Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/09/24
Area Forecast Discussion
National Weather Service Des Moines IA
545 PM CST Thu Feb 8 2024
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
-Last day of much warmer temperatures; windy conditions gradually
decreasing tonight.
-Cooler but still slightly above average high temperatures
Friday through the rest of the forecast period
-Small chance (<25%) for rain(possibly some snowflakes) Friday
evening into early Saturday
-Mainly dry with some low end chances for precip mainly by midweek
&&
.DISCUSSION...
Issued at 240 PM CST Thu Feb 8 2024
Conditions have been quite windy across Iowa today, thanks to strong
WAA in the low levels and a strong 90kt mid level jet ahead of the
surface low centered over western Minnesota. The dry slot overhead
allowed for clearing this morning over the majority of Iowa,
remaining through at least much of the southeastern half of Iowa,
despite increased clouds filling in over the northwestern half of
the state this afternoon. This clearing has allowed for higher gusts
to mix down to the surface, with gusts generally reported around 35-
40 mph and isolated to 45 mph at times. These winds are expected to
continue through the rest of the afternoon, hence the remaining Wind
Advisory over much of the CWA. However, as the system exits the
region and WAA decreases this evening, expect winds to trend
downward from northwest to southeast. In terms of temperatures, a
handful of records have been broken across the state, a few being at
Des Moines at 63 degrees, breaking the 60 degree record in 1999, as
well as Waterloo also at 63 degrees, breaking their 1999 record of
55 degrees. Expect temperatures to increase a little more this
afternoon yet, with highs in the upper 50s through the mid 60s. As
the low continues to track northeast, a secondary boundary has begun
to make its way into the western portion of the forecast area this
afternoon. So far, light rain has generally been reported with this
wave, and will continue to push east/northeast through the rest of
this afternoon over portions of northern into central Iowa, with low
end accumulations over the area expected before drying out. As
the low departs this evening, winds are expected to shift more
westerly, which will allow for decreasing winds and the arrival
of cooler air. Temperatures will decrease into the 40s from west
to east tonight, with lows bottoming out into the 30s across
Iowa. Dry conditions are expected across the state throughout
much of Friday, though winds may remain breezy mainly over the
northern half of the state into the afternoon before turning
lighter. Highs will be about 10 to 15 degrees cooler compared to
the highs today, as values in the 40s to low 50s are expected.
A shortwave and associated weak surface low pressure system is still
signaled to push across the central plains Friday evening into early
Saturday. Models generally depict Iowa to remain in the cool sector
as this system looks to bring returning chances for light
precipitation, though the overall coverage of these precipitation
varies among models. With the most recent runs, the NAM and
Euro favor better forcing and moisture return in the area, with
more widespread precipitation chances across the southern half
of Iowa. The HRRR, RAP and GFS are drier with isolated showers
over parts of southern Iowa given weaker forcing and not as
prominent moisture return. Regardless of these differences,
agreement remains on rather low chances for precipitation
(<25%). Though rain largely is expected with this system,
temperatures hovering near freezing may allow for some
snowflakes to mix in at times. Despite this, not expecting any
major impacts by any means as accumulations generally under a
tenth of an inch of rain are expected.
Through much of the weekend, conditions are expected to remain
generally dry as a northerly mid level stream of ridging brings high
pressure into the region, which will keep conditions quiet and
cooler as northwest flow remains across the region. Highs are
generally expected in the upper 30s to 40s, and lows in the 20s to
low 30s. Models continue to depict a mid level trough across the
southwestern CONUS, and a developing strong low pressure system
tracking across the southern plains Sunday into Monday. The trend
remains for this system to remain further south of Iowa as it pushes
east/northwest. Will need to keep an eye on this system for any
potential shifts of this system, though not expecting this to occur
at this time. By Tuesday, dry weather looks to continue as a quick
area of high pressure pushes through, though guidance points to a
few weaker waves following, impacting at least a portion of the
state into Wednesday-Thursday that could bring additional chances
for rain/snow. As expected giving the timing out ahead of these
systems, solutions among deterministic long range and ensemble
guidance is quite varied on the track and strength of these waves,
so will keep an eye on them through future forecast cycles.
