Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/12/21
Area Forecast Discussion
National Weather Service Amarillo TX
646 PM CDT Mon Oct 11 2021
.AVIATION...00z TAF Cycle...
VFR conditions are expected to prevail at all sites, however some
low ST may increase just east of KAMA and KGUY tomorrow morning.
Main concern for terminals is low level shear which will be likely
mainly during the overnight hours tonight. Also can`t rule out
some thunderstorm activity near KAMA and KGUY tomorrow afternoon,
but confidence is too low to include in TAF at this time.
Ward
&&
.PREV DISCUSSION... /Issued 254 PM CDT Mon Oct 11 2021/
SHORT TERM...This Afternoon through Tuesday Night...
Summary: while uncertainty remains, severe thunderstorm potential
returns to the eastern Panhandles late Tuesday afternoon into
Tuesday night with all hazards in play to varying degrees. At this
time, large hail is the most likely hazard, followed by damaging
wind and then the risk for a couple isolated tornadoes.
Additionally, windy conditions are expected Tuesday, particularly
in the northwestern Panhandles. For meteorological details,
including a discussion of that remaining uncertainty, continue
reading below.
Details: 19Z WV satellite shows two strong upper waves over the
CONUS - an eastern wave over MO, a western wave over NV, a transient
upper ridge between these features, and an upper jet downstream of
the western wave. At the surface, high pressure has developed over
central TX in the wake of the eastern wave and lee troughing has
begun to resume in E CO as the western wave begins to move over the
Rockies.
Tonight, as lee troughing strengthens in E CO and the surface high
shifts eastward, decent gradient will set up over the Panhandles.
This should drive a stout low level jet, with breezy winds
continuing into the nighttime hours. Have leaned forecast low
temperatures warmer than NBM values as a result.
Moving on to tomorrow, given the aforementioned downstream jet,
western wave should continue to progress eastward to the Four
Corners. This should drive robust lee cyclogenesis in E CO. With the
surface high having continued to shift eastward, this will set up
robust southerly moist advection, with this advancing to the eastern
Panhandles by the afternoon. Modeled surface theta-e suggests two
surface boundaries will be present - a N-S oriented dryline in the
eastern Panhandles, which will sharpen with time as mixing occurs in
the western two thirds of the Panhandles and Gulf moisture is pulled
northward, and a Pacific front which will sweep eastward from NM
in the evening hours.
Multiple potential hazards may develop due to this setup, including
fire weather, strong synoptically driven winds, and severe weather.
The latter two will be discussed here. For fire weather, please see
the dedicated section below.
On the subject of synoptically driven winds, as the lee cyclone
deepens, tightening surface pressure gradient will drive breezy
winds during the daytime hours. Additionally, with height gradients
aloft similarly tightening, stacked 500/700/850mb jet looks to
develop just to the northwest of our forecast area. Given the
progged 55 knots seen at 700mb, were this to shift eastward, this
would support wind headlines for the western CWA. At this time, vast
majority of guidance keeps this jet to our northwest, so while
forecast winds were increased to the upper end of the NBM
distribution, have not issued any wind headlines. In any case, a
windy conditions are expected Tuesday in the northwestern
Panhandles.
Moving on to the severe weather risk, the amplified flow pattern and
strong jet aloft coupled with south-southeasterly winds east of the
dryline in the moist sector will result in long looping hodographs
with 0-6km bulk shear values greater than 50 knots, supporting
organized convection. Additionally, the backing of the surface winds
east of the dryline looks to lead to surface to 500m helicity values
of around 100 m2/s2, with these values increasing to over 200 m2/s2
as the low level jet increases around 00z. Southwesterly mid-level
flow looks to advect a modestly mixed layer with mid-level lapse
rates of around 7 C/km over the eastern Panhandles as well. Low
level moisture combined with those lapse rates aloft should lead
to MLCAPE values of around 1000 J/kg. These parameters suggest
all severe hazards - large hail, damaging winds, and tornadoes -
would be possible.
At this time, most probable solution is, given the orientation of
deep shear vectors orthogonal to the dryline, for a short window in
the late afternoon and early evening with discrete supercellular
convection. During this short window, large hail, damaging winds,
and a tornado risk, in that order of likelihood, would be present.
Upscale growth should then occur as mid-level cooling arrives in
earnest with the wave and low level convergence increases as the
Pacific front overtakes the dryline. In addition to becoming less
discrete, storms will likely become elevated as the boundary layer
decouples, with deep layer shear continuing to support a risk for
large hail as the evening progresses. A damaging wind risk will also
remain given the potential for the more robust downdrafts to bring
down the strong winds aloft and break through the stabilizing
surface layer, something that has occurred before with these
surging Pacific fronts.
However, considerable uncertainty remains, with the most vital
question surrounding whether or not that surface based
instability can be realized, as the base of that modestly mixed
layer aloft may serve to keep surface-based parcels capped through
the evening. If capping is stronger than forecast or 850mb/sfc
moisture arrives from the south too late into the evening - and
guidance has been trending slightly toward a later arrival -
surface based storms would likely not develop, reducing damaging
wind and, in particular, tornado risk but with hail risk
remaining as organized elevated storms develop as the upper wave
and Pacific front approach. Should this arrive a bit sooner than
forecast or, as the NAM has been suggesting, the midlevel capping
is weaker and/or remains weak deep into the evening hours, tornado
risk would become more prominent. At this time, am not inclined
to lean toward the NAM solution given the progged 800mb inversion
in the extended 15z RAP run. But, will need to keep this solution
in mind given the high level of potential impact should it verify.
Ferguson
LONG TERM...Wednesday through Sunday Night...
Although the cold front Tuesday night will be fairly quick moving,
we will still be looking at temperatures in the 30s for the
northwest Wednesday morning and in the 40s to the south and east.
Upper level trough will eject to the northeast towards the Dakotas,
but a second longwave trough will begin to deepen over the Four
Corners area and will provide west to southwest flow to the area.
Temperatures are expected to recover into the 70s on Wednesday to
maybe lower 80s across the southeast. Lows Thursday morning will be
about the same as Wednesday, maybe a degree or two cooler.
Temperatures on Thursday will be a bit warmer than Wednesday, but
there may be an exception to this for the northwest Panhandles. This
is due to the next cold front progged to arrive Thursday evening. If
it moves in a bit faster than we may not get peak heating for areas
to the northwest. Overall, a cold front is expected Thursday night
into Friday. This will raise the chances of precipitation once
again. This cold front will keep temperatures for the most part in
the mid 50s to lower 60s. The chances for precipitation are
increasing, but the timing is still uncertain. There is a chance
that this cold airmass will be stronger than currently progged, as
the surface wetbulb temperatures are in the 30s across the north
with possible precipitation Friday afternoon. Right now it`s not
cold enough to consider any kind of wintry precipitation, but
we`ll continue to monitor this to see if it trends colder.
As the upper trough exits to the east, we`re looking at pretty cold
temperatures across the Panhandles Saturday morning, with widespread
30s, and possible freezes in the northwest. Winds look like they
will be fairly light and the skies will be mostly clear, thus a
decent chance that most of the Panhandles could see a frost as well.
We will transition to mostly westerly flow for the rest of the
extended, this will lead to mostly dry and mild conditions for the
rest of the extended. Highs expected to be in the mid 60s to lower
70s for Saturday, and widespread 70s for Sunday.
Weber
AVIATION...18Z TAFs...
Primary aviation concern over the next 24 hours is low level wind
shear in the surface to 1500 foot layer at all sites overnight as
a 45-50 knot low level jet develops. Otherwise, winds will remain
mainly some form of southerly, with gusts to around 30 knots
possible tomorrow as the aforementioned jet mixes to the surface.
Ferguson
FIRE WEATHER...
Tuesday, as a robust upper wave advances over the Four Corners,
height gradients aloft at 500/700/850mb will tighten. As this
occurs, associated lee surface cyclone will deepen in E CO. This
should drive breezy to windy conditions, particularly in the
northwestern Panhandles, which will be near a stacked 500/700/850mb
jet. In the northwestern Panhandles, 20 foot winds out of the
southwest of 20 to 30 mph with gusts to 45 mph look to occur.
However, RH values look to remain above 25 percent, so resulting
RFTIs of 2 to 4 will be entirely wind driven. Additionally, recent
rainfall in this area, while not nearly enough to make up for the
antecedent dry period, should also help limit fire starts. After
coordination with WFOs PUB and ABQ, have eschewed a Red Flag Warning
or Fire Weather Watch at this time given the RH concerns.
Ferguson
&&
.AMA Watches/Warnings/Advisories...
TX...None.
OK...None.
&&
$$
7/99
Area Forecast Discussion
National Weather Service Denver/Boulder CO
734 PM MDT Mon Oct 11 2021
.UPDATE...
