Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/08/22
Area Forecast Discussion
National Weather Service Cleveland OH
1101 PM EST Fri Jan 7 2022
.SYNOPSIS...
A high pressure ridge builds eastward across the eastern Great
Lakes and Upper Ohio Valley through tonight. A weak warm front
will sweep north across our region on Saturday before a cold
front sweeps east on Sunday. Behind the cold front, a trough
should linger over and near the Great Lakes Sunday night into
Monday as another ridge attempts to build from the west.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
A ridge of high pressure continues to expand across northern
Ohio and Lake Erie. Snow showers remain across Cuyahoga County
where low level convergence between the backing flow at the
surface interacts with the northwest flow aloft. Snow showers
also continue in NW Pennsylvania where cyclonic flow remains and
moisture is a little deeper. We have been able to cancel the
winter weather headlines for Ashtabula and Crawford County PA
where snow is very light and some breaks are even developing in
the cloud field. The RAP shows residual moisture at 850mb
pulling out of NE Ohio through about 1 AM. Moisture depth will
be quite shallow overnight, dropping to 4K feet or less. A
westerly flow in this layer will focus snow showers back towards
East Cleveland/Euclid, then shifting into SW Lake County after
midnight. Additional accumulations will tend to be fairly light,
but given the high snow ratios, may add up to 1 to locally 3
inches if bands persist.
Previous discussion... High pressure aloft builds from the west
through tonight as a lake-aggregate surface thermal trough
weakens gradually in the eastern Great Lakes region. The
accompanying surface ridge continues building eastward over CWA
through this evening before cresting over our region overnight
tonight. As a result, fair weather and gradual clearing are
expected for most of our CWA. However, lake effect snow (LES)
will persist downwind of Lake Erie. The LES weakened somewhat
earlier this afternoon, apparently due to limited daytime
heating of surrounding land and slight boundary layer
destabilization disrupting lake- induced CAPE and LES
organization. However, latest radar trends indicate LES is
beginning to restrengthen and that trend is expected to continue
through most of this evening as lake- induced CAPE of about 300
to 500 J/kg and lake-induced equilibrium levels near 7kft to
10kft AGL persist and a predominantly WNW mean low-level flow of
cold and sufficiently- moist air continues. Moderate to strong
ascent should be maximized in a cloudy DGZ at times, resulting
in efficient production of moderate to heavy snow and snowfall
rates up to 1 inch per hour in the heaviest LES bands.
Through this evening, there are two corridors where the
heaviest and most-persistent LES is expected to be focused:
far-northeast and east-central Cuyahoga County, southwestern
Lake County, and much of Geauga County in OH, and eastern Erie
County in PA. Further, cyclonically-curved low-level flow should
allow an upstream moisture connection to Lake Huron and
associated heavier LES to target eastern Erie County, PA from
about nightfall to midnight tonight. These corridors of heavier
LES in northeast OH and northwest PA are expected to receive an
additional 3 to 6 inches of snow accumulation through tonight,
with the bulk of accumulation before midnight. Storm-total
snowfall should reach 6 to 12 inches or so in these areas.
Additional and lighter LES is expected elsewhere in/near the
snowbelt with lesser accumulations. During the predawn hours of
Saturday morning, the aforementioned ridge will allow lingering
LES to weaken considerably as lake-induced CAPE wanes via a
lowering subsidence inversion. In addition, the LES will shift
northward and eventually retreat over Lake Erie as the mean low-
level flow backs to southwesterly on the backside of the ridge.
The Lake Effect Snow Warning and Winter Weather Advisory remain
in effect until 7 AM EST Saturday. Lows tonight should range
from the teens in/near the snowbelt to the upper single digits
to lower teens elsewhere due to gradual clearing contributing to
greater radiational cooling.
Fair weather and mainly clear conditions are expected CWA-wide
on Saturday as we become positioned along the western flank of
the high pressure ridge at the surface and aloft. A weak warm
front will sweep north through our area, but the frontal passage
will likely be precip-free due to a rather dry atmospheric
column at that point. Low-level WAA will contribute to daytime
highs reaching mainly the mid to upper 30`s, but lower 30`s are
expected in parts of interior northwest PA where deeper
lingering snowpack will likely limit daytime heating. Moist
isentropic ascent-related precip should gradually overspread our
region from the southwest and west Saturday night as a trough
aloft approaches from the north-central U.S. and associated
surface cold front approaches from the Upper MS Valley.
Simultaneously, low-level WAA persists. Model soundings indicate
it will take some time for precip to overcome the dry low-
levels via the wet-bulb effect and reach the surface. In most
instances, vertical profiles of temperature and wet-bulb
temperature should support plain rain as the precip type.
However, precip may begin as a brief period of snow, sleet, and
freezing rain, especially in interior northwest PA, where a
developing and elevated warm nose may overlay a cold surface-
based layer before the layer moderates. Any snow, sleet, and ice
accumulations look to be minor. Low temperatures should reach
the mid 20`s to mid 30`s Saturday evening before readings
moderate via WAA overnight.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
There will be two impactful weather events to watch for in the short
term forecast period. The first one will be a strong cold front
moving across the region Sunday. We will likely see our "mildest"
temperatures Sunday morning in the upper 30s to around 40 degrees
ahead of the cold front. After the frontal passage around midday
Sunday, temperatures will slowly fall during the afternoon with cold
air advection. Rain showers will be likely along and ahead of the
cold front Sunday morning. Temperatures appear to be warm both near
the surface and aloft to support mostly cold rain showers. After the
front passes, any lingering post frontal precip will likely change
over back to snow in the afternoon. Temperatures will continue to
plummet Sunday night with 850 mb temperatures falling to around -17C
overnight. The global models are not picking it up well yet, but we
should start to see the lake effect snow machine come alive again
for the primary and secondary Snowbelt region. The mean low level
flow Sunday night will be between 270 to 290 degrees. The LES will
start out light for Sunday night.
The model guidance is showing a slight hint of a surface trough
developing near the lakeshore areas on Monday and the overall flow
from the surface to at least 700 mb is looking prime for more
organized lake effect bands Monday into Monday night with a mean low
level flow more west-northwesterly between 280 to 300 degrees. With
additional strong cold air advection and 850 mb temps falling to
-18C to -22C, the western basin of Lake Erie will be open for
business the Snowbelt areas of NE Ohio and NW PA. There also
appears to potential be a Lake Huron connection that may come
down across Lake Erie for NW PA as well by Monday night. With
that said and still some uncertainty 72 hours out, the
potential is increasing for another round of significant lake
effect snowfall for the Snowbelt Monday through Tuesday morning
with the emphasis Monday afternoon and night.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
High pressure will build over Ohio on Tuesday and shut down the
remaining lake effect. Temperatures may start out in the single
digits away from the Snowbelt areas Tuesday morning. High temps will
struggle to reach the upper teens and lower 20s on Tuesday. We will
likely see wind chill values below Monday night into Tuesday.
Southerly winds return with a warm up on Wednesday with the back
side of the exiting surface high pressure. Another vigorous mid
level shortwave will move across the Great Lakes region Wednesday
night into Thursday with more cloud cover and a chance for light
rain/snow showers. Another cold front may drop down through the area
later in the week.
&&
.AVIATION /00Z Saturday THROUGH Wednesday/...
