Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/29/24
Area Forecast Discussion
National Weather Service Des Moines IA
640 PM CDT Mon Oct 28 2024
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
- Wind Advisory in effect for the daytime Tuesday. Sporadic Advisory level
wind gusts over 40 mph possible (~50% confidence) beginning after Midnight and into
Tuesday night.
- Marginal Risk for severe weather Tuesday late for the northwest, evolving into
a Slight Risk for the south Wednesday afternoon. Severe chances will be better
defined in the coming days.
- Near record temperatures possible with highs in the 80s and lows in the
60s within the next 48 hours.
&&
.DISCUSSION...
Issued at 300 PM CDT Mon Oct 28 2024
Iowa sits on the western side of a departing upper level ridge today
and the peak temperatures for the week have yet to be seen. Morning
objective analysis showed a trough over the western CONUS that will
be deepened by a 110kt+ upper level jet off the cost of the PNW. In
the OAX 12z RAOB, H850 temperatures of 17C are already above the
90th percentile for sounding climatology today with 20C temperatures
not far downstream of the 40kt jet. The winds at this level will
remain elevated as the pressure gradient tightens, exceeding 40kts
by this afternoon, keeping our winds elevated this afternoon with
gusts exceeding 35 mph, at times. Cloud cover and a WAA regime will
limit mixing through the entire PBL. The high pressure that has
blocked the Gulf moisture for an extended period has shifted east,
opening a channel of Gulf moisture into the Plains. This is partly
to blame for the cloud cover that is scattered about the region
today. The cloud cover will hinder highs from rising into record
territory this week, including today. Highs this afternoon will be
in the mid to upper 70s. It can`t be ruled out to see highs in the
80s in the far south if more sunshine is present today (confidence
is only at about 30%).
Winds remain elevated through the night tonight due to the pressure
gradient. The first plume of moisture advects to the northeast with
a dry slot setting in across the west. The LLJ will really increase
tonight, approaching 70kts after midnight. These high winds will
have a hard time reaching the ground because of WAA, but winds will
be high nonetheless. The pressure gradient winds below will inhibit
how much the PBL will decouple overnight. The HREF wind gusts values
are very high overnight in the southern half of the state. The mean
values hover right at 45 mph gusts with very little distribution
spread (spread between the 25-75th percentiles is only 3mph). It`s
certainly possible to see sporadic winds over 50mph, but this won`t
be a consistent feature due to the regime and time of day. The 12z
(and subsequent) HRRR wind gusts appear lower, but the very shallow
nocturnal inversion in its own sounding makes the lower gust
solution appear very unconvincing. An error of just a degree or two
would allow the Wind Advisory-level winds to reach the surface
overnight, this is also why the wind gusts in this model accelerate
so quickly once diurnal heating is introduced in later time steps.
Speaking to that, in the few hours right after sunrise, winds will
peak for the day with 45 mph+ winds widespread across the south
before 10am. Winds will decrease as the LLJ eases in the day, but
will remain at Wind Advisory criteria through the day across the
south. Sustained winds near 30 mph probable (70% confidence) with
wind gusts near 45 mph likely (80%) confidence. Have started with a
Wind Advisory for the daytime Tuesday for areas south of Highway 20
with refinement expected as guidance refreshes.
The other story in the short term is the temperatures. Lows both
tonight and tomorrow night are expected to break several site
records for high minimum temperatures. Highs tomorrow will cross
into the 80s and approach records at mainly Mason City and Waterloo.
Continued cloud cover will inhibit further warming. See the climate
section below for more information on records for the next few days.
Dew points will also reach 60 degrees Tuesday, an uncommon feat this
late in the season. There will be a pause in moisture in northwest
Iowa where RH values will drop to near 40% this afternoon. While the
moisture is high enough to make ignition of fires more difficult,
fires that do start may spread easily.