Issued at 729 PM MDT Mon Oct 11 2021
Just some minor adjustments for this evening. An area of showers
has developed from around Eagle northeast across Jackson county.
This will slowly lift NNE with a little drier area moving across
later tonight before the main area of showers moves in later
Tuesday morning. Clouds and PoPs were adjusted for this timing.
We`ll have to watch the wind speeds on the plains as they may be
near high wind criteria for a few hours on Tuesday out around
Limon and Akron. There`s also a high wind threat behind the trough
early Wednesday, especially for Larimer county. Still no clear
signal on the humidity accompanying the wind tomorrow as the
models don`t have a consistent relationship between the surface
low and bands of subsidence aloft or the location of strong low
level drying. In general, the cooling will make it hard to get
humidities below 20-25%. We`ll let the night shift make the final
call on whether a Red Flag Warning is needed.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 317 PM MDT Mon Oct 11 2021
A strong trough is seen on water vapor moving towards southern
Nevada with a couple warm conveyor belts out ahead of it. The first
conveyor belt which is over western Colorado is moisture starved and
is struggling to produce much of any showers in northwest Colorado.
Without an influx of moisture expected tonight, there won`t be many
showers over the northern mountains so PoPs were kept low. Across
the plains, it will be partly cloudy with near normal
temperatures tonight.
The strong trough will enter Colorado during the day tomorrow
eventually tracking over the Fort Collins area Tuesday night. Recent
models runs have slowed down the progression of this trough and the
onset of precipitation in our area. Tuesday morning looks mostly
dry across our CWA as a dry intrusion between the two
aforementioned warm conveyor belts will be overhead. The only area
that will see a chance of snow showers will be the high elevations
of the northern mountains. By the afternoon, instability will
develop over the mountains with strong QG ascent moving overhead.
This will help to create better coverage of showers over the
higher terrain with the snow level above 8 to 8.5 kft. Considering
the overall snow totals and winds through Wednesday, a Winter
Weather Advisory was issued for the Rabbit Ears Pass, Rocky
Mountain National Park, and the Medicine Bow Range starting
Tuesday morning. The I-70 corridor was left out of the advisory
since the storm total snowfall was mainly less than 4 inches in
that zone. It should be noted there could be some minor travel
impacts near the Eisenhower Tunnel Tuesday evening and Wednesday
morning if a stronger band of snow showers were to move across.
Otherwise, travel conditions will be fine across the I-70
corridor.
Across the plains, there will be a weak dryline that sets up over
the far northeast corner Tuesday afternoon. This will aid in the
development of isolated to scattered showers and storms. There will
be some instability to the east of this line but dew points will be
on the lower side which will keep the instability rather low. Shear
will be on the higher side but with the low instability, the threat
for large hail and tornadoes appears to be quite small. The main
severe threat will be strong wind gusts out of any storms that
develop since they will be able to bring down the strong winds
aloft. To the west of this dryline, there may be a few showers
that develop but coverage will be low and not much rain will reach
the ground. A dry intrusion arrives in the afternoon which may
mix down strong winds and very dry air to the surface. Winds
gusts will reach 40-45 mph especially across the Palmer Divide and
east-central plains. There is some concern this dry intrusion
could create increased fire danger which is discussed in the fire
section below. Otherwise, highs will be below normal in the
mountains and near to slightly above normal across the plains.
.LONG TERM...(Tuesday night through Monday)
Issued at 317 PM MDT Mon Oct 11 2021
A few chances for impacts for the period starting with snowfall in
the mountains/higher foothills overnight Tuesday resulting in a
Winter Weather Advisory for zones 31 & 33. Gusty downslope winds
are likely in the mountains/foothills early Wednesday. Given fresh
snowfall, blowing snow may also be a potential impact in
locations that have received at least an inch or two of snowfall.
There is also potential for a system to bring snow showers to the
mountains and possibly a first snowfall in the Urban Corridor late
Thursday into Friday.
Tuesday Night...
Model guidance has stayed fairly consistent with the trough and
associated low to lift to the northeast overnight Tuesday. Showers
and a few storms are likely over the eastern plains and will move
east. QG fields continue to look favorable for large-scale ascent
over the region Tuesday night to support snowfall in the
mountains/high foothills with higher amounts favored in the northern
mountains. Into the morning showers drift onto portions of the
plains with better chances in Weld County. While snow showers will
prevail in the mountains, any precip. over the plains will likely be
rain or rain/snow mix with the exception of portions of northern
Weld county.
Wednesday through early next week...
Wednesday, on the backside of the previous system, the region
will be in favorable regime for strong subsidence. Cross sections
show supportive conditions for strong downslope winds/gusts with
indications of a stable layer close to the surface coupled with
strong westerly component flow. Some model solutions are hinting
at the potential for gusts above 50 mph. Confidence is not high in
regards to that potential, but gusts up to 50 mph are likely in
portions of the mountains/foothills early Wednesday. Strong
subsidence will likely limit snow shower activity during the day
with a slight chance for a few lingering showers in the mountains.
The first chance for snowfall across the Urban Corridor and
plains may be in store late Thursday into Friday. Ensembles show
general agreement with this system; however, some differences in
timing are notable. Moisture will be fairly limited, but QG
vertical velocity fields are favorable to support development of
showers. In addition to a few inches in the mountains, model &
ensemble guidance continues to indicate potential for a transition
to snow in the Urban corridor and possibly eastward. Cold air in
place should support this potential, but amounts will likely be
minor.
Into the weekend, there is good agreement among ensemble guidance in
a transition to a less amplified upper level pattern. Ridging builds
into the region which will support a drying trend as well as a trend
toward slightly above normal temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 533 PM MDT Mon Oct 11 2021
VFR conditions will continue through the TAF period. SCT mid-level
clouds expected tonight as gusty winds will begin to decrease by
early Tuesday morning. Forecast challenges tonight through Tuesday
morning due to a possible Denver cyclone development. Placement of
this cyclone could be tricky but southerly winds will shift to a north
or northwesterly component. This will continue through Tuesday
morning and by 11-12Z should be more of a southwesterly flow.
Strong winds are likely Tuesday afternoon as a dryline moves
through. Wind gusts up to 35-40kts expected during the afternoon.
Tuesday evening, sustained winds will decrease to 10-12kts.
&&
.FIRE WEATHER...
Issued at 317 PM MDT Mon Oct 11 2021
A dry intrusion will move across the southern part of our CWA
Tuesday afternoon bringing strong winds and potentially much drier
air in from aloft. Wind gusts between 40-45 mph are expected
mainly across the Palmer Divide and east-central plains. There is
some uncertainty with regards to the timing of the dry intrusion
and how much dry air it can mix down from aloft. If the high
resolution models like the HRRR and NAM NEST are right, dew points
may drop into the upper single digits across Douglas, Elbert, and
Lincoln counties which would take the relative humidity values
down to around 15 percent. However, the models may be over mixing
or moving this system across too fast which would mean relative
humidity might be higher than those models predict. If those dry
dew points don`t verify, Red Flag conditions probably won`t be
met. In summary, there was too much uncertainty with regards to relative
humidity to upgrade to a Red Flag Warning so a Fire Weather Watch
was kept for zones 241 and 247.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 AM Tuesday to 6 AM MDT Wednesday
for COZ031-033.
Fire Weather Watch from Tuesday afternoon through Tuesday
evening for COZ241-247.
&&
$$
UPDATE...Gimmestad
SHORT TERM...Danielson
LONG TERM...Mensch
AVIATION...AD
FIRE WEATHER...Danielson
Area Forecast Discussion
National Weather Service Dodge City KS
515 PM CDT Mon Oct 11 2021
...Updated Aviation...
.SHORT TERM...(This evening through Tuesday)
Issued at 321 PM CDT Mon Oct 11 2021
...Widespread severe weather Tuesday evening and late night..
As yesterday`s storm continued to lift northeast away from the Great
Plains, the next much more impressive storm was taking shape across
the Great Basin. Water vapor satellite loop and RAP analysis showed
the classic development stage of a major mid-latitude cyclone with a
120kt jet streak at 400mb diving south-southeast along the northern
California coast with associated mid level potential vorticity (PV)
stream extending well into western Canada. This digging and maturing
process will continue this evening before the mid level cyclone
center really deepens across northern Arizona and eventually
Colorado later in the day Tuesday. Needless to day, the lower
tropospheric response to such dramatic development in the mid levels
will be robust on Tuesday. The leeside low near Denver at 12z
Tuesday will deepen from 1001mb to 987mb 24-hr later as the surface
low shifts northeast toward the Black Hills.
The significant low level response will lead to increased low level
winds out of the south-southeast, which will commence later on
tonight. This is when low level moisture will start to make its
northward push back into Kansas. The latest models today suggest the
58F isodrosotherm will reach DDC by 21z Tuesday with 63+ dewpoints
making it to the Red Hills of Comanche-Clark-Barber county by mid-
evening.