MVFR ceilings with lake effect snow showers remain across the
snowbelt of NE Ohio and NW Pennsylvania. Snow showers are
expected to be mostly light at terminals although can not rule
out visibilites briefly dropping to IFR at CLE/ERI/YNG, mainly
through 03Z. Beyond that time, moisture really diminishes and
the coverage of snow showers is expected to follow. MVFR clouds
are expected to linger across the snowbelt through much of the
night, gradually clearing from the southwest through 12Z.
Elsewhere, pockets of MVFR clouds remain but will tend to
scatter out through 03Z.
Westerly winds will back to southerly overnight. Winds will be
light at most terminals overnight, increasing to 10-15 knots on
Saturday afternoon, with some locations gusting to around 20
knots.
Outlook...Non-VFR possible with widespread snow and/or rain
Saturday night into Sunday. A brief period of freezing rain is
possible Saturday night. Periods of lake effect snow with non-
VFR possible generally east and southeast of Lake Erie Sunday
night through Tuesday.
&&
.MARINE...
We will continue the Small Craft Advisories for the central and
eastern nearshore areas through the early evening hours with no
changes to headlines. Winds and waves will slowly decrease tonight
over the lake as high pressure is nearby. Southerly winds will
return and increase on Saturday on the back side of the exiting high
pressure system. Winds will be 10 to 20 knots again on Saturday.
Winds will shift more south-southwest by Saturday evening and
increase 15 to 25 knots. We may be close again to SCA headlines but
with an offshore flow Saturday night into Sunday morning ahead of a
cold front. A strong cold frontal passage will shift the winds from
southwesterly to west-northwesterly 15 to 25 knots on Sunday with
SCA likely Sunday through at least Monday night with gusty northwest
flow and higher waves near the lakeshore. Lighter winds are expect
by Tuesday with high pressure nearby.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Lake Effect Snow Warning until 7 AM EST Saturday for
OHZ011>013.
PA...Lake Effect Snow Warning until 7 AM EST Saturday for PAZ001-
002. PAZ003.
MARINE...None.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...KEC/Jaszka
SHORT TERM...Griffin
LONG TERM...Griffin
AVIATION...KEC
MARINE...Griffin
Area Forecast Discussion
National Weather Service Corpus Christi TX
951 PM CST Fri Jan 7 2022
.AVIATION...
For the 00z TAFs, generally IFR/MVFR ceilings will prevail
tonight through Saturday afternoon. Patchy light rain is expected
overnight over portions of the Coastal Plains, along with isolated
showers near the coast. In addition, patchy fog may occur.
However, dense advection fog could occur along the coast north of
Port Aransas. Scattered showers/isolated thunderstorms are
expected over the Coastal Bend during the mid morning/early
afternoon hours Saturday.
&&
.PREV DISCUSSION... /Issued 324 PM CST Fri Jan 7 2022/
SHORT TERM (Tonight through Saturday Night)...
A shallow cold dome about 1500 feet thick remained anchored over
the region today underneath moist isentropic ascent. Surface obs
at 3 PM revealed a coastal low developing east of Brownsville
with an inverted trough extending north along our open waters.
This low is forecast to drift slowly north this evening allowing
northerly winds to veer more E-NE and tug slightly richer
dewpoints (and milder temps) toward the coast with time. As such,
temps should rise a couple degrees tonight along much of the
Coastal Bend. Rain chances tonight will be greatest mainly east of
the surface low and its trough axis, although model soundings
show sharper isentropic ascent and deeper saturation area wide
resulting in some light precip. Fog is also likely at times
overnight, including over the bays and immediate coastal waters.
Feel the SREF fog probabilities are too low in this setup given
its 20+ NAM members which are severely downplaying low visbys
compared to the HRRR and RAP. Warm sector instability east of the
surface trough should keep some thunder intact mainly offshore
tonight, before this axis expands north to the Victoria Crossroads
by Saturday morning and becomes increasingly elevated.
Saturday is shaping up just as cloudy as today for all but our
far western zones, so temp recovery should be suppressed once
again - albeit not as strong as today. Opted to cool temps below
the NBM and GFS with values closer to the CONSSHORT, although the
raw NAM remains considerably cooler. Still, if temps can reach
the lower 70s in our NE zones tomorrow there should be enough
surface based instability realized for some deeper convection,
although probably not as robust as the GFS indicates (2000 J/kg).
SPC`s Day2 has the western edge of a marginal risk grazing
Victoria and Calhoun Counties which aligns well with a PWAT axis
around 1.8". As the surface low and attendant trough weaken
tomorrow and lift north of the Victoria Crossroads, surface winds
will slacken and become more southerly. However, additional
isentropic ascent with a minor shortwave trough in SW flow and a
nocturnal LLJ should sustain some rain chances tomorrow night
mainly offshore with primarily low stratus (and perhaps fog)
found inland.
LONG TERM (Sunday through Friday)...
Moisture lingers Sunday as the coastal trough lifts farther
northeast along the Texas coast, with slight rain chances through
Sunday morning mainly east of I-37. An approaching cold front is
then expected to move through South Texas Sunday evening. With PWATs
just shy of 1.5 inches ahead of the boundary and instability between
1500-2500 J/kg, will expect isolated to scattered showers and
thunderstorms to develop ahead and along the front. Cooler and drier
air will filter in behind the front allowing rain chances to taper
off from north to south through early Monday morning.
After temperatures on Sunday in the 70s, temperatures will cool into
the low-to-mid 60s Monday and Tuesday, with overnight lows Monday
night dipping into the low to mid 40s for most locations (exception
being the coast in the low 50s).
Onshore flow returns Wednesday as another weak coastal trough
develops, returning moisture to the region. At the same time, SW-NE
flow will develop aloft as a mid-level low/trough digs through Baja
California, eventually moving east toward the TX/OK Panhandles
Thurday night/Friday. As the trough moves east, it should bring down
a cold front early next week, but we will cross that bridge when we
get there. With all that going on combined with PWATs up to 1.5
inches, chances for showers are expected daily from Wednesday
through Saturday. Instability is lacking over the region, so most
activity should remain as showers, but would not be surprised for
any isolated thunder over the gulf waters. Best chances for showers
(although accumulation will be limited) will be on Thursday.
Temperatures will gradually warm through the latter half of the
week, with highs reaching back into the mid to upper 70s by
Friday.
MARINE...
Moderate to strong easterly flow will develop this evening north
of a coastal low and result in SCA conditions over the waters.
Scattered to numerous showers and some thunderstorms will move
north tonight and Saturday, before diminishing in coverage
Saturday evening. Easterly winds will taper to weak to moderate
levels by Saturday morning before turning more southerly as the
low reaches the northern coastal waters. Another round of moderate
to strong southerly flow should unfold Saturday afternoon over
the Gulf waters and continue Saturday night with SCA conditions
possible. Onshore flow will weaken Sunday afternoon ahead of an
approaching cold front. The cold front is expected to move across
the coastal waters Sunday evening with strong northerly winds to
develop. Advisory conditions are likely Sunday night through early
Tuesday morning. Winds weaken through the rest of the day on
Tuesday and become weak to moderate onshore flow by early
Wednesday. Scattered showers and isolated thunderstorms will be
possible ahead and along the front Sunday and Monday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 51 67 64 78 50 / 30 30 10 20 30
Victoria 49 74 64 77 48 / 50 50 20 30 10
Laredo 48 70 57 78 50 / 40 0 0 10 20
Alice 49 68 61 81 49 / 30 20 10 20 20
Rockport 54 70 66 76 51 / 50 50 20 40 30
Cotulla 45 70 55 80 48 / 50 10 0 10 10
Kingsville 51 68 62 79 50 / 20 20 10 20 30
Navy Corpus 56 68 67 75 54 / 50 40 20 30 30
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory until 2 AM CST Saturday For the following
zones: Coastal waters from Baffin Bay to Port Aransas out
20 NM...Coastal waters from Port Aransas to Matagorda Ship
Channel out 20 NM...Waters from Baffin Bay to Port Aransas
from 20 to 60 NM...Waters from Port Aransas to Matagorda
Ship Channel from 20 to 60 NM.
