Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/14/21
Area Forecast Discussion
National Weather Service Denver/Boulder CO
918 PM MDT Wed Oct 13 2021
.UPDATE...
Issued at 855 PM MDT Wed Oct 13 2021
Today`s gusty winds have subsided quickly this evening, with only
localized gusts to around 30 mph remaining across portions of the
foothills and northern plains. Winds will continue to weaken
overnight, allowing for another chilly night with lows tempered
only by some mid and high level clouds. With temperatures
descending into the low to mid 30`s across the majority of our
plains, opted to issue a Frost Advisory for the remaining zones
not under a Freeze Warning (the exception is Lincoln and eastern
Elbert counties, where last nights` hard freeze precludes the need
for any products).
Otherwise, no significant changes were made to the short term
forecast. We remain on track for a quick-hitting system to bring
snow to the higher elevations Thursday, with a likely transition
to a rain/snow mix later in the evening in the vicinity of the
metro. Little to no accumulation is expected for most areas along
the urban corridor, with the highest chances for accumulation
outside of the mountains being for the Palmer Divide. Travelers
should be prepared for possible travel impacts in the mountains,
as brief heavier snow squalls may lead to a few inches of
accumulation on roadways over relatively short periods.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 330 PM MDT Wed Oct 13 2021
Strong subsidence is over our CWA this afternoon as the system
that impacted our area yesterday has moved on. The surface
pressure gradient across the northeastern plains is weakening and
wind speeds are starting to relax. Therefore, the High Wind
Warning was canceled for the northern plains this afternoon. There
is very shallow moisture and clouds to the west of the
Continental Divide with a few flurries ongoing. Little to no snow
accumulation is expected out of this through the evening.
Tonight, the subsident flow will continue although it will weaken as
a shortwave approaches from the Intermountain West. Out ahead of
this shortwave, there is some mid to upper level moisture which
may create a few snow showers across the western slope of the far
northern mountains. Less than an inch of snow is expected across
the mountain passes. The tricky part about tonight`s forecast will
be the low temperatures across the urban corridor and plains. Most
of that area will see low temperatures in the mid to low 30s. The
thinking is that upper level cloud cover and some weak winds will
keep much of the area from seeing temperatures at or below
freezing for very long. The one exception will be the Palmer
Divide as the higher elevation there helps temperatures lower a
bit more. A Freeze Warning was issued for zone 41 since some areas
weren`t below freezing for very long last night. Over by Limon,
they had a hard freeze last night so no highlights were issued.
The aforementioned shortwave trough will move over Colorado
during the afternoon on Thursday providing QG ascent. This system
will have rather cold air aloft associated with it which will lead
to strong low to mid level lapse rates up to 8.5-9 C/km
developing over the higher terrain. During the afternoon,
scattered snow showers will develop in the mountains and will
produce brief moderate snowfall rates. These showers will move
onto the plains during the late afternoon with the precipitation
falling as rain in most spots due to the relatively warm
temperatures. The one area that may see some snowflakes mixing in
at lower elevations will be the Palmer Divide since there will be
moderate precipitation rates along with temperatures falling into
the mid 30s. Otherwise, highs will be below normal with mostly
clouds skies.
A Winter Weather Advisory was considered for the central mountains
tomorrow afternoon and evening. Looking at snowfall totals
through Thursday night, the majority of zone 34 is not expected to
reach advisory criteria snow amounts except for maybe the
Loveland and A Basin ski areas. So an advisory was not issued. The
thought was that if the moderate snowfall rates develop over the
I-70 corridor tomorrow afternoon/evening, a Snow Squall Warning
may be issued to give everyone a heads up of the poor travel
conditions. If models tonight show an increase in QPF and
snowfall, an advisory may be issued.
.LONG TERM...(Thursday night through Wednesday)
Issued at 330 PM MDT Wed Oct 13 2021
The upper trough axis will be moving over Colorado Thursday
evening and widespread showers will be ongoing across the area.
Snowfall will persist across the mountains and higher foothills
with a rain-snow mix over the lower foothills, and the mix is
expected to spread to the adjacent plains early Thursday evening
behind a surge of cooler air. Limited areas of the plains may
change over all snow by late Thursday evening or early Thursday
night but most areas will remain mixed with surface temperatures a
few degrees above freezing but low wet bulb zero heights. The
surge should also provide a period of north-northeasterly upslope
flow in the evening, which will favor the Palmer Divide and parts
of for slight greater snowfall in the evening. Model consensus
remains good for a broad swath of 0.15 to 0.35 inches of QPF. The
NAM still has considerably less precipitation for the lower
elevations and it seems that other models are joining the HRRR
with something of a bullseye for QPF in eastern Adams and Arapahoe
Counties. Continue to expect total snow accumulations for the
Denver metro generally under half an inch of slush, with an inch
or two possible for most of the foothills and Palmer Divide.
Precipitation should end quickly Friday morning as the trough
moves east to the plains and synoptic scale subsidence sets in
behind it.
