Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/27/21
Area Forecast Discussion
National Weather Service Caribou ME
1034 PM EST Tue Jan 26 2021
.SYNOPSIS...
High pressure will move east of the region overnight. Low
pressure will track to our south on Wednesday. A stronger low
will pass well to our south Thursday, followed by an upper
level low from Ontario tracking southwest of the region Thursday
night and Fri. High pressure will build in from the west
Saturday and Sunday then move east Monday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
1020 PM Update...
Adjusted the pops across eastern Aroostook, especially the
Houlton region as the radar was picking up some light returns.
The latest HRRR/ARW was hinting at some light precip in this
areas pushing in from New Brunswick. The RAP soundings picked up
deep moisture through 800 mbs w/ese through the same level.
Decent llvl convergence in place w/some weak lift will allow for
some light precip in the form of snow/drizzle. For consistency
purposes kept the wx element as snow showers. Clouds across the
region have kept temps up and light adjustments were made to
match the latest conditions. The rest of the forecast was
unchanged.
Previous discussion...
The semi ridge axis will give way to an approaching upper level
trough. At the surface weak low pressure over Western New York
will track East-Southeast into the Gulf of Maine. Low level
moisture will advect northward from the Gulf of Maine into the
FA after sunset. As clouds thicken and the column moistens up
expect snow showers and eventually steady very light snow
develops. This system is running into a road block which is the
ridge axis that will be located over New Brunswick through
Wednesday. This forces the best lift, moisture and support for
light snow to be pushed south into the Gulf of Maine. At the
same time a weak surface feature pushing through the St.
Lawrence running into the ridging will kick off a few snow
showers & perhaps some very light snow across the northern FA.
By Wednesday morning only expecting a Dusting to perhaps 1/2" in
Downeast areas back to the Bangor region. Generally just a
dusting across the North down to the Central Highlands.
Increasing cloud cover with warm air advection aloft will mean
surface temperatures remain mild for this time of year with lows
in the 20s with teens in the North Woods.
Wednesday an 850mb high will be pushing south over the St.
Lawrence River and Gaspe Peninsula. This will likely kick back
some drier air to eat away at snow showers across Eastern areas
of Downeast Maine back to the Presque Isle area. Leftover
850-500mb moisture combined with remaining shortwave energy
suggest still seeing isolated to scattered snow showers from the
St. John Valley into the North Woods then south along GYX CWA to
Bangor region. Additional snowfall during the day of a tenth to
perhaps a half of an inch. Highs tomorrow will be very warm for
this time of year. Bangor will be near the freezing mark which
is 5 degrees above average. Caribou will top out in the upper
20s which is 10 degrees above average.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
With NAO still sig negative, mid lvl (700-500mb) anom
directional comp of the flow alf will remain Nrly component not just
thru the short term but nearly all of the long term. The net effect
of this flow regime will be to deflect more sig moisture from low
pres systems from the midwest/plains well to our south, leaving our
Rgn with minor sn accumulations from ocnl very light snow, flurries,
and/or isold to sct sn shwrs thru Fri.
Skies will remain mcldy Wed Ngt into Thu as weak subsidence
from the N tries to push whats left of any lgt sn as sct lgt sn
shwrs to Wrn ptns of the FA from the old dissipating midwest low
pres system. Later in the day Thu an upper low from NE Ont prov
digging SSE toward Cntl New Eng will bring more enhance sn
shwrs to spcly Cntrl and Wrn ptns of the FA thru Thu ngt into
erly Fri morn. Models do indicate a lmtd mid lvl warm advcn
conveyor belt on the east side of the upper low transecting
Cntrl/Wrn ptns of the FA ovrngt Thu that could result in lclzd
enhanced banding of sn shwrs ovr this ptn of the FA where PoPs
are greatest in the hi chc to low likely range.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Ptly to mcldy skies N and ptly cldy to mclr skies Cntrl
and Downeast is xpctd Fri Ngt thru Sun with brisk NNW winds are
xpctd behind the departure of the upper low, allowing somewhat
colder arctic air held just W of the Rgn ovr QB prov by N
Atlc/NE Can blocking to advc ewrd ovr the Rgn. The coldest dytm
temps look to be on Sat with a little recovery by Sun aftn. Fcst
lows will be closer to seasonal norms, with only lmtd late ngt
arctic sfc bas invsn potential for inland vly areas due to
remnant sfc-blyr winds and cld cvr. Mon attm still looks dry
with a cont`d slow moderation trend of aftn hi temps.
The first chc of any sig precip for ptns or all of our FA looks to
be more toward at least late Mon ngt and more likely Tue, with tmg,
track, and intensity details still uncertain attm, dependent on how
much blocking ovr far Nern CAn and the N Atlc remains and phasing
between Nrn/Srn branches of the upper jet. The consensus of longer
range models indicate a low tracking alg of just S of the Gulf of ME
from the mid Atlc states, suggest weighting high chc PoPs Downeast
to low chc or even slgt chc PoPs ovr the far N in all sn this
initial go round of the fcst and then adjust accordingly based on
consensus model trends in subsequent updates getting closer to the
event.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: Tonight... North Terminals: MVFR clgs becoming IFR
after 03z. Scattered snow showers becoming Light Snow. N-NE
winds around 5 kts. Southern Terminals: VFR becoming MVFR clgs
around 03z. Becoming IFR clgs/vsby by 09z. Light snow. N-NE
winds 5-10 kts.
Wednesday... IFR clgs early becoming MVFR mid morning. CAR to
HUL clgs rise to VFR late afternoon. MVFR continues at FVE, BGR
& BHB. NE winds 5-10 kts.
SHORT TO LONG TERM: Wed Ngt - Thu...mainly MVFR all TAF
sites with intervals of VFR clgs Downeast TAF sites. Isold sn
shwrs with brief MVFR vsbys. Lgt winds becoming N by Thu Ngt.
Thu Ngt - Fri Morn...mainly MVFR clgs all TAF sites with possible
MVFR vsbys in sct sn shwrs. Lgt to mdt NNW winds.
Sat...MVFR clgs Nrn TAF sites with VFR conditons Downeast sites.
Mdt NW winds.
Sat Ngt - Sun...VFR all TAF sites with lgt winds.
&&
.MARINE...
NEAR TERM: Winds/seas remain below SCA through the period. NE
Winds 5 to 15kts tonight becoming 10 to 15kts late Wed
afternoon. A few gusts after sunset Wed up to 20kts. Snow
showers this evening becoming light snow after midnight.
Visibility 3 to 5nm drop to 1 to 3nm. Light snow mixes with
rain Wednesday before tapering to showers late afternoon.
Visibility improves to 5nm or greater.
SHORT TO LONG TERM: Winds and seas will be at and msly below
marginal SCA thresholds Wed ngt thru Thu. Aftwrds, Thu ngt into
Sat Eve at at least SCA conditions are xpctd associated with
strong llvl cold advcn peaking int strong SCA with NW wind gusts
to 30kt Fri aftn thru Fri eve. Cannot rule out gale force gusts
during the peak time. Kept close to blended wv model guidance
for fcst wv hts thru these ptns of the fcst. Wvs will be mainly
composed of two spectral groups; a short 3-5sec Swrd propagating
group and a second open Atlc 10 to 15sec NW propagating
propagating group.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service State College PA
1026 PM EST Tue Jan 26 2021
.SYNOPSIS...
High pressure will build southward from Canada during the mid-
week. Other than some flurries over the north/west it will be
fair and cold. A weak storm system moving into the Ohio Valley
late this weekend or early next week may bring some snow and
rain to the region.
