Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/08/21
Area Forecast Discussion...Updated
National Weather Service Billings MT
904 PM MDT Thu Oct 7 2021
Southwest flow over the state, with embedded energy generating a
few showers. Coverage was more than last evening, with pockets of
heavier rain (Livingston hada could bouts of moderate rain) than
last night too. Overall, scattered band of precipitation was
working across central and eastern zones and will slide northeast
out of the area overnight. More activity was poised to the
southwest over eastern Idaho and northern Utah, and this should
swing into area Friday morning. Adjusted PoPs for above. TWH
Tonight through Saturday night...
Showers will continue across the western half of the area this
afternoon and evening. The radar does not seem quiet as active as
some of the earlier runs of the HRRR had. These may decrease a
little in coverage overnight, but areas from Miles City to
Sheridan west will see the chance for showers. There have been
some lightning upstream in these storms, so do have a mention of
some thunderstorms, mainly over the mountains. Tomorrow another
round of better energy moves into the area as a splitting trough
moves through the Northern Rockies. This will start the first
period of decent chance for precipitation the area in the
As temperatures cool in the higher elevations, the mountains will
transition to snow overnight, picking up several inches of snow
by Saturday evening. The lower elevations will remain as rain
through the day Saturday. The trough will move east overnight with
the the precipitation ending from west to east by Sunday morning.
Temperatures will generally be in the 60s for highs across most of
the lower elevations. The lows will mostly stay in the upper 30s
to mid 40s. Reimer
Sunday through Thursday...
After a mild Sunday, all eyes are on the very dynamic system that
crosses over the Rockies Monday through Thursday.
The story stays the same, with a deep cutoff upper low crossing
over the Rockies in the 4 corners region and moving north and
east, bringing ample precipitation and much cooler temperatures to
the area. Confidence is high for highs in the 40s, and lows
getting below freezing. Where confidence is split is on potential
and amounts for precipitation. Confidence is high for strong
upslope to occur late Monday through Tuesday bringing ample snow
to the mountains, and a rain/snow mix to the foothills of south-
central Montana, and the Bighorn mountains and foothills. It will
be snow in the mountains, with high probabilities of getting at
least 4 inches of snow. The foothills is a bit more uncertainty
with how low snow levels get that could promote the extent of the
rain/snow line. Regardless of the type, it will be a very wet
Lower confidence exists for southeast Montana. Latest ensemble
guidance has the upper low moving further east before coming
north, removing much of the dynamics helping to provide moisture
and ascent for heavy precipitation in that area. Also what`s still
a possibility is some strong winds as this low tightens near the
MT border We are still 5-6 days out, so we are not chasing this
latest scenario yet, but wanted to make everyone aware of the
possible high hit, yet equally possible complete miss of SE
Montana receiving rain or snow. Vertz
Scattered area of showers will swing through parts of south
central and southeast Montana the rest of the night. Brief
moderate rain is possible in the heavier showers, otherwise
conditions should remain VFR. Precipitation will swing northeast,
out of the area, overnight. Another round of activity will move up
from Idaho and Utah Friday morning. Mountains will be mostly
.PRELIMINARY POINT TEMP/POPS...
Fri Sat Sun Mon Tue Wed Thu
BIL 046/061 047/060 039/065 040/048 034/043 033/048 035/052
24/W 87/W 00/U 56/R 77/O 54/R 31/B
LVM 041/062 040/058 033/063 032/045 026/042 024/047 026/049
37/T 86/W 01/U 78/O 86/S 33/O 32/S
HDN 043/064 044/059 036/067 038/051 032/044 030/049 031/053
33/W 88/W 10/U 45/R 77/R 64/O 32/R
MLS 047/064 048/058 038/064 040/054 036/048 034/051 034/052
33/W 77/W 10/U 23/R 56/R 65/R 42/R
4BQ 048/069 049/056 040/063 040/056 035/046 034/048 033/050
31/B 78/W 30/U 13/R 57/R 75/R 42/R
BHK 046/066 047/058 038/062 038/058 037/049 035/049 033/049
13/W 88/T 40/U 12/R 45/R 76/R 42/R
SHR 043/067 041/054 034/065 034/052 027/041 026/046 026/049
34/W 89/W 20/U 35/R 78/O 65/O 32/O
Area Forecast Discussion
National Weather Service Goodland KS
937 PM MDT Thu Oct 7 2021
.SHORT TERM...(This evening through Friday morning)
Issued at 306 PM MDT Thu Oct 7 2021
RAP analysis has an upper level low over the upper Midwest with a
developing longwave trough just off the California coast as weak
ridge is over the central High Plains. The ridging continues the
current pattern of dry conditions with little cloud cover. Winds
have increased due to daytime mixing as a surface low cross over
SW Kansas bringing isolated wind gusts of 20+ knots to locales
along and south of Interstate 70. An area of clouds moves through
during the overnight hours as winds fall below 10 knots across
the area. The area of clouds is anticipated to keep the
temperatures in the upper 40s to low 50s despite the light winds.