Temperatures will see little change within the diurnal pattern
through the next work week, with highs in the upper 30s to 40s and
lows in the 20s to low 30s.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 541 PM CST Thu Feb 8 2024
A cold front is moving across Iowa and will keep gusty westerly
winds going for much of this evening before gradually
diminishing later tonight. The wind will slowly become more
northwesst on Friday. MVFR cigs are over northern Iowa
currently and those should retreat north some this evening. This
is the potential for MVFR cigs to return to at least northern
sites during the day on Friday.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM CST this evening for IAZ006-007-016-
017-025>028-036>039-046>050-058>062-071>075-082>086-093>097.
&&
$$
DISCUSSION...Bury
AVIATION...Donavon
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
235 PM PST Thu Feb 8 2024
.SYNOPSIS...Cooler conditions are expected tonight and Friday. A
couple of weak systems will bring a chance for light precipitation
Friday and again on Sunday, otherwise dry weather is expected.
Potential for more impactful precipitation is forecast for late
next week into next weekend.
&&
.DISCUSSION...Light or low impact precipitation is forecast for
Friday as a weak system drops down from the northwest. Upper
level ridging over the eastern Pacific has been building closer
to the coast this afternoon with cool, dry and stable conditions
prevailing across the forecast area today. High resolution
models, namely the HRRR and ARW indicate low potential for a few
light showers into early this evening, however. This is most
likely overdone with drier north-northwesterly low level flow and
warming temperatures aloft and increasing stability.
High resolution mesoscale model guidance indicates light and low
impact precipitation returning on Friday as weak trough in N-NW
flow moves southward across Del Norte and northern Humboldt.
HREF means indicate generally under 0.15in/6hr for Del Norte and few
hundredth or less for Humboldt. NAM-nest is much wetter while the
FV3 is completely dry. Global models on the other hand, namely the
GFS and ECMWF, are almost completely dry. NBM precip probs are
usually too low in these low QPF situations. Moist N-NW low level
flow is forecast to re-develop by Friday evening and additional
light or low impact precipitation is expected into the evening
hours.
Dry and stable weather is forecast to return on Saturday as the
offshore 500mb ridge progresses across the forecast area. Expect
considerable valley low clouds and fog in the morning on Sat.
Another weak shortwave trough is forecast to move over the ridge
by Sunday. Precipitation chances for a few hundredths are only
10-20% for Del Norte and northern Humboldt. Otherwise, dry
weather with higher daytime temperatures and chilly morning lows
are expected for much of the forecast area through this weekend.
Ensemble means indicate broad flat ridging with above normal 500mb
heights dominating early to mid next week. This will most likely
result in predominately dry and stable weather for NW California.
Weak shortwaves may move over the top of the ridge and provide
light (non-impactful) amounts of precip. Probabilities for an
inch or more of rain in 24 hours increases (20-30%) late next
week and next weekend as progressively stronger frontal systems
move into the dominant ridge. There are very large spreads in
precip and high uncertainty with timing. A good example of the
spread is Honeydew, a climatologically favorable location for
heavy rain. The 25th-75th percentile spread over a 24 hour period
ending 4 AM Sat is 0.0 to 2.96 inches. Probabilities for 2, 3 and
4 inches in 24 hour increase over the weekend, but once again with
large 24 hour spreads and huge timing differences. Stay tuned. DB
&&
.AVIATION...The most challenging part of the forecast will be any
lowered visibility due to moist low-levels and light or calm winds
developing, especially over KUKI. Kept the coastal terminals VFR,
but did go with a short-term IFR visibility for KUKI for late
tonight/early Friday morning as forecast soundings would support
this, although model ensembles are not picking up on this potential
feature. VFR conditions other than this as upper level ridging
builds in. Some increase to wind speeds from the north this
afternoon and early evening is anticipated, but not all that
significant. Some cloudiness is forecast to move in Friday, mostly