&&
.NEAR TERM /UNTIL 11 PM THIS EVENING/...
Final, brief round of light Mixed precip will be racing ENE
across the Central Mtns and region from the West Br Susq...NE
early this evening. Latest RAP soundings show that wet bulb
temps are still a few deg below zero throughout the lowest
several KFT AGL from KIPT north and east, so precip in that area
should be mainly snow.
Extended the Wint Weather Advisory til 03Z for our NE zones
where additional light amounts of snow, sleet and FZRA are
expected.
Temps will fall slowly across the western mtns, but will likely
jump a few deg F elsewhere for a short period this evening as
the sfc occluded front slides east across Central Ridge and
Valley region.
&&
.SHORT TERM /11 PM THIS EVENING THROUGH THURSDAY NIGHT/...
Colder air slides into the rest of the area overnight, but sfc
temps prob won`t dip that much due to clouds and the veering and
increasing wind. Little if any accums are expected, even in the
snowbelt as much of the precip will be from clouds getting more
shallow through the night. At most we`ll have an inch in the
fcst, generally over the higher elevs of the Laurels late
tonight/Wed am.
Mins will range from the mid 20s north to around 30F over much
of the southern half of the area. Gradient will be tight enough
thru the night and Wed to keep 10-20mph with gusts into the m-u
20s in the higher elevs and 8-15mph elsewhere as we veer to the
NNW. Gusts will be less noticeable on Wed. Otherwise, Wednesday
will be quiet elsewhere with seasonable temperatures. Just a few
flurries are expected in the west.
The storm which looked like it may brush the srn tier Wed
night-Thurs looks in most guid like it will stay (well) to our
south. Will keep just a 10 PoP for now, but expect nothing to
come from it as the wave remains open and moving quickly to the
east across the southern Mid-Atlantic. Temps will be colder,
though. Expect morning mins in the lower teens N and 15-22F
elsewhere on Thurs and maxes won`t be much higher than that -
only getting into the upper teens N and l30s far S.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Northwest flow associated with a shortwave moving through will
bring some light lake effect and upslope snow showers to the NW
Snowbelt and the Laurel Mountains. Amounts should be light with
totals at the end of Friday only at an inch or two, but dry air
from the high pressure behind the shortwave could knock down
these totals.
Friday night and Saturday will be very cold from a surge of
Arctic air. Wind gusts in the 20-30mph range Friday will keep
apparent temps in the single digits or below zero Friday morning
and Friday night.
The next system to watch will come late this weekend/early next
week. This set-up is similar to the snow/sleet event that
happened today; the caveat being that it will be much colder
before the onset of this next system. A low pressure moving up
from the Ohio River Valley Sunday then redevelops off of the
DelMarVa coast Sunday night. There is a great deal of
uncertainty in the precip type and storm track, with the 12Z
GFS being much more progressive than the EURO which is also
farther south in the track. Right now there is a chance of
wintry precip Sunday night through Tuesday, but we will have a
clearer idea of type and amounts as we get closer to the event.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Widespread low cigs will persist this evening ahead of low
pressure lifting across upstate New York. A trailing cold
front will push through the western half of the state late this
evening and the eastern part of the state between 06Z-09Z. A
drier northwest flow behind this front should bring rapid
improvement east (downwind) of the Appalachians, with VFR
conditions becoming likely from KIPT south through KMDT and
KLNS. However, residual low level moisture ascending the
mountains is likely to result in low MVFR cigs persisting behind
the front at KBFD and KJST.
Model soundings indicate MVFR cigs will persist at KBFD and KJST
through Wednesday, while downsloping flow yields predominantly
VFR conditions further east.
Outlook...
Thu...Gusty NW winds.
Fri...Gusty NW winds. Early AM snow squalls possible, mainly
northern Pa.
Sat...No sig wx expected.
Sun...Snow possible, mainly PM.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert/Dangelo
NEAR TERM...Lambert/Dangelo
SHORT TERM...Dangelo
LONG TERM...Gutierrez/Wagner
AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Dodge City KS
548 PM CST Tue Jan 26 2021
...Updated Aviation...
.SHORT TERM...(This evening through Wednesday)
Issued at 224 PM CST Tue Jan 26 2021
Winter Weather Advisory was expanded across all 27 DDC area
counties given there is not much of a favorable area for the
"minimal expected" snow. The models QPF form the HRRR and 12NAM
were not large amounts, however with snow ratios ramping up into
the high teens for the afternoon and evening, the risk for
snowfall amounts is probably to the higher end of the inch and a
half average in the official forecast. Locally 3 inches can be
expected which HRRR and NAM were still still producing bes over
the northern reaches of the area. The initial lift and snows are
now being seen on radar through the highway 83 corridor as of 2
pm, and will continue to increase in coverage over about the next
4 to 6 hours. Even an inch of snow will create travel impacts as
the cold temperatures will prevent any of the snow from melting.
Once the system exits tonight, anomalously deep cold air will be
left over the area with the NAM showing -14 deg C at 700 mb and
around -12 at 850, and likely residual flurries in the cold
stratus overnight.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 224 PM CST Tue Jan 26 2021
The coldest temperatures of the week will be early Wednesday
morning, with widespread single digits at least in the west and
maybe farther east. The low temperature pattern spatially would even
support temperatures below zero in the ark river Valley west of Garden
City, and MOS generally showing colder temperatures than models like
the NAM/WRF. Not as cold lows in the teens are most likely over
south central Kansas cities.
Stratus should clear out with time on Wednesday with high
temperatures still likely limited to the 20s over most of the
forecast area. Temperatures look like they will moderate about 15
degrees per day through Thursday and by Friday afternoon, 60s could
be widespread on southwest downslope winds from dodge city and west.
Global Spectral models indicate that by the weekend another buckle
in the upper jet across the central/plains, and surface low
developing out of Colorado - another opportunity for warm frontal
precipitation perhaps in the Friday night/Saturday window. The cold
front following that system does not look very cold and will not
likely have significant effects on the temperatures going into the
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 545 PM CST Tue Jan 26 2021
Widespread light to moderate snow is bringing IFR/LIFR flying
conditions to DDC, GCK, and HYS, while LBL has already cleared the
snow and is in MVFR. Over the next couple hours, the snow should
clear DDC and GCK, allowing visibility to improve. However, low
cigs should keep those terminals in IFR/MVFR through the night.
HYS will likely stay in IFR for several more hours as the snow
moves northeast. Conditions will begin to improve around 12Z as
the upper level wave exits our area, and all terminals should be
in VFR by 18Z. Winds will stay below 10 kts throughout this TAF
period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 9 28 15 47 / 90 0 0 0
GCK 4 28 15 46 / 80 0 0 0
EHA 14 40 25 55 / 40 0 0 0
LBL 11 35 19 54 / 60 0 0 0
HYS 5 22 8 39 / 90 0 0 0
P28 18 33 18 48 / 90 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight CST /11 PM MST/ tonight
for KSZ030-031-043>046-061>066-074>081-084>090.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Springer
Area Forecast Discussion
National Weather Service Houston/Galveston TX
603 PM CST Tue Jan 26 2021
.AVIATION [00Z TAF Issuance]...
Not planning on a lot of changes with the going TAF trends with re-
gard to the timing of the cold front tonight/overnight. Short range
guidance still indicating a fairly dry/quiet FROPA with CIGS likely
lifting quickly in its wake. Otherwise, will be keeping a close eye
on possible patchy MVFR CIGS near the coast overnight. 41
&&
.PREV DISCUSSION... /ISSUED 343 PM CST Tue Jan 26 2021/
SHORT TERM [Tonight Through Wednesday Night]...