&&
$$
WC/87...AVIATION
Area Forecast Discussion
National Weather Service State College PA
1046 PM EST Fri Jan 7 2022
.SYNOPSIS...
An upper trough will lift out of the region and high pressure
will build in from the west overnight and Saturday. A deepening
upper trough will build southeast over the region early next
week, preceded by the passage of an occluded cold front Sunday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Falling inversion heights upon the approach of high pressure is
causing snow showers/flurries to dwindle late this evening, with
breaking clouds east of the Alleghenies. This trend should
continue overnight, with any additional accumulations over
Warren County less than an inch.
Breaking clouds, a diminishing wind and a fresh snow cover
should allow temperatures to fall below NBM guidance overnight,
with readings by dawn likely ranging from 5-10F over the
Alleghenies and 10-15F elsewhere. Latest RAP indicates low
single digit lows are possible over the north central mountains
and Laurels. Lingering stratocu could hold readings up across
northwest mountains.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Fair weather and light wind is expected Saturday, as surface
high pressure builds across the state. Model RH profiles
support abundant sunshine and GEFS 2m temp anomalies suggest
highs will remain a few degrees below average, mainly upper 20s
to low 30s. Forecast soundings indicate some very dry air just
above a weak inversion, a scenario which supports undercutting
NBM dewpoints.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
*Icy weather to precede coldest air of the winter season Sun-Tue
1036mb high pressure over CPA Saturday will gradually retreat
to the east ahead of an approaching trough, but maintain a cold
wedge along and east of the Alleghenies. Modest return flow
ahead of the mid-level trough and associated surface front will
spread WAA/precipitation into the area early Sunday morning.
The 850mb temps will climb well above 0C, but surface temps and
surface wet-bulb temps will likely remain below freezing, at
least initially, across much of CPA. This is likely produce a
period of light freezing rain Sunday morning (with some sleet
possible at onset) across most of central Pa. Model soundings
indicate improving conditions during the afternoon, as low
level cold air is scoured out ahead of approaching occluded cold
front. Surface high positioned southeast of Pa is not ideal for
cold air damming, so opted to go with the NBM temps rising
above freezing over virtually the entire area by mid afternoon.
Latest guidance continues to show around 0.25 inches of QPF
Sunday. However, ice accretion should be about half that, due
to rising temps and an eventual change to light rain. Orographic
enhancement appears likely to result in rainfall >0.5 inches
over the Laurel Highlands, where arrival of warm air and change
to rain should occur early Sunday morning.
Temps in the 20s Saturday night should prove favorable for ice
accretion on all untreated surfaces (not confined only to
elevated sfcs). This should make for hazardous travel conditions
Sunday morning. An advisory is impending for Sunday morning
with medium to high confidence in measurable ice.
The coldest air of the season will pour into the region through
early next week within a broad cyclonic flow pattern. This
pattern will trigger lake effect snow accums across the NW
Alleghenies and Laurel Highlands. We were keen to trend lower
than NBM for MaxT Monday and higher for wind gusts and lake
effect POPs. Expect single digit and subzero wind chills. After
Sunday, temps are not forecast to rise above freezing until mid
to late week. Therefore, residual/melted snow, slush, and
standing water will refreeze and could result in some slippery
conditions.
Lake effect snow showers should diminish on Tuesday, as high
pressure builds in. A decent warmup is then anticipated
Wednesday, as the high slips off the coast and return southwest
flow develops. Medium range guidance indicates a weak clipper
will track north of the state Wednesday night/Thursday, perhaps
accompanied by a few snow showers, mainly over the north. The
latest ECENS and GEFS both develop a deepening upstream trough
late next week over the northern plains, which may phase with
a southern stream shortwave lifting out of the southern
Rockies. Current guidance indicates the primary low will track
north of Pa, suggesting the potential of a wintry mix by early
next weekend.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
Updated the TAFS a bit here late this evening. Still some
narrow bands of flurries and light snow showers across the
region. Winds still gusting to at least 20 mph at times.
Earlier discussion below.
Main change to the 00Z TAF package, was to have a TEMPO
group into the late evening for snow showers across the
north and west, given the narrow snow bands on radar. Also
held onto gusty winds a bit longer, than guidance had
indicated.
Winds should die off by Saturday morning, and shift more
to the south. Expect VFR conditions across the area during the
day, as high pressure moves just to the east by late in the day.
A strong southwest flow of milder air will work into the
area. Still have to watch out for some mixed precipitation
by Sunday morning. The main issue early on will be freezing
rain, and some sleet, not so much as snow.
Outlook...
Sun...Lowering conditions bring restrictions in rain or wintry
mix.
Mon...VFR across the southeast, chance of snow showers across
the north and west.
Tue...Improving conditions.
Wed...Mainly dry with VFR conditions.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 1 AM EST Saturday for PAZ004.
&&
$$
SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Fitzgerald/Steinbugl
AVIATION...Martin
Area Forecast Discussion
National Weather Service Des Moines IA
543 PM CST Fri Jan 7 2022
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Friday/
Issued at 312 PM CST Fri Jan 7 2022
Key Messages:
-- Freezing drizzle and fog potential, cloudy Saturday
-- Chillier air, gusty winds behind a front Saturday night/Sunday
-- Upward temperature trend, mainly dry Tuesday through Thursday
Details: Upper level pattern from GOES-East water vapor imagery has
a trough over the Northeastern US back into the Great Lakes with a
weak ridge moving across the Rockies and another trough moving
ashore the Pacific Northwest. Over Iowa, there has been a band of
clouds slowly moving eastward marking the beginning of low level
warm air advection (WAA). The effects of this WAA along with the mid-
level ridging arriving will not be felt today, but tomorrow.
Further, as the surface high pressure moves off to the southeast
this afternoon, the pressure gradient will tighten over the state
ahead of surface low pressure approaching from the northern Rockies.
This afternoon, observations across central Nebraska and South
Dakota are showing sustained winds of 15 to 30 knots and guidance
shows that these breezy conditions will arrive this evening and
continue into Saturday. While it will be a cold night -- though not
as cold as last night -- and breezy, wind chill values will stay
largely above/warmer than -20F to not need any wind chill headlines.
The winds, however, will bring low level moisture back into the
state. This moisture is visible in satellite imagery as the stratus
clouds over southern Texas this afternoon, which 12z HREF low level
clouds shows arriving/developing northward as early as daybreak
Saturday. Cross sections show an elevated, very thin layer of high
saturation just below 850mb, which is likely a passing area of
stratus. The main batch/persistent stratus will likely arrive toward
and after mid-morning and that is when the forecast ramps up cloud
cover. Cross sections and soundings from the NAM, GFS, RAP, and HRRR
show that the moisture depth with the morning and afternoon
saturation has increased and is around or a little above 1km. So
moisture depth is just sufficient for drizzle, which would be
favored given soundings showing no ice introduction aloft. There is
appreciable lift and with shear in the low levels allowing for
collision coalescence, have coordinated with neighbors to add
PoPs into our southeastern forecast area. Surface temperatures
will be warming, but will be starting from well below freezing so
likely much of this should end with freezing on contact and thus
freezing drizzle. If the depth of boundary layer moisture
continues to increase or advects faster northward, drizzle or
freezing drizzle would be possible toward I-80. Highs will
certainly be warmer than today and be a minimum of 15 degrees
higher, which is conservative and places that have sunshine,
particularly western into parts of northern Iowa, may be even
warmer.
