Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/01/23
Area Forecast Discussion
National Weather Service Burlington VT
1018 PM EDT Sat Sep 30 2023
.SYNOPSIS...
A ridge of high pressure at the surface and aloft will continue to
build across the North Country on Sunday into early this upcoming
week. This will provide the area with dry conditions and much above
normal temperatures with daily highs mid 70s to lower 80s and lows
mid 40s to upper 50s. Areas of dense valley fog is likely overnight
with some patchy smoke possible. The next chance for rain showers
arrives late week associated with a cold front.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
As of 1018 PM EDT Saturday...Forecast remain on track for
tonight. Have noted that several automated stations are
reporting reduced visibility in BR, but based on many air
quality monitoring sites showing increased concentrations of
fine particulates, feel this is likely due to wildfire smoke
near the surface. Latest HRRR/RAP aren`t really accounting for
this well, and it could continue to get worse overnight. Will
pass along to the next shift which may opt to include some smoke
in the forecast.
Previous Discussion...Fcst challenge wl be areal coverage of
fog tonight, followed by temps the next several periods. In
addition, have noted the 12Z HRRR near sfc smoke output shows
additional smoke impacting the area late Sunday night into
Monday morning, which is crntly located over northern Maine into
eastern Canada per vis satl/sfc obs.
Water vapor shows building mid/upper lvl ridge from the eastern
Great Lakes into southern Canada, while north/northeast flow
prevails from 925mb thru 500mb per area VADs. Large area of
subsidence associated with expanding high pres wl result in clear
skies and light winds tonight, allowing for areas of dense fog to
develop, especially climo favored valleys. Difficult to determine if
fog/br develops here at BTV, but sfc dwpt still at 56F this aftn,
supports potential for cross over to be reached and light advection
of the Winooski River Valley fog acrs the BTV airport toward
sunrise. Otherwise, lows range from near 40F SLK/NEK to l/m 50s
CPV/SLV. Another North Country Fall Chamber of Commerce day is on
tap for Sunday with plenty of sunshine once the fog burns off and
temps warming well into the 70s. Based on progged 925mb temps 1 to
2C warmer, expecting highs upper 60s to mid 70s. Some local haze
possible from lingering wildfire smoke, especially deeper valleys
where mixing with light flow aloft is limited. Little change
anticipated on Sunday night with areas of fog likely again and temps
a few degrees warmer. Will be watching for smoke potential closely,
especially given trends in the 12Z HRRR near sfc smoke output. Lows
mid 40s to mid/upper 50s with light trrn driven winds.
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
As of 305 PM EDT Saturday...The work week will start out dry as
ridging builds into the region. A weak shortwave will rotate around
the top of the ridge, with a weak frontal boundary slipping along
north of the international border. Given the lack of appreciable
moisture and forcing though, there won`t be much impacts beyond
increased cloud cover. High temperatures will remain above normal,
in the lower to mid 70s, with some locations possibly approaching
80F. Monday night lows will be in the upper 40s to upper 50s.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 305 PM EDT Saturday...The focus for the long term continues to
be summer-like temperatures, with the potential for daily records to
be broken. Overall thinking has not changed as latest guidance
continues to indicate anomalously strong ridging settling directly
over head through mid week. The result will be abundant sunshine and
continuing dry weather. Wednesday will be the warmest day of the
period, with highs reaching into the 80s areawide. See the climate
section below for full details. Dewpoints should generally remain in
the mid 50s to mid 60s, so not too uncomfortable, which should allow
for some cooling relief at night.
Things start to change by next weekend as the ridge shifts east,
making way for an upper trough digging into the Midwest/Great Lakes
and its associated cold front. There`s still some model differences
in the strength and timing of the upper trough, and therefore still
some uncertainty as to exactly when precipitation will move into our
area. Regardless, expect we`ll see much cooler and wetter conditions
by at least the 2nd half of next weekend.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Through 00Z Monday...VFR/SKC will continue this evening through
04-06Z before areas of LIFR fog develop and continue through
12-14Z. Highest confidence is at KSLK and MPV, though based on
persistence from last night, it`s also very likely at KMSS.