Yesterday`s surface cold front remains stalled well offshore, with
some lingering cloudiness still present across the barrier islands
and immediate inland areas. That being said, the gradual clearing
over the past 24 hours has allowed for more efficient daytime
heating this afternoon, while the shift to east-northeasterly winds
has limited CAA. Overall, daytime highs have risen above model
consensus with Hobby Airport reaching 77 at 3PM and Galveston
reaching the 75 earlier today.
As an upper trough traverses the Central Plains, the approach of a
reinforcing cold front overnight will provide an additional surge of
cooler air to SE TX as winds strengthen and shift northward. The
boundary should arrive at the Brazos Valley before midnight and will
likely clear the coast before sunrise on Wednesday. With limited
moisture availability given the influx of drier air yesterday, the
frontal passage should be largely a dry one. However, as indicated
by recent HRRR solutions, some isolated showers may arise near the
coast where near-surface moisture remains higher. This raises the
additional possibility of some patchy fog development in these
locations prior to the arrival of the front but coverage and
intensity should be limited.
Tonight`s lows should be fairly similar to last night`s with most
locations seeing values in the upper 40s to low 50s. As moderate to
strong northerly winds (with gusts rising to up to 25mph) develop in
the wake of the front, a further cooldown is expected tomorrow.
Daytime highs are unlikely to rise above 70, while overnight lows
may approach freezing in the northern zones and will otherwise be in
the mid-30s to lower 40s.
Cady
LONG TERM [Thursday through Tuesday]...
High pressure in the Midwest will dominate the Southern Planes
bringing clear to mostly clear skies and relatively drier
conditions. Thursday will be pleasant with highs climbing to around
60 after lows in the low to mid 40s. The large high will start
moving to the northeast on Friday into the Ontario area, giving
way to an onshore flow. Warmer and more moist will set back in
warming lows on Friday to the mid 40s and warming to the mid to
upper 60s.
A cold front, Saturday will increase rain chances, but most higher
chances remain to the north of I-10 but showers or a thunderstorm
can`t be ruled out along the boundary. Intensity is still looking
weak with PWATs peaking around 1.3 inches and not much
instability along the front. Highs will reach the mid 70s after a
morning low in the mid 50s to around 60. Early Sunday Morning, the
front will have passed and high pressure returns to the area.
Lows will still reach around mid 50s to around 60 with highs
around 70. Cooler temperatures will filter in with drier air and
clearing skies through mid week as high pressure moves across the
area. 35
MARINE...
SCA hoisted for the anticipated change post frontal. Northeast
winds this evening will relax and seas very slowly diminish. The
cold front arrives and winds crank up quickly - timing should
bring it to Matagorda Bay around 3 am and off of Galveston between
4 and 5 am. Winds of 15 to 25 knots will be common and wind gusts
of 30 knots with even a few of 35 knots in the 6am to noon
timeframe. Persistent offshore continues Wednesday afternoon
through Thursday evening through diminishing to 10-15 knots. Seas
will be slow to fall with the persistent offshore flow. Onshore
flow resumes Friday and could have a short period of sea fog
Saturday before the next cold front scours out the moisture Sunday
morning.
45
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 45 63 36 60 40 / 0 0 0 0 0
Houston (IAH) 51 67 41 61 42 / 0 0 0 0 0
Galveston (GLS) 56 65 49 56 52 / 10 0 0 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Small Craft Advisory from 3 AM to 10 PM CST Wednesday for the
following zones: Coastal waters from Freeport to Matagorda
Ship Channel TX out 20 NM...Coastal waters from High Island
to Freeport TX out 20 NM...Galveston Bay...Matagorda Bay...
Waters from Freeport to Matagorda Ship Channel TX from 20
to 60 NM...Waters from High Island to Freeport TX from 20
to 60 NM.
&&
$$
Discussion...99
Aviation/Marine...99
Area Forecast Discussion
National Weather Service Lincoln IL
917 PM CST Tue Jan 26 2021
.SYNOPSIS...
Issued at 334 PM CST Tue Jan 26 2021
Mostly quiet conditions expected tonight with overnight lows
dipping down into the teens to 20s. Light snow expected for
locations south of Interstate 74 on Wednesday with new snow
accumulation of less than 1 inch. Much colder temperatures arrive
Wednesday night with lows in the single digits to teens and
windchills near zero north of Interstate 74.
&&
.UPDATE...
Issued at 915 PM CST Tue Jan 26 2021
Steady northerly flow of dry mid-level air cleared out clouds in
our northern counties earlier this evening, allowing the Galesburg
temp to plummet to 11F with a 9F dewpoint at 8 pm. A fresh snow
cover helped with that for sure, as Peoria remained up at 22F
despite clear skies too. Galesburg warmed 2 deg to 13F with the
return of clouds at 9 pm. Satellite trends show clouds reforming
in portions of the cleared out area, and variable clouds are
likely to persist until the morning when precip from the next
system approaches our W counties. Have adjusted the low temps down
to account for the rapid evening cooling, but only a couple
degrees below the 8 pm reading. The remainder of the CWA is
relatively free of a snow pack, and temps are following expected
trends under the cloud cover. No other significant changes will be
needed for the evening update.
The onset of snow for tomorrow looks on track for late morning in
our western counties, with areas south of I-72 having the best
chance at a half inch to near an inch of snow.
&&
.SHORT TERM...(This evening through Friday Night)
ISSUED AT 245 PM CST Tue Jan 26 2021
Light snow/flurries north of I-74 continue to taper off this
afternoon as the upper shortwave they are tied to pushes further
east over northern IN and brief upper ridging fills in from the
west. Overnight lows will be chilly, with values ranging from the
teens across the north to the 20s further south.
The next system to impact the area arrives on Wednesday as an upper
wave lifts from the southwest US into the middle Mississippi River
Valley. Precipitation tied to an inverted surface trough looks to
spread into the area by Wednesday morning with chances continuing
into the afternoon hours. Not a ton of moisture is evident with this
system and it`s getting no help from the Gulf as a cold front
remains draped across the southeast US. However, small amounts of
QPF will bring some light precipitation to areas mainly along and
south of I-74 throughout the day on Wednesday. Forecast soundings
indicate in-cloud ice and surface temperatures support snow as the
primary precipitation type. Amounts will be on the lighter side with
less than 1 inch expected.
Things turn downright cold going into Wednesday night as Canadian
high pressure slides southward into the region. Overnight lows on
Monday will range from the low single digits across the northern
CWA where a snowpack is present to the teens further south. Winds
will be light under the surface high, but any little bout of wind
will create windchills of zero to the low teens from north to
south, respectively. High pressure sticks around for the end of
the week, keeping things mostly quiet and sunny.
Southerly/southwesterly surface flow will pull back in near normal
temperatures for Thursday and Friday. Highs on Thursday will be
in the upper 20s to middle 30s, with highs expected to be in the
30s to low 40s on Friday.
.LONG TERM...(Saturday through Tuesday)
ISSUED AT 245 PM CST Tue Jan 26 2021
Attention then turns to a stronger system progged move onshore the
southwest US and lift into Midwest come Saturday into Sunday. There
is still quite a bit of uncertainty with precipitation types due to
differences in the storm track and also timing. One thing is for
certain is that the Gulf of Mexico will be wide open for service,
allowing a plethora of moisture to get pulled northward. NAEFS
mean precipitable water progs much of central Illinois sitting in
90th percentile for the climatological mean with this system - so
lots of moisture to work with. As it stands, QPF amounts are
generally around 1 inch for much of the area, though the exact
type of precipitation is still uncertain. Will also need to keep
an eye on the potential for river flooding, especially across
southeast Illinois where a 0.50 to 0.75" of rain fell with
Monday`s system. Let the blend handle this storm at this time due
to the differences, which paints a mix of rain and snow across
much of the area, with the better chances for snow currently across
northern counties (this could changed!). Definitely something to
watch, with several days ahead to hammer out the details.
Precipitation with the weekend system may linger into early next
week as a shortwave or two embedded in the upper trough roll through
the area. Global models are in decent agreement that high pressure
should fill back in going into Tuesday as a large-scale ridge builds
across the western CONUS. Models diverge after that, though looking
even further ahead yet another storm system could impact parts of
the central US by the middle to end of next week - lots of
differences with this though.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 553 PM CST Tue Jan 26 2021
As low pressure departs to the east, dry air from the north is
working its way into central Illinois. A clearing line was near
PIA at 00z, with breaks in the IFR/MVFR clouds near BMI and CMI.
Satellite trends show clouds in NE Illinois drifting towards BMI
and CMI, so any VFR conditions there should be short-lived. It is
possible that SPI could see some VFR clearing later this evening,
per HRRR output.
The next weather disturbance will approach from the west on
Wednesday, spreading MVFR ceilings and light snow back into the
area by late Wednesday morning through Wednesday afternoon. SPI
and DEC could see IFR vis and cigs during some heavier snow
showers, otherwise MVFR conditions should persist through the
afternoon at our terminal sites. PIA could climb to VFR before the
end of the 00z TAF period.
Winds will prevail from the north around 10kt for much of the next
24 hours.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SYNOPSIS...NMB
SHORT TERM...NMB
LONG TERM...NMB
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Louisville KY
952 PM EST Tue Jan 26 2021
.Forecast Update...
Issued at 950 PM EST Tue Jan 26 2021
Evening high-resolution model data coming in still show a healthy
slug of cold moisture coming into the Ohio Valley tomorrow afternoon
and evening. Forecast soundings from the HRRR and NAM3km show a
fairly thick isothermal layer in the -8 to -10 C range, right in the
heart of the snow bands...along with good saturation underneath.
Cross sections also show strong lift within the better snow
formation zones, so 10 to 1 ratios may be too low. Regardless, think
the rates of snowfall will be enough to overcome initially warmer
road temperatures. Thus have decided to expand the winter weather
advisory a little farther west and extend it in time an hour
earlier. Would not be surprised if we need to continue the
expansion, but our far western zones do have the benefit of the snow
coming in at warmest road temperatures. Updated products will be out
shortly.
&&
.Short Term...(This evening through Wednesday Night)
Issued at 230 PM EST Tue Jan 26 2021
...Minor Snow Accumulations Wednesday Afternoon and Evening...
Fast westerly flow aloft is keeping us dry and helping southern KY
to break out into some sunshine. Upper low pushing into MI, with the
sfc low over Lake Erie and a trailing cold front dropping southward
through Illinois and Indiana. Next upper system is just starting to
eject out of the Four Corners area, and the main challenge will be
the impacts of any snow that impulse can put down late Wed afternoon
into Wed evening.
Expect a wind shift and some decent cold air advection tonight as
the front pushes through Kentucky. This will get our cold air in
place, and the wave coming out of the Four Corners moves too fast to
develop much of a sfc reflection, but will generate isentropic lift
as it crosses the Mississippi Valley.
Best window for precipitation in southern Indiana and central
Kentucky will be 18Z Wed to 03Z Thu, though sfc temps in the
mid/upper 30s could allow precip to start as rain or a mix. As is
often the case here, it gets interesting once the sun sets, so
accumulating snow is increasingly likely after 4-5PM depending on
where you are, and that will likely have impacts on the evening
commute, especially east of I-65 into the Bluegrass region of
Kentucky. Total accumulations up to 1 inch are likely in the
Bluegrass region. Winter Weather Advisory will be issued this
afternoon, with a start time of 4 PM Wed, which will leave an hour
or two cushion before real impacts start. The advisory area will
extend far enough west to capture where it will be snowing at
sunset.
Once the snow exits around midnight, decent cold air advection sets
up and temps will drop quickly, with Thu morning lows in the
lower/mid 20s. While it will be dry in this time frame, it`s cold
enough that we could see impacts of evening snow linger into the
Thursday morning commute.
.Long Term...(Thursday through Tuesday)
Issued at 242 PM EST Tue Jan 26 2021
The long term portion of the forecast will begin Thursday morning
with upper level ridging building in from the west and Canadian high
pressure overspreading the region at the surface. Expect a chilly
but mostly sunny day Thursday with morning lows in the low 20s and
afternoon highs reaching into the mid 30s accompanied by cold
northerly flow. With the surface high overhead Friday, expect
another mostly sunny day with light winds and a another cold start
with morning lows in the upper teens to low 20s. As the surface high
pushes east, a light southerly flow will result in weak WAA. This
combined with ample sunshine should push afternoon highs into the
low 40s.
By Saturday a closed 5H low over the Central US will push through
the region resulting in a wet weekend with a chance at some winter
weather for portions of southern Indiana and east central KY.
Isentropic ascent in response to mid level jet core (85kt) and an
approaching low level jet (60kt) will promote slight chance precip
Saturday morning, but model soundings show robust layer of dry air
that should serve to keep the surface dry until later in the
afternoon. Warm temperatures will result in rain initially, but with
diurnal cooling we expect to see a changeover to mix of rain/snow
across our northern counties in southern Indiana and the Bluegrass
region. Other locations should continue to see rain as temperatures
overnight into Sunday morning stay above 37F. Light rain will
continue Sunday as the surface low passes over the region with total
QPF for the event looking to be around an inch for most places. Will
likely see another changeover from rain to rain/snow mix early
Monday morning with potential flurries into the early afternoon. Any
snow accumulations as of right now appear to be located in southern
Indiana and the Bluegrass with up to an inch possible in those
locations.
With high pressure building in Monday, expect a dry start to the
beginning of the next work week.
&&
.Aviation...(00Z TAF Issuance)
Issued at 640 PM EST Tue Jan 26 2021
Seeing some breaks in the MVFR stratus deck this hour, but would not
be surprised to see it fill back in again once more before another
scattering after midnight. The SDF/LEX/HNB corridor then should fill
back in again with stratus below 2 kft by daybreak, ahead of our
next system. That system looks to bring in some precip in the
afternoon hours, with some IFR conditions looking more likely at
each of the sites before 00Z Thursday. Winds will switch around from
west northwest now to northerly later tonight.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory from 3 PM EST /2 PM CST/ Wednesday to 1
AM EST /midnight CST/ Thursday for INZ077>079-084-089>092.
KY...Winter Weather Advisory from 3 PM EST /2 PM CST/ Wednesday to 1
AM EST /midnight CST/ Thursday for KYZ024-025-027>043-
045>049-053>057-063>067.
&&
$$
Update...RJS
Short Term...RAS
Long Term...CG
Aviation...RJS
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
935 PM CST Tue Jan 26 2021
.UPDATE...
930 PM CST
The main focus is on lake effect snow for parts of northeast
Illinois and northwest Indiana on Wednesday. An SPS was just
issued to alert of the potential for travel impacts due to rapid
changes in conditions over short distances, including periods of
poor visibility and snow and/or slush on some roads. Some of the
00z CAM guidance is rather concerning tomorrow morning, but given
typically lower confidence in these scenarios on the west and far
south side of the lake, opted for SPS issuance as opposed to
Winter Weather Advisory. If it becomes apparent in analysis
overnight that the lake effect snow will become single banded with
moderate to heavy rates AND stall out for 2-3 hours+, then needing
a WWA is a good bet. Just wasn`t confident enough to make that
call this evening.
A dual banded structure of light lake effect snw showers have
drifted into Lake and eastern Porter Counties this evening. The
appearance on radar is not too impressive and a look at soundings
indicates that lift is on the weaker side, which should be the
case through the night. This will change on Wednesday morning as a
clipper-type mid-level short-wave will approach the region and
induce some cold advection down the length of Lake Michigan, with
850 mb temps cooling down to -11 to -13C. given the unusually mild
lake surface temps, this will bring 850 mb to lake delta Ts of up
to 15C and lake induced CAPE of 100-150 j/kg. As a con to the
setup that has been noted over the past few days, lake induced
equilibrium levels (inversion heights) are not all that
impressive, topping out at 5kft-6.5kft, depending on the model
sounding you look at (which means DGZ will only be partially
saturated). Also, while the delta Ts are more supportive than
would typically be the case with that air mass over the lake in
late January, still not extremely favorable.
On the other hand, what we will likely have in place to possibly
compensate for the somewhat negating factors of the setup is very
good lake induced low level convergence and strong lower level
omega (lift) due to the convective processes and large ascent
from the short-wave trough. Have noted that in the past at times
setups on the southwest to extreme southern tip of the lake can
perform better than expected from more marginal ELs in the
presence of very favorable convergence and low level lift. Adding
to this concern from past events is the 00z CAM guidance,
including the high-res WRFs (locally 6"+ on ARW!) and the HRRR
(though HRRR has been mostly overdone with LES this season).
All the above being said, the big question as always comes down
to residence time of the band over given locations. Feel fairly
confident that at least moderate to briefly heavy rates will
accompany the activity, but lower confidence on the all importance
residence time question. It appears the convergence will
retrograde the activity from current location into portions of
eastern Cook County and affecting downwind areas of eastern Will
and possibly eastern DuPage and northeast Will as well. The lake
effect band(s) would then eventually migrate back into Lake IN and
then Porter later Wednesday PM. With the above concerns, hit the
messaging harder in already issued SPS and plan to issue a graphic
shortly highlighting these concerns. Will brief midnight shift on
the potential and depending how trends emerge will dictate whether
a WWA is needed in the early morning.
Castro
&&
.SHORT TERM...
259 PM CST
Through Wednesday night...
Forecast challenges continue to focus on additional snowfall
accumulations from the lake effect snow showers tonight and on
Wednesday. While there is not much of a focus for these showers,
the expectation is that we will see these snow showers become
better focused into portions of Cook county and Lake county IN
tonight as a land breeze convergence zone sets up over southern
Lake Michigan. This land breeze convergence zone may keep the main
focus for these snow showers into central and southern Cook
county (and adjacent areas of Lake IN) through much of Wednesday
morning before this focus gradually shifts eastward into Lake and
Porter Counties in IN Wednesday afternoon and evening.
Lake effect parameters are not expected to get overly impressive
from a thermodyamics perspective. In fact, a recent AMDAR
sounding out of MDW suggests that lake induced equilibrium levels
are right at the -12C level, which is only about 5-6,000 feet
AGL. It appears unlikely that this will improve much, if at all,
overnight. This does add some concern to the quality of snow in
these lake effect bands. However, with a fairly consistent signal
for a good boundary layer focus along the lake breeze convergence
zone, this may act to compensate for the modest thermodynamic
parameters. For this reason, while this is unlikely to turn into a
major lake effect snow event for Cook or Lake county IN, we could
see enough of a focus to support a band of accumulating lake
effect snow showers into central and southern Cook/parts of Lake
IN late tonight through Wednesday morning. Our current forecast
mentions about 1 to 3 inches through Wednesday, with the highest
amounts near the lake in southern Cook and far northwestern IN.
As mentioned above, expect the focus for lake effect snow showers
to shift eastward into eastern Lake IN and Porter Wednesday
afternoon and evening. Some light accumulations will continue to
be possible in this area. Otherwise these lake effect snow
showers should come to an end altogether Wednesday night.
Outside of the lake effect snow, we look to see some decreasing
cloudiness tonight, especially over north central IL. With a
fresh snow pack on the ground, this could set the stage for a
cold night across this area, with temperatures falling into the
single digits in areas that see some decreasing clouds.
Temperatures on Wednesday then look to remain in the 20s over
north central IL, to around 30 southeast of I-55. Surface high
pressure looks to build eastward towards the area Wednesday night.
This could support an even colder night, with some subzero lows
and wind chills possible into early Thursday morning.
KJB
&&
.LONG TERM...
259 PM CST
Thursday through Tuesday...
Northerly flow will place our region under cold-air advection (CAA)
for approximately 36 hours by Thursday morning, and combined with
clear skies, we expect low temperatures Thursday morning to be cold,
with lower teens in the east, and single digits to below zero in the
west. High pressure will move over us to our east Thursday afternoon
into evening, keeping our skies clear, and flipping our winds to the
south. Although this wind shift will end the filtering of cold air
into our area, it will take some time for the the established cold
air to warm up, and temperatures will remain below freezing
throughout Thursday and into Friday morning. Eventually the sunshine
and warm-air advection (WAA) brings high temperatures to near
freezing, or even above freezing for southeastern counties Friday
during the day.
Our next weather-making system approaches Saturday. The pressure
gradient will tighten from south, and pump in warmer, moist air from
the south, with isentropic lift and associated precipitation well in
front of the surface low. With a couple of days of WAA, temperatures
at and just above the surface may get above freezing, so a wintry
mix scenario is initially possible with this system, but since the
system is still four days out, exact details are uncertain. Winds
will eventually turn northerly in the wake of this low pressure
system, allowing colder air to filter in Monday and Tuesday,
although lingering low clouds may modify our temperatures somewhat,
and keep us from bottoming out in the morning on those days.
BKL
&&
.AVIATION...
For the 00Z TAFs...
542 PM...Forecast concerns include...
Lake effect snow showers.
Northerly winds through the period.
Mvfr cigs through the period.
A band of lake effect snow showers has shifted southeast of mdw
and has also begun to weaken some but will affect gyy over the
next few hours. Flurries will also be possible for ord/mdw this
evening. Focus then shifts to another period of potential lake
effect snow around and just after daybreak Wednesday morning.
Medium confidence this will occur and likely affect gyy but low
confidence of how far west it may shift. Opted to carry flurries
for ord/mdw with a tempo for snow showers at mdw. If these were to
occur...vis could be considerably lower. This band may be near gyy
for several hours through midday before finally shifting east late
Wednesday afternoon.
Winds are expected to remain northerly through Wednesday afternoon
with a period of north/northwest possible tonight then going back
to north/northeast Wednesday morning then finally settling back to
northwest Wednesday afternoon/evening. Some gusts into the lower
20kt range will be possible this evening.
Mvfr cigs will likely continue across Lake Michigan and into
northwest Indiana through Wednesday afternoon. Some scattering is
possible at ord/mdw/dpa but confidence is low to try to time any
possible scattering. Another period of mvfr cigs would be likely
Wednesday morning with the above noted lake effect snow shower
potential. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...Gary to Michigan City IN until 9 AM Thursday.