Friday, southerly flow dominates as the trough moves further inland
over. Dry conditions continue with elevated fire weather concerns
along and west of Highway 27 as RH values fall into the lower teens
with winds from the south around 10 knots, with locally higher wind
gusts possible through the afternoon. Afternoon high temperatures
are forecasted to be in the low to mid 80s across the area. Clouds
increase during the late afternoon and evening hours west to east
limiting the overnight low temperatures to the low to upper 50s.
Saturday, the ridge moves to the east of the area as the above
mentioned trough moves closer to the area from the west and an
approaching cold front from the northwest. A strong jet through the
atmospheric profile will present in part to the trough as strong
westerly downslope winds will cause strong surface winds along with
warm temperatures. Temperatures for the day will be the tricky part
based on the speed of the cold front, behind the cold front
afternoon high temperatures look to be in the mid 70s to low 80s.
Ahead of the front where the southerly flow coupled with the
downslope winds interact will see afternoon high temperatures in the
mid 80s to perhaps low 90s in a few locales. A few record highs may
be in jeopardy with Hill City currently forecasted at 89 and their
record high for the day is 90 set back in 1965. Moving on to the
winds, using the NBM 90th Percentile as guidance, am currently
expecting sustained SSW winds of 20 knots (perhaps higher) with
gusts of 30-35 knots possible throughout the afternoon, some
localized areas of blowing dust are also possible. These strong
winds coupled with the warm temperatures and the dry conditions
will lead to near critical fire weather conditions for locations
along and south of Interstate 70 Saturday afternoon. If a fire
were to get started it would spread quickly with the strong winds
and dry conditions. A Fire Weather Watch was considered for
counties south of Interstate 70, but held off for now as RH
values continue to show Upper teens to low 20s for the area. As
the cold front and trough move through this will bring a slight
chance for rain showers Saturday night through Sunday morning.
Currently, the best forcing looks to remain just south and west of
the CWA but a small wiggle to the north would increase the
chances especially along and south of Interstate 70. Overnight
lows for Saturday night into Sunday morning are forecasted to be
in the low 40s to low 50s with colder temperatures located over
.LONG TERM...(Sunday through Thursday)
Issued at 231 PM MDT Thu Oct 7 2021
The focus in the long term period is on cooler temperatures and a
chance of rain.
The upper trough that has been approaching the area finally sweeps
across the high plains during the daytime and early evening hours
on Sunday. This upper trough lags behind the surface trough that
moves through the area by late Saturday. Isolated to scattered
light rain showers are possible with this first impulse through
the day on Sunday into Sunday night and early Monday morning with
dry conditions to follow Monday afternoon into Monday night. High
temperatures during this time will be generally in the 70s with
lows in the 40s.
Another deeper surface trough follows during the day on Tuesday
with a deeper upper trough moving across the area Tuesday night
into Wednesday. Scattered showers on Tuesday will become more
numerous Tuesday night and taper off again on Wednesday.
Temperatures will cool more in the wake of this system with highs
mainly in the 60s and lows in the lower 30s to middle 40s.
Dry conditions will follow on Thursday with cool temperatures
remaining in place.
With the dry conditions preceding this series of systems, windy
conditions may produce areas of blowing dust on Tuesday ahead of
the main batch of precipitation expected Tuesday night into early
Near freezing temperatures are possible mainly across eastern
Colorado early Wednesday and Thursday morning.