The system mentioned previously has slowed its approach in more
recent runs, now arriving in the west on Wednesday. Instability will
will be primarily focused across the south where it has the chance
to be uncapped and surface-based (as indicated by the RAP). Wind
shear will be favorable given the wind profile is generally strong.
The farther north you traverse, the less likely storms will have
surface based potential. Even with CAPE values below 1,000 J/kg, the
organization potential from the shear still makes this setup
favorable for severe weather. Rainfall amounts will also total more
than an inch, perhaps some places up to 2 inches, which will help
with the dryness experienced.
There is another potential for the PBL to stay coupled to the
surface tonight as the LLJ again tightens, bringing higher wind
potential once again tonight. Temperatures cool to more seasonable
standards to finish the week. More rain chances return for the
weekend. The pattern shift continues into next week as models
develop another trough in the Western CONUS.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 632 PM CDT Mon Oct 28 2024
Primary impact to TAFs will be winds overnight tonight and into
tomorrow. We are already seeing a decrease in wind gusts as the
surface decouples early this evening, however, given the winds
aloft, have not removed the gusts mention through the night for
KALO, KDSM, and KOTM in this TAF issuance. Should it seem
evident that the surface inversion will hold off any sporadic
gusts, will amend to remove these. Regardless of gusts
overnight, a strong LLJ will result in LLWS at the same
locations through tomorrow morning. Strong southerly winds then
pick up at all sites tomorrow, with gusts of 35 to 40+ kts
possible at times.
Aside from winds, mostly VFR conditions are expected through the
period, although some low clouds around 3.5 to 4 kft are
drifting over northwest Iowa this evening, which may impact KFOD
and KMCW. In this same area, models have suggested some fog
development through the morning hours. However, impacts appear
isolated and remain northwest of TAF sites, so have left any
MVFR or lower mention out of this round of TAFs.
&&
.CLIMATE...
Issued at 357 AM CDT Mon Oct 28 2024
.Forecast and Record Max Temps for Select Central Iowa Cities...
==================================================================
|Mon 10/28 Previous |Tues 10/29 Previous | Period
| Forecast Record/ | Forecast Record/ | of
City | Max T Year | Max T Year | Record
===================================================================
Des Moines | 77 84/1927 | 83 89/1937 | 1878-
Lamoni | 78 82/1944 | 80 89/1937 | 1897-*
Mason City | 74 77/1945 | 82 83/1937 | 1903-
Ottumwa | 76 84/1927 | 83 91/1937 | 1923-
Waterloo | 74 78/1927 | 84 85/1937 | 1895-
===================================================================
*Incomplete dataset
.Forecast and Record Max Minimum Temps for Select Central Iowa Cities...
==================================================================
|Tues 10/29 Previous |Wed 10/30 Previous | Period
| Forecast Record/ | Forecast Record/ | of
City | Min T Year | Min T Year | Record
===================================================================
Des Moines | 67 66/1946 | 67 63/1901 | 1878-
Mason City | 59 54/1974 | 62 58/1924 | 1903-
Ottumwa | 68 67/1946 | 69 59/1924 | 1923-
Waterloo | 62 59/1901 | 67 60/1927 | 1895-
===================================================================
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 9 AM to 8 PM CDT Tuesday for IAZ033>039-
044>050-057>062-070>075-081>086-092>097.
&&
$$
DISCUSSION...Jimenez
AVIATION...Dodson
CLIMATE...KCM
Area Forecast Discussion
National Weather Service Goodland KS
504 PM MDT Mon Oct 28 2024
.KEY MESSAGES...
- Very strong winds Tuesday afternoon with widespread sustained
winds 30 to 40 mph and gusts 45 to 55 mph. Potential for
sporadic 58+ mph gusts mainly west of K-27, which is also
where blowing dust concern is greatest.
- Dangerous critical fire weather conditions as the very strong
winds will combine with widespread relative humidity in the 13
to 20% range, leading to an upgrade of the Fire Weather Watch
to a Red Flag Warning.