Small Craft Advisory...Winthrop Harbor to Gary IN until 3 AM
Thursday.
&&
$$
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Area Forecast Discussion
National Weather Service Pueblo CO
800 PM MST Tue Jan 26 2021
.UPDATE...
Issued at 750 PM MST Tue Jan 26 2021
Snow continues to wind down, though a stubborn area of accumlating
snow lingers from KPUB ne into ern El Paso and Crowley counties.
Given rather sparse snowfall coverage and HRRR forecasts of a
continued downward trend in strength/coverage, will end all
Winter Wx Advisories with this update, keeping a mention of light
snow or flurries going until midnight, mainly over ern plains.
UPDATE Issued at 451 PM MST Tue Jan 26 2021
Dropped the advisory for the ern San Juans and all the ern mts
with this update. Will keep I-25 advisory going another hr or two
as still some light snow on radar across El Paso/nrn Pueblo
counties. On the plains, still a couple more hrs of light snow to
go, so will keep current advisory in place.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 257 PM MST Tue Jan 26 2021
...Snow decreasing across southern Colorado this evening...
Have made some minor changes to headlines this afternoon with
cancellations across portions of Fremont county and the Wet Mountain
Valley where cloud breaks have spread in. Have maintained
highlights for the remainder of the southeast plains as wrapped up
upper low across east central Colorado continues to eject to the
east northeast and deformation band precip continues to spiral to
the northeast. Heaviest snow will continue across the eastern-most
counties though with lingering troughiness out west, remnant energy
and instability will lead to some scattered convective snow showers
into the evening. Additional accumulations will be more localized
with these, though spotty areas could see a quick inch with the more
intense snow showers. Otherwise, expect an improving trend from west
to east with lingering low clouds and even some patchy fog across
the plains overnight over snow covered areas. Northwest to westerly
winds will erode stratus and fog eastward through Wednesday morning.
Lows tonight will be quite cold, especially where clearing is
realized. Lows in the -10 to -15 range will be possible across the
San Luis and upper Rio Grande valley overnight with some pockets of
even colder temperatures possible as very dry airmass advects in.
Have dropped lows from model blends.
Wednesday should see some improvement in temperatures though snow
covered areas on the plains will remain on the cold side where winds
stay light or southeasterly. This will be primarily north of
highway 50. Southerly and westerly winds into the surface lee trough
across southern portions of the plains and along and near the lower
eastern slopes of the southeast mountains should help temperatures
recover into the upper 30s/lower 40s aiding in snow melt. Light
winds and a very cold start may hold temperatures down below
freezing across the San Luis valley through the day while higher
mountains feel the affects of warming aloft behind the system and
rebound back into the 20s and lower 30s with teens above timberline.
-KT
.LONG TERM...(Wednesday night through Tuesday)
Issued at 257 PM MST Tue Jan 26 2021
Wednesday night through Friday...
High pressure is going to dominate most areas until the next system
approaches the CWA on Saturday. Both of the GFS and ECMWF models are
picking up on a weak upper level low from the subtropical ridge to
the southwest over the Pacific Ocean ahead of the longwave trough
that will absorb into the ridge over the region and could allow for
some higher level precipitous clouds on Thursday and Friday, that
could reach the surface at the higher elevations of the Sawatch
Range Thursday morning, while the mid and lower levels remain dry.
More than likely any showers will be in the form of virga as all
should evaporate before reaching the surface. Winds will become
strong and gusty for the higher mountain terrain by late Friday
evening as the longwave trough approaches the area. Later on Friday
some of the snow showers will begin over the San Juans, but remain
dry for the rest of the CWA.
Friday night through Sunday...
All of the deterministic models are in relative agreement with the
timing of the next major shortwave trough to influence the CWA late
friday night beginning around 06Z. Due to the orientation of this
trough, most of the precipitation will be confined to the
mountainous areas of the CWA, especially for Saturday morning, where
the greatest amounts of snowfall will be located on the southwestern
facing slopes of the San Juan Mountains. The low pressure center
associated with this trough will propagate quickly out over the
Great Plains and undergo some pretty strong lee side cyclogenesis as
it does, with both models agreeing of the general location of this
surface low to be centered around the panhandle of Oklahoma. As this
surface low continues to deepen, the tightening pressure gradient
will result in stronger winds on the backside of it to increase
later in the day on Saturday over the southeastern plains,
especially for Kiowa, Bent, Prowers, and Baca Counties. RH values
will be relatively low, but not in critical fire weather
criteria, with the lowest values around 20%...however it is still
worth monitoring for the potential of causing hazardous conditions
if there are any fires ignited. All snow showers that are still
lingering over the mountains will end by Sunday morning.
Sunday night through Tuesday...
A ridge will begin to build back in with warmer and drier conditions
will dominate the CWA.
Tuesday night through Wednesday...
The deterministic models do differ a bit with the orientation and
position of the low center associated with another approaching major
shortwave trough to move into the region Tuesday night of next week.
However, all of them have been pretty consistent over the recent
model runs at this being quite of an impactful storm with a
significant amount of snowfall for the mountainous areas of the CWA,
although the ECMWF has the plains getting a lot more snow, along
with some cold air damming as the trough deepens significantly
more than what the GFS displays. The GFS has the center of this
low being over northeastern Colorado whereas the ECMWF has this
low being located down in central Texas...so there is much is the
way of fine tuning with the models needed to determine where the
exact location of this system will be in the upcoming days.
-PS
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 257 PM MST Tue Jan 26 2021
MVFR to IFR conditions expected at the KCOS and KPUB terminals this
evening with lingering snow showers. Upslope winds will cause cigs
to drop back down into the LIFR category at KCOS before clearing out
towards morning. Similar conditions expected at KPUB. Both sites
should see increasing north to northwest downslope winds overnight
which will scour low clouds out to the east in the 09z-12z window
for KCOS and the 11z-14z timeframe for KPUB. Conditions will return
to VFR with light south to southeast winds expected for Wednesday.
VFR conditions will be dominant at KALS though a brief return of
MVFR could occur this evening with any stray showers. Skies will
clear out overnight with a small potential for patchy dense ground
fog to develop early Wednesday morning. Chances look too low to
mention in the TAF given right now given such dry air aloft.
Conditions will remain VFR on Wed with light southerly winds.
-KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PETERSEN
SHORT TERM...KT
LONG TERM...STEWARD
AVIATION...KT
Area Forecast Discussion
National Weather Service Springfield MO
954 PM CST Tue Jan 26 2021
.UPDATE...
Issued at 948 PM CST Tue Jan 26 2021
Increased snowfall tonight and Wednesday morning as models have
all trended that direction and are in good agreement. Most
significant increase was over the eastern CWA, where almost two
tenths of QPF was added to the forecast (it was 0.03-0.05"
previously). Still may not be high enough over the east as some
guidance (most notably the HRRR and NAM) shows some spots with
around 0.4" of QPF. Have issued Winter Weather Advisories across
the entire area. Even with light amounts over the west, road
temperatures will be below freezing, so accumulations on roads
(especially untreated) and slippery conditions are expected.
Greatest impacts will be along and east of the Highway 65 corridor
due to greater amounts and peak snowfall during peak travel hours
in the morning. See weather story graphics, the Situation Report,
HWO, or WSW for more precise details.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 202 PM CST Tue Jan 26 2021
Main concern will be a light accumulating snow late tonight and
early Wednesday. A fast moving upper disturbance/shortwave over
the southern Rockies will move quickly ene through our area early
tomorrow. Used a general short term model blend for precip amounts
yielding a general average of below an inch of snow for our cwfa
during late night/early morning time frame. Snow will be brief in
any one area, but with temperatures in the mid-upper 20s, will see
some pavement accumulation given the time of day.