There will likely be some non-severe or perhaps isolated marginally
severe elevated convection at the nose of the moist plume early-
midday Tuesday, but this should be confined to areas mostly south
and east of our forecast area (most of Oklahoma into south
central/southeast Kansas). Meanwhile, boundary layer convergence
will be increasing along the deepening leeside trough across far
western Kansas. Mid level cold advection will increase across far
western Kansas by late afternoon with the initial surface-based
storms forming some time in the 21-23Z time frame. Convective mode
is a big challenge, even with initial development given how strong
the mid level cold advection is expected to be. Another big
challenge will be surface temperatures, especially from Highway 283
and points east, as some of the CAMs show afternoon temperatures
stuck in the 60s all afternoon in our eastern forecast area while
other CAMs are not nearly as cool. Regardless, the initial storms
will be starting off farther west anyway, where there is much
greater confidence in temperatures warming to around 80F give or
take a couple degrees. As the atmosphere continues to destabilize
with ongoing mid level cold advection and surface dewpoints continue
to climb, surface-based CAPE will be increasing during the 00-03Z
time frame across a fair portion of southwest Kansas. This is also
the time frame when 0-1km AGL shear will be increasing.
The 15Z run of the RAP13 model shows 0-1km AGL SRH increasing from
around 100 m2/s2 to 400+ m2/s2 over the course of only 3 hours from
23Z to 02Z. This is very anomalous warm sector low level shear,
particularly when combined with lower 60s dewpoints. This is also
concerning when one factors in that the early 6-hourly, longer-fuse
runs of the HRRR are showing very aggressive convective signals via
forecast Composite Reflectivity product with attendant long Updraft
Helicity (UH) tracks of 200+ m2/s2. It should be noted that UH
tracks on the HRRR model or any other convective-allowing model do
not necessarily correspond to tornado production or even low level
mesocyclones. However, in this particular situation, the ingredients
for very intense and long-lived low level mesocyclones will be
there, if the primary storm mode can remain supercellular. The RAP
model forecast soundings show a rather concerning sickel-shape
hodograph well off the origin, so (a) fast-moving, and potential
long-lived tornado(es) are definitely not out of the question. If
there is an area of our CWA that would be most vulnerable to this
risk it would probably be areas south and east of a Meade to Dodge
City to Larned line...with the best 3-hour window being 01Z to 04Z
(8 PM to 11 PM CDT). This level of spatiotemporal detail is bound to
change to some degree, however these are some of the early signals
we are seeing as of early this afternoon.
The severe weather risk will wane across the DDC forecast area from
west to east fairly quickly after 05Z (Midnight CDT) with not
expected behind the main line of severe weather. Much drier,
westerly downslope winds will move in quickly after midnight.
.LONG TERM...(Tuesday night through Monday)
Issued at 321 PM CDT Mon Oct 11 2021
Yet another storm system will be moving across western Kansas -- the
second disturbance within the larger scale longwave trough. Since
the major storm tomorrow will be lifting north-northeast and
occluding rapidly in the process, the low level moisture will not be
pushed that far south, which will set the stage for another severe
weather event late Thursday/Thursday Night not too far southeast of
our forecast area. We will have to watch this one closely in case a
warm front advances farther north, perhaps clipping our far
southeast counties (mainly Barber) Thursday evening. Colder air will
push south behind this storm on Friday, and as a result, we will see
afternoon highs most likely in the 50s. The latest forecast now
calls for lows early Saturday morning in the lower to mid 30s with
perhaps a 28 or 29F reading in Hamilton County.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 515 PM CDT Mon Oct 11 2021
VFR will continue through this TAF cycle, with SKC through
midnight, followed by increasing midlevel cloud through sunrise.
South winds at 850 mb/2k ft AGL will increase sharply overnight,
and included low level wind shear in all TAFs. VFR will continue
through daylight Tuesday, with a mixture of mid/high clouds and
increasing cumulus in the afternoon. Scattered thunderstorms are
expected to initiate near US 83, from near GCK to near LBL, around
00z Wed. Kept this TAF package dry, but expect convective aviation
impacts at the airports just after this TAF cycle. Southeast winds
will be steadily increasing at all terminals through this TAF
period, with gusts 30-35 kts after 15z Tue, and gusts near/over
40 kts after 21z Tue.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 55 75 44 69 / 0 30 90 0
GCK 54 77 41 69 / 0 30 80 0
EHA 52 79 41 71 / 0 10 20 0
LBL 53 80 41 72 / 0 30 60 0
HYS 51 73 47 66 / 0 20 90 0
P28 54 71 53 72 / 0 40 100 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Turner
Area Forecast Discussion
National Weather Service Houston/Galveston TX
657 PM CDT Mon Oct 11 2021
.AVIATION [00Z TAF Issuance]...
MVFR conditions are expected to move in from the Gulf late this
evening into early Tuesday as a warm front lift northward into the
region. Patchy fog will also be possible, generally around KCLL;
however, low clouds/stratus will be more dominant. Conditions are
expected to improve after 14-15Z Tuesday with VFR conditions
through the remainder of the period. After some streamer showers
early in the morning, isolated storms will be possible in the
afternoon due to the combination of the boundary and daytime
heating. As of now, the best storm chances look to be over the
Brazos Valley (around KCLL). SSE will strengthen around 10-15kt
in the afternoon. 05
&&
.PREV DISCUSSION /Issued 335 PM CDT Mon Oct 11 2021/...
.SHORT TERM [Through Tomorrow Night]...
This morning`s cold front ushered in clearing skies, a light
northerly wind, and dew points near 60 leading to a rather pleasant
day across SE Texas. This front has stalled out just off the coast
and will be making a return tonight/tomorrow morning as it moves
back inland. The FV3 and most of the global guidance is rather quick
with its return with the warm front moving through the Houston Metro
area around midnight, then north of College Station by sunrise. Some
isolated showers will accompany the FROPA. HRRR is slower with the
frontal passage by about an hour or two, while the ARW is the
slowest of the CAM guidance. It brings the front through Houston
around sunrise and into the northern third of the area by the mid
morning. This solution brings the most showers and thunderstorms to
the northern portion of the our area as daytime heating helps
initiate storms along the boundary. This solution is the outlier at
the moment, but kept a mention of a slight chance to a chance of
thunderstorms tomorrow morning north of Conroe.
With the return of moist southerly flow, expecting dew points to
rise back into the mid 70s across the area tomorrow with partly
cloudy skies along the coast and mostly cloudy skies north of I-10.
Temperatures tonight and tomorrow night will be mild with lows in
the low to mid 70s (and near 80 along the immediate coast). High
temperatures tomorrow afternoon will climb to near 90. Record high
temperature tomorrow at Galveston is 89 degrees last set in 2020,
which will be within reach if enough sun is able to poke out along
the coast.
Fowler
.LONG TERM [Wednesday Through Monday]...
Steady onshore flow and increasing PWs prime the low levels on
Wednesday for some diurnally driven showers and thunderstorms.
Most of the focus will be towards our northwestern counties
(mainly west of I-45 and north of I-10) as a cold front stretching
from TX Hill Country to Missouri begins to strengthen across
Central TX. This front is expected to stall north of our area as
it gets cut off from its upper level closed low that will push
into Canada.
By Thursday another mid level shortwave will push through the
Southern Great Plains and induce a surface low, which will enhance
the previously stalled cold front. For the past several days, we
have been forecasting deep Pacific moisture from the remnants of
Tropical Storm Pamela being channeled into the jet stream and into
this front. That is still expected, but global models are coming
to more of a consensus as to where the most rainfall will occur.
Most of the focus looks to be outside of our CWA and more focused
on North and Central Texas. This is primarily where the strongest
upper level forcing will reside where the jet streak will enhance
upper level divergence and lift across that region. The GFS is
still hinting at a remnant 500 mb PVA impulse from Pamela pushing
through North/Central TX, which will aid in convective
initiation. However, our northwestern counties still have chance
PoPs on Thursday and a few counties with likely PoPs as they`ll
be on the fringes of this upper-level support along with deep
Pacific tropical PWs of 2.0 inches or more. Any shifts in the jet
pattern aloft and 500 mb vorticity advection will alter our rain
chances locally, so this forecast is still worth monitoring, but
as it stands right now rainfall totals appear to be an inch or
less on Thursday for our northwestern counties with locally higher
amounts possible.
Afterwards on Friday, the surface low over TX, the mid level
trough, and the cold front will begin to push west. Global models
differ with how fast this front moves out of our area, but it
will be sometime Saturday morning/afternoon. Slight chance to
chance PoPs remain on Friday as this front pushes out, but
rainfall totals are forecast to be a few tenths of an inch.
By Saturday onwards, cool and try temperatures are the next
interesting topic as high pressure builds in overhead and drier
air begins to filter in. Temperatures will peak in the upper 70s
and overnight lows will cool to the 50s with a few isolated areas
in the upper 40s.
