combined with increasing monsoonal moisture should allow
temperatures to drop a few degrees Wednesday keeping us below the
excessive heat criteria.
For the remainder of this afternoon and evening, we will see
thunderstorms firing once again over portions of Mohave County. Most
of the thunderstorm activity will remain pulsy, but with greater
dynamics and shear over far southern Mohave and northern La Paz
Counties, these could become more organized. The greatest threat
from convection this evening will be strong outflow winds. Several
hires models have remained consistent through the morning and early
afternoon showing a strong outflow boundary pushing west and
northwest across the lower Colorado River Valley between 7pm and
10pm. Wind up to 50 mph will be possible as it pushes through the
lower CRV. Eventually these winds make it to southern Nevada and
even into the Las Vegas Valley, but they are expected to be much
weaker by they time they reach this far north.
That southeasterly outflow wind will bring an increase in moisture
further west/northwest into the Mojave Desert and southeast Nevada
Wednesday for an uptick in thunderstorm chances. Could see a repeat
of storms moving into Mohave County off the higher terrain of
central Arizona, albeit potentially with less wind potential and
transitioning to more of a flash flood threat.
.LONG TERM...Thursday through Monday.
Not much change to forecast thinking today vs yesterday. Models
remain in very good agreement with each other and with previous
runs, so confidence is above average. The big hot ridge retains its
grip on our area, and by Thursday the easterly wave rotating around
its southern periphery should be over the northern Gulf of
California. This should help drag higher humidity and thunderstorm
chances a little farther west, reaching roughly the Interstate 15
corridor by Friday, then expanding farther west and north into
Lincoln, Nye, and far eastern Inyo counties over the weekend.
Meanwhile, temperatures come down a few degrees, remaining above
early August normals, but dropping just enough to keep HeatRisk out
of the Major and Extreme categories. Oppressively warm overnight
lows will continue in the lower elevations and urban areas, except
in areas which are affected by thunderstorms. There is still
agreement on a trough reaching the West Coast Monday, which could
start to knock temperatures and humidity down a little, especially
in areas northwest of Interstate 15. The big questions will be how
far south and east the effects of this trough might be felt, and for
how long.
&&
.AVIATION...For Harry Reid...Winds will gradually shift to the
southwest this afternoon with speeds of less than 10 knots.
Convection will begin this afternoon in northwest Arizona and
although the storms are not expected to reach the terminal,
southerly outflow winds may reach the terminal overnight. Gusts
between 15 and 20 knots are possible between 06Z and 12Z with
occasional lulls possible. Winds should decrease and become variable
later tomorrow morning. Southeasterly winds return tomorrow
afternoon with speeds of less than 10 knots.
For the rest of southern Nevada, northwest Arizona and southeast
California...The primary weather concern is gusty outflow winds this
evening and overnight originating from convection in Arizona. Peak
gusts of 30 knots will reach the Colorado River Valley terminals
between 03Z and 05Z. Lighter gusts between 15 and 20 knots will
reach the Las Vegas Valley terminals between 06 and 12Z. The
thunderstorms themselves are not expected to reach any terminal.
Besides the outflow, diurnal wind patterns are expected at these
locations as well as KDAG and KBIH.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM...Gorelow
LONG TERM...Morgan
AVIATION...Meltzer
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