For now given the small/light amounts will not issue an advisory.
Could see one from subsequent shifts as collaboration with other
offices and (subtle) forecast changes warrant.
Snow will end in our eastern counties near noon Wednesday.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 202 PM CST Tue Jan 26 2021
Wednesday Night-Friday: Canadian sfc high pressure will nose south
into the area with quiet weather. Light winds and a clearing sky
may help temperatures fall into the teens late Wed night/Thu
morning. Should see a quick warmup Thursday as the sfc high moves
off to the east. Friday afternoon temperatures are expected to
reach into the upper 40s and 50s for most areas.
Saturday: Another Pacific based system will move into Plains
Saturday. Guidance varies on timing, but it looks to be a quick
moving but fairly intense/strong upper wave as it moves through.
Progged rainfall has seen an uptick from yesterday with widespread
amounts around an inch now progged over a relatively short
period. Will need to monitor trends for possible flooding
impacts. With this system initializing offshore in the east
Pacific, we can expected further changes to the forecast.
Sunday-Tuesday: A large upper ridge is expected to build over the
central CONUS with quiet weather during this period. Beyond
Tuesday, (Wed-Thu) the period may become active depending on how
the upper level pattern sets up. Obviously a lot of variance on
the forecast guidance that far into the future.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 528 PM CST Tue Jan 26 2021
As snow moves into the area later tonight into Wednesday morning,
expect decreasing visibilities and ceilings. Low clouds will stick
around for a while after the snow exits the area, eventually
improving toward the end of this TAF period.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...Winter Weather Advisory until noon CST Wednesday for MOZ055>058-
068>071-079>083-090>092-095>098-103>106.
Winter Weather Advisory until 9 AM CST Wednesday for MOZ066-067-
077-078-088-089-093-094-101-102.
KS...Winter Weather Advisory until 9 AM CST Wednesday for KSZ073-097-
101.
&&
$$
UPDATE...Titus
SHORT TERM...DSA
LONG TERM...DSA
AVIATION...Titus
Area Forecast Discussion
National Weather Service Sacramento CA
357 PM PST Tue Jan 26 2021
.SYNOPSIS...
A long duration, high impact winter storm this evening into
Friday bringing periods of gusty winds and moderate to heavy rain
and mountain snow, and blizzard conditions over the Northern Sierra.
Potential for significant low elevation snow and damaging winds
tonight and Wednesday as well as burn scar impacts to the LNU
Complex and SCU Complex burn scars.
&&
.DISCUSSION...
The highly advertised strong winter storm is beginning to move
into Northern California this afternoon as the upper level trough
begins to move onshore. Current radar imagery shows showers
moving into the forecast area along the western edge, and they are
expected to expand to the east through the afternoon.
Precipitation will quickly become heavy tonight. NAM 3k and HRRR
are both indicating the formation of a NCFR (narrow cold frontal
band) along the cold front as it moves through the area, generally
after 8pm tonight through 8am tomorrow. This is expected to
produce very heavy precipitation with high rain and snow rates.
HREF suggests hourly snow rates with this band of 2 to 6 inches in
the Sierra, including over Interstate 80 and Highway 50. Winds
will also become extremely strong as the cold front passes through
with damaging gusts up to 50 to 60 mph expected in the Valley up
through the mountains, locally up to 70+ mph winds over higher
mountain peaks. These extreme snowfall rates plus strong winds
will produce extreme weather conditions and near zero to zero
visibility over the Northern Sierra. Therefore, a Blizzard Warning
has been issued for the Northern Sierra for elevations above 3000
feet. The Winter Storm Warning remains in effect for the
remainder of the mountains, foothills, and Northern Sacramento
Valley. Winds these strong plus heavy mountain snow are also
likely to cause downed trees or tree branches and powerlines.
Widespread power outages are possible tonight through tomorrow
morning.
In the Valley, rain rates around 1 to 2 inches per hour are
possible overnight tonight. HREF is suggesting the best chances
for the rain rain rates greater than 0.50 to 1 inch per hour will
be over western Yolo County into Solano County and south into
western San Joaquin and Stanislaus County, including the LNU
Complex and SCU Complex burn scars. Impacts such as debris flows
are definitely a concern overnight with this pattern. A Flash
Flood Watch remains in effect for both of those burn scars.
This will be a cold storm to begin with as the trough is dropping
down from the Gulf of Alaska. Snow levels will begin very low
this evening through tomorrow morning, generally 500 to 2000 feet,
dropping to the valley floor in the northern Sacramento Valley.
Several inches of snow is forecast to the valley floor in Shasta
County and Tehama County. This snow at these low levels could
cause major travel delays as well as downed tree branches and
localized power outages. Snow levels will rise to around 3000 feet
by tomorrow afternoon, remaining locally down to 2000 feet in
Shasta county.
The trough axis will continue to deepen just off the California
coast tomorrow, stalling the cold front over the area.
Precipitation will continue through the day, though it will be
lighter than overnight. Then precipitation is expected to pick up
again overnight Wednesday into Thursday, heaviest along and south
of Interstate 80. This could bring renewed concerns for the LNU
Complex and SCU Complex burn scars, which is why the Flash Flood
Watch is through 4pm Thursday. Snow levels will generally be
between 3000 to 4000 feet, rising above 4000 feet during the day
Thursday. Showers will continue overnight Thursday and lighter through
the day on Friday, mainly over the higher elevations. -HEC
&&
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Cluster analysis is in good agreement troughing off the Pacific
Northwest Coast will continue into next week. This unsettled
synoptic pattern is typical for this time of year and will bring
beneficial moisture to the area. Another more impactful winter
storm could reach Northern California by early next week.
Preliminarily, we could see over an inch of rain for valley
locations as well as several feet of snow for higher elevations.
The euro ensemble is indicating a 100% chance of snow exceeding 3
feet for a large region over the higher elevations of the Sierra
including mountain passes. Anomaly tables are also hinting at the
possibility for some gusty winds with this system as well. There
is still uncertainty in the forecast so check back for updates.
&&
.AVIATION...
Widespread MVFR/IFR conditions develop across the Central Valley
between after 00Z Wednesday with IFR/LIFR developing over the
mountains associated with heavy rain and snow moves into the area.
Low snow levels with accumulating snow likely at KRDD and KRBL
beginning this evening. Increasing southerly surface wind gusts
35-50 kts, locally higher, after 03Z Wednesday.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 2 AM PST Friday for Burney Basin /
Eastern Shasta County-Central Sacramento Valley-Motherlode-
Mountains Southwestern Shasta County to Western Colusa County-
Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-
Shasta Lake Area / Northern Shasta County-Western Plumas
County/Lassen Park.
Blizzard Warning until 2 AM PST Friday for West Slope Northern
Sierra Nevada.
High Wind Warning from 8 PM this evening to noon PST Wednesday
for Carquinez Strait and Delta-Central Sacramento Valley-
Motherlode-Mountains Southwestern Shasta County to Western
Colusa County-Northeast Foothills/Sacramento Valley-Northern
Sacramento Valley-Northern San Joaquin Valley-Southern
Sacramento Valley.
Flash Flood Watch through Thursday afternoon for Northern San
Joaquin Valley-Southern Sacramento Valley.
&&
$$
Area Forecast Discussion
National Weather Service Tallahassee FL
1001 PM EST Tue Jan 26 2021
.UPDATE...