in the 4-6KT foot ceiling range, keeping us VFR. MH
&&
.MARINE...Fresh to strong northerly breezes over the waters
today are expected to gradually ease tonight into Friday as the
pressure gradient loosens. Seas will remain steep and elevated
across the waters today into tonight as a decaying long to mid
period westerly swell combines with a shorter period northwesterly
waves. Significant wave heights around 10-13 feet are forecast
into this evening with dominate periods fluctuating from 11 to 17
seconds. The Hazardous Seas Warning for the southern outer waters
has been extended into this evening for short period waves up to
10 ft. A longer period westerly swell will build tonight and
maintain combined seas around 10 feet through early Friday
morning. Another long period westerly will build on Saturday and
may pose a risk to beachgoers due to increased wave run up on the
beaches. Depending on the short period wave components, a beach
hazard statement may need to issued. Beyond Sat, a calmer wind
regime with split flow across the waters is forecast. Light
southerlies will eventually unfold throughout with seas trending
down by early next week. ZVS/DB
&&
.BEACH HAZARDS..Higher than normal tides is forecast to continue
today and this weekend, with the high tides expected to peak on
Friday. For today, high tides are forecast to be at 8.1 feet at the
North Spit tide gauge at around 9:18 AM. Northerly winds will lessen
the height of surge, but both surge and tidal anomalies will still
combine with the high tide at the North Spit with water levels
between 8.9 and 9.0 feet by 9:48 AM. Minor coastal flooding around
King Salmon and Jackson Ranch Road in the Arcata Bottoms will be
likely between 8AM and noon. A Coastal Flooding Advisory will be in
effect from 8AM through 12PM Today.
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 3 AM PST Friday for PZZ450.
Small Craft Advisory until 9 AM PST Friday for PZZ455.
Small Craft Advisory until 3 PM PST Friday for PZZ470.
Hazardous Seas Warning until 9 PM PST this evening for
PZZ475.
&&
$$
Visit us at https://www.weather.gov/eureka
Follow us on Facebook and Twitter at:
https://www.facebook.com/NWSEureka
https://www.twitter.com/NWSEureka
For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service Grand Rapids MI
853 PM EST Thu Feb 8 2024
.KEY MESSAGES...
- Chance of thunder this evening, mild Friday
- Temperatures Trend Back to Normal Starting Sunday
- More Active Pattern Next Week with Chance for Snow Monday
&&
.UPDATE...
Issued at 846 PM EST Thu Feb 8 2024
No major changes to the ongoing forecast. One area of
thunderstorms was currently moving onshore near South Haven.
While the storms have been gradually weakening, they could still
have gusty winds as they move inland. Additional storms were
moving offshore of WI. Those could make it into the our CWA
closer to 10 pm. Any stronger downpours could lead to some
gusts up over 40 mph over the next couple of hours given the low
level in the area. High res models like the HRRR have been
showing the gusty wind potential over the past couple of runs.
Based on the current movement, any remaining storms would likely
push east of Lansing at around midnight.
&&
.DISCUSSION...
Issued at 250 PM EST Thu Feb 8 2024
- Chance of thunder this evening, mild Friday
It looks and feels a little Spring-like outside as temperatures
nose in on and surpass 60. Additionally, the sky via visible
satellite (and a quick peek outside) looks somewhat Spring-like
with some altocumulus castellanus clouds which are indicated of
some mid level instability. Indeed, local radar shows some light
echos to the west from virga, mainly.
Surface observations show a frontal boundary over central Iowa
connecting to a low in western MN. The northern part of this
front is occluded and will move through the cwa later tonight.
Ahead of it, impressive mid level lapse rates around 7c/km will
move across the lake. The convection allowing models point
toward some convection...strong showers/isolated thunder
developing due to the surface frontal convergence and mid level
instability. If we see thunder, it will most likely occur from
late evening through roughly 3AM, which isn`t ideal for
convection; severe storms aren`t expected. However, given the
wind gradient already in place and 50kts at h85, any storms
could approach severe limits. Instability is somewhat weak
during this time...MUCAPE around 700 j/kg but enough to create
a few storms.