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 936 PM MDT Thu Oct 7 2021
VFR conditions will prevail at KGLD and KMCK through the forecast
period. Winds will remain light and variable overnight and through
the morning, increasing to around 5-10kts from the southeast in
Issued at 306 PM MDT Thu Oct 7 2021
Saturday October 9th, 2021
Hill City: Record 90 degrees in 1965
Forecasted temperature 89 degrees
Colby: Record 91 degrees in 1991
Forecasted temperature 86 degrees
Tribune: Record 93 degrees in 1991
Forecasted temperature 87 degrees
Area Forecast Discussion
National Weather Service Wichita KS
624 PM CDT Thu Oct 7 2021
.SHORT TERM...(This evening through Sunday night)
Issued at 248 PM CDT Thu Oct 7 2021
Bottom line up front: Well above normal temperatures for
Fri and Sat. Chance of storms on Sun afternoon/evening and again on
Pesky upper low currently over eastern MO, continues to make slow
progress to the east of the forecast area, with warm advection and
clearing skies returning to most of the forecast area. The mid
level warm advection and moisture advection led to a few
showers/storms developing over SW KS last night, with remnant
clouds moving across south central KS at this time.
For tonight, the latest short term RAP suggests that the mid level
warm advection and 850-700h moisture transport will increase for
areas east of I-135 this evening and tonight, with this moisture
transport and mid level isentropic ascent increasing over eastern
KS into SE KS by early on Fri. For now plan on keeping the gist of
the forecast dry, as dry air below the increasing mid level
advection will limit any moisture from reaching the ground. Possibly
a few sprinkles or two, so will include this mention for SE KS.
Upper ridging building into the plains will support warmer
temperatures going into Fri and Sat, with forecast highs climbing
into the mid 80s to low 90s on Fri, with record or near record highs
expected on Sat. (see climate section below). Normal highs this time
of year are in the mid 70s!
The warm and breezy conditions continue for Sat as well, as optimal
downslope conditions lead to max temperatures well above normal for
Sat afternoon. With the near record highs and breezy south winds,
could also see some elevated grassland fire concerns, see the
fire weather section below for more details.
A cold front looks to move southeast across the forecast area on
Sunday, which will lead to most areas seeing cooler temperatures for
Sunday afternoon. Sunday evening through Monday gets interesting as
a strong shortwave moves out of the southern Rockies, and across
northern OK and southern KS for Sunday evening and takes a negative
tilt as it moves across southern KS. Will have to keep an eye on
this time frame, as there is some question about moisture quality
ahead of this system, but the strong lift and increasing moisture
will lead to shower and thunderstorm chance for Sunday
evening/night, with the highest chances for areas east of the KS
Turnpike. If surface moisture return increases, than there is a
chance of strong to severe storms over SE KS, for Sun evening, given
the high bulk shear values, as the cold front pushes into the Flint
Hills. Stay tuned. Latest model runs seem to be favoring shifting
the shower/storm chances further SE into areas east of the KS
.LONG TERM...(Monday through Thursday)
Issued at 248 PM CDT Thu Oct 7 2021
The active pattern looks to continue for Tue through Wed of next
week, as deterministic and ensemble consensus digs an unseasonably
strong/deep upper trough across the western US, eventually
ejecting it east/northeast into Plains. Models are similar in
digging this strong upper trough across the western US, but
uncertainty exists on the evolution of its eventual ejection onto
the Plains. Will have to keep an eye on this period as well, as
the potentially strong lift coupled with increasing low level
moisture return/instability could once again support widespread
showers/thunderstorms across the forecast area, with even the
potential for severe weather either Tue or Wed.
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 618 PM CDT Thu Oct 7 2021
VFR is anticipated as we look ahead at the 24-hr period for all
TAF locations. A developing LLJ will nose into southern KS tonight
bringing some marginal low level wind shear concerns over mainly
southern Kansas. Gusty south to southwest winds around 25 knots
will return across the area on Friday and may back to a
southeasterly direction later in the day. We could see some
transient mid clouds in the 7000-8000ft range impact portions of
southeast KS after 08-10Z through daybreak along the nose of the
LLJ but other than a brief sprinkle, little impact to aviation is
Issued at 248 PM CDT Thu Oct 7 2021
Near record high temperatures coupled with humidity values
in the lower 20 percent range and gusty south-southwest winds should
support elevated grassland fire danger concerns for Saturday,
especially where warm season grasses are drier. Thinking these fine
fuels are driest across generally southern/southeast Kansas, where
30-60 day rainfall deficits are greatest. Will need to keep an eye
on this period, especially if dewpoints trend drier and winds trend
stronger. At this time, it looks like high to very high grassland
fire danger values will exist across southern KS and the Flint Hills
for Saturday afternoon.