Expect breezy westerly to northwesterly winds, especially across
the Front Range mountains and northern and eastern plains, as the
back end of the trough moves overhead with about 100 knot jet
winds embedded. Warmer, drier and mostly clear conditions will set
in through the weekend beneath a broad ridge. By Sunday, highs
look to be back up to the 40s and 50s in the high country, 60s in
the foothills and lower 70s on the plains. Models show the next
trough coming on shore over the Pacific Northwest late Sunday and
cutting off a low as it moves over the Great Basin to the Central
Rockies by late Monday, and agreement about the timing and
placement has improved slightly. Precipitation chances are still
low but it looks like there could be a period of moderate ascent
and decent moisture late Monday through Tuesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 855 PM MDT Wed Oct 13 2021
East/southeast winds this evening will gradually become more
southerly overnight, then return to a southeast direction Thursday
morning. A weak system will bring lowering ceilings through the
afternoon, with rain showers likely beginning near 21Z. VFR
conditions will mostly prevail, save for brief vis reductions
during showers. Showers may transition to a mix of rain and snow
in the evening, and all snow late evening, however accumulations
on the tarmac appear unlikely at this time. Expect shower activity
to subside overnight, with a return to prevailing VFR conditions,
rising CIGS and typical drainage flow.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 9 AM MDT Thursday for COZ038>040-
042>045-048>051.
Freeze Warning from 2 AM to 9 AM MDT Thursday for COZ041.
&&
$$
UPDATE...Rodriguez
SHORT TERM...Danielson
LONG TERM...EJD
AVIATION...Rodriguez
Area Forecast Discussion
National Weather Service Goodland KS
952 PM MDT Wed Oct 13 2021
.UPDATE...
Issued at 437 PM MDT Wed Oct 13 2021
Added Cheyenne County Colorado to the Frost Advisory for tonight
as temperatures could drop to around 32 degrees resulting in frost
formation with the best chances in low lying areas within the
county.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 132 PM MDT Wed Oct 13 2021
500mb RAP analysis and satellite showed west-southwest flow over the
area today as a low pulled north of the region into the Northern
Plains. Gusty northwest winds were observed on the backside of the
departing system this morning into the afternoon, particularly north
of Interstate 70 where gusts of 30 to 45 mph occurred. At 1 PM MT,
skies were clear across the region with temperatures in the upper
50s to low 60s.
For Wednesday night, winds decline by the evening hours as the
Northern Plains system enters into Canada. Temperatures are forecast
to fall into the 30s across the region under clear skies. A Frost
Advisory remains in effect for areas along and north of Interstate
70 where lows in the 30-36 degree range are anticipated and winds
will be light. Winds are still looking to stay slightly higher in
the south which is generally located with warmer conditions. Current
advisory looks good and do not plan to make any edits at this time.
On Thursday, highs will be in the 50s/low 60s. Southwest flow
continues aloft as an upper trough progresses over the Rockies. This
disturbance generates cloud cover (coming in from the west) by the
afternoon hours, followed by the potential for some rain showers
entering eastern Colorado in the late afternoon/early evening.
Precipitation chances shift from eastern Colorado southeast along
and south of I-70 through the night. Temperatures fall near to below
freezing along and west of the Colorado border, where some light
snow will be possible. Little to no accumulation is expected.
.LONG TERM...(Friday through Wednesday) Issued at 247 PM MDT Wed
Oct 13 2021
To begin the extended period, an upper trough that is currently
digging SE across the Pacific Northwest will move across the Great
Plains Friday morning. With the current track of the trough, a
collision of moisture from the Gulf and the Pacific NW could occur
over the Tri-State area Friday morning. The trough will be shoved
east during the afternoon as a ridge begins to move over the High
Plains. Skies over the region will clear as high pressure moves in,
beginning a dry trend for majority of the period. NW flow over the
regions, temperatures are expected to remain cool with high
temperatures in the 50s across the Tri-State area. Winds could be a
little breezy, mainly west of Hwy 27, during the morning to early
afternoon hours with gusts up to 35 mph currently forecast.
Overnight lows are expected to fall into the mid 20s to lower 30s.
Friday night there is potential for areas and widespread frost
mainly east of Hwy 25 and the SE corner of Cheyenne County, CO.
Given clear conditions much of the day and light winds during the
evening/overnight, the frost potential could expand across the area
more.
Over the weekend, the ridge will continue to move east, with the
ridge axis passing over the forecast area Sunday evening. The area
is expected to warm over the weekend with highs in the mid to upper
60s Saturday and the low to mid 70s on Sunday. Elevated fire weather
is possible Sunday afternoon for areas west of Hwy 385 in Colorado
where RH values are currently forecast to drop into the upper teens
with peak wind gusts of 20-25 mph. Despite the increase in high
temperatures, the overnight hours could remain chilly with lows in
the 30s Saturday night and the mid 30s to lower 40s Sunday night.
There is also potential for frost both nights. There is some
uncertainty on frost development Sunday night as clouds begin to
move into the area.
Beginning on Monday, our next low pressure system will begin to move
across the Intermountain West. Monday is expected to remain quite
with temperatures in the mid 70s for highs and the mid 30s to lower
40s overnight. As mentioned in the previous discussion, Tuesday into
Wednesday morning is when the low is currently forecast to impact
the High Plains; however, there remains uncertainty on the
track/timing of the low. The 12Z run of the GFS has the upper low
moving over the CWA while the ECMWF has the core of the low moving
along the SD/NE border and is slightly quicker than the GFS. That
said, the GFS is more favorable at the moment for any portion of
the area to see precipitation. For now, the forecast is remaining
dry while we watch the upcoming system more closely. High
temperatures on Tuesday and Wednesday are forecast to be in the
60s with overnight lows in the 30s with a few locales east of
US-83 approaching 40.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 951 PM MDT Wed Oct 13 2021
The 06Z TAF period will see VFR conditions for the entire period.
LLWS is currently occurring from the NNE ranging from 30-35 knots
at KGLD. Guidance is having a hard time picking up on it
currently so will be introducing a couple hour period of low
confidence LLWS into the TAFS for this period. Light winds below
10kts are expected throughout the overnight period at both sites.