Lenninger
.MARINE...
Behind today`s front, winds and seas will decrease briefly, but
moderate onshore flow and building seas will resume by late
tonight and will continue through much of the week. A strong cold
front can be expected towards the end of the week with moderate to
strong north winds expected in its wake. Tidal forecasts have
come down slightly, but minor coastal flooding is still something
to closely monitor over the next few days with moderate onshore
flow combining with high astronomical tides. Rip current risks are
still forecast over the next few days as well, so beachgoers
should monitor the latest beach conditions if headed to the shore
and follow the usual beach safety tips.
Lenninger
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 70 89 74 90 71 / 30 50 20 30 30
Houston (IAH) 73 89 75 89 73 / 30 30 10 20 10
Galveston (GLS) 79 87 79 87 78 / 20 20 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk until 8 PM CDT this evening for the
following zones: Bolivar Peninsula...Brazoria
Islands...Galveston Island...Matagorda Islands.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Louisville KY
956 PM EDT Mon Oct 11 2021
.Mesoscale Update...
Issued at 956 PM EDT Mon Oct 11 2021
Surface cold front is still out to the west and just starting to
enter far western KY. Initial convection from this evening is just
approaching the I-65 corridor. However, this convection continues
to diminish as it heads into a more stable environment east of I-65.
Some additional convective development has started out across our NW
CWA. This activity should continue to move northeast through
southern IN this evening. Have generally trended the forecast to
chance PoPs mainly west of I-65 this evening with a shift to the
east late tonight as the cold front pushes through the region.
Issued at 741 PM EDT Mon Oct 11 2021
Convection continues to move eastward toward the I-65 corridor this
evening. This convection has really weakened over the last hour or
so due to the loss of heating and rapid depletion of instability as
one head east into the I-65 corridor. We expect these showers to
continue to move eastward and get into the I-65 corridor around 9-10
PM and then continue eastward into the overnight hours while
continuing to dissipate. The main risks with this activity would be
brief heavy rainfall, gusty winds to 25-30 MPH, and possibly a few
lightning strikes. The most widespread rainfall will mainly be
across our southern Indiana counties.
Issued at 552 PM EDT Mon Oct 11 2021
Afternoon surface analysis depicts an area of surface low pressure
across western IL with the surface frontal boundary extending
southward through SE MO and into far western IL. Two lines of
convection were noted on the regional radar imagery. The first was
located across central IL along the frontal boundary and just east
of the surface low. A secondary arcing line of convection extended
from just south of Chicago southward to Evansville and down toward
Hopkinsville.
This line of convection was moving slowly eastward with individual
cells moving northeastward. Mesoscale analysis shows decent
effective bulk shear values of 45-50kts across the region. However,
instability is rather lacking with MLCAPE values below 200-500 J/Kg
and with quite a bit of CINH in place. The large amount of CINH is
most likely due to large scale warm advection bringing in a layer of
warmer air aloft around 850-800 hPa. Low-level lapse rates were on
the order of 5.5-6 C/Km, though mid-level lapse rates were near 7/kg
just ahead of the line.
In general, the best combination of shear and instability remain well
northwest of the region at this time. We expect the line of
convection out to the west to continue to move to the east over the
next few hours. While shear values are decent enough for organized
convection, the lack of instability remains the limiting factor for
strong/severe convection. Brief heavy rainfall, lightning, and
gusty winds of 40 to maybe 45 MPH will be seen with the strongest
activity. With the loss of heating due to sunset upcoming, this
convection should continue to weaken as it approaches the I-65
corridor over the next few hours.
&&
.Short Term...(This evening through Tuesday)
Issued at 310 PM EDT Mon Oct 11 2021
Latest sfc analysis shows the stacked low currently spinning over
north-central Missouri, with the associated cold front trailing
through Arkansas and northern Louisiana. Fast moving showers and a
few storms have been observed across southern IL underneath the core
of the 850mb jet where mesoanalysis and nearby VAD Wind Profiles
depict winds of 45-50kts. CAMs continue to indicate a slowing trend,
delaying the arrival of the convective line later into the evening.
Earlier runs of CAMs depicted the line approaching Dubois County by
22z, but now thinking 23-00z is possible. RAP model soundings
suggest a stronger 850mb inversion due to the southwest oriented LLJ
advecting warm air into the region. This warm nose will weaken by
00z, but should still be present as 850mb winds remain around 35-
40kts. Instability aloft will keep convection elevated from 00-06z,
but overall environment remains a high shear/low CAPE regime. Model
soundings suggest peak effective bulk shear values near 50kts until
03z, which is realistic considering mesoanalysis currently depicts
effective bulk shear values of 50-55kts over southern IL and western
KY. Could see a few strong storms in our far western CWA, but
overall severe threat appears limited due to warm nosing.
By 03z, the line of showers and storms will be along I-65 and
weakening. Could have some lingering showers east of I-65 through
Tuesday morning along the frontal boundary, but otherwise it will be
dry for the rest of the day.
Low temperatures for Tuesday morning will vary depending on the
location of the cold front, with areas west of I-65 60 degrees or
below, and mid 60s across our far eastern CWA. For tomorrow,
temperatures will reach the upper 70s under clearing skycover and
WSW winds.
.Long Term...(Tuesday night through Monday)
Issued at 315 PM EDT Mon Oct 11 2021
Tuesday Night - Thursday Night...
Progressive upper ridging and surface high pressure will briefly
control our region Tuesday night into the first part of Wednesday.
This will bring dry conditions. Mostly dry conditions will continue
into Wednesday afternoon for most, however will have to keep a
slight chance of a shower as a weak warm advection wing extending
from the northern Plains system slides through our far western CWA.
Otherwise, the upper ridge should still have enough influence over
our area through Thursday night, keeping things dry. Southern IN
could get in on some precipitation chances later Thursday night as a
frontal boundary impinges upon the area and then stalls heading into
Friday.
Given the upper ridge and overall dry weather, temperatures will
continue to run above normal for this stretch. Most highs will be in
the upper 70s and low 80s, however a few mid 80s are possible by
Thursday. See the climate section for more info on potential records
in jeopardy. After cooler lows (but still above normal) in the 50s
on Tuesday night, milder lows in the 60s take hold for Wednesday and
Thursday nights.
Friday - Saturday...
Showers and a few storms become likely the deeper into Friday and
Friday night we get. This will occur as deeper moisture surges into
the area and rides along the stalled frontal boundary mentioned
above. A potent shortwave will approach heading into Friday night,
providing additional forcing to at least warrant likely pops. Timing
is still in question for Saturday as models diverge on the
evolution/amplitude/timing of the shortwave trough, but will leave
some mention lingering pops for this time. Things should be
improving from W to E later in the day regardless of model
differences by this time.
Temperatures will likely still be in the upper 70s and low 80s
across our SE, while our NW temps will be hindered by clouds and
precipitation chances. Depending on timing of the cold front, Friday
night temps will be tough to nail down and will have some bust
potential if things end up being slower. Saturday highs likely won`t
make it out of the 60s, especially if clouds and light precipitation
chances linger.
Saturday Night - Monday...
Higher confidence in a dry forecast to end the weekend and start the
new work week. This will occur as strong surface high pressure and
dry NW flow aloft take hold. Notably cooler air will take hold with
lows in the 40s and highs in the 60s.
&&
.Aviation...(00Z TAF Issuance)
Issued at 737 PM EDT Mon Oct 11 2021
IMPACTS:
Scattered showers this evening and into the overnight period.
DISCUSSION:
Broken line of showers with a few rumbles of thunder
continues to push eastward across the region. These showers should
clear KHNB within the hour. The showers will likely move through
the KSDF and KBWG terminals this evening and then eventually into
KLEX overnight. Still believe that this line of showers will
diminish rather quickly as it heads east due to the lack of
instability and loss of heating. Main question overnight is whether
there will be any low clouds that develop. Guidance suggests some
low stratus at KHNB/KLEX. Will keep things optimistic for now and
continue to monitor. VFR conditions are expected for Tuesday with
southwest winds of 8-10 knots.
CONFIDENCE: Medium on all elements.
&&
.Climate...
Issued at 314 PM EDT Mon Oct 11 2021
Strong southerly flow on Thursday will keep our temperatures well
above normal, possibly warm enough to near record warm-lows and warm-
highs for Thursday Oct 14. Below is a summary of forecast
temperatures, climatological normal values, and the daily record for
October 14.
====== Thursday Morning Warm Lows ======
Forecast / Normal / Record (Year)
SDF: 68 / 51 / 66 (2008*)
BWG: 66 / 49 / 66 (1985*)
LEX: 63 / 48 / 64 (1985*)
FFT: 64 / 46 / 67 (1954)
*and previous years.