The freezing drizzle will quickly come to an end as a cold front
associated with the surface low, which will have tracked from the
northern Rockies into the south central Canadian prairies, comes
crashing through the state late afternoon and evening. This will
result in gusty breezes from the northwest developing, which will
bring in chillier and drier air. As the backside of the broad mean
trough axis moves east on Sunday, a shortwave trough will arrive on
the backside. There is some low level QG convergence paired with the
left exit region of an upper level, 160 knot jet streak that is
moving southward out of Canada. Deterministic models have some
light QPF with most brushing our northeastern area if not
northeast of our forecast area. Out of the 0z/6z ensembles, GEFS
is the farthest southwest, which lines up with its stronger
forcing and the deterministic that is the farthest southwest with
its light QPF compared to other models. The bulk of the other
ensemble members from the 6z/12z CMC and ECMWF and now the 12z
GEFS are farther to the northeast. Thus, will keep PoPs for light
snow/very little accumulation over our northeastern forecast area
Sunday night into early Monday.
For next week, temperatures become milder/above normal with mid-
level flow varying from northwest to westerly as at least one
shortwave trough passing around midweek. 00z ECMWF extreme forecast
index is showing about 70 to 80% of its ensemble members having a
signal for a very warm Wednesday and Thursday (compared to the 20
year model climatology) over Siouxland (so not all of Iowa). NBM is
catching up to this warm signal compared to all available guidance
with the latest NBM iteration within the 25th-50th percentile on
Wednesday and now above the 75th percentile on Thursday. Certainly
will not deviate away from initial National Blend of Models this
far out given possible pitfalls, but highs this cycle are in the
40s to near 50 degrees over western Iowa. Outside of the
temperatures, deterministic models show an upper level pattern
that has a cutoff low over Baja California early to middle of next
week that will open up as it lifts toward the region. A
southeastward moving shortwave trough will pass through the region
before this, which could bring light precipitation around
Wednesday. This is only shown in a few ensemble members, but could
spoil the upper end of the mild temperatures. Otherwise, as the
cutoff low phases with a northern stream wave late next week with
its evolution varying amongst the global models, there is a signal
for a more widespread precipitation event across the region.
&&
.AVIATION.../For the 00Z TAFS through 00Z Saturday evening/
Issued at 543 PM CST Fri Jan 7 2022
Main challenges will be increasing wind/LLWS along with lowering
cigs to MVFR/IFR as low level stratus advects northeast with time
into Iowa. Still assessing the chances for fog impacts as well as
patchy fzdz impacts during the morning/afternoon hours Saturday.
HRRR continues to increase fog threat 12-18z across the region and
also some risk of patchy fzdz in the southeast nearer KOTM from
17z- 23z. Will monitor trends for next update at 06z. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Ansorge
AVIATION...REV
Area Forecast Discussion
National Weather Service Goodland KS
716 PM MST Fri Jan 7 2022
.UPDATE...
Issued at 713 PM MST Fri Jan 7 2022
Added patchy fog/freezing across eastern portions of Yuma county
and a majority of Dundy county. Guidance continues to indicate a
narrow corridor of fog development. HRRR forecast soundings around
Wray, Colorado also indicate a brief window of saturation which
would support the development of fog. The scenario seems plausible
given the recent snowfall and any potential minor melting that may
have occurred today.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 156 PM MST Fri Jan 7 2022
Temperatures flip flop a bit during the short term period with
the passage of a low pressure trough before the amplifying upper
level western U.S. ridge moves east of of the Rockies and
conditions remain warm and dry through next week.
Sunny skies and warmer south winds have been eating away at the
snow cover across the forecast area today. Expect that trend to
continue on Saturday. The colder area of surface high pressure
continues to push east ahead of a deepening lee surface trough in
advance of the upper trough that is expected to move east of the
Rockies by late Saturday. The surface trough consolidates into a
surface low that moves across the Texas panhandle region and into
the southern plains Saturday evening into Saturday night. The
dynamics with the upper trough remain behind the cold front that
moves across the area. This may create an area of a light rain
and snow mix that changes over to all snow Saturday evening that
extends eastward onto the plains of Colorado from Palmer Divide
region. Do not expect any appreciable precipitation with this
progressive system as it moves eastward across the forecast area
Saturday night. The main effect of this system will be to bring
cooler temperatures to the forecast area on Sunday as high
pressure moves in behind the front. That high pressure area moves
east of the forecast area Sunday night.
.LONG TERM...(Monday through Friday)
Issued at 155 PM MST Fri Jan 7 2022
A fairly quiet weather pattern is in place for much of the extended
forecast. The period begins with northwest flow aloft over the
Central High Plains and a ridge building over the western CONUS. an
upper trough extends from Minnesota to New England and south to
Ohio. Through the day, models have a closed low developing just off
shore of Southern California. This storm system will be something
to keep an eye on heading into the latter half of the week.
Expect a gradual warming trend through Wednesday afternoon with
highs returning to the mid-50s across much of the area in the
afternoon. Overnight lows will be in the teens and 20s.
The pattern transitions to a split flow situation over the course of
the week with the ridge remaining over the Central High Plains. The
storm system in the Pacific is expected to trek across the Desert
Southwest before making its way into Texas, Oklahoma and Kansas.
Models are bringing in some PoPs to the area, however, low
confidence persists in the possibility of receiving precipitation
from this system given the current expected track. This will be
something to monitor as we move into Thursday and Friday.
High temperatures Thursday and Friday will be in the 50s. Lows will
be in the 20s. Cooler air filters in on Friday with highs only in
the 40s and lows back to the teens.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 416 PM MST Fri Jan 7 2022
VFR conditions are anticipated throughout the duration of the TAF
period at both KMCK and KGLD. LLWS is expected for KGLD from
02-06Z and KMCK from 04-08Z due to a southwesterly jet. Surface
winds are expected to be similar to last night as breezy to gusty
winds up to 20 knots develop. A few runs of guidance develops low
stratus/fog over SW portions of Nebraska which seems plausible
given the recent snowfall. Confidence in this is to low at this
time to include in TAFS but will be monitored through this TAF
period.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...TT
SHORT TERM...LOCKHART
LONG TERM...AW
AVIATION...TT
Area Forecast Discussion
National Weather Service Wilmington NC
1008 PM EST Fri Jan 7 2022
.SYNOPSIS...
High pressure will bring cool and dry weather to the area tonight
and Saturday. Temperatures will warm again on Sunday ahead of an
approaching cold front. The front will move through Sunday night
into Monday morning with rainfall likely. Cold arctic air will
settle across the area Tuesday and Wednesday in the wake of the
cold front.
&&
.UPDATE...
Bumped lows tonight down in some areas, mainly typical cold
spots, based on current conditions. Not anticipating calm winds
tonight, but very dry air (dewpoints in the low to mid teens in
places) will continue advecting in from the north. HRRR in
particular is depicting this well. The low dewpoints and light
winds will allow for at least some radiational cooling. Lows
anywhere from lower 20s to upper 20s for most of the area.