Clouds begin to increase from west to east around sunrise as the
region`s next disturbance begins to enter the area. Winds will
slightly pick up between 10-15 knots, an isolated gust near 20
knots can`t be ruled out during the afternoon especially at KGLD.
A chance of rain and snow showers is possible along and west of
Highway 27 starting late Thursday afternoon and running through
the end of the TAF period, it is currently unknown how far west
this area of precipitation will reach, have opted to leave this
out of the KGLD TAF for now; KMCK is expected to remain dry.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Frost Advisory until 9 AM MDT /10 AM CDT/ Thursday for
KSZ001>004-013>016.
CO...Frost Advisory until 9 AM MDT Thursday for COZ090>092.
NE...Frost Advisory until 9 AM MDT /10 AM CDT/ Thursday for
NEZ079>081.
&&
$$
UPDATE...TT
SHORT TERM...JBH
LONG TERM...KMK
AVIATION...TT
Area Forecast Discussion
National Weather Service Indianapolis IN
1144 PM EDT Wed Oct 13 2021
...Updated Aviation Discussion...
.Forecast Update...
Issued at 1000 PM EDT Wed Oct 13 2021
Surface analysis late this evening shows high pressure in place
across the Carolinas and deep low pressure over North Dakota. This
was resulting in a moderate southerly flow in place across
Indiana...which is caught between these two systems. Water vapor
imagery shows a plume of tropical moisture stretching across Mexico
and Texas before spilling into the mid Mississippi and Ohio River
valleys. Regional radar returns show precip underneath this plume
stretching from TX to Central MO. Furthermore...GOES16 shows clouds
continuing to advect toward Indiana from the southwest within the
plume. Dew points across the area were moist...within the mid and
upper 60s.
Given the SW flow in place...will trend toward continued increasing
cloudiness overnight as we remain within the warm sector ahead of
the low to the NW. Pressure gradient in place across Indiana should
lead to some mixing overnight. This along with the increase in cloud
cover should result in temperatures failing to fall very much. HRRR
shows showers from the moisture plume arriving in NW Central Indiana
late overnight. Given the nearest echos are in MO...have limited
this chance to slight mainly in the NW. Better chances look to
arrive on Thursday.
&&
.Short Term...(This evening through Thursday night)
Issued at 239 PM EDT Wed Oct 13 2021
Rest of Today and Tonight...
A broad upper level trough to the west
initiating a multitude of waves across the Plains and Midwest, and
will continue to do so over the next several days. Currently a deep,
vertically stacked low is over SD, attached to a 100kt SW jet
streak. The low over the Plains is heavily occluded with some new
surface cyclogenesis occurring near a WAA maximum and boundary triple
point in N MO. This will reinforce a frontalgenetical zone, creating
a weak warm front, currently over SW portions of the state. As this
front moves to the NE, within the mean low level flow, isolated to
scattered showers will be possible. Chances for showers this
afternoon will be greatest in West/South central Indiana. A few
embedded thunderstorms are possible given some elevated instability,
around 500-750 J/kg MUCAPE, but will be unlikely. A dry period is
likely overnight as the warm front is well north of the region, with
the developing surface low to the west.
Temperatures this afternoon will remain in the mid 70s for most of
central Indiana, with some depression of temps possible within any
showers. Behind the warm front temperatures are closer to 80, but
timing of passage is likely to be too late to reach these values.
Overnight, temperatures will be seasonally high with lows in the
upper 60s. This is due to continued SW WAA behind the front and
extensive upper level clouds.
Tomorrow and Tomorrow Night...
The triple point low will move NE into C IL by tomorrow morning.
Along the low will be a stronger thermal gradient as the upper level
low catches up, providing cooler upper level air. Still, the CAA
behind this gradient is weak, limiting frontogenesis, and eastward
propagation. Along this zone and near the relatively low pressure,
showers will be likely. With PWAT values above seasonal averages,
expect moderate rainfall rates within showers. Expectations are for
this zone to eventually reach NW portions of the region late
tomorrow afternoon into the early evening hours, slowly moving to
the east. This system looks to become more organized Thursday night
as a region of diffluence develops above the surface low, aiding in
cyclogenesis. This will also help push showers through central
Indiana, with all of central Indiana expected to see measurable
precip overnight Thursday. With morning lows in the upper 60s, it
wont take much for temperatures to get near 80 tomorrow afternoon.
NW portions of central Indiana will stay a little cooler with more
extensive cloud cover and approaching showers from the west during
peak diurnal warming.
&&
.Long Term...(Friday through Wednesday)
Issued at 239 PM EDT Wed Oct 13 2021
All the ingredients to the potential for widespread moderate to
heavy rain and isolated severe thunderstorms on Friday as a cold
front slides southeast across central Indiana Friday and Friday
evening courtesy of an approaching sharp upper trough and surface
high pressure over the Rockies and High Plains.
Modest to moderate low level 35 knot jet pointing in from western
Kentucky will bring in precipitable water amounts to the 99th
percentile for this time of year. This will combine with strong deep
layer shear of over 50 knots and low level shear near 50 knots to
support the potential of isolated damaging winds despite only weak
instability. 115 plus knot upper level jet streak lifting northeast
around the base of the trough over northwestern Indiana or
northeastern Illinois late Friday supports moderate to heavy rain.
Thus, 90 plus percent PoPs look good for Friday with rain moving
east into Ohio overnight Friday night and Saturday morning. Look for
rainfall of half an inch to over an inch over most or all locations
Friday and Friday night.
Model soundings and time sections along with the upper trough moving
out support clearing skies from southwest to northeast on Saturday.