- Hard freeze possible across the entire Tri-State area
Wednesday night / Thursday morning.
- Another active pattern may return next weekend.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 206 PM MDT Mon Oct 28 2024
This afternoon`s water vapor imagery and RAP objective analysis
showed a large, deep trough in the mid-upper troposphere
encompassing much of the western CONUS. A strong and far-reaching
southwest flow pattern aloft was found across nearly the entire
length of the CONUS Rockies, leading to broad leeside trough from
the Dakotas south across western Nebraska into eastern New Mexico.
The main forecast challenge will be wind magnitude tomorrow and
whether High Wind conditions will be met (sustained 40+ mph for an
hour or any gusts 58+ mph). Latest guidance, including HREF
probabilities do not support High Wind conditions with very low
probabilities of 50+ mph gusts on the 12Z HREF, including out west
where boundary layer mixing will be deeper. Now, high-resolution
models tend to be underdone with peak wind gusts in synoptic
gradient scenarios, but even at that, NBM 95th percentile gusts top
out 52-55 mph, and that is just for areas mainly along and west of K-
27 corridor. For that reason, we decided to cancel the High Wind
Watch east of the K-27 corridor and let the next shift(s) decide on
how to handle the remaining 5 counties in the High Wind Watch.
Despite this, even if winds remain below High Wind criteria, patchy
to areas of blowing dust are likely to occur and we will keep that
in the grids.
As far as the thunderstorm potential goes, a slightly slower timing
of the main forcing for ascent downstream of mid-level potential
vorticity (PV) anomaly is likely to lead to a slower development
thunderstorm potential, and the timing may be too late for any
thunderstorms at all, even in the eastern counties. The problem for
initial thunderstorm development will be a very warm EML
overspreading the warm/moist lower troposphere preventing
thunderstorm development until well after sunset, if not after 06Z
Wednesday. By 06Z Wednesday, the best low level convergence along
the advancing cold front will be across far eastern GLD CWA, so this
is where we will be keeping some 20-30%. Deeper low level moisture
for more vigorous convective updrafts are expected to remain across
north central and central kansas, to the east of the GLD CWA which
will limit sustained severe weather potential, despite robust deep
layer and low level wind shear.
As the storm system finally lifts out Wednesday, strong low level
cold air advection will ensue, leading to a much cooler day on
Wednesday. We will watch for some light rain/rain showers in the mid
level deformation axis across the northwest half of the GLD CWA,
around the tri-state area, but all models show the storm lifting out
as an open wave, so 700mb frontogenesis in the deformation axis is
not expected to be all that impressive, especially given the fairly
progressive forward motion of the storm itself as it lifts out
Wednesday.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 206 PM MDT Mon Oct 28 2024
A widespread killing freeze (28 degrees or less) appears quite
likely Thursday morning with the fresh, cold airmass in place
following the early-mid week storm system. Latest NBM shows
continued 60-85% probabilities of less than 28 degree low
temperature across the northwestern half of the GLD CWA. This event
is supported by all the latest global models as they all show the
center of a cold surface high over eastern Colorado/western Kansas
12Z Thursday.
The surface high will push east fairly quickly as the large scale
pattern reverts back to southwest flow aloft late week. Thus, only
one night of widespread sub-freezing temperatures is expected. As we
head into the weekend into early next week, another active pattern
is likely to evolve, leading to probabilist shift toward wetter
weather across the Central Plains in the 6-10 day period, however
there is tremendous uncertainty in how the synoptic details will pan
out, so keep checking back for updates.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 500 PM MDT Mon Oct 28 2024
For KGLD & KMCK... VFR conditions are forecast for the period,
though blowing dust tomorrow afternoon may pose some problems.
The best chances for concentrated blowing dust look to be
southwest of the terminals, so currently am keeping VFR
conditions. A brief period of low level wind shear is forecast
as the low level jet develops, but then a low-mid level feature
is forecast to move through and weaken the winds. Best time
frame looks to be between 03-09Z. Surface winds will then
strengthen from the southwest during the daytime hours tomorrow,
with wind gusts in the 30-45 kts range likely during the
afternoon hours.