====== Thursday Afternoon Highs ======
Forecast / Normal / Record (Year)
SDF: 84 / 71 / 85 (2017*)
BWG: 83 / 73 / 94 (1928)
LEX: 81 / 70 / 86 (1897)
FFT: 84 / 70 / 87 (1969)
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Mesoscale....MJ
Short Term...CJP
Long Term....BJS
Aviation.....MJ
Climate......BJS
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1019 PM EDT Mon Oct 11 2021
.SYNOPSIS...
Low pressure will slowly pull away from the coast through Tuesday.
High pressure regains control by mid week. A front is expected to
push through the area this weekend.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 1020 PM Mon...Weak low offshore continues to weaken but
clouds continue to lower as low-level inversion strengthens at
around 900 mb. Forecast in good shape and no major changes were
needed this cycle.
Prev disc...Low pressure continues to slowly pull away from the
coast and is now around 75 miles east of Cape Hatteras.
Northerly winds will prevail overnight and gradually weaken as
the low moves away. Low clouds expected to continue with
sufficient moisture trapped below a strong low level inversion
around 850mb. Most of the precip has shifted offshore with a few
light returns continuing around Core Banks. Most areas should
remain dry overnight but coastal sections may see periods of
drizzle or a light shower. Clouds and light winds will prevent
temps from falling much tonight and expect lows generally in the
low to mid 60s.
Elevated water levels continue along the coast as we are coming
out of a King Tide event which, combined with strong and
persistent northerly winds and large surf, will continue to
bring a threat of coastal flooding along the coast and areas
adjacent to the southern Pamlico Sound. See the coastal
flooding section below for details.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
As of 415 PM Monday...High pressure continues to ridge into the
mid-Atlantic with low pressure meandering east of the VA Capes.
Expect mainly cloudy skies with low level moisture lingering
across the area in the morning but expect more breaks of
sunshine as we move into the afternoon. Clouds will be most
persistent across NE sections closer to the low pressure center
and could see a few light showers or drizzle here at times.
Highs expected in the mid to upper 70s with a few low 80s
possible southern sections.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
As of 3 AM Mon...Generally quiet weather with above normal temps
expected through the period. A front will push through eastern
NC this weekend, with cooler temperatures behind it.
Tuesday through Friday...Ridging at the surface and aloft is
expected Eastern NC through late week, resulting in generally
dry wx and above normal temps. Isolated coastal showers will be
possible into Tuesday night with weakening low pressure still
off the coast and low level NNE flow. Highs grad warm into the
low to mid 80s mid to late week. Overnight temps will fall into
the 60s.
Saturday and Sunday...Strengthening sfc low will lift into the
Great Lakes and Canada, with the attendant cold front progged
to push through the coastal NC Saturday night and early Sunday
morning. Still some minor timing differences this far out, but
expect front offshore Sunday morning. Sfc high will gradually
build in from the west Sun into early next week, with troughing
aloft. Isolated to scattered showers possible with the front
Saturday night and possibly lingering into Sunday. Temps and
dewpoints return to near normal behind the front.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
SHORT TERM /through Tuesday/...
As of 805 PM Mon...Another tricky forecast for tonight with low
clouds again being the fly in the ointment. Current conditions
across the terminals are solid MVFR cigs with light northerly
winds, with IFR conditions over portions of OBX. LAMP guidance
tonight has come more in line with the more pessimistic
deterministic models with a high likelihood of at least MVFR
cigs through 18Z tomorrow as moisture remains trapped under a
low-level inversion. Biggest question again is the potential for
IFR cigs. The reliable HRRR hints at a regime similar to last
night with brief periods of IFR right around daybreak, while the
NAM is overly aggressive and brings widespread IFR conditions
after 06Z per model soundings. The HRRR soundings are close to
the LAMP and HREF ensembles, and leaned the forecast in its
direction. Confidence level for overnight: moderate.
Inversion slowly erodes tomorrow morning as winds back
northwesterly, and expect VFR conditions to break out across
eastern North Carolina after 18z.
LONG TERM /Tuesday night through Friday/...
As of 3 AM Mon...Pred VFR most of the period but areas of fog
and stratus will be possible again Tuesday night and Wednesday
morning.
&&
.MARINE...
SHORT TERM /Through Tuesday/...
As of 805 PM Mon...Winds and seas have fallen across southern
and central offshore waters, and winds over soundside waters
are now generally 15 kt or less. Allowed SCA for Pamlico and
waters offshore of Cape Lookout to expire.
Prev disc...Low pressure currently about 75 mi east of Cape
Hatteras will slowly lift NE to off the VA Capes through the
short term. N winds will gradually diminish tonight and expect
winds to be below 20 kt after midnight and gradually back to NW.
Large seas will continue along the coast tonight, especially
north of Ocracoke Inlet, but are expected to drop below 6 ft by
late Tuesday morning. Wave models continue to be underdone with
seas north of Ocracoke Inlet and increased by a foot or two
through tonight.
LONG TERM /Tuesday night through Friday/...
As of 3 AM Mon...High pressure will build over the waters
Wednesday through late week, with improving conditions. N winds
10-15 kt Wed, 5-15 kt Thu, and variable winds 5-10 kt Fri. Seas
2-4 ft Thu, subsiding to 2-3 ft Fri.
&&
.TIDES/COASTAL FLOODING...
As of 345 PM Mon...A coastal flood advisory continues for
elevated soundside water levels 1-2 ft agl, along the southern
Pamlico Sound, Core Sound, tidal Neuse Rvr and smaller creeks
through early this evening. Continue the advisory for the Outer
Banks and Eastern Carteret through Tuesday afternoon for ocean
and soundside, mainly concerned about the high tide early
Tuesday afternoon. Minor ocean overwash will be possible along
Hwy 12 on Hatteras Island through Tuesday afternoon`s high tide
(around 1 PM) with continued onshore winds, wave run up and King
Tides. High threat of rip currents with strong shorebreak
continues north of Cape Hatteras through Tuesday afternoon.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement through Tuesday evening for NCZ203-205.
Coastal Flood Advisory until 5 PM EDT Tuesday for NCZ196-
203>205.
MARINE...Small Craft Advisory until 10 AM EDT Tuesday for AMZ150-152-
154.
&&
$$
SYNOPSIS...MHX
NEAR TERM...SK/MS
SHORT TERM...SK
LONG TERM...CQD
AVIATION...CQD/MS
MARINE...CQD/SK/MS
TIDES/COASTAL FLOODING...MHX
Area Forecast Discussion
National Weather Service Marquette MI
745 PM EDT Mon Oct 11 2021
.SHORT TERM...(This evening through Tuesday)
Issued at 429 PM EDT MON OCT 11 2021
Water vapor imagery and RAP analysis show western troffing
amplifying again. Downstream, what was once a potent shortwave has
weakened, lifting ne from MN into northern Ontario. Next vigorous
shortwave is currently lifting nne across MO, and this will be the
feature of interest for the short term portion of the fcst. Jet
streak associated with the northern Ontario shortwave aided
shra/tsra across the eastern fcst area earlier today. Fcst area is
currently in a lull in pcpn as the one wave is now well to the nne
and bulk of pcpn associated with next wave hasn`t yet arrived. A few
shra well in advance of the wave are streaking into s central Upper
MI. It`s a warm Oct day. Where skies have temporarily become mostly
sunny across the nw half, temps have risen to around 70F.
Vigorous shortwave currently over MO will lift into the Upper Great
Lakes tonight/Tue (weakly closed mid-level low will pass near the
Straits Tue aftn). A good shield of shra/tsra is currently
associated with this feature. With no significant weakening of the
wave prior to reaching the area, expect this pcpn to lift n across
the fcst area tonight/Tue morning. Heavier pcpn will occur across
the central and eastern fcst area. With precipitable water
increasing to 1.5 to 1.7 inches, 225-250pct of normal, hvy downpours
will accompany some of the shra. Rainfall amounts of 1-2 inches are
certainly possible across the central and eastern fcst area. If
heavier shra are persistent at any location, could see local 2-3
inch rainfall totals. Bulk of model guidance indicates MUCAPE
peaking only in the 200-500j/kg range over the eastern fcst area.
NAM is the only exception, showing upwards of 1300j/kg over the far
eastern fcst area, but with estimated effective shear under 25kt,
svr risk would still be minimal. A mention of tsra was included in
fcst over all but the w where instability is nil tonight/Tue
morning.
Shra will diminish Tue aftn, but greater coverage of shra will
linger across the w and n central under cyclonic upslope nw to n
flow. Could be a little diurnal component to shra in the aftn if
there are some breaks in the cloud cover, but that looks unlikely
with guidance indicating abundant low-level moisture/considerable
cloud cover. With the clouds and shra around, temps won`t rise much
from the mild nighttime conditions tonight. Expect lows tonight
ranging from the low/mid 50s F w to around 60F e. Highs Tue should
range from around 60 w to the mid 60s e.