&&
.NEAR TERM /THROUGH SATURDAY/...
Primarily a temperature forecast with a nearly dry column in place,
flow aloft becoming zonal, and Canadian high pressure building into
the area at the surface. During Saturday the center of the high is
expected to migrate over VA/NC maintaining cool temperatures. In fact
the highs on Saturday will be about 5F below normal even with full
sun. Much lighter winds expected tonight, and during Saturday given
the weaker pressure gradient with the high moving nearly
overhead.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
Surface high pressure in the mid-Atlantic states exits stage right
into the Atlantic, setting up return flow. SSW flow gets
considerably deeper this period, causing a brief warming trend.
Saturday night, lows dip down to below freezing inland to the mid
30s at the coast. Increasing cloud cover on Sunday, as an Alberta
Clipper system brings a cold front to the area. Precipitable water
surges to near an inch Sunday afternoon, and pre-frontal warming
reaches a peak, with highs in the upper 60s to near 70. Rain chances
increase quickly in a west to east fashion by Sunday
afternoon/evening. Forecast rainfall totals have actually ticked up
a little with this update, which is rather rare for a clipper
system, especially considering the parent low surges northeastward
after it nears the Great Lakes region. Due to lack of forcing,
maintaining some skepticism here, though there is plenty of moisture
to work with. Sunday night lows only hit the mid-to-upper 40s.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Cold front will start to push offshore by Monday morning, with rain
chances expiring in the late AM hours. High pressure quickly builds
in, and the front brings some of the coldest air we`ve seen this
season. Monday`s high temperature (mid 50s) will come in before
sunrise, with temperatures decreasing throughout the daytime hours.
Forecast stays predominantly dry from here on out. Look for highs in
the 40s Tuesday and Wednesday, with lows well into the 20s Monday
night. Forecast continues to show lows in the teens in the usual
cold spots Tuesday night. Temperatures start to rebound back to near
seasonal norms towards the end of the work week.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
VFR through the valid TAF period. North to northwest winds
have weakened and no longer seeing any gusts. Light northerly
flow overnight will become northeast Sat. Limited moisture
through Sat eve will keep skies clear.
Extended Outlook...VFR continues. Conditions then deteriorate
Sunday night as rain and lowering CIGs arrive with the next cold
front.
&&
.MARINE...
Through Saturday...Maritime conditions will continue to slowly
improve as high pressure builds across the area tonight through
Saturday. As the center of the high migrates by north of the waters
the flow will veer from a northerly direction to the NE tonight,
then NE to E during Saturday. Speeds are expected to be around 15
knots through much of tonight, then 10-15 kt or less during
Saturday. Seas will initially start at 3-5 ft, to around 2 ft
nearshore given the offshore trajectory. During Saturday expect seas
to average 3 ft.
Saturday Night through Wednesday...SSW flow at 15kts starts building
in through Sunday, as a cold front approaches. Seas at 1-2ft quickly
build to 3-4ft throughout this time. After the front passes by
Monday morning, winds veer to the north, remaining like that through
Tuesday. Winds are breezy at 15-20kts, but for now, remain below
Small Craft Advisory thresholds. If an advisory is needed, it would
only be for a few hours in the Monday night - Tuesday morning
timeframe. Seas hold rather steady at 2-4ft. By Wednesday, winds
veer slightly to the northeast, finally decreasing to around 10kts.
Seas follow along with the decreasing trend, coming down to 1-3ft.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...ILM
UPDATE...III
NEAR TERM...SRP
SHORT TERM...IGB
LONG TERM...IGB
AVIATION...III
MARINE...IGB/SRP
Area Forecast Discussion
National Weather Service New Orleans LA
815 PM CST Fri Jan 7 2022
...EVENING UPDATE...
Performed a quick gridded forecast update this evening to match up
with observations and satellite trends. GOES-16 Night Fog Channel
Diff continues to illustrate a layer of low clouds generally
along and south of the I-10/12 corridor from right near Baton
Rouge on east. The 00Z KLIX RAOB was launched right under this
canopy revealing ceilings around 2600ft AGL, but remains
relatively thin in vertical depth to only around 3500ft with very
dry air sampled above. Low-level winds will continue to pick up
throughout the overnight hours, helping to drag these clouds
north into daybreak Saturday. No adjustments needed for low
temperatures Saturday morning as the deterministic NBM lies
generally in the warmer 75th percentile of spread, especially in
areas already underneath clouds where temperatures will be much
slower to fall and bottom out warmer. Otherwise, far northern
areas will continue to drop off faster earlier but with clouds
spreading all the way north likely after midnight, this will slow
temperatures down some as well.
We will see a warm front surge northeast during the day on
Saturday, starting out with scattered showers over marine areas
mid to late morning. Recent trends with the HRRR depict enough
convergence/isentropic lift and building warm-sector instability
to support a messy cluster of cells across coastal SE LA and
adjacent marine areas. Can`t rule out a few stronger storms over
coastal areas Saturday afternoon/evening, to a few severe storms
over marine zones. H5 temperatures in the -12 to -14C range will
support hail in any taller updrafts. Can`t rule out some
waterspouts for cells more rooted near the surface near the
boundary location or within the warm sector, but anything further
north of the boundary forced by isentropic ascent will stay
elevated and become more stratiform/shower-y up to central and
northern areas. Any lingering diurnally-driven convection over
coastal areas will dissipate shortly after sunset. KLG
&&
PREV DISCUSSION... /issued 333 PM CST Fri Jan 7 2022/
SHORT TERM (Saturday through Monday)...
A fast moving vorticity max will slide up from south Texas and
move through the forecast area tomorrow into tomorrow night.
Strong positive vorticity advection and favorable jet dynamics
will provide enough forcing in the mid to upper levels to induce
both increased cloud development and convective activity by
tomorrow morning over coastal portions of Southeast Louisiana. The
cloud cover and convection will then spread inland and impact the
entire CWA by tomorrow afternoon as the parent vorticity max
moves through Louisiana and Mississippi. Model sounding analysis
indicates that a marine layer influence will keep the low level
airmass fairly stable, but lapse rates between 3 and 6km will be
very supportive of elevated convective development through the day
and even into tomorrow night. This elevated convection will
produce heavier downpours and lightning strikes. A fair degree of
storm relative helicity will also be in place, and there could be
some decent mesocyclonic development aloft. Fortunately, the
stable layer near the surface will prevent any thunderstorms from
becoming severe. At most, some of the strongest convection could
produce sub-severe hail tomorrow afternoon. Temperatures will be
warmer than normal with readings climbing into the upper 60s and
lower 70s after a cool morning in the 30s and 40s. The surge of
moisture into the area tomorrow night will keep temperatures very
warm in the upper 50s and lower 60s.
On Sunday, a positively tilted northern stream trough axis will
slide from the Southern Plains through the Lower Mississippi
Valley and then into the Southeastern states. This elongated
trough axis will induce frontogenesis over the Southern Plains,
and this cold front is expected to sweep through the forecast area
late Sunday into Sunday night. Although the upper level support
will begin to decline as jet dynamics become less favorable, there
should still be sufficient low to mid-level forcing along the
cold front to induce convective activity from late Sunday morning
through Sunday evening. Model sounding analysis indicates a very
similar set up in terms of dynamics to that seen on Saturday.
Strong directional shear will be in place with SRH values of 200
to 300 m2/s2, but speed shear will be lacking due to the weak jet
dynamics aloft. Thermodynamics should be very supportive of
convective development as low level lapse rates improve to around
6.5C/km and MLCAPE pushes 1500 J/KG. Given these parameters, some
deeper surface based convective cells will be possible from late
Sunday morning through Sunday evening, and some of these cells
will likely develop rotation. At this time, the main concern
will be for a few tornadoes to develop in the deepest and most
persistent convection. Temperatures will remain very warm on
Sunday with highs a good 10 to 15 degrees above normal in the
middle to upper 70s.
The cold front will begin to push through the area Sunday evening
over northern and western zones and then fully clear the CWA by
late Monday morning as the front sweeps into the northern Gulf.
Lingering thunderstorm activity is expected Sunday evening, but
the band of stronger storms will be shifting into the coastal
waters by late Sunday night into early Monday morning. Behind the
front, winds will increase from the north and temperatures will
begin to sharply fall. Lows by Monday morning should cool into the
40s and lower 50s across the area with the coldest readings in the
low to mid 40s expected over parts of Southwest Mississippi.
Monday itself will be a cool day with gradually clearing skies
expected from north of south. Highs will struggle into the upper
50s and lower 60s. The combination of clear skies and light winds
on Monday night will allow temperatures to plummet into the 30s
and lower 40s. Some areas of Southwest Mississippi and parts of
the Northshore could see a light freeze late Monday night.
LONG TERM (Tuesday through Friday)...
Deep layer ridging will be in firm control of the region on
Tuesday and Wednesday. Strong subsidence will dominate the area on
Tuesday with clear skies expected. By Wednesday, some return flow
in the low levels could produce scattered strato-cumulus
development. Further moisture advection into the area Wednesday
night will likely produce an extensive stratus deck across the
entire CWA. Temperatures will begin to modify as the 925mb thermal
trough axis shifts to the east with readings warming from the
upper 50s on Tuesday into the lower to middle 60s on Wednesday.
Lows will remain colder than average Tuesday night, and another
light freeze will be possible over coastal and southwest MS along
with parts of the Northshore near the Pearl River. The increased
low level moisture advection and expected stratus deck on
Wednesday night will keep temperatures warmer in the 40s and lower
50s.
The ridge axis is expected to break down on Thursday as a fast
moving southern stream shortwave trough axis slides into the
region. There are some timing differences with the trough axis,
and have opted to stick with the ensemble based NBM solution for
this timeframe. As a result, the forecast calls for near to
slightly above normal temperatures each day in the middle to upper
60s. This solution also suggests a fairly dry day on Thursday with
overcast skies and some very isolated shower activity taking
place. The main thrust of the trough axis is forecast to move
through on Friday, and higher POP of 30 to 40 percent is currently
forecast. At this time, sounding profiles from the ECMWF and the
GFS indicate a saturated sounding with moist adiabatic lapse rates
and little in the way of instability. As a result, rain is
expected, but thunderstorm are not in the forecast at this time.
AVIATION (00Z TAF DISCUSSION)...
Latest obs/satellite trends indicate a low stratus/stratocu deck
generally along and south of I-10/12, with CIGs ranging right
around 2kft AGL. This has led to MVFR flight categories for
terminals in this vicinity. Expect these clouds to slowly spread
north tonight in response to return flow in the low-levels, and
have approx timed northern terminals for a consensus of guidance
through daybreak. Low clouds may persist beyond daybreak Saturday
morning and into the afternoon hours for a few locations, with
VFR/MVFR flight categories expected to persist. By late
morning/afternoon, spotty light showers across marine areas will
spread north and east inland throughout the day. For now,
introduced VCSH at the end of the forecast for select TAF sites to
account for terminals with better rain chances. Otherwise, expect
a mix of MVFR/VFR flight categories due to low clouds outside of
any shower activity Saturday afternoon and evening. KLG
MARINE...
A period of increased gradient flow and rougher seas is expected
through early next week. Initially, a strong pressure gradient
between a high to the east of the area and a strengthening low to
the west will produce onshore flow of 15 to 20 knots and choppy
seas of 3 to 6 feet through Sunday. After the low pulls to the
east, a cold front will push through the area Sunday night. Strong
cold air advection over the warmer waters will allow winds of 20
to 30 knots to mix down to the surface resulting in a prolonged
period of small craft advisory conditions from Sunday night
through Tuesday. Conditions should begin to improve on Wednesday
as a surface high becomes more centered over the waters and
gradient flow relaxes below 15 knots.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 38 70 60 75 / 0 20 50 100
BTR 43 70 62 78 / 0 40 60 90
ASD 41 71 60 78 / 0 40 50 80
MSY 49 71 64 78 / 0 50 50 80
GPT 43 68 60 72 / 0 20 40 80
PQL 40 68 58 74 / 0 10 30 80
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory from midnight tonight to 6 PM CST Saturday
for GMZ550-552-570-572.
MS...None.
GM...Small Craft Advisory from midnight tonight to 6 PM CST Saturday
for GMZ552-570-572.
&&
$$
Area Forecast Discussion
National Weather Service Spokane WA
356 PM PST Fri Jan 7 2022
.SYNOPSIS...
Windy conditions will continue across most of the region with
gusts of 40 to 50 mph with locally higher gusts possible over
southeast Washington into north-central Idaho. Quieter and more
seasonal weather will arrive over the weekend and persist into
early next week. Then, toward the middle of next week
precipitation chances rise, which may include a mixture of
precipitation types.
&&
.DISCUSSION...
Rest of this afternoon and overnight...The main weather of consequence
during this time period will revolve around the cold front
currently sweeping through the Inland NW. As of 2pm, the surface
analysis depicted a 987 low over extreme SE BC with pressure rises
moving across the WA/ID border. These pressure rises are
indicative of the cold frontal position which is moving steadily
eastward. The cold front will do several things during this period
* Winds: The strongest winds are likely currently occurring over
most of eastern Washington and north-central Idaho right now or
will shortly. Thus far we seen gusts generally in the 45-55 mph
range over southern portions of the Palouse, higher elevations
surrounding the LC Valley, near the Blue Mountains, and higher
Cascade ridges. Pullman briefly touched 58 mph, with a nearby
report on the Camas Prairie of 62 mph. Over the Cascades, we saw
some gust of 80-88 mph over the higher ridges and peaks. The
only locations which might not have peaked are around the
Wenatchee Area (where the winds have been less than 5 mph) and
on the Waterville Plateau (where obs are scarce but we have seen
evidence of drifting snow) . The cross-Cascade pressure
gradient continues to grow so we expect the winds will
inevitable intensify at these locations. If the HRRR model is
right (it has been consistent which boosts confidence) we should
winds of 50-60 mph developing on the Waterville Plateau during
the next couple hours. Consequently our current batch of wind
highlights which include advisories for most locations south of
Hwy 2 in Washington and for north-central, and warnings for
extreme southeast Washington, higher terrain near the LC Valley,
Camas Prairie, and Waterville Plateau look plausible. The
strongest winds are likely during the next couple hours and then
should decrease through the evening into the overnight hours.
* Snow: Most of the precipitation will be waning shortly as the
drier air filters in behind the cold front. The main exceptions
will occur near the Cascade Crest, where there is a possibility
of a Puget Sound Convergence Zone occasionally intercepting
portions of Chelan County. Typically these dont spread very
far east of the crest, but there are some models which briefly
bring it as far east as Wenatchee. The odds arent good
though. Snow is also likely to continue over the Idaho Panhandle
mountains, initially near the cold front and then we expect
banded snow showers to form through the evening into the
overnight hours. In any case, the snow accumulations will range
from 3 to 6 inches over these locations with little if any in
the valleys. The current batch of winter storm warnings will be
allowed to expire at 4 pm.
* Temperatures: There is good model agreement that the dewpoints
behind the front will plunge into the single digits north of
Highway 2. This will combine with clear or clearing skies and
much lighter winds than elsewhere across the region. Combine
this with fresh snow, lots of it, and it sets up the perfect
recipe for very cold temperatures. The NBM temperatures in these
locations seem a little too warm and have generally undercut
them by quite a bit. Right now we forecast lows in the single
digits above zero. But it very well could turn out some
locations dip below zero. Meanwhile farther south and east, the
winds are expected to keep up with the premise of cloud cover
which should lead to appreciably milder temperatures.
Nonetheless if these areas clear our forecast lows in the mid to
upper 20s will prove too mild.
Saturday...The weather will turn much quieter as an upper level
ridge begins to buckle into the region. Although this will be a
largely dry pattern for most, there is a weak disturbance which is
forecast to hit the Cascades by midday and sweep into north Idaho
by afternoon. This will spread more snow into the Cascades and
north Idaho, however amounts will generally be 1 to 3 inches over
the mountains with only minimal accumulations in the valleys of
north Idaho. Winds will also be much weaker tomorrow, but it wont
exactly be calm. Over most of the eastern third of Washington into
NC Idaho we are forecasting winds of 5-15 mph with gusts of 20-25
mph. High temperatures will largely be in the upper 20s to mid
30s. fx
Saturday night through Thursday: Upper level ridging will move into
the region late Saturday with the last showers shutting off over the
mountains Saturday afternoon. This will bring us into an overall
quieter and drier period for the late weekend into early next week.
Systems moving into the northern British Columbia coast will work to
flatten the ridge Tuesday which would allow a weak to moderate
atmospheric river to take aim at the northern Washington coast. With
westerly flow aloft, the main threat for precipitation looks to
remain for the Washington Cascades and the northern Idaho Panhandle.
Strong warm air advection beginning Tuesday afternoon will help
raise temperatures Tuesday and Wednesday with Wednesday looking to
be the warmest day of the upcoming week. At lower elevations, there
is much lower confidence in the precipitation forecast. While the
threat for precipitation remains low, the warm advection could
provide some extra lift and increase chances for snow, rain, and
freezing rain. During the overnight hours, surface temperatures look
to be below freezing Tuesday and Wednesday nights with a warm nose
aloft. This will increase chances for freezing rain mainly for the
Cascade valleys and the lower Basin. This will have to be monitored
over the next few days. Otherwise, fog looks to be possible
overnight and early morning. Temperatures will be in the upper 20s
and low 30s Sunday and Monday and warm into mid to upper 30s with
lower elevations warming into the low 40s by Wednesday. Another
system looks to move into the Pacific Northwest late Wednesday into
Thursday, but models aren`t quite in agreement yet on how this
system will evolve. vmt
&&
.AVIATION...
00Z TAFS: The main challenge for tonight`s forecast will be the
winds behind the passing cold front. We suspect the strongest
speeds over the TAF sites will be from now through 03z with gusts
of 40-45 kts possible at PUW with lighter amounts elsewhere. With
the stronger winds surfacing, the risk of low-level wind shear has
been minimized, except for EAT where the surface winds are only
gusting to around 20 mph, although the winds just off the ground
are 50-60 mph. The winds should subside for all locations
overnight. The the main challenge is what to do with the clouds.
For locations near the WA/ID border, we suspect variable MVFR to
VFR conditions are possible through the evening with some
improvements thereafter. How long the improvements will last is
questionable though. All the hi- res models are showing an
increasing amount of low-level moisture and lighter winds.
Meanwhile a strong high pressure ridge will build over the region
suggesting an increasing threat of low clouds and possible
MVFR/IFR conditions. It might hold off until after this TAF
period, but the risk will increase markedly thereafter as a
widespread stratus deck is expected to form. fx
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 24 31 21 32 17 28 / 0 0 0 0 0 0
Coeur d`Alene 24 31 23 34 17 32 / 20 10 10 0 0 0
Pullman 26 31 21 31 19 30 / 10 0 0 0 0 0
Lewiston 30 37 24 35 22 34 / 30 0 0 0 0 0
Colville 11 28 17 31 13 31 / 0 0 10 0 0 0
Sandpoint 23 30 24 33 19 32 / 40 20 20 0 0 0
Kellogg 26 31 23 37 20 37 / 60 50 10 0 0 0
Moses Lake 20 31 19 30 16 27 / 0 0 0 0 0 0
Wenatchee 21 32 20 28 21 30 / 10 0 0 0 0 10
Omak 15 28 19 29 20 30 / 0 0 10 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Wind Advisory until 7 PM PST this evening for Coeur d`Alene
Area-Idaho Palouse.
High Wind Warning until 7 PM PST this evening for Lewis and
Southern Nez Perce Counties-Lewiston Area.
WA...Wind Advisory until 7 PM PST this evening for Central
Chelan County-Moses Lake Area-Spokane Area-Upper Columbia
Basin-Washington Palouse-Wenatchee Area.
High Wind Warning until 7 PM PST this evening for Lower Garfield
and Asotin Counties-Waterville Plateau.
&&
$$
Area Forecast Discussion
National Weather Service Pocatello ID
807 PM MST Fri Jan 7 2022
.UPDATE...Have allowed the Winter Weather Advisory to expire.
Radar shows scattered showers moving through generally the
southern half of the forecast area. Additional accumulations
should remain light. Gusty winds remain the concern, with mid-
evening winds still gusting over 40 mph across the middle of the
Arco Desert, and along portions of the eastern highlands,
impacting mainly US 26, ID 32 and ID 33. Indications are for winds
to gradually drop off through the overnight, so there could still
be some locations with lingering blowing snow concerns. Otherwise
rest of forecast remains on track. DMH
&&
.PREV DISCUSSION... /issued 225 PM MST Fri Jan 7 2022/
SHORT TERM...Today and Saturday.
A cold front, the last system for a while, is moving through the
area. Winds are moderate to strong, (mainly for our northern
areas), sustained 20 to 30 mph with gusts to 35 to 45 mph with
localized areas gusting to near 55 mph. Main areas are the Arco
Desert, Upper Snake Plain, Ridgetops, Antelope Flats, and Botts
between Sugar City and Driggs. Winds stay elevated (sustained over
20 to 30 mph) through late afternoon/early evening (5 to 7 PM)
and then start gradually declining through the evening into mid
Saturday morning. Snow levels are 5000 to 6000 feet with the higher
snow levels ahead of the front along our eastern areas by the
Wyoming line. With warmer temperatures there has been a lot of low
level snow melt off from Pocatello to Blackfoot and the southern
Eastern Magic valley by Burley. Localized minor ponding in low
lying areas is possible through this evening. Expect temperatures
to drop below freezing by morning with this cold front. See hydro
discussion for more detail. The best areas for snow this afternoon
into early evening are the western Sawtooths, the eastern portion
of the mountains near Island Park, and the Wasatch mountains with
4 to 8 inches of snow with mountain peaks getting around 12
inches. The Big Holes and the Caribou range look to get 2 to 5
inches with around 8 inches for mountain peaks. Advisories remain
in place for all these areas until 8 pm this evening due to snow
and wind. Blowing and drifting of snow, especially for higher
elevations, will be problematic for travel. The snow level will
drop and light valley snow is possible behind the frontal boundary
the afternoon into early evening. Little to no snow accumulation
is expected below 5000 feet. The one exception may be the Portneuf
Gap to Inkom. This area could get around 1 to 2 inches of snow
down low late this afternoon into early evening. There is some
patchy fog possible tomorrow morning but will be very limited due
to winds. TWyatt
LONG TERM...SUNDAY THROUGH NEXT FRIDAY...