&&
.FIRE WEATHER...
Issued at 206 PM MDT Mon Oct 28 2024
Critical fire weather conditions are likely as south to southwest
winds will increase to the 25 to 35 mph range. Winds will be well
above the critical threshold, however relative humidity will be
borderline. Regardless, given the magnitude of southwest wind with
gusts in the 45-55 mph range, some leeway was given in the RH
criteria with respect to Red Flag Warning issuance.
&&
.CLIMATE...
Issued at 156 AM MDT Sun Oct 27 2024
October 29th Warmest Minimum (Low) Temperature Records For ASOS
Sites. A Quicker Cold Frontal Passage on Tuesday Will More Than
Likely Result In These Records Not Being Met:
Goodland.....50 degrees in 1922.
McCook.......53 degrees in 1956.
Burlington...52 degrees in 1922
Hill City....62 degrees in 1927.
October 29th High Temperature Records For ASOS Sites Within Five
Degrees of Reaching Their Record:
McCook.......87 degrees in 2003.
Hill City... 89 degrees in 1937.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Fire Weather Watch Tuesday afternoon for KSZ002>004-013>016-
027>029-041-042.
High Wind Watch Tuesday afternoon for KSZ013>016-027>029-041-
042.
CO...Fire Weather Watch Tuesday afternoon for COZ253-254.
High Wind Watch Tuesday afternoon for COZ091-092.
NE...None.
&&
$$
SHORT TERM...NWS DDC/Umscheid
LONG TERM...NWS DDC/Umscheid
AVIATION...KAK
FIRE WEATHER...NWS DDC/Umscheid
CLIMATE...Trigg
Area Forecast Discussion
National Weather Service San Francisco CA
731 PM PDT Mon Oct 28 2024
...New UPDATE...
.SYNOPSIS...
Issued at 1228 PM PDT Mon Oct 28 2024
An active weather pattern will bring cold weather through the week
with periods of rain and strong wind.
&&
.UPDATE...
Issued at 725 PM PDT Mon Oct 28 2024
Only a couple of rain showers on radar in Eastern Napa County and
Eastern Contra Costa County with rain shower activity continuing
to diminish as daytime heating is lost. The main hazard in the
short term will be the cold. Tonight will be the coldest night
this week as strong and gusty northwesterly winds continue through
the morning and clear skies allow for radiational cooling. The
forecast remains on track with no necessary changes needed at this
time.
&&
.SHORT TERM...
(This evening through Tuesday)
Issued at 1228 PM PDT Mon Oct 28 2024
KMUX is back online, and just in time to watch the surface based
convection develop into the afternoon. Showers are currently
isolated, but coverage is gradually increasing as the surface
continues to warm. Some returns have touched the 50 dBz threshold,
though not over any rain gauges yet, so there`s still some
uncertainty regarding how much is actually hitting the ground.
The latest HRRR runs shows surface based CAPE of 200-400 J/kg,
peaking in the early afternoon, and we have surpassed the
convective temperature of 64F at Oakland. This means there is a
good amount of low-level instability. The limiting factors are a
0.64" PWAT, and elevated inversion at 700 mb. Most of the cloud
layer is below the freezing level, and lightning is still very
unlikely.
A coastal jet is expected to develop this evening, bringing strong
winds to the coast and SF Bay. Sustained winds of 20 mph with
gusts up to 35 mph are expected. Storms will peter out through
the night as the skies clear. This, combined with the strong
northerly winds, will allow the temperature to rapidly drop
overnight. Tuesday morning will bring some of the coldest
temperatures seen since May. Other than the cold, the skies will
be clear and winds decreasing. This is the only guaranteed dry day
through the week. Perhaps a good day for the procrastinators to
visit to the pumpkin patch.