.LONG TERM...(Tuesday night through Monday)
Issued at 343 PM EDT MON OCT 11 2021
Model guidance continues to show an active weather pattern
persisting across the Great Lakes for the long term forecast,
bringing multiple waves of precipitation to the area. Temperatures
still look on par with trends above average readings for the early
portions of this week, and cooler temperatures anticipated for the
the weekend. However, the cool temperatures look to be seasonal for
a short period as upper level ridging takes place over the Upper
Midwest to begin next week. Precipitation is expected to remain as
rainfall for the extended forecast package. The active weather
pattern and possible lake effect rain showers during this upcoming
weekend may bring an end to several areas that have fall foliage
remaining in localized areas.
Tuesday night will see the exit of the shortwave disturbance as it
pushes to the east, with light rain shower activity lingering behind
the occluded surface low for the east half of the area. The weak
frontal boundary will cause cloud cover to persist for most of the
night, with mild temperatures remaining across the area...mainly in
the upper 40s to mid 50s. The cooler air at the surface will be
short-lived as the upper air pattern quickly shifts to an amplifying
ridge further upstream, over the Upper Midwest and Great Lakes late
Tuesday night through early Thursday. Because of this setup,
temperatures are not expected to remain cool Wednesday. Onshore flow
via surface high pressure will likely keep cover over portions of
the UP, but southerly flow from an approaching warm front, and dry
air will advect into the region throughout the day, causing an
uptick in surface temperatures as clouds are scoured out of the
area. Above average readings in the 60s are likely once again as
850mb temperatures range from 9-15C. The Canadian model is the most
aggressive with the temperatures at 850mb, which could bring
localized high temps into the lower 70s when combined with the
southerly flow on Wednesday. Wouldn`t be surprised to see downslope
effects for areas closest to the Lake Superior shoreline in
Marquette County have localized higher temperatures. While we have
surface high pressure moving across the Great Lakes, a strong mid-
latitude cyclone will develop to the east of the Rocky Mountains on
Wednesday. This weather system is progged to remain to our west, but
the eventual occlusion of the surface low pressure will still bring
a cold front across our area by Thursday.
Thursday through Saturday, the ULL associated with the eventual
occlusion of the surface low will ever so slowly propagate toward
James Bay. Multiple shortwaves disturbances will propagate along the
upper level flow. The energy associated with the shortwaves and ULL
axes will bring rain showers to Upper Michigan from Friday through
the weekend. Seasonal temperatures will be ushered into the area
courtesy of a strong cold FROPA across the UP. The warm lake
temperatures combined with much colder air aloft at 850mb between 0
to -3C will assist with lake enhanced initiation of precipitation
during the weekend, thus cloud cover will assist with keeping
temperatures cool.
As we look toward the beginning of next week, extended deterministic
guidance shows another round of upper level ridging building across
the Upper Midwest toward the Great Lakes. On the heels of that
amplifying ridge, another shortwave disturbance may evolve quickly,
bringing additional chances of precipitation to the cwa toward the
middle of next week. Needless to say, the active weather pattern and
rain showers will help with areas still experiencing abnormally dry
conditions. The near average, to slightly above average temperatures
will keep any precipitation we see as liquid QPF through the first
half of the month.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 744 PM EDT MON OCT 11 2021
Low pressure system lifting northward through the Upper Midwest this
evening will bring showers and lowering cigs to all of the terminals
overnight. High confidence that IWD and CMX will go into IFR with
perhaps a period of LIFR at IWD with upslope NE winds tomorrow
morning. SAW will likely see the lowest conditions with a long
period of LIFR very likely given the persistent NE upslope flow
there as well. Would not be surprised to see periods of vis/cig
below airfield minimums tomorrow morning but was not confident
enough to explicitly include it in the TAF yet. There will be a very
gradual improving trend tomorrow afternoon as the low pulls away,
although northerly flow behind the low will keep upslope-driven
showers and low cigs around through the end of this TAF period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 429 PM EDT MON OCT 11 2021
Low pres currently over ne MO will weaken as it lifts nne, reaching
Upper MI Tue morning and then drifting out over eastern Lake
Superior Tue aftn. Before it moves closer, winds will become vrbl 5-
15kt this evening. Winds will then become ne with gusts to 20-25kt
overnight. As the weakening low moves out over eastern Lake Superior
Tue aftn, winds will diminish across that portion of the lake. To
the w, n to ne winds will gust upwards of 25kt across central Lake
Superior to the n and w of the Keweenaw to Isle Royale. Winds will
then gradually diminish Tue night. After winds under 20kt Wed
morning, se winds will ramp up Wed aftn as strong low pres lifts
across the Dakotas. Expect gusts to 25-30kt Wed night. Could be a
few gale force gusts to 35kt across central and eastern Lake
Superior. Winds will shift w to sw for Thu. Strongest winds on Thu
will be across western Lake Superior. Expect gusts to 25-30kt, but
there could be a few gale force gusts to 35kt. Westerly winds
gusting up to 25kt should be common Fri/Sat.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...BW
AVIATION...RJC
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Paducah KY
635 PM CDT Mon Oct 11 2021
.UPDATE...
Issued at 635 PM CDT Mon Oct 11 2021
Updated Aviation discussion for the 00z TAF issuance.
&&
.SHORT TERM...(Tonight through Tuesday)
Issued at 324 PM CDT Mon Oct 11 2021
The band of showers and storms that currently extends from Edwards
County Illinois to Fulton County Kentucky will continue to make
slow eastward progress. The latest HRRR indicates that it should
clear southwest Indiana and the Owensboro around 00Z, and the
southern Pennyrile by 02Z. We continue to monitor for severe
weather (damaging winds), but at this point the gradient
southerly winds have been as strong in places as we have seen from
the convection. In general, the convection will be moving into
lesser shear and instability as it moves eastward, so a downward
trend is expected as it moves east.
Strong south winds outside of thunderstorms will continue to gust
25-35kts through sunset, as they veer to southwest behind the
convection. They will remain southwesterly and eventually drop to
10 kts or less. Stuck with the NBM low temperatures that
basically span the 50s from west to east across the area.
Tuesday will be sunny and continued warm despite weak surface high
pressure briefly settling over the area.
.LONG TERM...(Tuesday Night through Monday)
Issued at 324 PM CDT Mon Oct 11 2021
Another occluded storm system will lift north northeast into the
northern Plains Tuesday night into Wednesday. This will result in
warm, moist advection across our region, with some chance of
convection reaching western portions of southeast Missouri after
midnight Tuesday night. Chance PoPs will overspread most of the
region Wednesday, but as the upper system continues to pull
farther north, the forcing weakens in the afternoon. The
associated cold front will remain to the north of the area by the
end of the day Wednesday, as it will be nearly parallel to the
strong southwest flow aloft.
Wednesday night through Thursday night the boundary should stay
northwest of the area, and that could keep a good bit of our area
dry through this period. However, we do have some pretty hefty
NBM PoPs over southeast Missouri and southern Illinois Thursday
and Thursday night. This may be overdone.
A stronger, more progressive upper trough will eventually push
onto the Plains Thursday night into Friday and that will
eventually push the cold front through our region at some point
Friday afternoon through Friday night. The GFS is on the fast side
of the curve, while the EC and CMC are slower and almost pivot the
trough to a negative-tilt orientation as it moves through our
region. If this occurs some severe storms will be possible Friday
night.
Behind this system we should clear out quickly Saturday afternoon
and the rest of the weekend and next Monday should be dry and
pleasantly cool for a change.
&&
.AVIATION...
Issued at 635 PM CDT Mon Oct 11 2021
The last of the line of showers and thunderstorms that has marched
across the region this afternoon has nearly cleared all the
terminals, with impacts to OWB expected to last only until 01z.
Otherwise gradient winds will begin to relax tonight. We`re
already beginning to lose the gusts at some stations, though
sustained winds of 08-15 kts from the S-SW will continue through
04-06z. Cigs will remain VFR, though some BKN decks around 5000`
may move into MVN overnight behind the departing surface low to
our north. SKC and light W-SW winds expected for much of the day
Tuesday.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...DWS
SHORT TERM...DRS
LONG TERM...DRS
AVIATION...DWS
Area Forecast Discussion
National Weather Service Portland OR
819 PM PDT Mon Oct 11 2021
.SYNOPSIS...After the coldest night of the Fall so far, a series of
weak fronts will bring light rainfall amounts before a potentially
stronger storm system impacts the region over the weekend.
&&
.SHORT TERM...THIS EVENING THROUGH THURSDAY...Isolated showers are
finally dissipating from the southern waters and a small section of
the eastern Willamette Valley and adjacent Cascades under the high
pressure. The Frost Advisory will continue as planned, and will be
in effect for late tonight through tomorrow morning. While there is
a weak signal (i.e., 10-20% chances) for fog and/or low stratus
development in the Willamette Valley in the HREF`s probabilistic
cloud forecast for early tomorrow morning (roughly the 4-9 AM
timeframe), frost would inhibit this if it is able to begin slightly
sooner. And if fog and low clouds fail to develop, temperatures will
be able to fall even slightly lower than what most model guidance is
currently suggesting. For now, am sticking with the 50/50 blend of
NBM`s 25th percentile and CONS RAW`s forecast for minimum
temperatures. However, another caveat in consideration is the wind
overnight tonight. With the high pressure well established over the
area, pressure gradients should be generally weak which would favor
very light to calm winds. However, if model guidance is
underperforming winds even a little bit, then boundary layer mixing
tonight could keep temperatures at the very surface from reaching
their minimum. Still, widespread frost is a good bet if even the
warmer model solutions verify, which seems unlikely at this point
(especially since today`s high temperatures are still on track), so
the Advisory stands. Once the sun rises to illuminate the eastern
sky, the surface will absorb its radiance and the frost will
consequently dissipate.
A cold/occluded front that will break off of a weakening surface low
in the Gulf of Alaska will dive southeast into the area tomorrow
afternoon and evening. Ahead of it will arrive first high and mid-
level clouds, then low stratus and chances for gentle rain - first
along the coast before gradually spreading east. Some showers could
even arrive early enough along the coast to prevent frost from
developing there, though if high resolution guidance is correct any
rain activity would be sparse prior to around 11 AM (long after any
trace of frost has burned off in the sun`s radiance). The question
is whether enough low to mid level clouds will arrive there to
hamper radiational cooling sufficiently to prevent frost. The latest
run of HREF has probabilities increasing to more than 40% between 8
and 9 AM there, so it will be interesting to see how things unfold.
At any rate, much of the latter half of the day should wind up
rainy, but rainfall totals are looking on the low side (still around
.1" to .3", with isolated greater amounts in higher elevations) due
to the weak forcing mechanisms responsible for it.
The cold front finally sweeps across the area from west to east
Tuesday evening (along the coast) into early Wednesday morning (in
the central Oregon Cascades). Behind it, the pattern turns more
showery, with most high resolution simulated reflectivity guidance
showing a spattering of high reflectivity echoes beginning over the
waters after dark tomorrow evening. The HRRR and NAMNest are even
hinting that weak convection supporting locally gusty winds and
briefly heavy rain may be possible immediately ahead of the cold
front tomorrow afternoon evening across the waters and eventually
along the coast. A clap or two of thunder may be possible both with
this line of forced convection and with any convective showers
behind the front, but the chances have not been looking impressive
enough (mainly since temps > -20C at 500mb) to add that to the
forecast at this time. Isolated to scattered showers appear likely
to stick around for most of the day Wednesday and even the first
part of Wednesday night, with snow possible above roughly 3000-3500
feet.
Thursday is looking to be the nicest day of the short term period,
with the ECMWF, GFS, and CMC all suggesting virtually no measurable
precipitation everywhere in the area. It`ll be slightly warmer than
Tuesday and Wednesday with high temperatures perhaps exceeding 60F,
especially in the southern and central Willamette Valley where
sunshine appears most likely. -Bumgardner
.LONG TERM...FRIDAY THROUGH MONDAY...Between a deep low in the Gulf
of Alaska and another trough in the Great Basin, our area looks to
enter the long term period Friday morning under a positively tilted
ridge of high pressure. Thereafter, model disagreement starts to
make the forecast a challenge. While the a zonal flow type of
general upper pattern is well established, the deterministic GFS,
ECMWF, and CMC each have slightly different takes on the timing of
rain arrival: The GFS has rain entering our area in advance of an
approaching low late Friday morning, the Euro has it beginning
Friday afternoon, and the CMC has it holding off until late Saturday
night. Our area looks to be just south of the main upper low until
at least late Saturday, but an elongated area of precipitation along
a west to east-oriented, quasistationary frontal boundary is
difficult to position. All three of the long time range
deterministic models show this precipitation feature (which looks
not unlike an atmospheric river), but differ in their depiction of
its orientation and position - especially in terms of its latitude.
A further north track of the frontal boundary, such as what the CMC
is suggesting, would imply lots of rainfall in the Washington
Cascades but little in our area; a south track, like what the ECMWF
is showing, would give our entire area lots of rain; and the
position of the feature somewhere in the middle, like what the GFS
depicts, would give our northern areas lots of rain, but keep the
remainder of the area (roughly south of Salem) completely dry. At
this point it`s just too far out to call it, so have kept hands off
of the NBM`s forecast for now, though this will bear watching over
the next few days.
More substantial precipitation for at least a part of our area
should arrive with the main feature at some point (depending on its
now-uncertain time of arrival) during the Saturday through Monday
timeframe, but, just as the position of the stationary front is
uncertain, so will be the position of this low. A south track could
certainly bring another round of chances for thunderstorms in the
lowlands and snow in the high elevations, but a north track could
leave most of the area without measurable precipitation. Confidence
is increasing as models trend to bring us area-wide precipitation
during the Saturday night to Sunday timeframe, but confidence in
thunderstorms anywhere in the area remains low enough at this time
to preclude an addition of thunder.
The other notable mention for the long term period is Saturday`s
(relative) warmth. Maximum temperatures in at least the low to mid
60s are looking likely, but of course this will depend on whether
rain and low clouds from the aforementioned frontal boundary are
impacting our area. NBM`s interquartile range of probable maximum
temperatures is now 61-68F for Saturday at PDX, and the southern
Willamette Valley is looking even warmer, so it may wind up being a
pleasant day after all (at least for temperatures). -Bumgardner
&&
.AVIATION...06z TAFS: High pressure moving across the region tonight
will bring predominantly VFR conditions before an incoming cold front
will spread lowering ceilings and rain back into the region
between 21z Tuesday and 06z Wednesday. Coastal locations will
likely see MVFR conditions return between ~21z Tuesday and 00z
Wednesday. The cold front looks to be strong enough that a brief 1-2
hour burst of IFR conditions will also likely affect the coast around
frontal passage, which appears will happen between ~00-02z Wednesday.
Flight restrictions will take longer to move into the Willamette
Valley Tuesday evening, but MVFR conditions appear likely to take
hold for between ~03-06z Wednesday for interior taf sites.
For detailed regional Pac NW aviation weather information, go
online to: https://weather.gov/zse
KPDX AND APPROACHES...High pressure moving across the region
tonight will bring predominantly VFR conditions before an
incoming cold front will spread lowering ceilings and rain back
into the region between 00-06z Wednesday. Expect MVFR conditions
to at least briefly return to the terminal around ~02-05z
Wednesday. In the meantime, clear skies, light winds and dewpoints
hovering in the 30s should allow temperatures to cool off efficiently
with frost development likely on exposed surfaces. /Neuman
&&
.MARINE...High pressure building across the waters will allow
winds and seas to gradually subside tonight. The reprieve in the
weather will be short lived, however, as another front drops
southeastward towards the region on Tuesday. Expect increasing
southerly winds with widespread Small Craft Advisory level wind
gusts of 25 to 30 kt spreading across the waters. High resolution
model guidance does suggest there is a chance Gale Force wind
gusts of 35 kt could briefly occur just ahead of the front across
the northern waters in the late afternoon and evening hours. By
brief, these winds would likely occur for an hour or less. The one
area of concern where these stronger wind gusts could hold on longer
is within 10 NM of the coast between Tillamook and Pacific Counties,
particularly right off the mouth of the Columbia River. Will let
the overnight shift digest a full suite of model data before
upgrading any advisory to a warning for late Tuesdsay afternoon and
early evening.
Otherwise, expect gusty northwest to northerly winds to spread
across the waters behind the cold front. A northwesterly swell
should follow suit and push seas back into the 10 to 12 ft range
late Tuesday night through at least Wednesday night. A couple
weak fronts will likely cross the waters Thursday and Friday, but
impacts should be relatively small aside from keeping seas elevated,
generally in the 7-9 ft range, and perhaps bringing a brief period
or two of Small Craft Advisory level wind gusts of 25 kt.
A more active weather pattern may try to take hold over the
weekend as a stronger low pressure and attendant front bring a
threat of solid Gale Force winds and larger seas to the waters.
/Neuman
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Frost Advisory from midnight tonight to 9 AM PDT Tuesday for
Central Coast Range of Western Oregon-Central Oregon Coast-
Central Willamette Valley-Coast Range of Northwest Oregon-
Greater Portland Metro Area-Lower Columbia-North Oregon
Coast-South Willamette Valley-Western Columbia River Gorge.
WA...Frost Advisory from midnight tonight to 9 AM PDT Tuesday for
Greater Vancouver Area-I-5 Corridor in Cowlitz County-
South Washington Coast-Western Columbia River Gorge-
Willapa Hills.