Gusty northwest winds/cold advection will result in a chilly
Saturday despite the sunshine. Look for afternoon highs 5 to 10
degrees below normal with highs in the upper 50s to lower 60s and
overnight lows Saturday night in the lower 40s.
An upper ridge will move overhead as surface high pressure moves
into the Ohio Valley early next week. This will provide subsidence
and combined with bone dry atmosphere will result in little cloud
cover and recovering temperatures. Temperatures should return to
slightly above normal by Monday with highs in the upper 60s and
lower 70s.
&&
.Aviation...(06Z TAF Issuance)
Issued at 1144 PM EDT Wed Oct 13 2021
IMPACTS:
- VFR Conditions are expected for the next 18-20 hours.
- MVFR Cigs are possible aft 150300Z.
DISCUSSION:
VFR conditions are expected to continue for much of this taf period.
VFR Clouds will be persistent this taf period. This will be due to a
tropical plume of moisture as seen on water vapor imagery which is
streaming across TX to the Ohio Valley. This will result in mid and
high level cloud ceilings tonight and Thursday.
Embedded waves within the plume aloft are expected to push across
Indiana...generating showers and perhaps a thunderstorms on Thursday
afternoon. Best forcing within the plume look is suggested to arrive
after 150300Z and later. Confidence for specific timing on these
features is low...thus have used a window of VCSH for the moment.
Also instability at this time appears limited and although a rumble
of thunder is possible...confidence is not high enough to be worthy
of a VCTS mention. Any shower that strikes a TAF site might produce
brief MVFR Cigs and visibilities.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...Puma
Short Term...Updike
Long Term...MK
Aviation...JP
Area Forecast Discussion
National Weather Service Northern Indiana
728 PM EDT Wed Oct 13 2021
.SYNOPSIS...
Issued at 335 PM EDT Wed Oct 13 2021
A few rounds of showers and thunderstorms will be possible both
late this afternoon and again overnight mainly across northwestern
and western parts of Indiana into far southwestern Lower Michigan.
Much better chances for showers and storms arrive Thursday
afternoon, lingering into Friday evening.
&&
.SHORT TERM...(This Evening through Thursday)
Issued at 328 PM EDT Wed Oct 13 2021
Initial focus lies with warm front pushing NE across central IL
with a narrow band of showers and thunderstorms immediately ahead
of it. Latest radar returns also shows some lighter showers trying
to develop out a bit ahead of the main front on the nose of
slightly increased theta-e influx. Models have been fairly
consistent on any convection maybe edging into far SW/W areas over
the next several hours, but also encountering quite a bit of dry
air that quite likely will result in their demise. HRRR has been
capturing overall setup nicely so will follow it`s lead and
maintain slgt chc to at most a very low chc pops in the W/SW
areas through 00Z.
After 00Z focus will shift to a quasistationary boundary from SE
OK NE into far W IL and its very slow creep east into Thursday as
a series of weak disturbances move along with with at least a
chance for showers and thunderstorms. Increasing LLJ tonight
likely to allow an uptick overnight, but have some concerns
exactly where that will setup. Best chances will reside across far
NW areas (maybe reaching to the South Bend area towards morning)
and then a brief lull into Thurs AM before renewed development in
the afternoon. Only real changes at this point was to tighten pop
gradient in the east where it will take a while for any precip to
make it (quite possibly into mid to late Thursday afternoon).
These "drier" areas will have a much better chance of seeing a few
peeks of sunshine and temps climbing towards or above 80 with
areas in the NW in the 70s due to clouds and rain.
&&
.LONG TERM...(Thursday Night through Wednesday)
Issued at 328 PM EDT Wed Oct 13 2021
Best rain chances still focused on Thursday night into Friday
evening as frontal boundary stalls over the area with loss of any
real eastward push until later Friday into Friday night as the
main longwave trough across the Plains edges east. High PWATs
(over 1.5") will remain in place across the area with periods of
showers and embedded storms expected to expand Thurs night and
persist through much of Friday. Severe threat (marginal) will
exist during the afternoon and evening hours across the SE half of
the area as sfc low tracks from SW to NE across the center of the
area. Bulk shear on the order of 50 to possibly as high as 70 kts
will be in place with curved hodographs. However, extensive
cloud cover and precip will likely hinder increase in instability
and higher chances for severe storms. Something to monitor as we
draw closer.
Finally the front will edge across the area Friday night, ending
the precip but also ushering in much cooler air for the weekend,
especially Sat with highs struggling to reach 60 and lows Sat
night dipping into the 40s. For those not ready to see those cool
temps (especially at night), fear not as some moderation back to
normal or above normal temps will occur into early next week with
high pressure taking hold.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 726 PM EDT Wed Oct 13 2021
A few showers and storms rolled through SBN during the evening
hours, but the next chance for showers will wait until later
tonight as the cold front approaches from the west. This will
lower CIGs into MVFR and could briefly lower VISBY as well, as
heavy rain moves through. Chances for showers will continue
through the day at SBN as waves of vorticity move through. Showers
are expected to reach FWA during the morning into the midday time
frame and continue during the afternoon. A thunderstorm may be
possible at both sites as long as cloud cover hasn`t cut off
diurnal heating by then.