Only a few updates were made to the forecast tonight. Looking at
the latest satellite imagery, moist onshore flow will redevelop
along our coastal waters as a stationary front drifts slowly north
overnight. This will yield areas of fog across the area,
especially along the coastline where a marine dense fog advisory
is now in effect. Rain along the coastline will slowly diminish
before additional showers develop early Wednesday morning as
stronger forcing moves in from the west.
&&
.PREV DISCUSSION [741 PM EST]...
.NEAR TERM [Through Wednesday]...
Short wave ridging is building over the area in advance of the next
upper system...a well organized upper low which is quite evident
spinning over the southern Rockies this afternoon. Low level wind
fields have relaxed resulting in diminished shear late today and
widespread clouds and a marine layer have limited instability. Still
enough instability for an isolated severe storm over southern GA and
over the inland Big Bend but once we lose the sun things will
stabilize quickly. Precip focus will then shift to developing LLJ
that will spread inland overnight as the warm sector reasserts
itself. Will carry high PoPs centered on the I-10 corridor though
late evening then shift higher chances north thru AL/GA. Added
areas of fog to all zones and the potential exists for dense fog
closer to the coast.
The aforementioned next upper system will move thru the TN Vally
tmrw and drive a seasonally strong cold front through the area by
late afternoon. Llvl wind fields look to really respond ahead of
this feature, esply over our GA counties. We will likely have some
instability again, especially over the southern half of our area
with SBCAPE fcst over 1000 J/KG by recent HRRR runs. Severe weather
threat exists and the SPC recently upgraded us to a Marginal Risk
for Day-2. Best timing for severe weather looks a little earlier -
most likely in the 10A to 3p EST time frame.
.SHORT TERM [Wednesday Night Through Thursday Night]...
The cold front should be exiting or close to clearing our eastern
CWA at the start of the short-term. Lingering showers are possible
along the I-75 corridor and Big Bend Wed night. Cool and dry
conditions filter in behind the front under breezy northwesterly
winds, which will quickly drop low temperatures to the upper 30s/low
40s from northwest to southeast on Wed night/Thurs morning. Strong
cold-air advection is expected to keep high temperatures generally
below 60. A chilly Thurs night is on tap when most areas see
temperatures around freezing. With light winds and lingering low-
level moisture in place under high pressure, patchy frost will be
possible away from the coast in the pre-dawn and early-morning
hours.
.LONG TERM [Friday Through Tuesday]...
Cool and dry conditions prevail through Sat as we remain in a post-
frontal airmass and broad ridging temporarily builds over the
eastern US. The ridge should allow daytime temperatures to gradually
warm from mid/upper 50s on Fri to the 60s on Sat (lows in the
mid/upper 30s away from the coast).
As the weekend draws to a close, another shortwave trough is
expected to march east across the south-central US and trigger
surface cyclogenesis over the Midwest Sat night. The wave then lifts
northeast and drags a cold front across our area before clearing us
by Mon. Rain chances return late Sat, increase areawide on Sun, then
diminish from west to east Sun evening. There appears to be enough
instability over our waters and portions of the Tri-State Area to
support some thunderstorms, so included a slight chance. It is too
soon to determine if severe weather will be possible. Pleasant
weather concludes the period.
The increased moisture ahead of the aforementioned front will make
Sun the warmest day of the long-term (highs mostly in the low 70s.
Prior to frontal passage, low temperatures are forecast to be in the
40s and 50s. After FROPA, highs are expected to be in the 60s, with
lows in the upper 30s (except along the immediate coast).
.AVIATION...
[Through 00Z Thursday]
Ridging aloft will build over the area late today and overnight
with some decrease in convective coverage expected. Conditions
will be predominate IFR with a few VFR breaks this afternoon then
mainly IFR with some LIFR tonight with moist southerly flow off
the Gulf.
.MARINE...
A cold front draped over the southeast US has been producing
scattered showers and storms across mainly our westernmost waters
and coastal Panhandle this afternoon. This activity has made for
cautionary boating conditions in those zones today. The potential
for areas of fog also exists late tonight into tomorrow morning.
Held off on a Marine Dense Fog Advisory because of the uncertainty
with the nearby convection.
Convective activity is forecast to persist through Wed and shift
east with the progress of the front. Therefore, cautionary boating
conditions prevail today and tomorrow, with locally hazardous winds
and seas near thunderstorms. Once the front clears the area, strong
northerly winds filter in its wake, leading to Advisory levels Wed
night through early Thurs. Gale-force gusts will be a possibility as
well. Cautionary or borderline winds and seas are expected heading
into the weekend. Rain chances return on Sat night.
.FIRE WEATHER...
Scattered showers and thunderstorms will preclude any fire concerns
through Wed before a cold front clears our area to make for dry and
breezy conditions late Wed through Thurs. However, min RH values are
expected to remain above critical thresholds. Rain chances return
Sun evening. There is potential for areas of fog to develop late
tonight into tomorrow morning, followed by low dispersions in
southeast AL and our northern-tier GA counties in the afternoon.
.HYDROLOGY...
Through 18z Tuesday rainfall amounts have been heaviest
across South Walton, where rainfall amounts of 3-5 inches have been
common. Along the line of storms from near Ebro, FL to Colquitt, GA,
rainfall amounts of 1 to 2 inches have been fairly common. Radar
trends show some eastward progress to the line, and rainfall rates
have diminished some over the last couple of hours. Based on the
afternoon model guidance, an additional 1-3 inches of rain is
expected across the Florida Panhandle and into Southwestern Georgia.
Localized heavier amounts could lead to flooding, generally in urban
areas.
As rain tapers off tonight, another round of storms is expected on
Wednesday. However, these storms should be much more progressive and
only produce brief heavy downpours. As a result, any flood risk is
much less on Wednesday compared to Tuesday.
Riverine impacts should be minimal given the rainfall distribution
so far today and the expected amounts through the next 36 hours. The
Ochlockonee River will likely return to action stage, but with the
heaviest rain missing the Withloacoochee basin, there shouldn`t be
any river flood issues there.
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur (while following all local, state, and CDC guidelines) by
calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 65 77 41 57 33 / 70 60 10 0 0
Panama City 64 72 41 57 36 / 60 70 0 0 0
Dothan 63 72 38 54 32 / 60 70 0 0 0
Albany 62 71 38 55 31 / 50 80 10 0 0
Valdosta 64 75 41 56 34 / 50 60 20 0 0
Cross City 61 74 43 60 32 / 10 60 20 0 0
Apalachicola 63 73 42 57 37 / 40 70 0 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk until 4 AM EST /3 AM CST/ Wednesday for
Coastal Bay-Coastal Franklin-Coastal Gulf-South Walton.
GA...None.
AL...None.
GM...Dense Fog Advisory until 1 PM EST /noon CST/ Wednesday for
Apalachee Bay or Coastal Waters From Keaton Beach to
Ochlockonee River FL out to 20 Nm-Coastal Waters From
Ochlockonee River to Apalachicola Fl out to 20 Nm-Coastal
waters from Suwannee River to Keaton Beach FL out 20 NM-
Coastal waters from Mexico Beach to Apalachicola FL out 20
NM-Coastal waters from Mexico Beach to Okaloosa Walton
County Line FL out 20 NM.
&&
$$
UPDATE...Dobbs
NEAR TERM...Johnstone
SHORT TERM...IG3
LONG TERM...IG3
AVIATION...Dobbs
MARINE...IG3
FIRE WEATHER...IG3
HYDROLOGY...Godsey