As the occluded front sweeps east, cooler air will flow into the
cwa late tonight and scour out the precipitation. While Friday
temperatures will be cooler than today, highs will still reach
into the 50s southeast of a Grand Haven to Alma line.
A short wave riding northeast along the occluded front will
generate some light rain showers and also help to drag down
colder air late Friday night. It`s possible that some wet snow
may mix in with the rain after midnight.
- Temperatures Trend Back to Normal Starting Sunday -
Northwest flow fills in behind the front Saturday afternoon with
upper troughing taking hold. This northwest cold advection flow
supports cooler temps that will be a bit closer to seasonal starting
Sunday. Highs return to the 30s with overnight lows in the 20s.
- More Active Pattern Next Week with Chance for Snow Monday -
Upper troughing takes hold Saturday supporting the start of a more
active weather pattern with occasional chances for precipitation.
The first chance arrives Monday as a southern stream wave ejects out
of the Gulf into the Ohio River Valley. The general evolution of
this system is under question, as its main trajectory is heavily
influenced by a northern stream wave that the southern stream wave
eventually phases with over the Mid-Atlantic. General thinking
continues to be a glancing blow of snow showers to our southeastern
forecast area. A northwards shift would obviously increase
precipitation chances, while a southwards shift would possibly
eliminate the chance for accumulating snow. There remains a noticeable
spread across ensemble forecasts, so a good deal of uncertainty
still exists.
Another chance for precipitation arrives mid-week as a northern
stream clipper drops into the region, but as always this far into
the extended, lots of uncertainty exists. Overall, no majorly
impactful winter weather systems are on the horizon.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 642 PM EST Thu Feb 8 2024
The area of thunderstorms in southern WI and northern IL was
tracking northeast. As they move into MI, they will likely be
weakening however it appears that they will have enough momentum
to generate gusty winds and a few lightning strikes. Thus we
added those hazards to the TAFs. Outside of the convection, low
level wind shear was a concern and will continue to be a risk
into the night. While the precipitation will push east of the
TAF sites overnight, gusty winds will linger into much of
Friday.
&&
.MARINE...
Issued at 250 PM EST Thu Feb 8 2024
No changes to the Small Craft Advisory.
Low pressure moving across Lake Superior is creating a tighter
pressure gradient and corresponding higher wind gusts. The gusty
winds will continue through mid day Friday and then subside.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 4 PM EST Friday for LMZ844>849.
&&
$$
UPDATE...MJS
DISCUSSION...04/Thielke
AVIATION...MJS
MARINE...04
Area Forecast Discussion
National Weather Service Louisville KY
839 PM EST Thu Feb 8 2024
.KEY MESSAGES...
* Gusty Southerly Winds up to 30 mph Tonight.
* Temperatures remain mild through the weekend, upper 50s/ low 60s.
* Thunderstorms possible early Saturday morning with a non-zero
severe weather risk.
* Waves of rainfall totaling 1" to 1.75" across southern KY by early
next week. Lesser amounts across southern IN and central KY.
Sunday looks dry.
&&
.UPDATE...
Issued at 837 PM EST Thu Feb 8 2024
Light rain showers have developed this evening, mainly east of I-65
at this hour. Radar returns on how widespread it appears may be a
bit deceiving as there is quite a bit of low-level dry air near the
surface (T/Td spreads around 20 to 25 degrees), so do not expect
this to add up to much (trace amounts to perhaps a hundreth or
two). Forecast remains on track.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 235 PM EST Thu Feb 8 2024
The combination of deep southerly flow and breaks in the high clouds
this afternoon have allowed temperatures to climb into the low 60s
this afternoon. This is a result of a deepening sfc low over the
Upper Midwest and strong southwesterly winds aloft between the
departing upper ridge along the spine of the Appalachians and the
negatively tilted shortwave trough directly above the aforementioned
sfc low. Along with the 15-20 degrees above normal temperatures, the
tight pressure gradient associated with the sfc low and moderately
strong LLJ (30-40 kts) has provided wind gusts of 25-30 mph with a
few isolated gusts over 30 mph so far this afternoon. Winds will
remain gusty into the evening and part of the overnight as the
system slowly works over the big lake they call Gitche Gumee (Lake
Superior) and into central Ontario Canada by tomorrow. There is a
chance of some light showers later this evening as a weak vort lobe
swings through central KY/southern IN. Current ACAR soundings show
plenty of dry air below 500mb and even as the mid-layers begin to
saturate later this evening, the low levels remain dry as the vort
lobe works through so any rain activity will be limited. Wind gusts
will relax some overnight into tomorrow morning but it will remain
breezy with sustained southerly winds around 10-15 mph, cloud cover
will be in place and with the continues WAA lows overnight will be
quite warm for early February (25-30 degrees above normal) in the
low 50s with a few upper 40s across the Bluegrass down into the Lake
Cumberland region.