Will also continue mention of MVFR stratus at SBN Thursday morning
with winds staying elevated enough to preclude any mention of fog
this time. Have inserted a short period of LLWS in SBN during the
early morning hours THU, but could easily see enough mixing to have
the next forecaster remove it.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...Fisher
SHORT TERM...Fisher
LONG TERM...Fisher
AVIATION...Roller
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Area Forecast Discussion
National Weather Service North Platte NE
625 PM CDT Wed Oct 13 2021
.SHORT TERM...(This evening through Thursday night)
Issued at 332 PM CDT Wed Oct 13 2021
The High Wind Warning in effect across much of wrn Nebraska will
continue in effect until 6 pm CDT. The RAP model shows the belt of
60kt 700mb winds lifting north and east through the Sandhills this
afternoon. The Real-Time Meso Analysis product suggests this process
is underway. The strong wind gusts to 60 mph have yet to reach
highway 20 across nrn Nebraska but sustained winds at Thedford and a
NEDOR site near Brownlee and Gordon were sustained near 40 mph. The
KVTN ASOS gusted to 54 mph at 130 pm this afternoon.
In the wake of the powerful fall cyclone moving through the
nrn High Plains this afternoon, Pacific high pressure will build
into the central Rockies and strengthen to 1030-35 mb by Friday
morning. This should set the stage for widespread freezing
temperatures across wrn and ncntl Nebraska Thursday and Friday
mornings.
The min temperature forecast both mornings uses the guidance blend
plus the bias corrected short term model blend. This forecast is
cooler than the previous forecast but still modest and near the 50th
percentile of the national model blend. A weak upper level
disturbance across the nrn Rockies this afternoon could spread mid
and high clouds through parts of wrn Nebraska Thursday morning. This
could disrupt the radiative cooling process and prevent cooler lows
than forecast. There is also the potential for sfc winds to remain
partially coupled with the boundary layer winds which would weaken
the sfc inversion. So the forecast uses a middle of the road
approach.
.LONG TERM...(Friday through Wednesday)
Issued at 332 PM CDT Wed Oct 13 2021
The 1035mb sfc high pressure predicted to build across the cntl
Rockies will drift south and east through the Midsouth and be
located across the southeast U.S. by next Monday. Ridging from the
high will extend west through the south Texas coast blocking
return moisture to wrn and ncntl Nebraska. 850-300mb RH falls to
30 percent Saturday morning and remains 40 percent or less through
Tuesday. This should produce a period of generally clear skies
through at least Sunday.
At the same time an upper level ridge will build off the West Coast
and migrate east into the cntl Plains. Another long wave trof will
move ashore in the Pacific Northwest and this should send a surge of
warm air across the Rockies in Nebraska. The models are in good
agreement warming temperatures at the h850mb level from 5C Saturday
to 15C or warmer Monday. Highs in the 70s are in place Sunday and
Monday. Thereafter, the models are in good agreement dropping a cold
front into Nebraska. WPC suggested a chance of showers Monday night
with the cold front leading to rain totals of less than 1/4 inch.
This is a result of the sfc high pressure across the south delaying
return moisture to the central Plains. The official forecast
maintains dry weather through Tuesday. Later forecasts may add a
chance of showers with the cold front Monday night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 621 PM CDT Wed Oct 13 2021
VFR conditions expected to prevail through tomorrow evening. Winds
will gradually weaken late this evening as the storm system pulls
away to the northeast. Winds aloft remain elevated overnight
across southwest Nebraska, and will lead to a period of
northwesterly LLWS before weakening around 14/06Z. Mid-lvl clouds
stream into southwest Nebraska tomorrow afternoon, though CIGs
remain VFR.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 1 AM CDT /midnight MDT/ to 10 AM CDT /9 AM
MDT/ Thursday for NEZ004>006-008-009-022>027-035>038-056>059-
069>071-094.
Frost Advisory from 1 AM to 10 AM CDT Thursday for NEZ007-010-
028-029.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Brown
Area Forecast Discussion
National Weather Service New Orleans LA
929 PM CDT Wed Oct 13 2021
.EVENING UPDATE...Only a slight adjustment in POP values over the
eastern waters this evening to better reflect where a weak band of
showers has formed. Otherwise, no major changes to the ongoing
forecast package this evening.
Later tonight, conditions remain favorable for a fairly
widespread radiation fog event to form over portions of Southwest
Mississippi and the Northshore parishes of Southeast Louisiana due
to a combination of high relative humidity and lighter boundary
layer flow. Closer to the coast, conditions are expected to be
less favorable as the boundary layer remains fairly well mixed due
to stronger boundary layer flow. At most, some low clouds may
form around daybreak tomorrow in coastal areas. PG
&&
.PREV DISCUSSION... /issued 636 PM CDT Wed Oct 13 2021/
AVIATION (00Z TAF DISCUSSION)...Conditions look very favorable
for a decent radiation fog and low stratus event to occur at
several of the terminals later tonight into early tomorrow
morning. The combination of high relative humidity and light
boundary layer flow will support the development of widespread
dense fog from around 09z through 15z before beginning to clear.
IFR and lower conditions will be most prevalent at KMCB, KHDC,
KASD, and KBTR. At KHUM, boundary layer flow will be slightly
stronger, and this will support MVFR visibilities and IFR ceilings
of 500 to 1000 feet. Increased thermal mixing of the boundary
layer will lead to rapidly improving conditions after 15z, and all
of the terminals should be back into VFR status by 17z. PG
PREV DISCUSSION... /issued 359 PM CDT Wed Oct 13 2021/
SHORT TERM (This evening through Saturday)...
Another pleasant, yet warm day in the books again today. Glancing
at GOES-16 Ch.2 VIS Satellite shows plenty of low-level cumulus
scattered all around the CWA, oriented directly parallel to the
surface to low-level flow and enhanced along streets near moisture
sources. Quick look at the latest HRRR sounding for this
afternoon/evening shows what we have been seeing for days now,
with a well-mixed PBL after surface heating, with a slither of
moisture right at and above the LCL (~900mb) to the base of a
strong subsidence inversion (~830mb) which has allowed for a small
bubble of positive CAPE to help pop up these clouds, but limited
in vertical growth due to the strength of the inversion aloft.