Nocturnal southeast flow should limit fog at KRUT, while VCFG is
possible at KBTV/KEFK. After 12-14Z, SKC returns to all sites
with winds northerly around 6kts.
Outlook...
Sunday Night: VFR. Patchy BR.
Monday: VFR. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. NO SIG WX.
&&
.CLIMATE...
Daily maximum temperature record and forecast (in parentheses) Tuesday
through Thursday of next week.
Date KBTV KMPV KMSS KPBG KSLK
10-03 82(82)|1891 82(79)|1967 83(81)|1953 85(80)|1967 86(79)|1941
10-04 82(84)|1891 80(81)|2017 82(83)|1951 82(81)|1967 80(81)|1951
10-05 82(81)|1926 82(77)|1951 85(81)|1991 80(78)|2005 83(77)|1951
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Taber
NEAR TERM...Lahiff/Taber
SHORT TERM...Hastings
LONG TERM...Hastings
AVIATION...Lahiff
CLIMATE...Clay
Area Forecast Discussion
National Weather Service Goodland KS
416 PM MDT Sat Sep 30 2023
.SHORT TERM...(This evening through Monday Night)
Issued at 255 PM MDT Sat Sep 30 2023
At the beginning of the short term period, the latest RAP analysis
depicts a southwesterly flow over the CWA being between an upper air
trough in the western CONUS and an upper air ridge over the Great
Lakes region. Current satellite imagery shows some high clouds
moving northeast into the southern portions of the CWA with current
surface observations reporting dry conditions with southerly surface
winds gusting up to around 30 kts. Going forward through the rest of
Saturday, forecast guidance shows the southwesterly flow continuing
over the CWA with the western trough moving east over the CA/NV
border. An evening shortwave disturbance is seen just to the west of
the CWA as well. At the surface, models show the gusty southerly
winds continuing through the rest of the day being on east of a
surface trough in CO. Forecasted max wind gusts for the rest of the
day look to stay just below 40 kts at most, but will promote near
critical to locally critical fire weather in some portions of the
CWA. Widespread blowing dust is not expected, but localized blowing
dust cannot be rules out. Models are also showing chances for
showers and thunderstorms particularly in the CO counties in the
late afternoon and into the evening, but they look to be more high
based dry thunderstorms at this time. Currently in an SPC marginal
risk for the southwestern quadrant of the CWA with possible hazards
including strong winds. Will continue to monitor this going forward.
The low temperatures for tonight are forecast to be in middle 50s to
upper 60s.
On Sunday, model guidance depicts an upper air low developing over
NV that cuts itself off from the general upper air pattern in the
morning and travel eastward over the NV/UT border by the overnight
hours allowing for the southwesterly flow to persist throughout the
entire day. At the surface, models are forecasting a surface low to
move into southeastern WY causing a tight pressure gradient across
the CWA. Model forecast soundings show southerly surface winds
throughout the day gusting up to around 45 kts possible. These winds
will cause near critical fire weather conditions (though forecast
minimum RH values do not support it) along with some potential for
blowing dust within the region. Will continue to monitor for better
timing and location of possible blowing dust, but the latest GFS run
shows 0.5-1km winds under 40 kts during the day when the best
supporting lapse rates expect to occur. Opted to add a blowing dust
mention to where the winds are the strongest at this time. Daytime
highs for Sunday range between the lower and upper 80s followed by
overnight lows in the middle 50s to middle 60s.