Issued at 248 PM CDT Thu Oct 7 2021
Saturday, Oct 9th, Record temperatures and forecasted highs.
Record High Forecast Highs
Chanute 94 in 1963 93
Wichita 92 in 1963 95
Russell 92 in 2020 93
Salina 94 in 1921 94
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 60 91 67 92 / 10 0 0 0
Hutchinson 57 90 63 92 / 0 0 0 0
Newton 59 89 66 91 / 10 0 0 0
ElDorado 61 89 67 90 / 10 0 0 0
Winfield-KWLD 62 93 69 93 / 10 0 0 0
Russell 54 88 60 90 / 0 0 0 0
Great Bend 54 90 60 91 / 0 0 0 0
Salina 58 88 63 93 / 10 0 0 0
McPherson 57 90 63 91 / 10 0 0 0
Coffeyville 61 94 68 93 / 10 0 0 0
Chanute 61 92 68 92 / 10 0 0 0
Iola 60 90 67 91 / 10 0 0 0
Parsons-KPPF 61 94 68 92 / 10 0 0 0
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1140 PM EDT Thu Oct 7 2021
A cut-off low centered over Illinois will continue to weaken as
it lifts northeast into the Great Lakes. The showery pattern
associated with the low will transition into warm and dry
conditions for the weekend into early next week as ridging
builds into the Ohio Valley.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Update primarily blended the current radar picture and used the
HRRR and NAM12 to buffer into the immediate future of 2-3
hours, then took this trend of the earlier forecast and HRRR/NAM
into the overnight hours.
Upper low over IL remains cut off from steering flow as broad
ridging over the eastern United States shunts the jet stream
well north into northern Ontario and Hudson Bay. This low will
continue to weaken as it slowly eases northeast into the Great
The primary area of showers should shift northeast through the
night with a weak disturbance ejecting in this direction from
the parent low. Low temperatures will once again drop into the
low to mid 60s.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
The cut-off low will open into a trough by late Friday. While
this occurs, its proximity to the west of the CWA along with
afternoon heating will provide one more good chance of
precipitation. The orientation of the trough leads to highest
PoPs across the north, with gradually decreasing chances further
By Friday evening heading into the overnight, guidance suggests
conditions will begin to dry out from southwest to northeast.
This will be accompanied by decreasing clouds as well. Low
temperatures will drop into the upper 50s across most areas due
to less cloud cover.
.LONG TERM /SATURDAY THROUGH THURSDAY/...
The main themes in the long term period will continue to be above
normal temperatures and relatively humid conditions.
For the upcoming weekend, the remains of the pesky upper level low
will continue to weaken and move northeast toward southeast Canada
and the eastern Great Lakes. There could be a lingering low chance
of a shower/storm across the far eastern zones, otherwise partly
cloudy skies will prevail. Mid level ridging is expected to build
into the Ohio Valley Saturday night and Sunday. A frontal system to
our west and surface high pressure to the east will result in a
modest surface pressure gradient setup which will increase low level
southerly flow. This will allow temperatures to warm into the upper
70s to the lower 80s on Sunday.
By early next week, aforementioned frontal system and its parent mid
level trough will try to make in roads across the Great Lakes and
Ohio Valley, weakening some as they try to suppress the mid level
ridge to the east. Warm conditions on Monday will occur once again
(upper 70s to the lower 80s). A chance of showers, perhaps a
thunderstorm, will be introduced in the forecast from late Monday
into Monday night as the cold front pushes east. Much of the
activity is expected to be diminished in coverage by Tuesday.
Mid level ridging is expected to bounce back northward into the Ohio
Valley by mid week in advance of an even stronger mid level trough
across the Intermountain West and Great Plains. Some timing issues
exist at this juncture as to how fast/far east the associated cold
front will get. Right now, a slower solution is preferred which
brings the boundary during the Thursday into Friday time frame. Will
forecast a chance of showers for now. High temperatures will remain
in the 75 to 80 degree range.