This has kept all areas dry today, but very warm. Otherwise, some
thin upper-level cirrus continues to advect in along progressive
SW to NE flow in association with what is now Tropical Storm
Pamela over north-central Mexico but overall, a nice end to
another nice day.
Worthy to note trends on VIS satellite shows a convergent
boundary axis riding moist southeasterly flow over marine areas
well south of Mobile. Satellite trends show individual updrafts
struggling as this same inversion remains anchored in place,
however... would not be surprised an isolated shower or two pops
up in this region purely by subtle surface to low-level forcing
and moist environmental conditions in place, rotating northwest
across far SE LA / southern MS coast later this evening/early
tonight. The HRRR picks up on some of this, with NBM PoP`s still
coming in too low to mention directly in the forecast (5-10%
range). It`ll be interesting to see if some of this develops
later.
Otherwise, it`ll be quiet going into tonight, but focus turns
back to the potential for more patchy fog again tomorrow morning.
Guidance continues to hint strongly at some of the same areas,
with focus on typical foggy spots from southwestern MS, south into
the Atchafalaya Basin. Will have to monitor the amount of upper-
level clouds that could inhibit maximized radiative cooling
processes, but with NBM/SREF probabilities hinting at generally
the same areas yet again, will ride with patchy fog and refrain
from the mention of any dense fog ATTM, although some spotty areas
can not be ruled out. Will keep an eye on things.
Thursday we really begin to see a bit more of a deepening, moist
return flow pick up in the surface to low-levels, as indicated by
a steady transition in clockwise curving hodographs, just still
relatively weak in magnitude. This is when we begin to see a
response in the vertical as gradual deep-moist ascent weakens and
ascends the inversion that has helped by keeping us dry the past
several days. This in turn reveals much more moisture/instability
in the PBL to low-levels upwards to around 700mb, and with another
day of ample surface warming, we may have more room for updrafts
to grow enough to precipitate down as spotty showers. The NBM has
been persistent on keeping a lower mention of PoP`s going along
the I-10/12 corridor, which has looked good for days now. But with
the inversion still holding in tight in the 700mb layer and
above, updrafts will still struggle to produce enough noticeable
risk of lightning and thus, have removed mention of lightning
keeping these as shallow showers. Again, not entirely confident on
widespread showers, but a quick brief shower or two cannot be
ruled out tomorrow with overall light QPF in the forecast.
Same deal going into Thursday night/Friday morning with patchy
fog possible yet again across the same areas, perhaps a bit more
east to the MS coast this time around. But closing out the week on
Friday, focus shifts to the west at a cold front, eventually
picking up its pace in response to energy wrapping around deeper
western US troughing and amplifying, pressing northeast which
carries what is left of Pamela up to the Midwest/Great Lakes.
Friday will start out just like every day this week has with a
quick warming trend revealing partly cloudy skies and dry though
the morning. Meanwhile, scattered showers and a few t-storms spark
out ahead of the front from the TX coast, northeast through
central LA up across north-central MS. By this time, the pre-
frontal environment over the area steadily transitions into quasi-
zonal west to east flow from the lower troposphere, aloft all the
way to the tropopause, with some low-level curvature in the lowest
0-1km layer but very, very weak in magnitude. The thermal profile
never modifies, cools or dries in this westerly flow keeping
lapse rates extremely unimpressive aloft, with H5 temperatures
ranging around only -5 to -6C. Typically in such straight flow and
lack of environmental, large-scale dynamic ascent, showers/storms
become confined directly to the region of greatest low-level
convergence, that being right near or along the front. This should
produce a thin, broken line of showers and a few storms over
central LA Friday afternoon, racing east through the evening and
overnight hours. Can`t rule out some shallow showers out ahead
early on as instability builds, but overall rain amounts will be
lacking as this line passes through. Would not be surprised to see
a few folks stay completely dry missing rain all together. So
overall, no severe weather risk, and thunder chances will be best
for far western areas, dissipating towards the east as we lose
daytime instability.
Temperatures fall quickly behind the front, and the winds pick up
from the northwest overnight. We dry out and stay cool/mild all
day Saturday as CAA builds in quickly, deepening in height. A
comfortable, northerly breeze all day on Saturday with mostly
sunny skies (some patchy upper-level cirrus), a real taste of
fall. Enjoy!
LONG TERM (Saturday Night through Tuesday)...
Next focus this upcoming weekend will be on just how chilly we
get both Sunday and Monday mornings. Starting with Sunday,
guidance is not entirely comfortable on the idea of relaxing
gradient winds overnight, with CAA continuing through the morning
hours on Sunday as the surface high remains to our northwest.
Another feature to monitor, even though we are now well behind the
front, and ridging builds in from the western US into the central
Plains, the GFS hints at some subtle shortwave impulse riding
northeast across northern Mexico spreading upper-level clouds our
way during the day on Saturday and into Saturday night/Sunday
morning. The ECMWF is not picking up much on the strength of this
impulse, and is later with its motion towards our area but
regardless, this would have to be monitored if this cloud cover
could offset radiational cooling enough to prevent us to reach the
lower bias numbers we have been advertising for days now. A bit
of a tricky one.
Sunday will come in looking beautiful once again, but with a
layer of upper-level cirrus in place. Otherwise, with the high
finally settled in, afternoon winds will be lighter with all
around comfortable temperatures expected. Same challenges will
exist going into Sunday night/Monday morning with even thicker
upper-level clouds pulling in. Even though surface winds relax
enough to support maximized radiational cooling, once again the
degree/thickness of cloud cover may offset this process keeping us
not as chilly as anticipated. Noticed the NBM notch temperatures
up a few degrees which made it hard to take lows to the values
previously thought before, so will briefly ride on this trend
keeping temperatures not entirely as chilly Monday morning. Should
this trend continue, more modifications might be required, but
for now, a bit of a tricky item to watch.