Long-range models continue to support a longwave ridge of high
pressure building in across the wrn half of the United States
throughout the upcoming week, with the odds currently favoring a
long-duration, organized break in our active wx pattern. Many
locales should pull off daily rounds of sunshine mixed with passing
clouds, and winds should remain fairly light. As such, no wx
parameter is currently lighting up on the ECMWF EFI (Extreme
Forecast Index), supporting this low-impact scenario. That said,
confidence is highest Sun/Mon, before a low pressure system impinges
on the ridge over the PacNW, and another stalling out near srn CA.
Models currently keep the CA low too far south to affect our local
CWA, but we`ll have to watch the nrn low, as well as a third low
potentially approaching the region by Thurs and trying to either cut
through or ride over the ridge. Deterministic model agreement is
very poor on the evolution of all of these features, while blends
bring in some light PoPs Thu with both the EC and Canadian offering
slightly different scenarios that could result in some rain/snow
that day. All in all, stay tuned as we monitor these features, but
high-impact wx is not currently expected. High temps each day should
generally run within about 5 degrees of climatology for most sites,
generally mid-20s to lower 30s. Temp inversions are expected at
night.
KSmith
AVIATION...
Our final organized round of precip is on it`s way across SE Idaho,
along with gusty winds. Precip should end by 04-06z/9-11pm, except
lingering a bit later at KDIJ. Winds should also trend down tonight.
Most terminals will flirt between VFR and MVFR through the "event",
with any vsby reductions tied to where marginal temps will allow
precip to flip to snow (especially KDIJ). Confidence on the
"aftermath" tonight, however, is very low. While we feel confident
in precip/wind trends, and the mid-levels should be drying, the HREF
RH ensemble mean, MOS guidance, and NAM time-height plots all
maintain significant low-level moisture overnight. HRRR guidance is
NOT optimistic about fog/low stratus development, and indeed winds
may remain just strong enough to mitigate fog, but hard to imagine
there isn`t potential for lingering low stratus. For now, despite
limited support in the high res guidance, we`re running with an MVFR
low stratus deck at KBYI, KPIH, KIDA, and KDIJ in the TAFs.
Confidence may not increase on whether this will develop or not with
much lead time, although clearing in the mid-levels on satellite
will at least allow us to better monitor remaining low clouds in
conjunction with sfc obs. For the weekend, expect and end to precip,
lighter winds, and building high pressure, with main aviation
concerns tied to fog/low stratus potential each AM.
KSmith
HYDROLOGY...A localized ice jam continues along the Henrys Fork
near/just upstream (northeast) of St. Anthony, resulting in minor
flooding in low areas along the river (particularly along Rivers
Edge Dr). Water is impacting one shop/outbuilding. Two residences
have requested sandbags, but are otherwise not affected at this
time. Given the minor/localized nature of the flooding, and given
that the situation appears stable with no additional residences
impacted at this time, and given that we have no confidence on
when the ice jam may break up (we have a window today with temps
currently above freezing, but temps will cool again over the next
few days), we have gone ahead and cancelled the FLOOD ADVISORY
rather than keep extending it for potentially many days or weeks
with little resultant value. If the situation changes and the
flood threat increases, or if expanding impacts are reported, a
new FLOOD ADVISORY or FLOOD WARNING may be issued. We will
continue to monitor and coordinate with local officials. In the
meantime, we advise everyone to not approach or enter flood
waters.
Elsewhere across SE Idaho, active precip will wind down by Sat AM
with a period of dry wx thereafter, high temps will come in about
10 degrees cooler Sat and Sun, and no reports of additional ice
jams or have flooding have been received. Thus, no flooding is
currently expected over the next week. Recent warm temps have
resulted in some decent modeled snowmelt across the ern Magic
Valley, Raft River region, and Pocatello area, but any ponding of
water should remain fairly minor and typical of brief, mid-winter
thaws.
KSmith
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 8 PM MST this evening for IDZ060-
063-064-066-072.
&&
$$
Area Forecast Discussion
National Weather Service San Diego CA
118 PM PST Fri Jan 7 2022
.SYNOPSIS...
Pleasant weather will prevail through the weekend with a mix of
sun and clouds and near to slightly below average temperatures. A
trough of low pressure will move into the region by Monday,
bringing clouds and the possibility of some light showers. This
may also bring some relatively light Santa Ana winds behind it
across the coastal slopes and passes Monday through Wednesday with
warmer weather west of the mountains. Periods of weak troughing
and ridging will take over after this system exits, bringing more
dry weather.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM...(Today through Sunday)...
Patchy clouds continue at the immediate coastal areas at this
hour with not too much in the way of clearing for today as the
marine layer continues to maintain a strong presence. This will
bring greater onshore flow into tomorrow, spreading more cooling
into the region. A deeper marine layer will lead to some patchy
areas of fog more inland tonight with less extent, near the far
inland valleys, along with the possibility of drizzle. As high
pressure off the coast strengthens on Sunday, this will bring up
our temperatures a bit for the afternoon hours. Look for highs
near 70 for inland valleys and lower deserts with mid 60s at the
beaches.
&&
.LONG TERM...(Monday Onward)...
A trough of low pressure is expected to come into the region by
Monday. This is slated to become a cut off low from the main flow.
Forecast models are still having a bit of trouble pinning down
exact location and timing details of this system, but overall, the
system looks fairly weak. This may yield a chance for light rain
showers for many areas starting early Monday as the system comes
ashore. ECMWF ensembles are on the wetter side, while GFS
ensembles are more dry. Thinking we may get some light precip as
it enters the region on Monday, though it will be a bit dry in the
lower levels, so whatever falls should be light. As the low
pushes south, it may bring some rap around moisture with it as
well. More details to come!
Light Santa Ana winds are also possible with this system. Sunday`s
high pressure system will strengthen over the Great Basin on
Monday, leading to some light offshore flow. This will only be
enhanced by the cut off low drifting south, helping to bring
easterly flow aloft. Periods of Santa Ana winds can be expected,
though should not be too highly impactful with isolated gusts
35-40 MPH at times Monday through Wednesday. This will also lead
to some warming, especially Tuesday and Wednesday, with plentiful
highs near 70 west of the mountains.
&&
.AVIATION...
072100Z...Coast/Valleys...Low clouds with bases 1000-1800 feet MSL
continue along the coast, with local vis restrictions of 4-6 miles
in HZ. Clouds will spread gradually inland late this afternoon and
this evening, reaching the coastal mountain slopes overnight. Patchy
fog is possible in the far inland valleys, with reduced vis of 1-3
miles. Clearing expected after 18Z Saturday.
Mountains/Deserts...Clear skies with unrestricted vis today with
increasing high clouds at/above 20,000 feet MSL late today and
tonight.
&&
.MARINE...
No hazardous marine conditions are expected through Tuesday.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...APR
AVIATION/MARINE...Connolly