Trailing cold front associated with the aforementioned sfc low will
become quasi-stationary across both northern IL & IN. Moisture will
increase ahead of this system as dew points climb into the low/mid
50s by the afternoon. Most of the day looks to be dry but a 700mb
LLJ could add enough lift to provide a few scattered showers across
the KY/TN border during the day. Rain chances then will slowly
increase from the south to the north as second sfc low moves out of
the central Plains lifting a warm front across the TN Valley into
the Ohio Valley. Temperatures will once again be well above seasonal
normals with highs climbing into the mid and potentially upper 60s.
Given that many models have been underperforming the last several
days, decided to go slightly higher than guidance for the afternoon.
While not as gusty, winds will remain breezy out of the south-
southwest between 10-15mph and gust of 20-25mph.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 250 PM EST Thu Feb 8 2024
Friday Night through Saturday Night...
Friday night we`ll be watching a shortwave trough axis move just to
our north and into the southern Great Lakes. Low-level moisture
return looks likely across the mid-MS valley and into the lower Ohio
Valley in the overnight period, thanks to an increasing low-level
jet axis. Given the favorable upper level dynamics here, showers
are likely to become fairly widespread late Friday night.
08/12Z data continues to show a notable signal that strong/severe
storms could develop very late Friday night and early Saturday
morning across portions of the area. Model progs show plentiful
deep layer shear with decent low-level shear profiles, especially in
the HRRR and 3K NAM solutions. Initial convection is likely to
start of elevated above the nocturnal boundary layer as model
soundings do show some elevated instability across the area. However,
there may be a period of time early Saturday morning where storms
could become more surface based ahead of an approaching cold front.
The 08/12Z HRRR was the most aggressive with its shear and
instability profiles, but it also had decent support from the 3K
NAM, while the global models showed a more muted shear/instability
setup. Overall, the severe risk here remains quite uncertain and
very conditional. Should storms become surface based, the kinematic
and thermodynamics setup would support a risk of an isolated
tornado, marginally severe hail, and the potential for some gusty
winds. This will be something to watch over the next 24-36 hours.
Cold frontal boundary is looks to push through the region Saturday
morning and shunt much of the precipitation across the region to the
south. The boundary looks to stall out across southern KY and that
may allow light precipitation to persist down that way for much of
Saturday.
Lows Friday night will be in the low-mid 50s with highs on Saturday
remaining quite mild with readings in the upper 50s to the low-mid
60s. Lows Saturday night will cool into the upper 30s to around 40
in the north with lower-mid 40s across central and southern KY.
Sunday through Monday Night...
For Sunday, we should be in a lull between weather systems with a
dry period of weather expected with highs in the lower-middle 50s
over southern IN and the northern half of KY. Across southern KY
highs in the upper 50s to near 60 are forecast.
The next weather system of note is forecast to arrive later Sunday
night. Most of this morning`s 12Z guidance is a little slower with
precipitation arriving, most likely after midnight Sunday night.
While the model solution tracks still show a bit of spread, the
overall signal in the data supports a continuance of high PoPs in
the Sunday night/Monday time frame. The system itself continues to
look pretty strong and will likely become a mature mid-lat cyclone
as it reaches the east coast. Widespread rain showers with moderate
to occasional heavy rainfall is expected as this system moves
through our region. As it moves to the east Monday night, we`re
still seeing some evidence in the data (mainly the GFS) showing some
good frontogenetical forcing and perhaps a TROWAL feature on
the back side of the departing system. This could yield a rain
to snow scenario across the region as temperatures will be
falling in the wake of the front. Consequently, the Euro and
Canadian have a much weaker TROWAL feature with this system and
keep it much further to the north of our area. It`s possible
that a light accumulation could occur in the GFS scenario if the
TROWAL feature ends up developing and rates are sufficient to
overcome warm ground conditions, given the recent warmth across
the area. Overall, the snowfall accumulation risk, as of this
writing, remains low. However, we`ll continue to watch this
system over the weekend.
Rainfall amounts from Friday night through early next week look to
average around a half inch for our southern Indiana counties. Across
Kentucky, a solid half to one inch of rainfall looks likely in areas
between the Ohio River and the Cumberland Parkway. Amounts of 1 to
1.5 inches will be possible across our far SE sections down in the
Lake Cumberland region.
Tuesday through Thursday...
Current model solutions show a strong signal for drier conditions
Tuesday and into Wednesday. Highs Tuesday look to range from the
upper 40s to the lower 50s. Overnight lows will be in the lower
30s, with highs on Wednesday warming back into the lower 50s. A
clipper system will take aim at the region Wednesday night and rain
initially on the front side, with perhaps a change over to some
light snow by Thursday morning. Lows Wednesday night will be in the
lower 30s with highs on Thursday warming back into the upper 40s to
the lower 50s.
&&
.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 615 PM EST Thu Feb 8 2024
Low pressure moving through the Midwest and southern Great Lakes
will keep the LLJ and strong pressure gradients over the Ohio Valley
through the overnight hours. In the early morning, winds will begin
to relax and CIGs will begin to lower.
On Friday, moisture will move into the region from the southwest
ahead of the approaching cold front leading to showers over the
Kentucky terminals. Showers will begin as isolated and then become
more widespread Friday night into Saturday morning.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...DM
SHORT TERM...BTN
LONG TERM...MJ
AVIATION...SRM
Area Forecast Discussion
National Weather Service Marquette MI
1012 PM EST Thu Feb 8 2024
.KEY MESSAGES...
- South winds gusting up to 35 mph near Lake Superior today with
unseasonably warm temperatures in the 40s and 50s.
- Chances for rain increase from west to east mainly this
afternoon and evening with a low chance (~10%) chance of
thunderstorms possible across portions of central and eastern
Upper MI.
- Changeover to snow expected to begin by the early morning
hours of Friday
- West winds will gust to 40-45 mph on the Keweenaw during Friday.
- Unseasonably warm weather ends as temperatures trend back
closer to normal over the weekend, but still above normal.
With further cooling next week, temperatures will settle
to around normal.
- The trend toward colder weather will be supportive of lake
effect snow next week, periodically enhanced by clipper type
shortwaves, but at this point, snowfall is expected to be on
the light side overall.
&&
.UPDATE...
Issued at 1011 PM EST Thu Feb 8 2024
Low pressure is spinning over northern MN tonight, with water vapor
imagery showing another surge of moisture into the southern UP amid
persistent southwest flow ahead of an occluded front extending from
eastern MN through south-central WI. After the initial round of rain
showers that has long since moved out of the eastern UP, most of the
area is experiencing a brief dry period. The next batch of scattered
showers is working into the SW UP, and will largely be contained to
the western UP and western half of Lake Superior the rest of the
night. However, remnants of early evening convection in southern WI
are moving northeast across Lake Michigan tonight, and some of the
hi-res guidance is taking this into the far eastern UP.
Expect otherwise cloudy and mild conditions. Temperatures across the
eastern half of the UP should hold in the 40s the rest of the night,
but should fall into the mid/upper 30s to the west the second half
of the night with the occluded front surging northeast into the
area.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 310 PM EST Thu Feb 8 2024
GOES-16 visible imagery shows a tight comma-head feature
associated with a RAP-analyzed 990mb low pressure over southern
Minnesota. The western and eastern UP are still under clear
skies, but high level clouds have moved over the central UP.
Temperatures in the mid to upper 40s and low 50s have been
observed already, which is a 20+ degree departure from the
normal highs around 23 for February 8th. The record high at MQT
is safe (53, set in 1991) as it falls beyond the NBM 95th
percentile, but with the morning low of 34 this morning and
overnight lows tonight in the mid 30s even in the NBM 5th
percentile, the record warm low of 29 set in 1991 will likely
fall by 5 degrees. While the snow depth at the WFO still holds
on at 9 inches (enough to accrue 4 AWSSI points) the temperature
failing to fall below freezing with no snowfall accumulation
expected at the WFO tonight will ensure that the Marquette area
will once again be in record territory for mildest winter on
record by AWSSI.
A low level jet at 850mb will maintain at 30-40 kt through tonight,
which is not only responsible for the strength of the warm advection
bringing the warm weather, but also is responsible for some breezy
conditions. Add the 850mb warm advection with the 500mb PVA
associated with the parent shortwave and there will be enough lift
for a couple rounds of showers as shown in the HREF suite. The first
round looks to be most likely around 22Z in the east half, with a
second round that is more widespread but weaker closer to 02Z. Among
the CAMs, the HRRR is the most aggressive, showing thunderstorm
potential with both rounds, though only sparingly do the rest of the
HREF members show such strong simulated reflectivity. HREF mean
MUCAPE peaks at just shy of 500 J/kg from Menominee to Escanaba, but
whether or not that instability can be realized is another question.
With a shear vector of 30-50 kt, "storm" motion will be too fast to
be a significant threat of flooding despite the existing snowpack
enhancing runoff. This is reflected in the HREF maximum
precipitation totals being only a quarter to a half inch in the east
and a tenth to a quarter inch elsewhere. With severe weather
unlikely, the low (~10%) chance of thunder is merely a novelty in
spite of how highly unusual its presence is in the UP in early
February.
Winds shift from southerly to southwesterly behind a mostly dry
cold front overnight. This will usher in cooler temps
especially aloft, with the HREF mean ptype showing snow in the
Ironwood vicinity by 07Z and the rest of the Keweenaw by 12Z.
Snow totals will initially be quite small as the only synoptic
precipitation will be wraparound moisture from the low center
being north of Lake Superior, plus some local orographic
enhancement of southwesterlies coming on the western shores of
the Upper Peninsula.
&&
.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 504 PM EST Thu Feb 8 2024
Model trends that began to show up last week for the mid to late Feb
period are generally on track. That trend is for the recent
unseasonable warmth to trend back to temps that are on avg generally
around normal. Current pattern is amplified, featuring troffing over
the western U.S. and ridging over the eastern U.S. and throughout
the e half of Canada where a large area of +350m height anomalies
exists at 500mb. Thru the weekend, the pattern will deamplify and
progress, transitioning to western ridging and eastern troffing,
though the height anomalies will be modest in magnitude. This will
bring an end to the ongoing unseasonable warmth as temps trend back
closer to normal, but still above normal. During next week and into
the early part of the following week (week of Feb 18), medium range
models show widespread positive height anomalies/blockiness
developing at high latitudes, including ridging in western Canada
(nw Canada/AK in particular). This is certainly suggestive of an
overall colder trend for Upper MI later next week into the early
part of the following week. However, with the positive height
anomaly in western Canada shifting n and more solidly into the
Arctic with time, some degree of flow will resume into the western
U.S. This would work to prevent any sustained or prolonged arctic
air intrusions into the Great Lakes, if any arctic air masses do
surge southward. Overall, daily temps should simply settle to around
normal with the coldest period probably centered on the weekend of
Feb 17/18. As for pcpn, in the wake of the system lifting thru the
area tonight/Fri, colder air will bring a transition to generally
light wnw flow lake effect snow. A series of clipper shortwaves next
week will periodically enhance LES, but at this point, none of the
LES looks particularly noteworthy. So, expectation is for LES snow
accumulations to be on the light side next week.