For Monday, models show the upper air low progressing over the CO/WY
border by the evening hours before starting to open up into trough
during the overnight hours. The CWA is expected to be underneath the
front of the trough and having a southwesterly flow aloft with a
shortwave disturbance making its way through the flow during the
evening. At the surface, another windy day can be expected
particularly in the western portions of the CWA with winds up to
around 40 kts seen during the day. Near critical fire weather may be
possible with these winds though the minimum RH values once again do
not support it. Blowing dust potential might be there again with
these winds, but not enough confidence to mention in the forecast at
this time. There are also chances for showers and thunderstorms seen
across the CWA during the evening care of the upper air shortwave
disturbance as well as ample amounts of 850mb moisture entering
the region from the south throughout the day. Current QPF totals
look to range from a trace to just under a half inch in the far
southern portions. Latest forecast convective parameters show
perhaps a marginal risk for severe storms at this time, so will
continue to monitor this going forward. Daytime highs look to be
between the lower and upper 80s while overnight lows range between
the upper 40s and lower 60s.
.LONG TERM...(Tuesday through Saturday)
Issued at 114 PM MDT Sat Sep 30 2023
Forecast concerns for the later periods will continue to focus on
storm system sweeping over the area on Tuesday followed by a return
to more seasonable temperatures through the rest of the week. Medium
range deterministic models have shifted with the low position taking
a more northerly track, resulting in less of a wind threat behind
cold front that yesterday`s data. While confidence is lower than
yesterday, a not insignificant number of GEFS ensemble members
are holding onto a slower, more southerly solution so it will
remain something to watch although confidence has fallen. Aside
from post frontal wind potential small threat for strong/severe
thunderstorms will exist Tuesday afternoon ahead of cold front,
but looks like window for strong storms will be relatively short.
Other concern for the period will be the return of more seasonable
temperatures, especially lows. Overnight lows will begin to dip into
the 30s in several locations, with chances increasing for a
potential frost as next weekend approaches.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 416 PM MDT Sat Sep 30 2023
Both terminals will see VFR conditions through the forecast
period. Winds for KGLD, south 20-30kts. Gusts to 40kts possible
through about 01z-02z Sunday and again from 16z Sunday onward.
Winds for KMCK, south 15-25kts with gusts up to 30-35kts. LLWS
03z-13z Sunday 180@50kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...076
LONG TERM...JRM
AVIATION...JN
Area Forecast Discussion
National Weather Service Northern Indiana
705 PM EDT Sat Sep 30 2023
.SYNOPSIS...
Issued at 240 PM EDT Sat Sep 30 2023
More fog is likely tonight and may become locally dense late. Dry
and mild weather will continue into the middle of this upcoming
week with highs mostly in the upper 70s to mid 80s.
&&
.UPDATE...
Issued at 650 PM EDT Sat Sep 30 2023
No changes to current forecast or headlines.
Plenty of clear skies and light winds to set the stage for fog
potential once again overnight. Bit concerned on coverage of the
dense fog threat, but agree with afternoon forecaster that if it
takes shape, NW Ohio and Maumee River Valley area may be most
likely areas to be impacted (HRRR sharing this sentiment which
handled last nights fog quite well). Despite this and potential
for more patchy to areas of fog/dense fog, plenty of concerns to
continue with headlines, but not expand west as crossover temps in
the low 50s less likely to be met.
&&
.SHORT TERM...(This Evening through Sunday)
Issued at 240 PM EDT Sat Sep 30 2023
High pressure will continue to dominate the areas weather for the
next several days. With mostly clear skies and light easterly winds
again tonight, dense fog is likely to redevelop, especially over
northwest Ohio into southeast Lower Michigan. It could also expand
into parts of northeast Indiana, particularly the Maumee River
Valley. A Dense Fog Advisory will therefore be issued. After the fog
clears on Sunday, we can then expect another unseasonably warm day
with highs near 80 degrees under clear skies.
&&
.LONG TERM...(Sunday Night through Saturday)
Issued at 240 PM EDT Sat Sep 30 2023
The ridge of high pressure will remain over the region on Monday
and Tuesday, and then shift eastward and position itself over the
Mid-Atlantic on Wednesday. This will allow for warm and dry
daytime conditions to persist during the first half of the
workweek, and at least patchy fog each morning. A fairly deep
trough will then move in from the west on Thursday for our next
chance of rain and possibly thunderstorms. This will also bring a
much cooler airmass. By Friday, highs will only be in the mid 60s.
With cyclonic flow aloft lasting into next weekend, cloudy and
showery conditions should prevail.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 650 PM EDT Sat Sep 30 2023
Shorter duration period of fog/stratus development still expected
with greatest flight conditions impact likely at KFWA. HRRR model
did a nice job last night on coverage and impacts, but not as
strong tonight, leading to a somewhat lower confidence on specific
impacts and duration, but will continue with past trend and also
add a tempo mention for 1/4sm at KFWA.
Outside of this, VFR conditions expected with light winds.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Dense Fog Advisory from 2 AM to 10 AM EDT Sunday for INZ005>009-
017-018-024>027-116-216.
MI...Dense Fog Advisory from 2 AM to 10 AM EDT Sunday for MIZ079>081.
OH...Dense Fog Advisory from 2 AM to 10 AM EDT Sunday for OHZ001-002-
004-005-015-016-024-025.
LM...NONE.
&&
$$
UPDATE...Fisher
SYNOPSIS...T
SHORT TERM...Cobb
LONG TERM...Cobb
AVIATION...Fisher
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Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1101 PM CDT Sat Sep 30 2023
.UPDATE...
Issued at 1055 PM CDT Sat Sep 30 2023
Updated to include 06z aviation discussion below.
&&
.DISCUSSION...(This evening through Saturday)
Issued at 315 PM CDT Sat Sep 30 2023
KEY MESSAGES:
- Record highs expected Sunday.
- A cold front mid week will bring chances for showers and highs
next weekend 30 degrees cooler than this weekend.
Everything was going off as planned today, and then thunderstorms
decided to develop near Sioux Falls within an enhanced area of
moisture transport around the h85 level. MUCAPE upstream of this
moisture transport is up around 3000 j/kg, so it is a very unstable
airmass getting advected over a stationary front that meanders from
Sioux Falls up to the Twin Cities, then back down to La Crosse.
There`s been just enough lift to get isolated storms going. However,
with deep layer shear around 25 kts and large scale subsidence from
rising heights, these storms have really struggled to grow and
sustain themselves. Based on the RAP h85 moisture transport
forecast, this forcing for isolated storms should track more north
through the afternoon, with an isolated storm threat continuing for
the western half or so of MN. For the rest of tonight, we cut back
on PoPs pretty substantially as subsidence from rising heights and a
divergent h85 flow are both pretty strong negative factors for lift
and storm development. With the 12z CAMs retreating from convection
en masse, we did the same with our grids.
For Sunday, confidence is increasing that we will have record highs,
with low 90s in southwest MN. The lack of convection expected
tonight will result in a lack of cloud cover for Sunday, which
combined with lows only dropping back in the mid 60s to low 70s will
set the stage for the attempts at setting record highs we`re
expecting for October 1st. The ensemble situational awareness table
for the EPS mean values shows h5 and h7 heights Sunday and Monday
exceeding the CFS reforecast climatology, with h85 temps right up at
climatological max values. The only bit of silver lining for Sunday
is that as the warm front continues to push into northern MN, we`ll
see the dewpoints near 70 head that way as well, with our dewpoints
retreating back into the upper 50s south to the mid 60s in central
MN.
For next week, the trend noted in the last discussion about the next
system slowing down continues. We will remain in strong southerly
flow through Tuesday, which means another day of highs well into the
80s on Monday, with lower 80s for highs continuing into Tuesday.
Shower chances keep getting delayed as well with those not really
beginning until Tuesday afternoon out in western MN, with the best
chances for the MPX area coming Tuesday night. The trend also
continues for us being in a bit of a forcing no-man`s land with this
system, with the h5 wave tracking across the Dakotas and NW MN, with
the MPX area finding ourselves on the south end of a front with
increasingly diminishing forcing.
Still not changing with this front is much cooler air to end the
week as northwest flow and high pressure from Canada move in. The
coldest air looks to arrive next weekend, when highs will be in the
50s, or 30 degrees colder than this weekend. Also looking possible
next weekend is our first sub-freezing temperatures of the season
for central into western MN (closer to the center of the surface
highs). For central MN, this would be about a week and a half later
than normal for seeing their first freeze of the fall. For the end
of the week into next weekend, we have some small PoPs mainly east
of the MS River, tied mainly to cooler temperatures aloft and
cyclonic flow associated a deep trough that will dive down from the
Canadian Arctic into the Great Lakes.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1055 PM CDT Sat Sep 30 2023
One small area of convection remains from the large swath earlier
this evening, and this cluster of storms may produce a glancing blow
to KSTC briefly. Otherwise, dry conditions are expected at all TAF
sites, and this does mean precip-free conditions at the WI TAF sites
as any convection developing overnight looks to remain to the N of
both KRNH and KEAU. Residual low level moisture may make for some
low stratus in western MN. Otherwise, only FEW/SCT high clouds will
prevail overnight through much of Sunday. Winds will gradually turn
from E to S over the next 18-24 hours, with speeds becoming breezy
after sunrise Sunday. Speeds will increase to around 15G25kts for the
MN TAF sites and to around 10kts for the WI TAF sites.
KMSP...No additional concerns.
/OUTLOOK FOR KMSP/
Mon...VFR. Wind SSW 15G25 kts.
Tue...VFR. Wind SW 20G30 kts.
Wed...Chc MVFR/-SHRA. Wind NW 10-15 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
UPDATE...JPC
DISCUSSION...MPG
AVIATION...JPC
Area Forecast Discussion
National Weather Service Marquette MI
811 PM EDT Sat Sep 30 2023
.SHORT TERM...(Through Tonight)
Issued at 420 PM EDT SAT SEP 30 2023
Visible satellite shows widespread cloud cover across Upper Mi this
afternoon in the wake of the convective vort max and widespread
showers that moved through this morning. SPC RAP mesoanalysis
indicates only weak MLCAPE values in the west this afternoon, but
this weak instability will be capped by 100-200 j/kg of MLCIN so
it`s unlikely we`ll see more shower activity for the rest of this
afternoon. Under clouds temp readings have stayed mostly in the mid
to upper 60s, although there have been a few locations that have
cracked 70F.
Several of the CAMs show scattered showers/isolated thunderstorms
becoming reinvigorated tonight with WAA at the nose of a LLJ over
northern WI although the exact timing and coverage of the showers is
uncertain at best. Given the uncertainty have only chc pops for
showers tonight. Given the moist low-levels, expect fog to redevelop
tonight and it could become locally dense in some spots aided by se
to e upslope winds. Expect min temps from the mid 50s to lower 60s
under mostly cloudy skies.
.LONG TERM...(Sunday through Saturday)
Issued at 329 PM EDT SAT SEP 30 2023
Key Messages:
-Unseasonably warm, near record temps Sunday through Tuesday
-Frontal passage Wednesday brings temps back to normal for the end
of the week along with periods of showers
-Reinforcing shot of cold air possible by Saturday leading to cooler
than normal temps and lake effect rain showers next weekend
Omega block-type pattern will be in place over the CONUS to start
the period, with cutoff lows over the Great Basin and North
Atlantic, and anomalous ridging encompassing much of the central US
into southern Canada. +2 to +3 standardized anomaly 500 mb heights
characterize this ridge over the Upper Midwest/southern Canada. This
upper air pattern gradually shifts east during the upcoming week,
with height falls of substance holding off across the local area
until likely Wednesday. Anomalously warm airmass well get pumped
into the upper Great Lakes region/southern Canada Sunday through
Tuesday, with 850 mb temps likely topping out in the upper teens
(C), which represents a +1 to +3 standardized anomaly per the NAEFS.
Frontal passage associated with the inbound midlevel trough should
usher in a more seasonable airmass for the end of the week, while a
reinforcing shot of even cooler air appears possible for next
weekend. Medium-range deterministic and ensemble guidance has been
rather consistent depicting the above synoptic-scale evolution.
There will likely be at least some scattered showers and storms
around to start the period 12Z Sunday, but these are expected to
diminish through the morning hours as midlevel height rises build in
and the lower-level front washes out. We could be dealing with some
stubborn low cloudiness, especially during the morning hours and
especially downwind of Lake Michigan, and the forecast reflects a
slower clearing trend than NBM. Where clearing occurs soonest across
the interior west, a very warm day is expected with highs reaching
the low to mid-80s. Highs should range through the 70s over the east
half where clearing will be slower and low-level winds will be off
Lake Michigan.
For Sunday night into Tuesday, it appears to be an ideal setup for
unseasonably warm temperatures as the southwesterly low-level flow
sets up between high pressure over the northern Appalachians and low
pressure over the northern Plains. Temperatures should be able to
make the most of the limited day length with deep mixing and few
clouds forecast (although can`t rule out some lower clouds
developing downwind of Lake Michigan during the night and morning).
Went above NBM guidance for temps, closer to consensus MOS guidance.
This yields lows mainly in the upper 50s to upper 60s Sunday night
through Tuesday night, and highs mainly in the 80s (mid to upper 70s
along the Lake Michigan shoreline) Monday and Tuesday. These temps
will be near record highs and high minima, supported by ECMWF EFI
0.6-0.9 and SoT > 1, peaking Monday.
Frontal passage is on track for Wednesday/Wednesday night which will
likely be accompanied by showers. It does not look to be a sharp
front, and instability is limited, so thunderstorm coverage appears
low at this point. Trough settles overhead Thursday which could
result in some lingering showers. Temps should be back near normal
values with highs mainly in the low to mid-60s. Another digging
trough may follow for Fri/Sat, which will provide a reinforcing shot
of cold air with 850 mb temps likely falling below 0C. This will
likely result in some lake effect rain showers and seasonably cool
temps.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 808 PM EDT SAT SEP 30 2023
VFR conditions have briefly returned to the TAF sites, but it will
be short-lived with a frontal boundary draped across the area.
Scattered showers and thunderstorms are currently drifting over
eastern Upper Michigan, and they cannot entirely be ruled out from
re-developing tonight. With lack of confidence in timing and
placement though, will only carry a VCHS mention at SAW for now.
Nonetheless, MVFR conditions are progged to quickly return this
evening with further deterioration to IFR/LIFR at CMX and SAW.
Airport minimums will also be possible at CMX in dense fog.
Recovery will be slow with VFR not returning until tomorrow
afternoon at CMX and SAW. The exception will be IWD, which could
see some VFR conditions early tomorrow morning. Winds through the
period will generally be light and variable before becoming mostly
southerly.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 329 PM EDT SAT SEP 30 2023
Winds should remain less than 20 kt through Sunday. Patchy fog is
possible over the lake through Sunday morning, especially where
rainfall occurred. There is a slight chance of thunderstorms through
Sunday. Southerly winds will increase late Sunday night through
Wednesday, with winds gusting 20-25 kt at times. A cold front will
turn winds westerly Wednesday night, with 20-25 kt gusts possible
through the end of the week.
&&
.CLIMATE...
Issued at 334 AM EDT SAT SEP 30 2023
Record high temperatures at the NWS Office in Negaunee:
Sep 30: 80 (2000)
Oct. 1: 83 (1976)
Oct. 2: 87 (1992)
Oct. 3: 78 (2005)
Oct. 4: 76 (2007/2011)
Record warm low temperatures at the NWS Office in Negaunee:
Sep 30: 58 (2002)
Oct. 1: 57 (2000)
Oct. 2: 60 (2005)
Oct. 3: 65 (2005)
Oct. 4: 60 (2005)
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...Thompson
AVIATION...TDUD
MARINE...Thompson
CLIMATE...Voss
Area Forecast Discussion
National Weather Service Las Vegas NV
730 PM PDT Sat Sep 30 2023
.SYNOPSIS...A strong Pacific system moving into the region will
bring scattered showers and thunderstorms, gusty southwesterly
winds, and sharply cooler temperatures through Sunday. Temperatures
will begin rebounding early next week as this system clears out and
high pressure moves in.
&&
.UPDATE...Starting to see showers and thunderstorms develop within
the Lake Mead NRA, from Cottonwood Cove north to Lake Mead just
ahead of potent vorticity center pivoting through base of trough
over southern California. Have also been seeing streets of showers
and thunderstorms develop over eastern/northern Mohave County. Got a
report from a BLM fire team working a prescribed burn near Mt.
Trumbull in northern Mohave County of dime sized hail. Earlier run-
to-run consistency of the HRRR has not been the greatest in
attempting to depict convection potential for Las Vegas. Last two
runs of the HRRR latching onto the idea of this area just east of
Las Vegas lifting north-northeast over Lake Mead NRA/northeast Clark
County through 10-11 pm this evening, and eventually Lincoln County
and southwest Utah overnight.
The area of strong convection under the cold pool aloft over
northern Inyo, Esmeralda and central Nye Counties has been
weakening. We have seen a dusting of new snow at higher elevation,
significant amount of graupel northwest of Beatty along Highway 95,
and locally heavy rain with one station near Scotty`s Junction
reporting 1.64" in the past 6 hours.
Latest model data still arriving so will likely kick out an update
later.
&&
.SHORT TERM...through Sunday night. Midday satellite loop showed
complex low pressure area centered near the central Sierra. Well to
the east, large-scale lift had helped generate dense mid and high
level clouds which were blanketing much of our CWA. Nearer the low
center, the back edge of the thicker clouds had begun to move
through Inyo County, and scattered thunderstorms were developing
from the White Mountains to Tonopah to Beatty. Mesoanalysis showed
500 J/kg of CAPE in this area, along with -3 LIs and up to 35 knots
of effective bulk shear. More thunderstorms are expected through the
afternoon and evening as the back edge of the overcast layer moves
east, with the best window of opportunity in Las Vegas being roughly
5 to 9 pm. The main threat with storms will be high winds due to
strong ambient winds already in place. Locally heavy rain could also
cause problems for areas which are still trying to recover from
severe August flooding, and small hail is also likely given the cold
temperatures aloft. Thunderstorm chances should continue through
Sunday night, particularly in the southern Great Basin, as the cold
core aloft meanders over the region. This will also translate to
unseasonably chilly surface temperatures, with highs Sunday even
further below normal than today. Lighter winds are expected Sunday
away from thunderstorms.
.LONG TERM...Monday through Friday.
The low will start to weaken and shift east with a chance of some
light showers lingering in Lincoln and northern Mohave Counties
Monday. Have to watch for potential first freeze of the season for
Lincoln County. 01Z NBM probability of Caliente reaching 32 or below
is 13% Monday morning. High temperatures not as cold Monday, but
still some 10-15 degrees below normal.
Pleasant work week in store as it will be dry and warmer under ridge
with temperatures returning to normal Thursday and Friday.
&&
.AVIATION...For Harry Reid...The biggest concern for the terminal is
a period of thunderstorms possible roughly 00-04Z this evening. The
main threats with storms will be erratic gusty winds and ceilings
dropping to or below 8000 feet. Away from storms, south to southwest
winds gusting around 25 knots are expected through early evening
before decreasing tonight. Quieter weather is expected Sunday.
For the rest of southern Nevada, northwest Arizona and southeast
California...Scattered thunderstorms will develop through the
afternoon and spread northeast, with the greatest coverage near and
north of Interstate 40. The main threats with storms will be erratic
gusty winds and lower ceilings with terrain obscuration. Away from
storms, VFR conditions are expected with south to southwest winds
gusting 25 to 35 knots through the afternoon, then decreasing from
west to east this evening. Lighter winds are expected Sunday, with
thunderstorm chances persisting in the southern Great Basin tonight
through Sunday.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
SHORT TERM...Morgan
LONG TERM...Pierce
AVIATION...Morgan
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