&&
.LONG TERM...
(Tuesday night through next Sunday)
Issued at 1228 PM PDT Mon Oct 28 2024
Colder than normal temperatures will continue through Saturday.
A reinforcing trough moves through the Pacific Northwest,
renewing rain chances from late Wednesday through Thursday. The
probability of precipitation is high for this next event, but the
moisture plume will move through fast, and the overall
accumulation is still around 1/10"-1/4", again focused north of
the Golden Gate. A 3rd system will move through on Friday-Saturday,
bringing yet another chance for rain. There is still a lot of
uncertainty regarding this system, but the coverage looks more
widespread.
By Sunday, 500 mb cluster analysis shows a 75% chance for another
inside slider type pattern with a cut-off low pressure system over
the SW. This would flip the switch back to warm, dry, offshore
winds. Some guidance suggests this new pattern could last well
into next week. While it`s too early to figure out the specifics,
it`s a good reminder that despite the chilly weather this week,
fire season is not over.
&&
.AVIATION...
(00Z TAFS)
Issued at 459 PM PDT Mon Oct 28 2024
Mostly VFR with occasional MVFR over some of the terminals but low
cigs are short fused. Ceilings diminish overnight and high
confidence that VFR will prevail through the TAF period, with less
confidence over Monterey Bay, where there is a chance for MVFR cigs
but chances are less than 20-30%. Breezy and gusty westerly winds
will continue until tonight where winds diminish to light to
moderate, but will rebuild to breezy winds, with gusty wind in the
passes and gaps.
Vicinity of SFO...High confidence that VFR will prevail through the
TAF period, but some low SCT cigs will hang around the terminal
until late tonight. Winds will diminish to moderate overnight but
will rebuild to breezy by Tuesday afternoon.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Mostly VFR but a MVFR ceiling has developed
but should lift soon. Moderate confidence on VFR prevailing through
the TAF period, but upper air conditions should stay on the drier
side.
&&
.MARINE...
(Tonight through next Saturday)
Issued at 459 PM PDT Mon Oct 28 2024
The gradient between subtropical high pressure and a trough over
southern Nevada is supporting a fresh NW breeze and rough seas
across the marine zones. Winds will increase to a strong NNW
breeze overnight before decreasing through the day Tuesday.
Another cold front will move through Wednesday night, increasing
winds back to a fresh NW breeze and rebuilding rough seas through
the day Thursday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Tuesday for Mry Bay-SF Bay N
of Bay Bridge.
Small Craft Advisory until 9 AM PDT Tuesday for Pt Arena to Pt
Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt
Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 PM PDT Tuesday for Pigeon Pt to Pt
Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM.
Small Craft Advisory until 3 PM PDT Tuesday for Pt Arena to Pt
Reyes 10-60 NM.
&&
$$
SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...SO
MARINE...Flynn
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea
Area Forecast Discussion
National Weather Service Las Vegas NV
755 PM PDT Mon Oct 28 2024
.SYNOPSIS...An incoming weather system will bring widespread gusty
winds to the region today followed by cooler conditions and shower
activity on Tuesday. Showers will mainly be confined to the higher
elevations of Southern Nevada. Cooler conditions will persist
through the week with another weather system taking aim at the
region by the weekend.
&&
.UPDATE...Cold front is moving through central Nye County and
Death Valley NP currently. A mix of light rain and higher elevation
snow is occurring under narrow axis of cooling cloud tops between
Scottys Castle and Tonopah. Guidance remains consistent bringing the
cold front through the Las Vegas Valley between 11 pm and 1 am
tonight. HRRR supports light showers continuing along the cold front
through southern Nye County and into the Spring Mountains and Sheep
Range between 11 pm and 2 am Tuesday. More uncertainty for the
valley, as maybe areas near the mountains in the northwest valley
could see a brief showers. Strongest frontogenesis late tonight into
Tuesday morning will occur over the northern half of Lincoln County.