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
Overall weather pattern is sound, but the resultant shower
activity resides in a muddled combination of convergent zones
and shortwave energy. None of the deterministic models are
providing enough evidence that their particular placement of QPF
fields is favored over another. There are significant breaks and
wide areas of zero QPF in one area or another for the next 24
hours. While a VCSH may be the truth as to a forecasting
ability for all of the TAF sites, this approach is heavy handed
and there could be a lot more dry periods such as what was
experienced over the region today.
ATTM, the best indications of rain occurs between midnight and
daybreak, a little later between 08-09Z and daybreak for ILN CMH
and LCK. Models were trying to indicate low stratus and IFR
vsbys nearer sunrise, forecast of rain being more prevalent
during these times had me leave the worst of the low cigs/vsbys
out as just a possible outlying solution.
During daylight hours on Friday, the better chance of activity
will lie over the Scioto valley and then w-nwwd from metro
Columbus to nearer Lima. However, this falls under the same
caveats of the precip that is being forecast overnight - highly
circumstantial and low confidence in placement/timing, slightly
higher confidence in occurrence even given all of my hedging
leading up to it.
VFR cigs/vsbys will drop to MVFR cigs and rainfall will bring
MVFR vsbys when it occurs. A drop in a category to IFR
cigs/vsbys are possible, especially if any stratus develops
later overnight. Given the weak <5kt winds shifting from ne to
sly, this remains a potential that will need to be monitored for
OUTLOOK...No significant weather is expected.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
859 PM PDT Thu Oct 7 2021
.SYNOPSIS...A weak low pushes onshore tonight into early Friday
and may generate a few light showers over southern parts of the
Bay Area and the Central Coast. Otherwise continued dry and
unseasonably cool on Friday. High pressure rebuilds this weekend
with seasonably mild and dry weather. A system dropping into the
Great Basin early next week may produce periods of gusty north
winds Monday into Tuesday that will increase fire weather
.DISCUSSION...as of 08:59 PM PDT Thursday...Current water vapor
imagery shows a positively tilted trough about 500 miles off the
coast, which is helping to transport mid and upper level moisture
over much of central and northern CA. Persistent cloud cover,
coupled with continued cooling of the boundary layer and onshore
winds helped suppress temperatures to well below seasonal norms.
All of our climate sites topped out in the 60s and 70s, marking
the first day any site failed to reach the 80 degree mark since
As the trough approaches the coast overnight, it may provide just
enough forcing to wring out some scattered light showers or
drizzle. Hi-res ensemble members do pick up on this, with any
showers ending by the mid-morning hours around our area. Not more
than a few hundredths of an inch can be expected where precip does
fall. Continued cooling throughout the boundary layer, and
increased onshore flow as the trough comes ashore, will allow for
even cooler conditions tomorrow. Most sites will remain in the 60s
tomorrow, even inland, with upper 50s possible along the coast.
This translates to temperatures 10 to 20 degrees below normal
inland, and 5 to 15 degrees below normal closer to the coast.
Despite some sunshine breaking out in the afternoon, the airmass
over us will be very chilly, as 850mb temps fall to around 3 to 5
The weekend will bring a rebound in temperatures as ridging builds
in behind the trough, providing subsidence and clearing skies.
Saturday will still be cool, but will feel more pleasant with
sunny conditions and lighter winds. Sunday, temperatures will warm
closer to normal for most of the area.
All attention turns to increasing northerly winds and rapidly
drying conditions Monday and Tuesday, as an "Inside slider" event
impacts interior parts of our CWA. Since mid-range models have
come into better agreement over the positioning of a deepening
trough over the Great Basin on Monday, a Fire Weather Watch has
been issued, beginning Monday morning, for the interior North Bay
Mountains and East Bay hills and interior valleys. Please see the
previous discussion for more details. There is still considerable
uncertainty as to the magnitude of this event, as it is still
three and a half days out, and out of the range of hi-res model
solutions. Stay tuned for updates.