Monday, this impulse passes with upper-level clouds thinning out,
and mid-level altocumulus hanging tight behind leading to a
partly to mostly cloudy day. But good news is clouds will thin out
going through the overnight hours with nice weather overall
beyond into Tuesday. Eventually, this surface high pulls east
enough to allow for a steady moistening/warming trend going into
mid-week, but for now, not seeing any significant impacts in the
long-range.
AVIATION (18Z DISCUSSION)...
Expect mainly VFR conditions for all area terminals this
afternoon/evening and into tonight. Latest satellite trends show
patchy low-level cumulus streets generally in the 3-4kft range,
with occasionally breezy surface winds at 08 to 10 knots meaning
little, if any impacts are expected through the next 12 hours.
Guidance continues to confidently illustrate the potential for low
CIG`s/patchy surface fog again tonight, mainly around KBTR to
KHDC and KMCB after 08Z through 13Z Wednesday morning, mainly
confined to fog-prone areas. Mentioning prevailing lower categories
in these terminals, but will fine tune better details as the
evening progresses. Expect improving conditions for all terminals
beyond this time frame Wednesday morning. KLG
MARINE...
Weak onshore flow will persist for the rest of the week, leading
to light overall weaves/seas. A cold front passes through coastal
waters late Friday night and early Saturday, bringing strong
northerly winds spreading across marine areas. At this time,
strong boundary layer winds producing gusty surface winds will
possibly lead to Small Craft Advisory headlines for a brief point
on Saturday. Some potential for a confused sea state during the
day on Saturday as wave/seas pick up to 2 to 4ft for protected
waters, to 4 to 7ft for outer Gulf waters. Otherwise, winds
diminish going into Sunday and early next week with wave/seas
diminishing through the middle of next week. KLG
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 67 88 69 87 / 0 10 0 50
BTR 68 88 70 87 / 10 20 10 50
ASD 67 88 69 89 / 10 20 10 40
MSY 73 89 73 89 / 10 20 10 40
GPT 69 86 70 86 / 10 10 10 30
PQL 67 87 68 87 / 0 10 10 20
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
645 PM EDT Wed Oct 13 2021
.SHORT TERM...(This evening through Thursday)
Issued at 429 PM EDT WED OCT 13 2021
Water vapor imagery and RAP analysis show troffing over the western
U.S. with a potent shortwave lifting across SD. At the sfc,
associated 989mb low pres is located over n central SD with
occluding front arcing se across sw MN and IA then southward from
there. Solid shield of shra/tsra in advance of the front early today
has largely dissipated while approaching Upper MI. More shra/tsra
are developing in northern and eastern MN. Closer to home, it`s been
generally a cloudy day across the fcst area. Due to the clouds,
temps have not risen much from this morning`s lows. Current readings
are generally in the low/mid 60s F.
As the low over the Dakotas continues lifting nne tonight, occluding
front will pivot ne across the fcst area. Best deep layer forcing
will pass by to the w and nw of Upper MI. In addition, despite
rather strong low-level wind fields (850mb winds up to around 45kt),
isentropic ascent is rather weak and not strongly focused due to the
weak thermal gradient across the Upper Great Lakes. As a result,
pcpn coverage tonight should be no more than isold to sct in
association with the fropa. Many locations shouldn`t see any pcpn at
all. Above the stable low-levels, there is sufficient instability
(MUCAPE of 200-500j/kg in the 1-3km layer) to maintain a mention of
tsra. SE sfc winds will increase this evening, but low-level
stability will keep winds in check. One supporting factor for the
wind increase will be the pres falls of 5-6mb/3hr currently across
northern MN. Although the pres falls will be weakening while lifting
n, they will aid some wind increase. Expect gusts to 20-30mph for a
time at most locations. Gusts could be locally higher in the
downslope areas of the Keweenaw.
Mid-level drying will surge into the area after fropa, setting the
stage for a mostly sunny day on Thu. SW winds will keep any moisture
off Lake Superior from aiding stratocu development across the fcst
area. Some lower level moisture will rotate into the western fcst
area on the se side of the system lifting n and ne vcnty of the
Manitoba/Ontario border, so expect some stratocu development far w
during the day. 850mb temps will range from 3C w to 12C e to start
the day. By late aftn, little change will occur w while temps fall
slightly to about 10C e. This should support highs around 60F w to
the upper 60s F. Temps could reach 70F or so e, but sw winds up Lake
MI should temper warming a bit from what it could be.
.LONG TERM...(Thursday night through Wednesday)
Issued at 345 PM EDT WED OCT 13 2021
The streak of unseasonably warm weather transitions to near normal
temperatures Friday through this weekend. This cooler air mass seems
likely to produce lake effect rain across the eastern CWA
Saturday into Sunday. Drier air moves in later Sunday associated
with a building ridge that brings a return of above normal
temperatures early next week. The next trough approaches the area
late Tuesday into Wednesday, but sensible weather impacts are
unclear at this time.
A seasonably strong surface low will be positioned to our northwest
Thursday night as a secondary surface low develops over the Southern
Plains. This surface low rapidly lifts northeast toward Detroit on
Friday, but should track far enough south to avoid precipitation
with this system. A much cooler air mass with 850 mb temps around 0C
flows in behind this system on Friday night. Record warm lake
average temperatures around 15C result in inversion heights up to
around 700 mb. This is more than adequate for lake effect rain
showers for areas favored in WNW flow, especially across the east.