With lowering snow levels impactful snow accumulations up to 6" will
occur in the Wilson Creek Mountains, northeast of Pioche. Still
expecting an inch of less along Highway 93 north out of Pioche. Much
of the precipitation shield shifts east into Utah Tuesday morning
with isolated light showers/virga redeveloping over the higher
terrain of southern Nevada and northwest Arizona in the afternoon.
No change needed for our current headlines, will send out an update
by 9 pm once more guidance arrives.
&&
.SHORT TERM...through Wednesday.
Gusty winds continue across much of the region early this
afternoon ahead of an incoming trough poised to bring much cooler
conditions by tomorrow. Thus far, wind speeds through noon have
remained below their early morning peaks, but anticipate as mixing
continues to deepen and pressure gradients continue to tighten, a
secondary wind maximum will occur late this afternoon, especially
across downslope areas east of terrain features. With downslope
enhancement, wind gusts over 75 mph remain possible in the Spring
Mountains, with gusts over 60 mph possible across the western edge
of the Las Vegas Valley and near Red Rock Canyon.
Tonight, winds will shift to the northwest along a cold front as
colder air invades the region. A narrow band of light
precipitation is also expected across southern Nevada as the front
moves though, with some light snowfall possible in northern
Lincoln County above 7000 feet. Some light showers or sprinkles
may form as far south as Las Vegas prior to sunrise associated
with the front.
Tomorrow, northwesterly breezes and cooler temperatures will be
the most noticable weather elements in play. Though with cold air
aloft beneath the upper level trough which will have overspread
the Great Basin, a few light showers are possible into the
afternoon hours, mainly across southern Nevada and northwest
Arizona.
.LONG TERM...Wednesday through next weekend.
A shortwave ridge will build in on Wednesday as our trough to the
east slides into the Plains and while another trough approaches
the PacNW. Temperatures Wednesday will remain cool under the
influence of the post frontal airmass, and will likely start off
well below freezing across the higher terrain of the southern
Great Basin and northwest Plateau of Northwest Arizona. This will
be the first freeze of the season for the Colorado City area and a
freeze watch remains in effect for Friday morning. A slow
moderation of temperatures is expected Thursday and Friday before
the next weather system approaches. Guidance remains split on a
more inland (Cooler/Windier/Drier) trajectory of this storm
versus a track dropping south along the West Coast, which would
favor wetter conditions and not quite as much wind. The forecast
reflects a compromise solution with slight chances of
precipitation advertised as well as a modest cool down, but this
period of the forecast will be refined as ensemble agreement
improves.
&&
.AVIATION...For Harry Reid...Gusty southwest winds are expected through
the remainder of the afternoon and into this evening. Gusts are
expected to be in the 30-40 knot range, but a few gusts this
afternoon could approach 45 knots at times. Winds are then
forecast to slowly wane during the evening before the cold front
and north winds arrive overnight. Wind direction may be a bit
erratic at times after the front`s arrival as winds swirl around
the valley. Mid-level clouds clear out around daybreak this
morning, leaving FEW- SCT high clouds around. Mid-level clouds
return with the cold front while precipitation chances remain less
than 10%. Winds Tuesday will remain out of the northwest through
much of the day, with wind speeds generally between 10-20 knots.
For the rest of southern Nevada, northwest Arizona and southeast
California...Southwest to west winds will continue to increase this
afternoon, peaking during the mid-afternoon hours and gradually
decreasing this evening. Wind gusts of 25-40 knots can be expected
at all the area TAF sites this afternoon/evening, with the strongest
values at KDAG. Most of the area will see sunny skies this
afternoon, but some lower and mid level clouds will move in
overnight potentially down to around 8k feet. Although there could
be a few light showers around, most of the area will remain dry.
Northwest winds will occur over much of the area Tuesday with speeds
generally between 10-20 knots.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
DISCUSSION...Outler
AVIATION...Gorelow
For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter