Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/26/20
Area Forecast Discussion
National Weather Service La Crosse WI
625 PM CDT Sun Oct 25 2020
.SHORT TERM...(This evening through Monday)
Issued at 330 PM CDT Sun Oct 25 2020
...Very Cold with Near Record or Record Cold Monday and Tuesday...
Forecast concerns in the short term will be light snow
accumulations ending and record snow and cold temperatures.
Record snowfalls for RST and LSE are weak for today
(10/25)...only 0.4" at RST set in 1981 and LSE a trace for eight
other years. At 18Z, we had tied those records. Here at ARX, we
measured 0.1" through 18Z. See temperature records below.
The MPX sounding was had high relative humidity through 500mb and it
was mostly -8 deg C to -16 deg C. The 300mb winds did show a
coupled jet and combined with lift,the approaching 500mb trough
and frontogenesis, we had a band of snow. This band was also
coincident with the 850mb front where temperatures were warmer
than -9 deg C and light east or northeast winds to the south and
colder than -9 deg C temperatures with northeast to northwest wind
north of the front. IR satellite, radar, and observations at noon
showed a band of light to moderate snow locally from Blue Earth to
Rochester toward Chimney Rock. This band extended well to the
southwest across Nebraska to Colorado. There were reports of some
sleet mixed in and the snow was just pushing into La Crosse. By
3pm...the light snow had overspread much of the forecast area, but
was lightest in northeast Iowa and for Clark County. The back edge
of the widespread returns from snow was over southwest Minnesota
KFRM. The next band is spreading northeast from western Nebraska
and will have to metwatch this.
Tonight...The forcing will continue, however the 850mb front will
shift southward into Illinois by 12Z and we loose. The RAP had a
good handle on the 700-500mb frontogenesis this morning and has
another round of frontogenesis this evening. The CAMs in general
are not as robust with snow this evening with less than an inch of
additional accumulation, but should watch for this as we still
have some upper level support in the area and are saturated in the
dendritic growth zone tonight and will want to keep an eye as the
next ripple lifts northeast. Expect the band of light snow to
shift southeast of the forecast area by 12Z.
The clouds will hang on tonight and this should help low
temperatures remain in the 20s. A mix of clouds and sun is on tap
for Monday, but it should be cold and may be close to a record .
Some lingering moisture could generate some clouds and instability
snow showers. The instability showers are showing up across North
Dakota and northern Minnesota, so these could develop Monday.
.LONG TERM...(Monday night through Sunday)
Issued at 330 PM CDT Sun Oct 25 2020
The extended period is generally dry across the forecast area with
moderating temperatures.
A broad area of surface high pressure will extend from the
Rockies toward the Great Lakes. Meanwhile, the closed 500mb low is
forecast to be over AZ/NM. Forecast soundings and timesections
hint that there may be some middle clouds that could hinder low
temperatures. For now, we do have a record low forecast at RST and
a near record low at LSE. Through the work week, a milder
westerly flow is forecast to develop Wednesday. A weak cold front
slips south Wednesday night and Thursday, however southwest
surface flow returns Friday. A ridge of high pressure builds in
for Saturday with near normal highs in the 50s. This breaks down
for Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 625 PM CDT Sun Oct 25 2020
Light snow will begin to diminish this evening with improving
visibilities. MVFR ceilings will last into tonight before lifting to
VFR around 07z after the snowfall completely ends. Then the VFR
cloud deck will persist into tomorrow before scattering out later
in the afternoon. Winds will remain generally from the
north/northwest around 10 knots or less throughout the TAF period.
&&
.CLIMATE...
Issued at 330 PM CDT Sun Oct 25 2020
Record Low Maximum La Crosse is forecast to have a high in the
upper 30s Monday. Their record of 34 degrees for 10/26 was set in
1887. RST has a high of 32 forecast, but their record low max is
22 set in 1887.
Tuesday, the record low maximum is 29 set in 1925 for La Crosse
and the forecast is 40. For RST, the record is 33 set in 1967 and
1933 and the forecast is 34.
Record Low Tuesday Morning
At La Crosse, the record low of 17 was set in 1976 and the
forecast is 20. At Rochester, the record low of 13 was set in 1936
and the forecast is 14.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Zapotocny
LONG TERM...Zapotocny
AVIATION...Peters
CLIMATE...Zapotocny
Area Forecast Discussion
National Weather Service Burlington VT
1028 PM EDT Sun Oct 25 2020
.SYNOPSIS...
A warm front will lift north toward the North Country tonight
with precipitation moving into northern New York just before
daybreak on Monday. A mix of snow and sleet will be possible
across northern New York during the pre-dawn hours but will
quickly transition to rain during the early morning hours and
spread into Vermont throughout the morning hours. Minor snow
accumulations are possible but will quickly melt as temperatures
warm into the 40s. Rain will come to an end Monday
evening/Monday night with the possibility of a few snow showers
later Monday night. Drier weather is is store for the North
Country Tuesday and Wednesday but increased chances for
precipitation will be seen on Thursday and Friday as the
remnants of a tropical system moves across southern New England.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
As of 1013 PM EDT Sunday...Still expecting precipitation to move
into the North Country after midnight in advance of an
approaching warm front. Precipitation will be light at the onset
and through the morning hours, with snow possible on mountains
summits during this time. Recent model guidance has trended
quicker with the onset of precipitation, and slight adjustments
were made to the forecast accordingly. In addition, recent model
guidance has indicated cooler temperatures at mid-levels, thus
decreasing the likelihood of any mixed-precipitation for higher
elevations. For such reasons, the areal coverage of sleet/snow
mix has been decreased, with rain or snow a more likely
solution. All precipitation now looks to transition entirely to
rain between 8 AM and 11 AM as temperatures warm above freezing
across the forecast area. The rest of the going forecast
remains on track. See previous discussion below.
Previous Discussion...Just as the low clouds finally eroded
this morning, mid-level clouds quickly streamed into the region
from the southwest to produce filtered sunshine this afternoon.
This abundance of cloud cover coupled with a cold air mass
overhead has causes our temperatures to struggle to warm into
the upper 30s to mid 40s. Cloud cover will only continue to
increase through the afternoon and evening hours as a warm front
lifts north toward the region. Given warm air advection in the
low to mid-levels and increased cloudiness, we have gone ahead
and bumped temperatures up a few degrees overnight.
Precipitation ahead of an approaching warm front will begin to
move into northern New York after midnight tonight.
Precipitation will likely start off as a quick shot of snow
across northern New York and then will quickly begin to mix with
some sleet as temperatures aloft begin to warm. Based on the
latest NAM and HRRR thermal profiles, the warm nose in
combination with wet-bulbing at the sfc will lead to a near
isothermal profile which will limit the depth of the elevated
warm layer. This should keep snow from completely melting as it
falls to ground which increases the refreeze potential of the
hydrometeors. This snow/sleet mix will likely last just an hour
or two before temperatures quickly warm above freezing and the
mixes precipitation changes to rain around sunrise. Further east
in Vermont, precipitation will mainly fall as rain as the warm
air should funnel up the Champlain Valley with increasingly
southerly winds and spread across the remainder of the state
right at the onset of precipitation. Nevertheless, a quick tenth
or two of snow accumulation may be possible but would quickly
melt as temperatures warm into the 40s on Monday. Rain will
taper off to rain showers Monday night with a few snow showers
possible across the northern Adirondacks and northeastern
Vermont. However, don`t get too excited as it`ll be a race
between cold air filtering back into the region behind a cold
font and moisture exiting to the east. Any snow showers that do
occur would likely drop little to no accumulation.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 303 PM EDT Sunday...Fairly quiet for this period with
surface high pressure cresting over the region. A few snow/rain
showers will linger over the higher terrain early Tuesday
morning, but these will dissipate by afternoon as drier air
works into the area. However, another shot of increasing
moisture will return later in the afternoon/evening as an upper
jet and shortwave quickly move across the Great Lakes and over
the North Country. These features may allow a few rain or snow
showers to develop, first over the the Adirondacks late Tuesday
afternoon and eventually into the higher terrain of Vermont in
the evening. The increased moisture will be brief however, so
should any precipitation develop, it would be light in nature
and come to an end by midnight or so with drier air returning.
Cooler-than-normal conditions will continue Tuesday and Tuesday
night; highs will mainly be in the 40s with some locations not
getting out of the 30s. Low temperatures will be in the mid 20s
to around 30.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 303 PM EDT Sunday...The main concern for the long term
will be the remnants of Tropical Storm Zeta, which is progged to
lift northward from the Gulf Coast, along the Appalachians to
off the Mid-Atlantic Coast by the end of the week. Meanwhile, a
potent upper low will move from the Four Corners region
eastward, also eventually moving off the East Coast. There are
still model differences in the handling of these two systems,
but consensus does indicate we`ll see precipitation spreading
over at least our southern sections sometime in the Thursday
afternoon-Friday morning timeframe, though the heaviest QPF
looks to remain to our south. Have introduced low- chance PoPs
for this timeframe. Ahead of this system, high pressure will
keep Wednesday and Wednesday night dry, with daytime
temperatures continuing in the 40s to around 50 and overnight
lows in the 30s. Once the upper trough/northern stream cold
front pushes to our east on Friday, Canadian high pressure will
bring much colder air to our region for the end of the week.
Friday and Friday night in particular look quite chilly, with
highs only in the 30s to around 40 and lows in the teens and
20s.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Through 00Z Tuesday...Cloud cover will continue to increase
throughout overnight hours with overcast mid- level clouds
expected by late this evening. We will see ceilings drop to MVFR
after 06Z across northern New York and after 09Z across Vermont
with many terminals trending toward IFR ceilings by 12Z Monday.
Precipitation ahead of a warm front will move into northern New
York late tonight with a mix of snow and sleet possible at KSLK
and KMSS for about 2 hours before transitioning over to rain as
temperatures warm. This could produce a brief period of IFR
visibilities as frozen precipitation falls but will improve
slightly as mixed precipitation changes over to rain. Based on
the latest temperature trends, any precipitation across Vermont
is expected to fall as rain which will likely keep visibilities
between 5 and 7 SM throughout the day. All sites besides KMSS
will have LLWS develop during Monday afternoon with low level
jet around 50 kts at 850 mb passing overhead and winds at the
surface still under 15 kts.
Outlook...
Monday Night: MVFR/IFR conditions possible. Chance RA, Chance
SHRA.
Tuesday: Mainly VFR, with local MVFR possible. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: Mainly VFR, with areas MVFR possible. Slight chance RA.
Thursday Night: Mainly MVFR, with local IFR possible. Slight
chance RA, Slight chance SN.
Friday: Mainly VFR, with areas MVFR possible. Slight chance SHRA,
Slight chance SHSN.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Clay
NEAR TERM...Clay/Hammond
SHORT TERM...Hastings
LONG TERM...Hastings
AVIATION...Neiles
Area Forecast Discussion
National Weather Service State College PA
1138 PM EDT Sun Oct 25 2020
.SYNOPSIS...
A weak area of low pressure will track up the east coast tonight.
Behind this system, a weakening cold front will push in from
the Great Lakes on Monday, then stall out south of the state.
High pressure is likely to briefly build into Pennsylvania on
Wednesday. Then, the remnants of Zeta are likely to track just
south of the state next Thursday.
&&
.NEAR TERM /UNTIL 8 AM MONDAY MORNING/...
Vort max can be imagined/seen in the radar returns floating
directly over KCCX around 02Z. It is such a fine-scale feature
that it appears to not be modeled well. The negative/
detrimental forcing to the west of that feature is already
evident. There is very little precip behind the feature and it
is spotty at worst. Expect some precip to fill in eventually,
but the next few hours should see our main slug of precip
continue to slide NE. Better forcing is progged to come along
late tonight for mainly the NW third/half of the CWA.
Prev...
Light rain or drizzle cover almost the entire radar scope at
this point, but the nrn tier counties are staying dry thus far
with sfc dewpoints in the u20s and l30s. Temps probably won`t
change more than 5F thru the night, and may rise slightly later
tonight as the (light) wind continues to veer. 36F at K2G4
(Oakland MD) and 37F at K2G4 (Somerset) makes it seem like it
could be pretty close to being snow there! But, the lowest
8-10kft is entirely above freezing with a warm nose of 7C per
latest RAP fcst sounding.
Prev...
Afternoon satellite/radar composite shows steadiest light
rainfall occurring over coastal MD/DE southwards to eastern VA.
Very light rain and drizzle covers much of the southern third of
central PA. Cool, dry and stable boundary layer air lies to the
north, with air temperatures in the mid to upper 40s and
dewpoints in the lower to middle 30s. Deep layer moisture conts
to slowly increase from south to north throughout the day, with
0.75" PW contour shifting to the I-80 corridor late this
afternoon. By that time, best forcing/UVM focused from the Ridge
and Valley Region and Lower Susq for highest POPs there into
tonight. Best forcing passes east of the region by later tonight,
but lingering very light rain or drizzle appear likely overnight
given the southeast flow and model soundings that are nearly
saturated from the surface to 700mb. Highest POPs overnight are
placed across the northern mountains, where orographic forcing
should translate to measurable rain in most spots.
&&
.SHORT TERM /8 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
Morning light rain or drizzle gives way to some improvement
Monday afternoon , as boundary layer flow shifts to the south
ahead of approaching cold/occluded front. The southern counties
stand the best chance of breaking into the warm sector with
brightening skies and temperatures rising into the 60s.
Elsewhere, the prospects of any clearing appear dim across the
northern mountains based on model soundings.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
A few light showers are possible mainly across the NW Mon night
as a weak upper disturbance moves over a low-mid level stalled
frontal boundary. A similar disturbance will bring another
chance of light rain showers across the west Tue afternoon and
evening.
The best day for dry conditions will be Wednesday. A series
of fronts, a cutoff low from the southwestern states, and the
remains of Zeta track toward the area on Thursday into Friday.
Long range guidance continues to show potential for 1 inch or
more of rain in this period.
Colder air will work into the area on Friday. It is possible
that some snow could mix across the far north for a brief time,
before the moisture pulls away.
A large high will bring dry and colder weather behind the
weather system Friday. This high is abnormally large and cold,
will cover much of the lower 48 states for a brief time, before
the westerlies lift quickly back to the north. The airmass is
very cold for late October, mainly records are expected to fall
across the west early this week. Minus 20 air at 850 mb forecast
west of Hudson Bay later this week.
&&
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
Low cigs continue across the area with all terminals MVFR or
lower. In general, terminals in the Laurels and across the lower
Susq valley were IFR at 03z. Conditions will continue to worsen
tonight as cigs and vsby continue to lower in low clouds and
areas of drizzle. LIFR is possible late tonight or early Mon at
BFD and JST.
IFR conditions will persist into much of the day Monday for most
of the area. Cigs may rise to low-end MVFR in the central
mountains and perhaps the lower Susq Mon afternoon as low level
flow turns to a more SWrly downsloping direction.
Outlook...
Sun night-Tue...Restrictions likely in lower clouds and and
periodic light rain.
Wed...Mostly VFR.
Thu...More wet weather expected with MVFR and IFR conditions
possible.
Friday...MVFR and IFR conditions expected with showers. Windy.
Improving conditions late, as showers move out of the area.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...DeVoir/Fitzgerald
NEAR TERM...DeVoir/Fitzgerald/Dangelo
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Martin/Colbert
AVIATION...Martin/Colbert
Area Forecast Discussion
National Weather Service Quad Cities IA IL
710 PM CDT Sun Oct 25 2020
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 323 PM CDT Sun Oct 25 2020
Cloudy, cold and somewhat breezy conditions were found across the
area this afternoon. 2 pm temperatures, from the mid 30s north to
lower 40s south and east, were running about 20 degrees below
average late October highs. Area radars and surface reports
showed a broad area of snow in an axis of frontogenetical forcing
from northern NE, through northern IA, southern MN into western
WI. Weak lift has been grazing eastern IA at times today, but was
being undercut by a dry low level north to northeast flow,
advecting an airmass with dewpoints only in the 20s.This was
leading to evaporation and gradually lowering cloud bases. Aloft,
the flow was strong out of the west-southwest ahead of a positive
tilted trough from the Dakotas to ID. Weak shortwaves embedded in
this flow and an upper level jet couplet will continue to provide
rounds of lift, primarily f-gen forcing, that will overspread the
forecast area tonight through early Monday, leading to widespread
light precipitation, likely in the form of snow. Colder, early
winter-like temperatures then follow for Monday night, followed by
slightly warmer, but continued below normal temperatures for much
of the week.
&&
.SHORT TERM...(This Evening through Monday)
ISSUED AT 323 PM CDT Sun Oct 25 2020
Pinpointing areas of enhanced lift and the associated onset of
accumulating snowfall remains the challenge in the near term.
Temperatures will be initially marginal, or too warm, for snow
over much of the area, but with the low dewpoints, the wet bulb
cooling should lead to enough cooling where snow begins to reach
the surface, supporting precipitation mostly in the form of snow
tonight and Monday. The banded nature of the lift and continued
influx of dry air are still expected to limit accumulations to
widespread trace or a dusting, with smaller bands up to one inch.
Accumulations will be primarily on grass and elevated surfaces at
the onset, followed by possible light accumulation on paved
surfaces late tonight into Monday morning, possibly leading to
slick conditions for the morning commute.
Tonight, the initial onset will likely occur in two locations. One
will be over the highway 20 corridor, closest to the on-going snow
that was as close as Waterloo and Oelwein at 2 pm. Light snow
will likely be falling there by sunset. The other may set up along
the I-80 corridor from east central IA into NW IL this evening,
based on a weak upper level feature in central IA and related
light precip over south central IA. Hints of virga on KDVN radar
into east central IA also back this potential development. These
trends will be watched closely, but for now, slight to low end
chance pops are in place for this evening, increasing to likely
after midnight when better upper divergence develops over eastern
IA into NW IL to enhance f-gen bands. Confidence in where these
will set up is low, thus leading to widespread chance to likely
pops overnight. Modest lift, mostly outside of the dendritic
growth zone and a lack of instability should keep snowfall rates
low and thus overnight totals less than one inch.
Monday morning: Short term models, especially the RAP suggest
another F-gen axis and round of possible light measurable snow,
setting up from roughly OTM to MLI around 6 am to 8 am. While
confidence in this is not high, it will be worth watching
overnight for possible impacts on the morning commute. Otherwise,
lift wanes over the north by mid morning and diminishes southward.
Cannot rule out at least light precipitation lingering in the far
south through much of the day. Cloud cover and continued cold air
advection will hold high temperatures in most areas in the 30s.
.LONG TERM...(Monday Night through Sunday)
ISSUED AT 323 PM CDT Sun Oct 25 2020
Key Messages...
1) Cold, possibly near-record near Dubuque, Tue morning
2) Dry Tue and Wed, mainly rain south Thu, then dry again Fri
through Sunday
3) Well below normal Tuesday with gradual warming trend to slightly
below normal by next weekend
Monday night into Tuesday morning, skies will gradually clear from
NW to SE as a ridge of high pressure extending from the central
Plains into the upper MS River Valley builds into the area. The
clearing skies, dry air mass in place, and light winds will allow
temperatures to drop into the 20s to lower 30s. Some cold drainage
areas in the NW third of the CWA may slip into the upper teens. The
current forecast low for the Dubuque Airport is 22F, which is only 3
degrees above the record low.
Tuesday and Wednesday, high pressure will provide dry conditions for
the area, while a weak low remains over the southern Plains and
lower MS Valley region awaiting possible phasing with Zeta. Highs
will go from the chilly upper 30s to mid 40s Tuesday, to the upper
40s to mid 50s Wednesday.
Wednesday night and Thursday, the low in the southern Plains will
phase with the remnants of Zeta as it lifts NE from the Gulf into
TN. It is still a little uncertain on the track and phasing, but
this could bring some wet weather to areas south of Highway 30 for
Thursday. The current blend has the best chances (30-40 percent)
across the southern third of the CWA. This is day 5, thus there is
plenty of time to fine tune the details.
Friday through Sunday, high pressure will return to the area
bringing milder conditions along with plenty of sunshine. High
temperatures will be in the 50s, but will still be a touch below
normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
ISSUED AT 711 PM CDT Sun Oct 25 2020
Light to moderate snow was slowly moving into the area across
western Iowa. Clouds will begin to lower as well, especially
closer to 12z where MVFR then eventually IFR cigs will be into the
area. Light snow will likely affect CID and DBQ before a burst of
snow reaches MLI near 12z Monday. This snow could lead to a quick
half inch on elevated surfaces along with reductions of vsbys to
under 1 mile. Confidence in timing and location of band keeps this
from entering the TAF.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Sheets
SHORT TERM...Sheets
LONG TERM...14
AVIATION...Gibbs
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
655 PM CDT Sun Oct 25 2020
.AVIATION...
Southerly flow and VFR conditions prevail across the airports this
evening and expect this to continue for the next several hours before
MVFR and possible IFR conditions settle in overnight. These
restrictions are likely to continue through much of the remaining
period. A cold front will approach the area tomorrow and while there
remains an outside chance that the front hangs up north of the area,
will stick with the consensus of the high-res guidance that favors
the cold and dense airmass to make it into the area late tomorrow
afternoon. Should see some possible drizzle by morning and possible
showers around and behind the frontal passage.
&&
.PREV DISCUSSION... /ISSUED 244 PM CDT Sun Oct 25 2020/
SHORT TERM (Tonight through Monday Night)...
Warmer conditions prevail today as southerly low level flow has
developed. Low level moisture will also continue to steadily
increase through the afternoon and tonight. This will lead to much
warmer overnight lows tonight with some locations stuck in the low
70s. Also, low stratus is expected to develop again tonight and also
the potential for some isolated showers and patchy drizzle beneath
the inversion early Monday morning.
The main forecast concern is the much talked about cold front, which
this afternoon stretched from south of Wichita Falls to south of
Lubbock. The front should progress south tonight through West-
Central Texas. The leading edge of the frontal air mass will become
more shallow as it approaches South-Central Texas Monday, given the
mid and upper level low cutting off to the west. However, the air
mass to the north of the front is cold and dense.
We are therefore favoring the faster 12Z 3KM NAM, ARW, NMM, and HRRR
solutions. These tend to handle shallow cold air masses. While the
NAM struggled with the last shallow front last Monday, this airmass
is denser. These faster models also have some support from the 12Z
ECMWF and CMC with the farther southward progression of the front by
Monday night. With that said, we are showing the front entering the
Hill Country and Val Verde County between 10AM-2PM and into the I-35
corridor 3PM-7PM. The frontal position and timing becomes much less
certain east of I-35, if it makes it. Temperatures should sharply
fall in the afternoon across the Hill Country behind the front, into
the upper 40s and lower 50s by sunset. Farther south the high
temperature forecast is a little more tricky, but generally with a
frontal passage that late in the afternoon highs should be able to
make it into the low 80s near and east of the I-35 corridor and then
sharply fall in the evening, assuming the front moves through. By
Tuesday morning we should see most of the area in the 40s, with
upper 30s possible across the northern Hill Country. Showers will be
possible along and ahead of the front. Isentropic ascent behind the
front should allow for chances for rain to continue Monday night,
especially across the western half of the CWA.
Finally, it should be noted that the GFS continues to be a large
outlier on the 12Z run, hanging the front to the north of the area
Monday and Monday night as it develops a frontal wave along it just
to the northwest of the CWA. Obviously there is a huge bust
potential in the temperatures Monday afternoon and Monday night if
the GFS were to verify.
LONG TERM (Tuesday through Sunday)...
As mentioned above, there is still quite a discrepancy in the models
as far as temperatures, with the GFS a good 20 plus degrees warmer
than the NAM for Tuesday, as it slows the progression of front into
the area. For this package, highs on Tuesday are a blended solution
weighted toward the NAM. So, given that the front does not hang up in
the middle of our CWA, temperatures Tuesday will be in the 40s for
the Hill Country, 50s along and around the I-35 corridor, and low 60s
along the Coastal Plains. Better chances for showers with this
system extend through Wednesday as the upper low moves across North
Texas. Rain totals will likely stay below 1 inch with better chance
for the higher totals in the Hill Country and Edwards Plateau.
Wednesday, the rain chances along the clouds will clear from west to
east. High on Wednesday will still be below normal with highs in the
upper 50s and 60s. Thursday and into the weekend show a pleasant cool
and dry forecast with highs staying in the 70s for most of the area
through Sunday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 71 79 46 51 47 / 20 50 50 40 40
Austin Bergstrom Intl Airport 71 80 47 53 47 / 20 40 50 40 40
New Braunfels Muni Airport 71 81 47 55 48 / 20 30 50 40 30
Burnet Muni Airport 67 72 41 46 42 / 30 60 50 50 50
Del Rio Intl Airport 71 76 44 49 44 / 10 20 70 60 60
Georgetown Muni Airport 69 76 44 49 45 / 20 60 50 50 40
Hondo Muni Airport 71 80 47 54 45 / 20 20 40 40 40
San Marcos Muni Airport 71 80 47 54 47 / 20 30 50 40 30
La Grange - Fayette Regional 72 82 50 59 51 / 10 30 40 30 30
San Antonio Intl Airport 72 80 47 55 48 / 20 30 50 50 50
Stinson Muni Airport 72 84 49 56 49 / 20 20 40 40 40
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Hampshire
Long-Term...17
Area Forecast Discussion
National Weather Service Green Bay WI
643 PM CDT Sun Oct 25 2020
Updated aviation portion for 00Z TAF issuance
and new information added to update section
.UPDATE...
Issued at 639 PM CDT Sun Oct 25 2020
Light snow continued across the area, probably mixed with a
little rain at times along the immediate lakeshore. The current
band of precipitation should shift east of the area in a few
hours, leaving just some occasional light snow and flurries for
the rest of the evening. The HRRR suggested another wave of light
precipitation would lift across about the SE 1/3 of the area
after midnight. There was little support for that on the other
model QPFs, but the radar mosaic did show increasing returns in
SW IA shifting NE, and the latest NAM/GFS runs had an area of FGEN
coming across the area at that time that would support some weak
ascent and light precipitation. Increased PoPs as little and
carried light precipitation later into the night to support this
possibility. Will continue to monitor, and if radar trends
continue to look favorable will increase PoPs further for E-C WI
for the late night period.
&&
.SHORT TERM...Tonight and Monday
Issued at 254 PM CDT Sun Oct 25 2020
Surface observations at 19Z indicated that light snow had started
across much of central and north- central WI. A little farther
south light rain was being reported in Wautoma. Will continue to
see light snow spread east across the area during the next couple
hours. Rain will likely mix with the snow across east- central WI
were sfc temperatures are warmer in the upper 30s to around 40
degrees. Temps cool off after sunset, with any mixed rain/snow
across the east transitioning to snow aside from right along
Lake Michigan. Precip is being driven by a coupled upper jet and
some weak fgen which will continue to influence the area through
tonight. While there remains plenty of moisture and saturation
through the DGZ, this forcing is weak. Therefore, very minor
changes made to the QPF/snowfall total forecast, with up to an
inch possible across central and northern Wisconsin, and a couple
tenths forecast across east- central WI where more rain will occur.
While amounts are minor, this will still be enough to create some
slick spots on roadways along with lower visibilities. Downstream
obs indicate visibility as low as 1 mile is possible as the snow
moves through.
Tonight...Precip comes to end for most locations between 06Z to
12Z as a sfc high pressure stretches into the area wiping out much
of the moisture, and the forcing shifts south. The exception is
northern Vilas County where northwest winds may create some lake
enhanced snow showers or flurries through mid- morning, and in
far eastern WI where light snow may not end until shortly after
sunrise. With overnight lows in the 20s to lower 30s, it`s
possible area roads remain slippery in spots for the morning
commute.
Monday...Clouds will stick around through the morning with some
breaks possible in the afternoon. As Wisconsin remains situated in
a broad upper trough, cooler temps continue, with highs ranging
from about 32 to 40 degrees tomorrow, which is 10 to 15 degrees
below normal for late October.
.LONG TERM...Monday Night Through Sunday
Issued at 254 PM CDT Sun Oct 25 2020
Main concerns in the extend forecast will be the colder than normal
temperatures through much of the work week.
Monday night through Tuesday night: Yet another trough is expected
to pass through the western Great Lakes Monday night into Tuesday.
At the same time, a stronger surface ridge is expected to build
across the area and linger through much of this time period. The
anticyclonic flow and dry air in place, will keep precipitation-free
conditions across the area. Expect gradual clearing conditions
Monday night into Tuesday. High temperatures are forecast to be
mainly in the 30s with overnight lows into the low teens to low 20s.
A few single digits are possible in the typical cold spots on Monday
night.
Wednesday into Wednesday night: The next/flatter trough axis is
expected to pass through the area during this time period. A cold
front is also forecast to pass through northeast Wisconsin Wednesday
afternoon into Wednesday evening, before shifting to the east
overnight. Moisture looks to be fairly limited, but it is possible
that some light rain/snow showers could develop across the area. If
any precipitation does develop, the best chances would be near the
Upper Peninsula border. At this point, have kept the ongoing dry
forecast. Highs are forecast to be in the upper 30s to mid 40s. Lows
are forecast to be in the low 20s to low 30s.
Rest of the extended: Much of the rest of the forecast period looks
to be fairly quiet overall. Moisture will be fairly limited, so
precipitation chances will be greatly reduced through much of the
extended. Below normal temperatures will linger through Thursday
before a gradual warming trend begins for the end of the work week.
This will be as a western ridge begins to shift east and flatten.
Will stick with a consensus of the models for that time period,
bringing mainly quiet conditions and temperatures warming closer to
normal.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 639 PM CDT Sun Oct 25 2020
Anticipate the current mix of MVFR and IFR conditions to settle in
at primarily MVFR during the evening. Need to see continued
support on radar before introducing another period of IFR
visibilities to E-C WI late tonight.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........Skowronski
SHORT TERM.....KLJ
LONG TERM......Cooley
AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Lincoln IL
753 PM CDT Sun Oct 25 2020
.SYNOPSIS...
Issued at 753 PM CDT Sun Oct 25 2020
Rain and snow will move into portions of central Illinois
overnight, with better chances of more widespread rain coming
during the late morning into the evening. Expect precipitation to
linger through Monday night south of I-70. After a couple dry
days, another round of rain is expected Wednesday night into
Thursday.
&&
.UPDATE...
Issued at 753 PM CDT Sun Oct 25 2020
A few areas of light rain/drizzle have been tracking northeast
near and east of I-57 this evening, with just a couple spots
receiving measurable rain. Main feature remains the area of
rain/snow advancing east across Iowa. Latest HRRR suggests an
arrival around midnight near Galesburg, with some expansion
southwest along the Illinois River valley as the night progresses.
Forecast soundings indicate potential for a complete switchover
near Galesburg for a couple hours around sunrise, with more of a
rain/snow mix across the Illinois River valley.
Meanwhile, precipitation expected to quickly spread northeast
from Kansas early Monday morning. Some of the guidance indicates
perhaps a quicker arrival of this latter precipitation, so PoP`s
were increased some across the southwest CWA during the morning.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 331 PM CDT Sun Oct 25 2020
Clouds continue to inhibit much in terms of temperature
acceleration. These clouds are associated with an advancing
large-scale weather system that will move over the Midwest through
the first half of the week. Watching radar this afternoon, some
light returns have developed across the southeastern CWA, due to
the baroclinic frontal zone. These light sprinkles will be
possible through the evening, before dissipating after sunset.
The main system will continue to approach the Midwest overnight,
with temperatures again dropping to the 30s and 40s. As the
slightly tilted upper level shifts southward, this will move the
current radar returns across the upper Midwest to the south.
Heading into early Monday morning, temps will be near freezing
along and northwest of the Illinois River Valley, allowing for the
development of snow in the lower atmosphere. At this time, with
the warm sfc layer, not expecting any freezing rain...limiting
all precip to snowfall or rain. As temperatures begin to warm
through the morning, should see the wintry mix change to all
rainfall from nw to se. During the afternoon, a weak wave will
slide through the southern half of Illinois, enhancing rainfall
chances across the southern CWA. This will be aided by upper level
High pressure off the se coast of the US, lifting additional
moisture to the region. As with past model runs, the total amount
of precipitation remains maxed out near 0.50 inches along the I-70
corridor. Further south, across PAH/LSX CWA, amounts range upwards
of 1 inch.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 331 PM CDT Sun Oct 25 2020
Heading through Monday night, the upper level split Lows will
work south and east, allowing for precipitation to begin ending
from nw to se. This will slowly work through the region overnight
into Tuesday, when the system will lose moisture feeding.
Now introduce another tropical system brewing in the Gulf of
Mexico, along with the cut-off Low from the desert sw that was
associated with the system that arrives tonight. As the Low
advances eastward through the far southern Plains, it will be held
back by the approaching tropical system mid-week. Once the
tropical system moves onshore, the sfc Low will be directed
northeast, as the tropical remnants maintain control of the sfc
weather pattern. This will move into the Ohio River Valley region
during the early part of Thursday. Current models have updated to
bring the rainfall on the backside of the system, along with
remaining moisture from the cut-off Low through the central and
southern Illinois area. If this holds, widespread rainfall will be
likely throughout Thursday, before another stretch of dry weather
and High pressure takes hold and dominates through the weekend.
Models appear quiet from about Friday through Sunday, with the
possibility of continued quiet weather into the next week...but
with model predictions that far out, things are likely to change.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 603 PM CDT Sun Oct 25 2020
Ceilings have slipped below 3,000 feet at the central Illinois TAF
sites, and should remain MVFR through the upcoming forecast
period. Some gradual lowering of ceilings are expected after 06Z
and will generally be a bit above 1,000 feet into Monday
afternoon. While some light rain/snow mix will occur at times late
tonight into Monday morning, areas from KSPI-KCMI most likely to
see steady rain occur through the afternoon.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Geelhart
SYNOPSIS...Geelhart
SHORT TERM...Baker
LONG TERM...Baker
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service North Platte NE
623 PM CDT Sun Oct 25 2020
.SHORT TERM...(This evening through Monday night)
Issued at 331 PM CDT Sun Oct 25 2020
A historic October cold Spell is underway across wrn and ncntl
Nebraska this afternoon with record cold high temperatures. The RAP
model suggests the potential for 1 or 2 hours of partial clearing
early Monday morning. Although precipitable water remains relatively
high, around 0.20 inches, the breaks in the cloud cover would
support a brief period of radiational cooling which could send lows
below zero across Sheridan and western Cherry counties.
The temperature forecast tonight uses the bias corrected MAV
guidance which sends temperatures below zero northwest, but
preserves lows in the teens and single digits south and east where
cloud cover will block radiational cooling.
The first and primary snow event across nrn Nebraska produced 4 to 8
inches of snow. A second area of snow has developed across wrn
Nebraska this afternoon and a third is expected across southwest
Nebraska later this evening. These areas of snow should be
capable of 2 to 4 inches of snowfall. The Winter Storm warning
and Winter Weather Advisory can be cancelled across nrn Nebraska
where an inch or less snow is in the forecast. Sheridan county
will remain in the winter storm warning for orographic snow and
lee convergence around the Black Hills.
Clear skies are expected across nrn Nebraska Monday with gradual
clearing in place across srn Nebraska. The temperature forecast for
record cold highs in the teens and lower 20s Monday is based on the
bias corrected short term model blend. It is a warmer forecast than
the very cold bias corrected MAV guidance.
Arctic high pressure moves overhead Monday and then slowly south
through wrn KS Monday night. The models are in very good agreement
continuing cold air advection Monday and Monday night with h850mb
temperatures bottoming out in the Platte Valley near -15C Tuesday
morning. During this same time, precipitable water falls to 0.10
inches or less. Some models delay this dry air until a few hours
past sunrise but all models show it across the Sandhills overnight.
Very strong radiational cooling is expected across the Sandhills for
several hours Monday night which should drain south into the
Platte valleys. Lows near or below zero are in place across the
wrn Sandhills and Platte valleys using the bias corrected MAV
guidance. West winds at 5 to 10 mph will produce wind chill
readings below -20F. Later forecasts might include a wind chill
advisory for parts of wrn Nebraska.
This event could be historic as subzero temperatures have never been
recorded during October in North Platte where weather records began
in 1874.
.LONG TERM...(Tuesday through Sunday)
Issued at 331 PM CDT Sun Oct 25 2020
There is little change in the extended forecast philosophy. The
models are in very good agreement warming temperatures at the
h850mb level to around 15C by next weekend. This should support
highs in the 60s as suggested by both the GFS and ECM guidance.
The blended forecast has 50s to around 60 in place. Later
forecasts will likely mark highs up a few degrees.
Another potential impact to the extended forecast is the upper
level low swinging through the srn Plains Tuesday and Wednesday.
The system has the potential to spread high cloudiness across wrn
and ncntl Nebraska. The system will also pull a hybrid Pacific
Canadian cold front through Nebraska.
Otherwise the extended forecast is uneventful and a dry forecast is
in place Tuesday through Sunday. A slight chance of rain or snow is
in place across just far southern Nebraska for the upper low moving
through the srn Plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 623 PM CDT Sun Oct 25 2020
Light to moderate snow continues across much of the forecast area,
although the primary band of snow will slowly drop through
southwest Nebraska tonight. Bouts of IFR cigs/visby are likely
with the main band, which roughly lines up from KOGA to KLBF to
KBBW as of 25/23z. Meanwhile, winds lighten and low cloud cover
begins to break across northern Nebraska overnight. All terminals
should return to VFR with little to no precip by 26/15z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 7 AM CDT /6 AM MDT/ Monday for
NEZ022>024-035-036-056>058-069.
Winter Weather Advisory until 7 AM CDT Monday for NEZ037-038-059-
070-071.
Winter Storm Warning until midnight MDT tonight for NEZ004.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Snively
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
916 PM CDT Sun Oct 25 2020
.UPDATE...
915 PM CDT
The main weather message of periodic light precipitation
overnight into Monday morning, some of which will be light snow,
continues as is. The main forecast update was to increase
precipitation chances for the early overnight period (~12-3 a.m.)
for north of I-80, where some rain/snow...mainly light...is
looking more likely, and in some locations especially along/north
of I-88 this will probably just be snow. We can envision a
dusting to a half inch of snow with this being possible.
Precipitation type after that remains somewhat uncertain, owing
to marginal vertical profiles with respect to moisture, but there
will likely be periodic light precipitation through the A.M. hours
especially over the northern and central forecast area. Impacts
to the morning commute still look to be limited - wet roads and
possibly some reduced visibility due to pockets of falling snow -
are the most likely outcome.
Quite the temperature map early this evening, especially for
October, showing single digit surface temperatures underneath a
stout surface high pressure of 1039 mb over Montana and Wyoming.
The cold air is spilling eastward from this with northerly flow
across the local area and temperatures down into the mid 30s in
the far northern CWA. Aloft, a marked temperature gradient was
observed at 700 mb on 00Z Plains soundings, with 17C degrees of
difference between DDC and LBF and almost as much further east
between SGF and OAX. This gradient is being overrode by a 120 kt
upper jet at 250 mb as sampled at OAX and seen on the various
water vapor ABIs on GOES-16. This evening has seen a blossoming of
precipitation associated with this speed max and associated mid-
level wave as well as implied frontogenesis. These forcing
mechanisms which will move over the area overnight. Another low
amplitude wave was located further southwest entering western
Kansas and this should help continue, or re-invigorate chances
over the CWA during the post-daybreak hours.
Extrapolating the current precipitation over Iowa keeps much of it
just north of the CWA, however the HRRR and especially
experimental HRRR have been keying in on increasing direct frontal
circulation strengthening and precipitation increasing through
midnight across eastern Iowa into northwest Illinois spreading
into north central Illinois shortly after. Given the placement of
the speed max and low amplitude wave, this seems plausible and
the Iowa activity thus far has generally been outpacing most
guidance, adding a little more credibility to precipitation
arriving a smidge earlier. For precipitation type, cloud top
temperatures currently over the area would indicate little
saturation in the ice nucleation layer, but to the west as that
wave approaches there has been an increase in saturation depth
(also shown on the 00Z OAX sounding). While some observations
have reported unknown precipitation or even rain, most of the
mPING reports and radar presentation over Iowa have pointed toward
snow. Wet bulb cooling will also help for snow to be more
dominant in the northern CWA, at least if the column is saturated
enough. If it`s not, then a light rain or drizzle would be more
favored. The same will be true through the rest of the morning
when the next low amplitude wave is forecast to pass, although
high- resolution models show greater spread in placement with the
low QPF from that.
MTF
&&
.SHORT TERM...
Through Monday night...
310 PM...Primary forecast concern and challenge remains the
potential for an area of light snow across northwest IL Monday
morning.
A few lake effect rain showers will be possible this evening into
the overnight hours and have been fairly persistent on the hrrr
runs today. Confidence is rather low for how far inland these
move into IL. Have increase pops a bit for this possibility but
these should move southeast into early Monday morning likely
affecting far southeast Cook and parts of northwest IN by daybreak
Monday morning. Temperatures near/over the lake look to remain
near 40 or warmer so precip type with this activity is expected to
be all rain.
There is quite a bit of uncertainty regarding precipitation
chances for tonight into Monday...though fairly good agreement
that precip/qpf amounts will be light. With weak forcing with this
wave...precipitation may also be intermittent. However...just
about all the models are showing some amount of precipitation and
opted to bump pops up to likely...while maintaining the low qpf
amounts. Enough colder air spreads into the area that precip will
likely mix with and then change to snow across the northwest cwa.
If there is a persistent area of light snow...there will likely be
a dusting to a few tenths of an inch of snow especially on grassy
surfaces...mainly northwest of a ugn/arr/vys line. The rain may
mix with snow across the Chicago metro area but low confidence
regarding how far southeast into the cwa there could be a mix and
where precip remains mixed...likely no accumulation.
Precipitation appears to diminish from north to south from mid
morning to mid afternoon Monday and there remains high uncertainty
for how much precipitation may occur Monday night as several of
the models now show precipitation in the far southern cwa...along
with the potential for some lake effect rain showers into Indiana
Monday night. Trimmed pops some during Monday afternoon and Monday
evening but if trends continue...much of this time period could
end up being dry. High temps on Monday may struggle to reach 40
across much of the northwest cwa and if clouds were to scatter out
across the north by Tuesday morning...low temps during that time
period could be several degrees colder than current upper 20s. cms
&&
.LONG TERM...
341 PM CDT
Tuesday through Sunday...
A relatively quieter, but cool stretch of weather appears to be on
hand for the long term portion of the forecast. The main highlight
of the extended period appears to be the potential for precipitation
late Wednesday into Thursday.
While some precipitation from Monday`s system could linger across
our southeastern CWA Tuesday morning, Tuesday is otherwise
expected to be a dry, but seasonably cool day with high
temperatures in the 40s and overnight lows around or below
freezing. Wednesday is also looking like a mostly dry day, but a
bit warmer than Tuesday with highs in the low-mid 50s.
Our next chance for precipitation will come Wednesday night and
Thursday as unsettled weather in the southern CONUS gets pulled
northeastward. A closed upper low is expected to track eastward
across the southern Plains on Wednesday, with an associated surface
low expected to blossom beneath the nose of the southern stream jet.
At around the same time, Tropical Storm/Hurricane Zeta will be
making landfall on the Gulf Coast and will interact with the low
pressure system as it continues inland. Guidance varies somewhat
over exactly how these two systems will evolve as they interact, but
most long range guidance indicates that an expansive precip shield
will build northward late on Wednesday into Thursday. There is
some inconsistency between the guidance as to how far north this
precip shield will end up reaching, so felt that current NBM PoPs
for Thursday seemed reasonable with chance PoPs more or less south
of I-80 and slight chance PoPs farther northward. Depending on
how much the surface low deepens as it tracks to the south of the
area, Thursday also has the potential to be a fairly gusty day
with northerly wind gusts of around 30 mph possible.
Things will quiet down once more on Friday and remain that way into
Halloween weekend as high pressure develops across the region amidst
broad central CONUS ridging. Highs in the mid-upper 50s are
currently forecast for this time frame before a cold front drops
south through the region on Sunday and likely cools temperatures
down a bit for the beginning of the following work week. Current
indications are that this will be a dry front, and thus, there is
currently no formal precip mention in the forecast for Sunday.
Ogorek
&&
.AVIATION...
For the 00Z TAFs...
Mixed MVFR/VFR ceilings at TAF issuance will continue well into
this evening before lowering into low-end MVFR levels late this
evening into Monday morning as a series of weak mid-level
disturbances track across the region. Lake effect rain showers
beginning to develop offshore of southeast Wisconsin are expected
to drift south across ORD/MDW and into GYY overnight. Ceilings may
briefly lower into high-end IFR levels at ORD/MDW as this occurs.
Additionally, a convergent boundary with these showers will allow
winds to back just west of north overnight through Monday
morning.
Slightly colder conditions will also advect into northern
Illinois overnight as the multiple disturbances moves through the
region. While confidence is relatively high that precip will
occur, the precipitation type is less certain. Freezing levels
will lower below 1kft across north-central and northeast Illinois,
including Chicago, late tonight. Precip is likely to fall as
light SN at RFD. SN chances will gradually decrease and RA chances
will increase with eastward extent, but a RA/SN mix and possibly
all SN at times, is expected from roughly 11-15Z at ORD and
potentially MDW. Visibility should remain MVFR or higher, but
could briefly lower into IFR levels with any persistent switch to
all SN.
Precip will gradually end while becoming all rain by early
afternoon. MVFR ceilings will persist through the remainder of the
day and potentially well into the evening Monday. Winds during
the afternoon will likely vary from 350-010, then favor slightly
west of north by the evening.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...IL nearshore waters until 7 PM Monday.
Small Craft Advisory...LMZ743-LMZ744-LMZ745...4 AM Monday to 1
AM Tuesday.
&&
$$
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Area Forecast Discussion
National Weather Service Memphis TN
1006 PM CDT Sun Oct 25 2020
.DISCUSSION...
Expect a cold and chilly night tonight, with lows in the lower
50s again. Drizzle has begun again around the area with the
latest GOES Satellite showing a thick stratus deck and a few high
clouds. Expect high pressure through tomorrow night with
temperatures a lot like todays highs. Only changes made to the
forecast were to temperatures to account for cloud cover.
Otherwise, no major changes were made to the forecast.
SGW
PREV DISCUSSION... /issued 324 PM CDT Sun Oct 25 2020/
DISCUSSION...
Another dreary day across the Mid-South. Drizzle has finally stopped,
but low clouds continue to linger across the majority of the FA.
Latest GOES satellite shows a clear slot moving north central
Mississippi, however, more low clouds are building in from the
west. Temperatures are running below guidance again, with readings
only in the 50s areawide.
Short term...Tonight through Wednesday Night...
Mainly benign weather will be the rule through at least tomorrow
night. Low clouds will hang around overnight, keeping temperatures
from falling too much. We should see temperatures warm a bit more
on Monday, as clouds lift a bit. Expect temperatures to rise into
the 60s areawide with dry conditions.
By Monday night, showers will begin to move into northeast
Arkansas as a cold front moves into the area. This front is
expected to remain stalled north of I-40 through at least Tuesday
afternoon. By late Tuesday, the front is expected to lift back
north as a warm front. This will bring showers and thunderstorms
to southern parts of the forecast area.
Tropical Storm Zeta, currently near the Yucatan Peninsula, is
expected to make landfall along the Gulf Coast sometime during the
day on Wednesday. Models differ greatly on location and intensity
of Zeta. The EURO keeps Zeta rather weak and brings it much
further west, while the GFS continues a much stronger storm making
landfall along the Florida Panhandle. Both models also struggle
to phase the system with the upper level low over the Southern
Plains.
The setup still remains messy at this time. Nonetheless, the main
impact still appears to be bouts of heavy rainfall early
Wednesday morning through late Wednesday evening. Early WPC QPF
totals range from 2 to 4 inches across the entire area. Besides
heavy rainfall, the severe threat looks low. Will continue with
current HWO wording for now.
Long Term...Thursday through next weekend...
Still some timing differences on Thursday, as the GFS keeps light
rain over the region on Thursday, whereas, the EURO lifts the
system out of the region quickly. By Friday, both models are in
agreement that surface high pressure will build in through the
weekend. This will lead to a dry and seasonable pattern through
early next week.
AC3
&&
.AVIATION...
00Z TAFs
Primary forecast concern remains ceilings, which will start out
the evening similar to the past two days, near the IFR/MVFR
threshold, with patchy drizzle.
Unlike the past two days, short range ensembles, HRRR and LAV
guidance depict overnight ceiling improvement above the FL020
alternate fuel threshold, with even some VFR ceilings between MEM
and JBR. The optimistic ceiling scenarios accompany decreasing
surface dewpoints, along the reduced coverage of drizzle under
low amplitude midlevel ridging.
00Z TAFs tend toward more persistence and 18Z NAM Bufr soundings
that depicted a persistent saturated low level inversion well into
Monday.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
634 PM EDT Sun Oct 25 2020
.SHORT TERM...(This evening through Monday)
Issued at 352 PM EDT SUN OCT 25 2020
Lake-effect snow continues this afternoon, with decent snowfall
rates seen across Marquette County and out west near Ironwood to
Bergland as a mesolow could be seen moving onshore via GOES imagery.
IWD observations have been down near 1/2 mile to 1/4 at times, which
usually suggests 1 inch an hour rates. The caveat to all this is
with sfc temperatures near freezing and with an abv freezing ground,
accumulations and roadways don`t seem to be as much and bad as we`d
normally see if it was say late November into December. MDOT camera
on M64 near Merriweather, shows decent snowfall rates and
accumulation on trees, but the roadway is open. The same can be seen
near the Marquette welcome center off US41 in Harvey, with minor
slushy accumulations on the shoulder. Due to this, felt comfortable
leaving the SPS across the west, and the advisory across the central
for now. The question heading into tonight then is how long do these
snowbands remain with the weak boundary layer flow and then if they
do remain, how much snow accumulates as temperatures fall?
This morning`s CAMs didn`t handle this afternoon`s lake-effect well,
and this afternoon`s CAMs for tonight are, well...all over the
place. Weak boundary layer flow is making this lake-effect snow a
little tough to predict, especially when guidance is so all over the
place. I started with a persistence approach and adjusted PoPs based
on sfc wind direction. Since I don`t think any one location will
have a more dominant band over another, I spread the QPF out more
evenly bringing 2 to 4 more inches across Marquette and Alger
counties, with of course locally higher amounts possible. Across the
west, weak westerly flow is moving in which should start to create
diminishing PoPs and I have 1 to 3 inches out that way. If PoPs hang
on a little longer into tonight, could see some local 4 inch reports
as well. Latest HRRR and ESRL HRRR do suggest a mesolow develops
tonight, remaining over Lake SUperior, but following parallel to
Marquette County. If part of this makes it on to shore, could see a
quick accumulation from it. Roads could get a little slick tonight
as temperatures fall in the 20s.
By tomorrow, winds continue to back a bit more to the west, with
weak flow prevailing. Lake-effect bands should follow this wind
shift, with most showers ending by 18Z tomorrow. As a ridge of high
pressure shifts in from the west, model soundings suggest subsidence
to dry the column out, with some clearing skies from west to east in
the afternoon looking possible. Look for highs to still be below
normal in the low to mid 30s west and mid to upper 30s east.
.LONG TERM...(Monday night through Sunday)
Issued at 341 PM EDT SUN OCT 25 2020
Models finally advertise a break in the cold, wet pattern for the
extended as the persistent broad mid-upper level trough across much
of the continent will be replaced by zonal flow and a milder,
Pacific air mass late week into next weekend.
Beginning Monday night, as a sfc high pres ridge moves overhead, the
attendant dry air mass and light winds should result in an
unseasonably cold night. Fresh snowfall and PWATs of .25 inch or
less will only enhance radiational cooling. Siding on the low-end of
model guidance, expect overnight lows over the west half in the
teens with maybe even some single digits possible over the typical
interior west cold spots. In the east and by the lakeshores,
expecting lows to bottom out in the low 20s to high teens.
A series of shortwaves moving through south central Canada will
bring a surface trough/cold front through the Upper Great Lakes late
Wed/Wed night. Tue still looks dry, but then later Tue night into
Wed weak forcing from passing shortwaves could support some light
rain/snow showers brushing northern and eastern portions of the cwa.
CAA behind Wed night`s cold fropa will support some scattered light
lake effect snow showers for the north wind snowbelts on Thu.
Friday-Saturday, a broad mid-upper level ridge from the Plains will
be building over the region resulting to dry conditions and a
warming trend. Expect highs in the lower to mid 40s on Friday. WAA
in a southwest flow really kicks in on Sat as model consensus shows
850 mb temps climbing as high as 10C, perhaps even higher, under
sunny skies. Should be one of the warmest Halloweens in recent
memory with highs likely well into the 50s, perhaps even reaching
the lower 60s at a few locations under a breezy southwest flow.
Sunday, a Pacific-based shortwave moving in from the west will bring
in increasing clouds and maybe some isolated rain showers as high
temps fall back into the lower to mid 40s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 633 PM EDT SUN OCT 25 2020
Continuous lake-effect snow will continue into the overnight with
light winds allowing the snow to be persistent. IFR/LIFR conditions
will continue this evening at all sites before drier air works in
and starts to slowly diminish the intensity of the snow. All sites
will go to MVFR later tonight.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 352 PM EDT SUN OCT 25 2020
Light winds will prevail through Monday as high pressure moves over
Lake Superior. This high pressure drifts south and east Monday night
as a clipper low pressure system moves over Lake Winnipeg and skirts
by Lake Superior to the north. With Lake Superior caught between
these two systems, the pressure gradient tightens and SW winds
increase to gales up to 35 knots across the west half and north
central portions of the lake Tuesday night into Wednesday. Winds
diminish Wednesday evening as high pressure moves back over Lake
Superior, which will persist into the weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 6 AM EDT Monday for MIZ005-006.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JAW
LONG TERM...Voss
AVIATION...07
MARINE...JAW
Area Forecast Discussion
National Weather Service Pueblo CO
932 PM MDT Sun Oct 25 2020
.UPDATE...
Issued at 927 PM MDT Sun Oct 25 2020
Updated forecast sent, made only some minor downward revisions to
snow amounts in Teller/El Paso counties, remainder of the forecast
is in good shape. Will note some brief freezing rain reported at
KALS as of 9pm, expect this to transition to snow in the next hour
or so as entire column drops below freezing.
UPDATE Issued at 758 PM MDT Sun Oct 25 2020
Quick look at currently arriving 00z NAM and last few runs of the
HRRR suggest heavy snow band from the Sangres up through Pueblo
county will fade somewhat later this evening, before another band
sets up slightly farther north after midnight. Still appears
biggest snowfall totals will end up over the Sangres and Wets,
with amounts approaching 2 feet possible by Monday morning.
Arkansas Valley from Pueblo west to Salida, and I-25 corridor from
Pueblo to Trinidad also look like winners with some spots over a
foot by morning. Overall, current fcst snow amounts look on track
at most locations, although El Paso/Teller counties may
underperform forecast somewhat, as heavier snow stays south, and
may nudge amounts down a few inches for COS metro and Woodland
Park area with update late this evening.
&&
.SHORT TERM...(This evening through Monday)
Issued at 337 PM MDT Sun Oct 25 2020
...High Impact Snow Storm Tonight and Monday...
An unseasonably strong and cold weather system to bring heavy snow
and record cold temperatures to much of south central and southeast
Colorado tonight and Monday.
Current water vapor imagery and upper air analysis is indicating a
strong storm system digging across the Northern Rockies with a
strong polar jet digging down the backside of the system across the
Great Basin at this time. Water vapor imagery is also indicating a
weaker system just offshore of the southern California Coast, with
Pacific moisture streaming out ahead of these system across the
Desert SW at this time.
For tonight and Monday...Latest models continue to support a high
impact snow event with widespread moderate to heavy snowfall across
all of south central and southeast Colorado, as the Northern Rockies
trough continues to dig south across the Central Rockies and merges
with the weaker system moving across the southern California Coast
before developing a cutoff low across central Arizona by late
tomorrow afternoon. The merging of the polar and subtropical jets
across southern Colorado with bring bands of moderate to heavy snow
tonight into Monday morning, with snow expected to taper from north
to south Monday afternoon and evening. Greatest accumulations remain
expected across the eastern San Juan mountains through the San Luis
Valley and southeast mts, where 1 to 2 feet of snow remains
expected, with locally up to 3 ft possible across the higher peaks
of the San Juan`s and Sangre de Cristo`s. Latest higher res models
also continue to indicate a band of snowfall persisting across the
Wet Mts, the Wet Mt Vally and the middle Arkansas River valley into
eastern Pueblo County, with some guidance giving Pueblo up to 20
inches snow. While that seems high, we will need to continue to
monitor the latest higher res guidance for this possibility. I did,
however, increase totals across the eastern Las Animas County into
Baca County, where hrrr also indicates a band of 4 to 8 inches
possible. Very cold temperatures will be the other aspect of this
high impact storm, with temperatures cooling to the single digits
and teens across the plains overnight, with new record lows likely
set in COS on Monday (previous is 16F set in 1913). Monday record
lows at PUB might be harder to reach with the expected
precipitation, as current record is 4F set in 1997. New record low
max temps will be set on Monday with current Oct 26th records being
31F at COS and 34F at PUB.
.LONG TERM...(Monday night through Sunday)
Issued at 337 PM MDT Sun Oct 25 2020
Latest long range ensemble models tend to favor a slower movement
with a shift to the north late for the upper low, which is closer to
what the EC has been showing the past couple of days.
Monday night through Wednesday...The upper low pressure system is
expected to be over the Four Corners late Mon aftn, and continue to
drop south into southern AZ during the overnight hours. Therefore,
the heavier snowfall across the forecast area is expected to taper
off from the northeast to the southwest, and the current ending time
of midnight for the winter weather highlights still looks good.
However, snow over the southern mts and mixed pcpn along the lower
elevations of the southern border will likely continue through the
day Tue as the low pushes into NM. The low then starts moving to the
northeast, crossing into the TX Panhandle Wed aftn. Pcpn chances
will start to increase once again over the southeast quad of the
state, and persist into very early Thu morning.
It still looks like Tue morning will be the coldest period of
extended forecast, with clearing skies and fresh snow cover dropping
temps into the single digits. Light winds will likely create wind
chills of 5 below to 15 below zero. Plan on highs in the 30s for
most locations Tue, then the 40s on Wed.
Thursday through Sunday...Upper ridge of high pressure builds back
into the southwestern US, so dry and warmer conditions are
anticipated for the remainder of the extended forecast. Look for
Plan on highs in the 40s to lower 50s for most areas on Thu,
gradually climbing into the 50s for the high valleys and upper 50s
to mid 60s for the plains by Sun. Moore
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 337 PM MDT Sun Oct 25 2020
IFR and LIFR conditions in snow expected to persist through the
overnight hours at COS and PUB. Snow accumulations of 4 to 7 inches
remain possible at the terminals through the period, with snowfall
expected to taper and slowly diminish from north to south through
the day Monday.
Gusty southwest winds of 20-40KT to persist at ALS through the
afternoon, which has produced MVFR and localized IFR conditions at
times in BLDU. Winds to diminish through the late afternoon and
become more easterly and increase once again this evening, as strong
cold front banks up across the Front Range allowing for a much
colder airmass to move into the region. This cold airmass will also
bring widespread IFR/LIFR conditions in snow tonight with snow
slowly diminishing Monday afternoon. Accumulations at the terminal
of 3 to 6 inches remain possible by the end of the taf period.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM MDT Monday for COZ089-093>099.
Winter Storm Warning until 6 PM MDT Monday for COZ058>064-
069>071-076>080-083-086>088.
Winter Storm Warning until midnight MDT Monday night for
COZ065>068-072>075.
Winter Storm Warning until noon MDT Monday for COZ081-082-084-
085.
&&
$$
UPDATE...PETERSEN
SHORT TERM...MW
LONG TERM...MOORE
AVIATION...MW
Area Forecast Discussion
National Weather Service San Diego CA
900 PM PDT Sun Oct 25 2020
.SYNOPSIS...
Scattered light showers from the coast to the mountains will come to
an end this evening as a vigorous upper trough passes across the
region. This will be followed by developing Santa Ana winds after
midnight tonight, strengthening through Monday and lasting through
Tuesday. Strong and potentially damaging winds are forecast from the
San Bernardino and Riverside County mountains, the Inland Empire and
inland Orange County. The strong northeast winds combined with
crashing humidity will lead to critical fire weather conditions
across these areas late tonight through Tuesday, a dangerous
situation should any fires start. Less wind will occur overall for
San Diego County. An upper ridge will build in mid and late week,
leading to weakening winds and warming conditions.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
-Forecast Highlights-
* Strong Santa Ana Winds Develop Late Tonight-Tuesday SBD to OC
* Damaging Wind Potential and Critical Fire Weather Conditions
Evening Forecast Update:
The latest high resolution HRRR shows the Santa Ana wind event
quickly unfolding late tonight from around dawn through the day
Monday. Peak winds could top 70 mph at times through and immediately
below the passes and canyons, which will have the potential to cause
wind damage and disrupt power and travel conditions. The latest
forecast remains on track, and therefore no significant updates to
the forecast were needed this evening. An updated rain report was
just issued and patchy light rain showers will continue through late
this evening, especially in San Diego County. You can see the latest
rain report at the top of our website and on our social media feeds.
A peak wind report was also issued, which features the onshore
strong winds, which are now dying off, before switching to offshore
after midnight.
Previous Forecaster Discussion, issued at 304 PM PDT:
A vigorous upper trough with core moving over the Great Basin is
phasing with an upper low off our coast. This feature will move
south across our region tonight. Scattered showers ahead of it
(light/insignificant) will come to an end followed by potential high
impact weather for parts of our service area as a strong Santa Ana
wind develops.
The winds will switch to northeast after midnight tonight at around
2 AM and this will commence this much advertised Santa Ana Wind
event. Santa Ana winds will steadily increase overnight and become
potentially damaging extending into Tuesday afternoon impacting the
coastal mountain slopes of the San Bernardino and Riverside County
mountains, the Inland Empire extending to inland Orange County. The
period of greatest concern is from dawn Monday through 11 PM Monday.
There will be mixing and winds will be most widespread and gusty
late tonight through about noon Monday. Hi-res models suggest that
by mid afternoon Monday extending through Monday evening, we
transition to an environment favorable for mountain waves and WRF
cross sections show surfacing mountain waves over parts of the
Inland Empire and inland Orange County. This could mean that
although winds may let up in some areas late Monday morning into the
afternoon, if mountain waves surface, sudden and damaging wind gusts
to 70 mph could occur. This is the time of best dynamic forcing for
SoCal, which could allow for severe wind gusts to occur.
Again, the corridor of strongest winds will impact areas below the
Cajon Pass stretching across the northern Inland Empire in and
around Rancho Cucamonga, Ontario, Glen Avon, extending southwest
into inland Orange County, including areas in and around Orange,
Tustin, Lake Forest to San Clemente. The wind orientation is not
favorable for widespread, strong winds across San Diego County.
The only exception is north of Oceanside, which could see strong
wind gusts of 50+ mph. Otherwise, the strong winds over San Diego
County look to remain localized to ridge tops and much less
intense than further north.
Temperatures will tumble especially across the mountains and
deserts. Lows in the lower 30s are forecast for the high desert.
Sensitive vegetation could be killed there as localized temps to
around the freezing mark are forecast.
Compressional warming west of the mountains will occur with
noticeably warmer readings on Tuesday as Santa Anas continue. The
winds will relax Tuesday afternoon/evening as the forcing moves east
and away from the region.
Upper ridging will build in mid/late week. This will lead to
tranquil weather conditions along with gradual warming. The marine
layer likely will make a return late this week for nighttime and
morning low cloudiness making a comeback after clear days Monday
through Thursday.
&&
.AVIATION...
252000Z...Coast/Valleys/Coastal Mountain Slopes...BKN-OVC cloud
layers with bases ranging from 2500-4500 feet MSL and tops to 6500
feet MSL will continue through tonight, with scattered -SHRA
bringing local vis 3-5 miles. Only local SCT conditions will occur.
Higher terrain will be obscured at times. Clouds will dissipate 10Z-
16Z Mon with areas of surface northeast winds 20-35 knots and gusts
to 55 knots developing Mon mainly after 12Z VCNTY KSNA, KRAL, KONT,
KSBD, KRIV.
Mountain Crests/Desert Mountain Slopes/Deserts...Mostly clear with
unrestricted vis through Monday, except for clouds/fog near the
mountain crests through this evening. Areas of gusty west winds 20-
30 knots with gusts to 50 knots will continue in the mountains,
through San Gorgonio Pass, and into the deserts through tonight,
with northeast winds 20-35 knots and gusts to 55 knots developing
tonight, mainly near the mountain crests, continuing Monday.
&&
.MARINE...
Northeast winds will increase over the nearshore water late
tonight with gusts to 25 knots possible off the northern San Diego
County coast. A Small Craft Advisory is in effect from 5 AM Monday
through 5 AM Tuesday due to areas of northeast winds which will
gust to 30 knots, creating conditions hazardous to small craft
operators. Benign marine conditions will return Tuesday.
&&
.FIRE WEATHER...
...Red Flag Warning 2 AM Monday Through 6 PM Tuesday for Strong
Northeast Winds and Extremely Low Relative Humidity for the San
Bernardino and Riverside County Mountains, the Inland Empire, San
Gorgonio Pass, and Inland Orange County...
Santa Ana winds will begin after midnight tonight, increasing in
speed overnight and continuing through Tuesday. The strongest winds
are forecast to occur between dawn Monday through Monday evening.
Northeast winds of 20 to 40 mph with gusts to 70 mph are expected.
The Santa Ana will bring extremely dry air into Southern California
with relative humidity falling to 5-10% away from the coast Monday
through Tuesday. Little overnight recovery is expected.
The corridor of strongest winds will impact areas below the Cajon
Pass stretching across the northern Inland Empire in and around
Rancho Cucamonga, Ontario, Glen Avon, extending southwest into
inland Orange County, including areas in and around Orange, Tustin,
Lake Forest to San Clemente. The winds are expected to ease Tuesday
afternoon, but will still be locally gusty.
The strength and areal coverage of wind for San Diego County will be
lower. The strongest winds there will occur north of Oceanside.
For east County it looks like the strongest winds will remain on
the ridges where gusts to 50 mph or so will be possible. Still,
locally gusty winds briefly to 20-40 mph into the foothills and
valleys along with low relative humidity of 5-10% will lead to
elevated fire weather conditions for the mountains and valleys of
San Diego County Monday through Tuesday.
&&
.HYDROLOGY...
Scattered, light showers will continue from the coast to the coastal
mountain slopes through this evening, favoring San Diego County.
Total rainfall amounts will be less than 0.10 inches at most
locales. However, the coastal mountain slopes are forecast to
receive 0.20 to perhaps up to 0.50 inches, with the max along the
San Diego County mountain coastal slopes. Max hourly rainfall rates
will be 0.10/hr. Any runoff will be quite limited.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 10 PM PDT this evening for Coachella Valley-
Riverside County Mountains-San Diego County Deserts-San
Diego County Mountains-San Gorgonio Pass Near Banning.
Frost Advisory from 3 AM to 9 AM PDT Monday for Apple and
Lucerne Valleys.
Red Flag Warning from 2 AM Monday to 6 PM PDT Tuesday for Orange
County Inland Areas-Riverside County Mountains-Including
The San Jacinto Ranger District Of The San Bernardino
National Forest-San Bernardino County Mountains-Including
The Mountain Top And Front Country Ranger Districts Of The
San Bernardino National Forest-San Bernardino and Riverside
County Valleys -The Inland Empire-San Gorgonio Pass Near
Banning-Santa Ana Mountains-Including The Trabuco Ranger
District of the Cleveland National Forest.
Wind Advisory from 2 AM to 5 PM PDT Monday for Orange County
Coastal Areas-San Diego County Coastal Areas-San Diego
County Valleys.
Wind Advisory from 2 AM to 11 PM PDT Monday for Coachella Valley-
San Gorgonio Pass Near Banning.
High Wind Warning from 2 AM Monday to 2 PM PDT Tuesday for
Orange County Inland Areas-San Bernardino County Mountains-
San Bernardino and Riverside County Valleys-The Inland
Empire-Santa Ana Mountains and Foothills.
PZ...Small Craft Advisory from 5 AM Monday to 5 AM PDT Tuesday for
Coastal Waters from San Mateo Point to the Mexican Border
and out to 30 nm-Waters from San Mateo point to the Mexican
Border Extending 30 to 60 nm out including San Clemente
Island.
&&
$$
PUBLIC...Gregoria/JMB
AVIATION/MARINE...PG
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Monday)
Issued at 324 PM CDT Sun Oct 25 2020
Northern stream upper wave continues to deepen southward towards the
four corners region while a secondary cutoff low is beginning to
enter the southern CA coast. Broad quasi-zonal westerly flow ahead
of the wave has aided in persistent low level moisture and weak
ascent as the stratus deck lowers through the afternoon and evening.
Light drizzle has been observed over north central and portions of
east central Kansas thus far and would expect the light precip to
linger before the system arrives tonight. If temps fall near or
below freezing, this may result in a light glaze on elevated
surfaces.
The first of two disturbances rounds the Four Corner basin this
evening while the cutoff low ejects into the southern plains by
morning. Widespread frontogenetical forcing in the h85-h7 layer
dropping southward into north central Kansas aft 00Z will be the
driver in precipitation rapidly developing and expanding eastward
into most of the CWA by 09z. Latest model trends are a bit faster
with the colder, freezing temps, and given our western areas have
not warmed and are hovering near freezing already, the wintry precip
transition to all snow should be brief overnight. Impact to morning
commute is likely as wintry precip should be ongoing with the
exception for areas south of I-35.
Model solutions begin to differ Monday afternoon as the mid level
vort max associated with the cut off low develops another band of
higher QPF in the southeast KS to central MO vicinity. Temperature
profiles vary by a few degrees towards east central KS which may
result in freezing rain or sleet mixing in with the snow. While this
will cut down on snowfall totals, a light glaze of ice may add to
the additional impact of travel for tomorrow. It is also worthy to
note the RAP forecast soundings were showing elevated instability
mid to late morning across the area - indicative of banding snow and
locally higher amounts across east central Kansas so cannot rule
out the potential for locally higher snowfall totals.
Current snowfall forecast is generally 1 to 4 inches this evening
through Tuesday evening with locally higher amounts possible if any
banded snowfall or convection were to occur. Headlines included
expanding the Winter Weather Advisory further east to encompass the
entire area as well as extending the time through 06Z Tuesday to
account for lingering light snow and light freezing drizzle. Plan to
also mention the freezing temps as forecast lows tonight will be in
the 20s to low 30s.
.LONG TERM...(Monday night through Sunday)
Issued at 324 PM CDT Sun Oct 25 2020
A second killing freeze is likely Tuesday morning with lows in
the upper teens to low 20s, effectively ending the growing season.
Multiple rounds of precipitation, including wintry precipitation,
remains possible Tuesday through Thursday as the upper low occludes
as it shifts across the southern plains. Precip on Tuesday is mostly
confined to areas south of Interstate 70 where light snow mixes with
sleet and rain through the daytime. Confidence remains low on how
far north the wintry mix impacts the area, and the amounts so
evaluation of extending the winter weather advisory will be made in
later forecasts. Rain appears most likely Wednesday and Thursday as
the warmer air raises temps back into the 40s for highs. Models exit
the upper low by Thursday evening with drier, and more mild
temperatures next weekend as highs peak in the low 60s and overnight
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 628 PM CDT Sun Oct 25 2020
A messy TAF period is ahead with periods of drizzle and snow. IFR
conditions should prevail at all sites within the next 1-2 hours
with light drizzle developing shortly thereafter. A transition to
snowfall is expected during the late evening hours. We will have
to monitor the potential for any banded snowfall which would
result in very low VSBY and likely lowered CIGS. Otherwise, light
snow should accompany much of the daytime hours Monday. Northerly
winds will remain at 10-15 kts.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 4 AM Monday to 1 AM CDT Tuesday for
KSZ012-024-026-039-040-055-056-058-059.
Winter Weather Advisory until 7 PM CDT Monday for KSZ008-009-020-
021-034-035.
Winter Weather Advisory from 1 AM Monday to 1 AM CDT Tuesday for
KSZ010-011-022-023-036>038-054.
&&
$$
SHORT TERM...22
LONG TERM...22
AVIATION...Baerg
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
500 PM MDT Sun Oct 25 2020
.DISCUSSION...(This Evening Through Sunday)
Issued at 154 PM MDT Sun Oct 25 2020
The latest water vapor images and RAP model analysis shows a deep
trough over most of the western/central CONUS with a large ridge
off the West Coast. Upper low pressure was centered over the
ID/UT/WY area with a strongly positive tilt. A 90-100 upper jet
was over the area, and a short-wave trough was moving northeast
across CO/UT toward the southwestern CWA. Radar indicates that
snow has ended over most of the CWA, except for the far
southwestern corner of SD. However, given the approach of the
upper wave, along with the colder/deeper clouds approaching from
the southwest, will keep snow in the forecast for the far
southwestern CWA into this evening. CAMs and ensemble guidance
also supports this. Otherwise, the winter weather highlights have
expired or been cancelled, and only some light snow and areas of
drifting snow will remain possible over southern/open areas into
early this evening.
NAEFS and ECMWF ensemble climatologies show 850-mb temperatures
getting down to less than the 1st percentile tonight over parts of
the CWA. With the fresh snow cover, decreasing winds, and gradually
diminishing clouds overnight, temperatures will fall to record or
near-record lows on Monday morning. Then, highs on Monday will be
near record-low maxes as snow cover and the residual cold air
mass will be in place. The 850-mb temperatures will then rise
markedly Monday night through Tuesday. This will lead to a non-
diurnal pattern to low temperatures Monday night, with lows around
midnight and then steady to rising temperatures thereafter.
Dry weather and an overall warming trend will ensue for the rest of
the week as the ridge-trough pattern shifts eastward, albeit high
temperatures will be moderated by the snow cover such that below-
average temperatures will remain through Thursday. Highs may get
back to average for Friday through Sunday as 850-mb temperatures
flirt with 10-15C.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 457 PM MDT Sun Oct 25 2020
A few areas of IFR conditions in light snow will persist over
southwest South Dakota through early evening. Otherwise MVFR
ceilings will continue through early tonight across portions of
northeast Wyoming and western South Dakota. VFR conditions
expected across the area on Monday.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION...Bunkers
AVIATION...7