.PREV DISCUSSION...as of 02:34 PM PDT Thursday...Satellite shows high
to mid level moisture continuing to stream into the area this
afternoon. Temperatures remain cooler today, and will continue
trend below normal for this evening and Friday. We will see a weak
boundary move onshore later tonight and an upper level trough,
currently off the coast, will swing onshore Friday. 12Z CAM runs
(including the HRRR and NAM Nest) show the best chances for light
rain to be along the Santa Lucias and higher terrain of San
Benito county early Friday morning. Moisture values remain light,
with PW values around 0.6 - 0.9inches. More moisture will advect
over the waters late Friday night, giving some of the coastal
North Bay areas a shot at some drizzle and light rain for early
Saturday morning. However, inland areas north of the Bay Area will
see little to no chances for precipitation in the forecast.
After the upper level trough swings onshore, it will move eastward
quickly and allow an upper level ridge to build in. Warmer
temperatures are in store for the weekend, with light winds and
Our next system is on our door step early next week. Ensembles
have been confident run to run for the last 36-48 hours with the
strength of this next upper level low. Deterministic GFS and ECM
want to move a stronger upper level trough onshore by the Pac NW
Sunday. This trough will continue to deepen as it moves southward,
over NV by Monday. As it moves over NV, the back side of the
trough will move over northern CA. Stronger northerly flow aloft
will advect a cooler airmass at the surface. Even with a cold
front passing through Monday, giving the Bay Area higher surface
pressure with that cooler air, a stronger northerly gradient will
still exist right above the surface. This will lead to the
potential for gusty north winds down the Sac Valley Monday and
lasting into Tuesday. These stronger winds are paired with little
to no recent rain in the interior parts of the North and East
bay, which could lead to fire weather concerns. This is not a
typical "Inside Slider", as the SFO/WMC gradient is only
forecasted to be ~ -5mb (which we need -13+ for a decent offshore
wind event). However, the airmass will still be quite dry. With
this said, there are still some ensemble members that want to keep
stronger north winds more focused to the east, and allow for
northwesterly winds over the CWA. This solution would have more of
an onshore component, and would allow RH values to jump back up.
We will be monitoring this event through the weekend.
Temperatures look to warm mid week next week, with calmer onshore
.AVIATION...as of 5:40 PM PDT Thursday...For the 00z TAFs. It`s
VFR though there are also patchy low clouds /MVFR/ mainly along
the coast moving inland on onshore winds. Patchy coastal drizzle
and/or light rain developing, inland there`s a slight chance of
showers late tonight and Friday morning. Conditions improving to
VFR at the terminals late Friday morning and afternoon.
Vicinity of KSFO...MVFR early this evening, VFR mid to late
evening then low clouds /MVFR/ returning Friday morning along with
light drizzle and/or light rain. Westerly wind diminishing tonight
and Friday morning, VFR with a west wind increasing to near 20 knots
Friday afternoon and early evening.
KSFO Bridge Approach...Similar to KSFO.
Monterey Bay...A mix of MVFR and VFR through the evening, MVFR
late tonight and Friday morning along with light drizzle and/or
light rain. VFR with west winds near 10 to 15 knots Friday afternoon
.MARINE...as of 07:25 PM PDT Thursday...Gusty northwest winds will
result in steep wind waves from 8 to 11 feet at 10 to 11 seconds
and hazardous conditions, particularly for smaller vessels. Light
to moderate winds are expected at the start of the weekend with a
weak boundary passing over the waters providing a slight chance
for light showers Saturday morning. The next front with strong
wind gusts will approach the coastal waters on Sunday night into
early next week.
.Tngt...SCA...Mry Bay until 9 PM
SCA...Pt Arena to Pt Reyes 0-10 nm until 9 PM
SCA...Pt Reyes to Pigeon Pt 0-10 nm until 9 PM
SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 9 PM
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm from 3 AM
SCA...Pt Reyes to Pigeon Pt 0-10 nm from 3 AM
PUBLIC FORECAST: Lorber/Dhuyvetter
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Area Forecast Discussion
National Weather Service Paducah KY
710 PM CDT Thu Oct 7 2021
Issued at 710 PM CDT Thu Oct 7 2021
Updated aviation discussion.
.SHORT TERM...(Tonight through Friday night)
Issued at 333 PM CDT Thu Oct 7 2021
Isolated to scattered showers and thunderstorms have blossomed this
afternoon as our vertically-stacked cut-off low continues to sit
near STL. Currently, the greatest precipitation coverage is located
over the Wabash Valley into northwest KY. Additional activity is
developing further to the west across southeast MO into southern IL.
At the surface, an occluded frontal boundary extends nearly parallel
to the Mississippi River into western TN. While we are not expecting
severe weather, ample SBCAPE of 1000-1500 J/kg is present over the
forecast area along with a very modest 15-25 kts of EBshear via RAP
mesoanalysis. Can`t rule out an isolated gusty thunderstorm with
small hail this afternoon, particularly in the Wabash Valley.
As we go into the evening hours, most of the precipitation will
diminish in coverage. However, maintained slgt PoPs along and north
of Interstate 64 overnight as a weak shortwave passes across
southern IL into southern IN. Most CAM guidance is depicting light
QPF in this area overnight through roughly 15z Friday. Additionally,
added a mention of patchy fog into the forecast for southeast MO in
the predawn hours. This is where skies are likeliest to be clear and
BL decoupling is most likely to occur, allowing for stable layer fog
development. Otherwise, Friday will be quiet and very warm for
October as H5 heights begin to increase from west to east. High
temperatures will reach the lower to middle 80s. We`ll also retain a
touch of humidity with dew point temperatures remaining in the lower
to middle 60s. Kept Friday night dry for now, but may need to
introduce slgt PoPs along the I-64/Wabash Valley corridor in
response to robust mid-level isentropic upglide on the nose of a H5
ridge building over the forecast area. Low temperatures Friday night
will fall into the lower 60s.
.LONG TERM...(Saturday through Thursday)
Issued at 333 PM CDT Thu Oct 7 2021
The leading edge of a vertically-stacked southwest to northeast
oriented ridge axis will moving into the WFO PAH forecast area from
Arkansas Saturday morning, with a gradually increasing pressure
gradient and a weak reflection of a surface based warm front that
will move through the area between 12z-21z on Saturday.
There may be some cloudiness during the morning, but strong warm
air advection should still overcome any cloud cover to continue to
rise near 10 degrees over normals for this time of year, topping
out in the middle 80s. These temperatures have been consistently
on the high end (between the 75th and 95th percentile) of the NBM
initialization. This upward trend has been collaborated with
surrounding NWS offices in recent days.
For Sunday, with lesser cloud cover, strong warm advection, and
only moderate dewpoint increase expected by the afternoon,
temperatures should meet or exceed highs that occurred on Sunday.
Although close, was uncertain whether max temperatures would be
close enough to reach record or exceed record highs earlier in the
For this afternoon`s package, the only site that may be in
jeopardy of approaching or exceeding a record high would be in
Evansville IN. Right now, am forecasting 89 degrees Fahrenheit.
The current record on the books is 88F, last set in 2010.
Although most of the numerical model suite initialized well across
the nation this morning, there still continues to be timing and
spatial variations on how the models are handling the movement of
shortwaves on the eastern limb of the broad trough that covers the
western half of the United States. Although model runs have
waffled on the initial start time of convection into southeast
Missouri and southwest Illinois late Sunday night/early Monday
morning, timing appears to be honing in on late Sunday night for
onset into the western sections of the WFO PAH forecast area.
The biggest challenge has been the eastward extent of the
precipitation through the WFO PAH forecast area Monday into Monday
evening as the leading shortwave on the eastern limb of the large
trough rockets northeast, with the second shortwave holding off
until the late afternoon and evening to transit across the area.
The ensembles have not been very bullish on significant QPF/POP
over the area, so have consistently kept chance PoPs in place for
Monday for the forecasts issued since Wednesday.
Forecast confidence remains quite low for the onset of
precipitation early Wednesday, but the forecast signal for rain
late Wednesday into Thursday still has been consistent and
reasonable. Kept a chance for precipitation in place early
Wednesday for collaborative purposes.
Adjusted Max/Min temperatures upward above the NBM initialization
by 1-2 degrees after Monday, similarly lowering dewpoints by a
similar amount during the same time period.
Issued at 710 PM CDT Thu Oct 7 2021
Isolated showers are possible this evening and overnight across
mainly parts of southern IL and southwestern IN. However, any
impacts to terminals should be minimal, and brief. An MVFR cig is
possible near sunrise in the vicinity of the KMVN terminal, but
otherwise cigs are forecast to remain VFR across the region. Some
late night fog may affect parts of southeastern MO where the surface
winds will be weaker, including the KCGI terminal. We will continue
with MVFR vsbys for now. Light winds overnight should go more toward
the west after daybreak, especially east of the MS River.
Utah, but as mentioned in the previous forecast discussion, a
secondary shortwave low will ride down the trough and push into our
area late Friday night, returning chances of scattered showers to
the higher elevations of the southern Great Basin Saturday morning.
Any snow that falls from these systems will remain confined to the
Sierra Nevada, and will remain above 7000 feet. Little to no impact
expected with forecast snowfall amounts.
[WIND] In addition to widespread precipitation chances, this storm
system will bring with it gusty south-southwesterly winds, with
gusts between 40 and 50 mph possible along a line north and west of
Interstate 15. For these areas, we have issued a Wind Advisory from
10am until 9pm on Friday. Due to downslope wind potential off the
Spring Mountains, Highway 95 will have a trouble spot from Las Vegas
to Indian Springs with the threat of dangerous crosswinds. Due to
downslope wind potential off the Sierra Nevada, State Route 395 will
experience dangerous cross winds as well from Olancha south to the
San Bernardino County line. Blowing dust in these areas have the
potential to drop visibilities as well.
[TEMPERATURES] Temperatures will experience a drop of about 6 to 10
degrees between today`s highs and Friday`s highs, bringing the
region to about 10 degrees below seasonal averages.
.LONG TERM...Sunday through Thursday.
Brief ridging over the region will allow temperatures to rebound
over the weekend by about 5 degrees. Unfortunately for our warm-
weather-lovers, this will be brief, as we anticipate the arrival of
an additional upper level low early next week.
Strong winds will return, with the potential for additional Wind
Advisory issuances across the region on Monday and Tuesday.
Precipitation chances return on Monday, largely in the form of snow
across the higher elevations of Lincoln County, northern Mohave
County, and the Spring/Sheep Mountains of Clark County, with a snow
level around 3500 feet. We will continue to monitor the forecast and
latest trends to determine if Winter Weather Advisories are
warranted. In addition to precipitation and wind, temperatures will
take another nose dive, effectively dropping the region to 15 to 20
degrees below seasonal normals. For many, this may result in the
first freeze of the season (not for you, Las Vegas).
Models seem to be lining up well regarding the strength and position
of this trough, but a slight shift either north or south of its
current forecast position could drastically impact rain and snow
amounts across our area. Stay tuned to the forecast as it develops.
Ridging will return, allowing temperatures to climb closer to
seasonal normals for the weekend.
.AVIATION...For McCarran...While the winds transition from
easterly to southerly there is a chance that 10-12 kt winds may
briefly hover right around 160 degrees with the potential for
wind gusts around 20 kts. After sunset winds will become more
southwesterly and remain that way through Friday evening.
Beginning around 12Z Friday there is the chance for isolated to
scattered showers with gusty southwest winds around 25 kts. These
showers should clear out during the afternoon, but the gusty winds
will persist through at least the end of the 18Z TAF period. With
the exception of clouds associated with rain showers on Friday,
BKN-OVC conditions with bases between 10 and 25 kft will persist
through Friday evening. BKN conditions with bases below 10 kft are
possible on Friday morning between 12Z and 18Z are possible as
showers move into the area.
For the rest of southern Nevada, northwest Arizona and southeast
California...The chance of isolated and scattered rain showers
between 12Z and 18Z on Friday exists for all remaining TAF sites.
Chances for showers and thunderstorms will peak in the morning and
decrease throughout the afternoon on Friday. Beginning this
afternoon through Friday evening wind direction will favor the
south/southwest with the exception of KDAG where winds will favor a
more westerly direction. Wind gusts between 15-25 kts are possible
at all TAF sites this afternoon and early tomorrow morning as storms
begin to pop up. Winds will continue to pick up during the day on
Friday with gusts between 20-30 kts possible. BKN-OVC skies will
likely persist through Friday afternoon, but these cloud bases
should remain above 10 kft. Haze from California wild fires will
impact KBIH this evening with the potential for visibility to drop
to 6SM, but this haze should clear out by Friday morning.
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
For more forecast information...see us on our webpage:
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