PZ...Small Craft Advisory until 10 PM PDT Tuesday for coastal waters
from Cape Shoalwater WA to Florence OR out 60 nm.
Small Craft Advisory until midnight PDT tonight for Columbia
River Bar.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
953 PM MDT Mon Oct 11 2021
.UPDATE...
Issued at 946 PM MDT Mon Oct 11 2021
Based on the 00z model runs and various CAMs, have made some
small adjustments to fire weather products this evening. First,
have dropped the fire weather watch for Baca and Prowers Counties,
as despite the risk of lightning, relative humidity looks to stay
above 20 percent for these areas. Did upgrade ern Las Animas
County to a Red Flag Warning, as drier air sweeps eastward here late
in the afternoon. Left High Wind Warning alone for now, though
HRRR has backed off on wind gust speeds somewhat, especially
across Pueblo County. Remainder of the forecast looks on track,
with snow about to start over the San Juans in the next few hours.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 328 PM MDT Mon Oct 11 2021
... A strong storm system will bring multiple hazards to the region
starting tonight through Tuesday...
--- Main Threats/Concerns ---
1) Severe weather possible over the far eastern plains, with the
main threat area extending from a line from Eads to Kim. Main
threats will be severe winds up to 60 mph.
2) Heavy mountain snow along the southwestern San Juan mountains
overnight, with snowfall amounts up to 12 in expected, with locally
isolated amounts up to 15 in possible.
3) Fire weather conditions are expected along the I25 and Hwy 50
corridors, where strong winds, low humidities, and dry fuels will
increase fire danger. A fire weather watch is still in effect for
the far southeastern plains.
4) Strong to severe environmental winds are expected along the Raton
Mesa and east of the southern Sangre de Cristo Mountain areas, with
wind gust up to 60 mph likely.
---Discussion---
Synoptically within the short term period, a large and powerful
trough will be digging over the Colorado region throughout the short
term period, tonight and Tuesday. As this takes place, and the
trough pushes eastward, synoptic level ascent/dynamics will greatly
increase across the area, allowing for enhanced upper level support.
Winds throughout the whole column will considerably rise in response
the the system in place, as a jet maximum swings around the southern
periphery of the trough; winds down to 700 mb will be around 50 kts
over the eastern plains.
Tonight... The primary concern for overnight will be the development
of snow along the mountains...
1) As the aforementioned trough begins digging over the region,
strong west/southwest winds will develop over western parts of the
Pueblo forecast area. These winds will become focused into the
mountains along the Continental Divide, particularly the San Juan
Mountains. The strongest winds and focus of SW winds will be mid to
late morning over that area, before winds veer and become more
westerly. With the winds channeled into the San Juan Mountains,
strong orographic forcing will take place and will be enhanced by
the strong synoptic support passing over Colorado. With the focused
forcing in place, stratiform precipitation is expected, and with
cold temperatures aloft and at the surface, this precipitation is
anticipated to be snow at the higher elevations. This snow will
likely be heavy at times given the dynamics in play. With this type
of heavy snow, roads can become snow covered quickly and with gusty
winds, visibilities can drop fast. Most over the San Juans should
see up to 12 in, but isolated higher amounts of up to 15 in are
possible, especially wherever the heaviest snow bands take place.
Lighter snow amounts are expected over parts of other mountains
ranges, such as the La Garita, Sawatch, Sangre de Cristo, and
Mosquito Mountain ranges, where values will range between 2-8 in,
with the La Garitas getting the high end of that spectrum.
Elsewhere over the Pueblo CWA, expect dry and cold conditions
overnight, and winds to begin increasing as the storm system
approaches.
Tuesday... During the day Tuesday, multiple hazards will materialize
over the southern Colorado region...
1) Regarding severe weather concerns, the best threat area will
likely be along a line extending southward from Eads to around the
Kim area. With the stout system in place, shear will not be an
issue, with cloud layer shear 40+ kts, which will help with storm
organization. Mid level moisture will increase within the dry slot
of the storm system, as the strength of the system advects a
moisture plume from the Gulf of California region over the eastern
plains. At the surface, moisture will be drier, so the moisture
aloft will be the main source of moisture for convection. The CAPE
will be more marginal, with the most unstable CAPE ranging from 200-
500 J/kg, but this will be sufficient for convective updrafts given
the wind profiles in place. With the above said, isolated to widely
scattered elevated thunderstorms, with little precipitation reaching
the surface, are likely to initiate over the far eastern plains as
synoptic ascent increase ahead of the trough. Given the higher winds
aloft, downdrafts will likely be able to transfer this momentum to
the surface, helping to enhance the downdrafts themselves. The
primary threats from this will be strong to severe winds up to 60
mph.
2) Regarding the fire weather concerns, the best conditions will
align along the I25 and Hwy 50 corridors. Downsloping winds will dry
rapidly as they push eastward off of the higher terrain. This drying
will drop humidity values into the mid teens, and likely even lower,
as mixing takes place during the afternoon. Winds over the regions
of concern are expected to be within 25 to 35 kts sustained, with
gust likely 40+ kts. These conditions will greatly increase the risk
of fires igniting and spreading quickly. Also enhancing the threat,
with the low precipitation thunderstorms out over the plains, the
risk for lightning induced fires will be high.
3) Lastly, regarding the high wind threat, the primary areas
expected to be impacted will be the southern I25 corridor and along
the Hwy 160 corridor. These high winds will be in response to the
aforementioned jet maximum swinging over the southern Colorado
region. The higher terrain along the previously mentioned corridors
will be, simply put, closer to the speed maximum aloft given the
higher terrain. This will make it easier for these areas to actually
realize an increased wind threat, as the winds will have less of a
distance to mix down to the surface. The strongest winds are
expected during the afternoon, when the jet maximum is directly
overhead, and the most efficient mixing will take place; the winds
should weaken by the evening. It is worth noting, strong katabatic
winds along the higher terrain of the eastern mountains are possible
due to a tightening PGF in response to the colder air within the San
Luis Valley and warmer temperatures on the eastern plains.
Expect the different types of hazardous weather to slowly diminish
and/or move out of the Pueblo CWA as the storm system continues its
push eastward.
.LONG TERM...(Tuesday night through Monday)
Issued at 328 PM MDT Mon Oct 11 2021
The long term period will bring a mixed bag of conditions
to the Pueblo forecast area. Wednesday, flow will become more zonal
for a short period of time behind the exiting system from Tuesday
and an approaching system that will impact the area Thursday/Friday.
This flatter flow will keep things relatively quieter weather wise,
though some lingering snow showers are possible along the central
mountains given the westerly flow into them. Thursday into Friday,
the GEFS and EPS ensemble models are in relatively good agreement
about the evolution of things, bringing in another digging trough
throughout that two day period. This pattern will bring an increased
chance of high elevation snow and low elevation rain. The troughing
pattern would also bring higher chances of below normal temperatures
for the entire southern Colorado region. Beyond Friday a ridging
pattern develops over the western US. The ridging pattern would help
to bring better odds of warmer than normal temperatures for this
time of year, and to keep precipitation chances low. There is a
signal within the ensemble models that more troughing could take
place Monday, but the signal is currently weak, but something to
keep in mind, as that pattern generally brings more unsettled
weather to the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 328 PM MDT Mon Oct 11 2021
For KCOS, KPUB, and KALS, VFR conditions are expected through the
forecast period. Breezy winds will persist this afternoon with
sustained speeds of 10-15 kt and gusts of 20-25 kt -- generally from
the southeast at KCOS and KPUB, and the south to southwest at KALS.
Winds will weaken this evening into tonight. For Tuesday, much
stronger south to southwest winds are expected, with wind speeds
reaching 20-30 kt and gusts reaching 35-45 kt during the afternoon.
Blowing dust will be possible Tuesday afternoon, which may result in
localized visibility restrictions. Scattered storms with strong
winds may also form over the far eastern plains Tuesday afternoon
and evening, though this activity should remain east of the TAF
sites.
Over the Colorado mountains, snow is forecast to develop from west
to east. The snow will become heavy at times over the eastern San
Juan Mountains and the La Garita Mountains areas. Wind gusts around
40 kt will combine with the snow to result in blowing and drifting
snow. These factors will cause significant restrictions to
visibilities and ceilings over the mountains, including mountain
passes, from tonight into Tuesday. However, these restrictions are
not expected to affect the TAF sites.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 8 PM MDT Tuesday for COZ222-
226>235.
High Wind Warning from 6 AM to 8 PM MDT Tuesday for COZ086>088-
094-099.
Winter Weather Advisory until 6 PM MDT Tuesday for COZ066.
Winter Storm Warning until 6 PM MDT Tuesday for COZ068.
&&
$$
UPDATE...PETERSEN
SHORT TERM...SIMCOE
LONG TERM...SIMCOE
AVIATION...COHEN