Drier air moving in on Sunday effectively ends lake effect precip
as the surface ridge axis moves overhead.
This ridge axis shifts east Monday into Tuesday providing a couple
days of nice and sunny weather. The next trough and associated
surface low approaches from the west late on Tuesday. A quick peak
at day seven WPC cluster analysis shows ensemble guidance is almost
evenly split. The variety of possible solutions ranges from a closed
low directly overhead to a subtle shortwave embedded within an
expansive ridge. Based on the past year of weather it seems wise to
favor the warmer/drier solutions, but maybe this system will be the
straw that broke the camel`s back? Only time will tell.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 644 PM EDT WED OCT 13 2021
Changeable conditions are expected this fcst period. There may be a
few shra, perhaps tsra, ahead of the front, but confidence in any of
the terminals being impacted is low. Winds will also become gusty to
20-30kt this evening with gustiness continuing into Thu in general.
At IWD and CMX, VFR remain for most of the forecast period. At SAW,
MVFR cigs should prevail thru this evening before improving to VFR
by daybreak.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 429 PM EDT WED OCT 13 2021
As strong low pres lifts nne through the Dakotas into southern
Manitoba tonight, e to se winds will increase. Expect winds up to
30kt. A few gale force gusts to 35kt are possible w this evening and
e during the early part of the overnight period. Front associated
with the low will sweep across Lake Superior late tonight and Thu
morning, bringing a wind shift to the sw. These sw winds up the w
half of Lake Superior should continue to gust up to 30kt thru Thu. A
few gale force gusts to 35kt will be possible. To the e, winds will
diminish some with gusts lowering to around 20kt on Thu. W to sw
winds will gust to 20-25kt Fri, strongest again w half. As a more
seasonal air mass arrives over the lake this weekend, w to nw winds
should frequently gust to 25-30kt. Could be a few gale force gusts
to 35kt Sat night.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...EK
AVIATION...07
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Tulsa OK
937 PM CDT Wed Oct 13 2021
.DISCUSSION...
Third round of convection of the day is underway across far eastern
Oklahoma and northwestern Arkansas. Weak instability persists across
southeastern Oklahoma and west central Arkansas this evening. Fairly
strong wind fields exist across the region, with wind fields from the
surface through 500 mb gradually veering and strengthening with
height, resulting in strong deep-layer, as well as low-level, wind
shear. A couple spots along the ongoing convective line have shown
some rotation, and will continue to monitor the leading edge of the
line should stronger circulations develop, similar to previous storm
that moved across Sebastian and Franklin Counties. Indeed, latest
HRRR continues to show weak updraft helicity swaths overnight across
eastern Oklahoma and northwestern Arkansas.
Latest data suggest precipitable water values have already increased
to 2" along and ahead of ongoing convective line. Convection has
been very efficient in producing heavy rainfall rates this evening,
and some training has resulted in some heavy amounts, especially
across northern Pushmataha, Latimer, Le Flore, into Sebastian
Counties where 2-4" amounts have occurred since late afternoon. So
far, we`ve been able to address heavy rain with Flood Advisories,
but more rain across some of the aforementioned areas overnight will
likely start causing flash flooding. Flash Flood Watch will continue
as is at this time.
&&
.PREV DISCUSSION... /Issued 640 PM CDT Wed Oct 13 2021/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Showers and thunder will affect most of southeast Oklahoma and
western Arkansas sites through the night. MVFR cigs and vsbys will
be common in these areas, with some IFR conditions possible in
heavier thunderstorms. CIGS should lower to MVFR areawide later
tonight as tropical moisture continues to feed in to the area,
while showers and thunderstorms will also begin to spread north
some throughout the night. NE Oklahoma sites could see some shower
activity later tonight, but confidence in how far north precip
spreads is not high at this moment. Additional thunderstorm
development will be possible tomorrow afternoon with some heating
and deep moisture still in place. MVFR conditions should last into
tomorrow afternoon at least for most sites and some may stay MVFR
through the rest of the period.
Bowlan
PREV DISCUSSION... /Issued 221 PM CDT Wed Oct 13 2021/
DISCUSSION...
Showers and storms continue to push off to the east, mainly
impacting southeast Oklahoma and northwest Arkansas this
afternoon. This area will remain the focus for additional rounds
of rainfall tonight and into tomorrow as deep moisture from the
remnants of Pamela advect into the area under southwesterly flow
aloft. Within a corridor of PWATs of 2 inches or better, a
somewhat narrow axis of heavy rainfall is expected across SE OK
and NW AR tonight into Thursday where amounts of 2-4 inches. The
Flash Flood Watch has been expanded north and east and now
includes all NW AR counties, and is effective from 7 pm this
evening through 7 pm Thursday. A lull in rain coverage is possible
tomorrow evening ahead of the fall cold front that will move
through Friday. Will carry higher PoPs after 06z Friday when after
that time the front will be nearing NE OK. Boundary pushes
through the rest of the forecast area Friday, with rain chances
ending from west to east. Temperatures more typical of fall will
ensue as much cooler and drier air infiltrate the region. Settled
conditions will continue through the weekend and into next week.
Sans a few minor adjustments in early period temps, stayed close
to the NBM temperatures for this forecast cycle.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Flash Flood Watch through Thursday evening for OKZ049-053-069-
072>076.
AR...Flash Flood Watch through Thursday evening for ARZ001-002-010-
011-019-020-029.
&&
$$
SHORT TERM...69
LONG TERM....23
AVIATION....04