Beginning Fri, in the wake of the cold front sweeping across the
area tonight/early Fri, caa will result in any lingering light
-shra mixing with or changing over to -shsn over the w in the
morning and then later in the day over the central counties. -SHRA
will change over to -shsn for the eastern counties Fri evening.
850mb temps don`t fall to lower than -4/-5C during the day, so
little in the way of lake enhancement will occur in the low-level
cyclonic westerly flow Fri. Thus, in the end, pcpn coverage should
be limited to isold to sct. Downslope westerly flow over s central
Upper MI will lead to dry weather there on Fri. It will be windy
across the Keweenaw on Fri. Although mixed layer is shallow, fcst
soundings indicate winds up to 40kt can be tapped to support gusts
40-45mph. HRRR and ARW indicate winds up to around 45kt in the mixed
layer which would lead to gusts upwards of 50mph. Will be something
to monitor in the next round of model runs to determine if wind advy
will be needed for the Keweenaw on Fri.
Fri night/Sat, 850mb temps continue to fall, reaching at least
-11C over western Lake Superior by Sat morning and over eastern Lake
Superior by Sat aftn. This further temp drop accompanies the passage
of secondary sfc trof that will veer low-level winds wnw to nw. The
passing sfc trof will lead to increasing LES. Moisture depth
extending to aoa 10kft provides a very favorable LES environment.
However, a sharp inversion present at around 4kft and lack of more
substantial overwater instability will keep the LES in check. A few
of the colder model solutions drop the DGZ to blo the inversion,
which would increase SLRs. However, overall, not expecting much more
than 1-3 inches of snow Fri night/Sat for areas favored by w to nw
winds.
Scattered LES will continue Sat night into Sun under general wnw to
nw low-level flow, but it will diminish from w to e as drier air
begins to work in from the w and as low-level flow trends more
anticyclonic with approaching sfc high pres ridge. Snow
accumulations shouldn`t be more than around an inch.
Evolving pattern toward more of a nw flow next week will support a
colder pattern, closer to normal, that will be more supportive of
LES. The nw flow will also lead to clipper type shortwaves
periodically tracking across the Upper Great Lakes. Timing/amplitude
of these waves will be problematic as shown by the lack of run-to-
run consistency among the models. In any event, expect more frequent
LES, but as previously mentioned, none of it looks noteworthy at
this point. This idea is supported by ensembles showing probability
of QPF equal to or greater than 0.1 inches for any 24hr period next
week at no more than 50-60pct.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 633 PM EST Thu Feb 8 2024
VFR continues so far this evening, but another round of rain moving
in by 03Z will usher in MVFR ceilings and reduced visiblity.
Ceilings may drop further to IFR late tonight, most likely at
IWD. SAW will also be dealing with a LLWS threat through the
early overnight hours as a low level jet passes by the central
UP. MVFR ceilings linger Friday, and light lake effect snow
showers may cause reductions in visiblity at times as well -
mainly at CMX. Gusty southerly winds will become southwest to
westerly with time over the TAF period.
&&
.MARINE...
Issued at 504 PM EST Thu Feb 8 2024
In response to low pres moving from MN toward northern Ontario, a
low-level jet has been shifting across Lake Superior today, but that
is now exiting to the e. As a result, s to se winds across eastern
Lake Superior are settling back a bit and will be in the 20-30kt
range this evening. Winds of 15-25kt will be the rule across the
western lake. A cold front associated with the low will then sweep
across Lake Superior overnight into early Fri. With passage of the
front, sw to w winds will ramp up to 35-40kt gales from w to e.
Expect the strongest winds just w and n of the Keweenaw. Winds will
fall blo gale force from w to e from mid aftn Fri thru Fri evening.
NW winds of mostly 20-30kt are expected Fri night/Sat, strongest
across the e half of Lake Superior. W to nw winds around 20kt are
expected on Sun and then under 20kt for Mon. Winds will increase to
20-25kt on Tue.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning from 7 AM EST /6 AM CST/ to 7 PM EST /6 PM CST/
Friday for LSZ162-240>244-263-264.
Small Craft Advisory until 7 AM EST /6 AM CST/ Friday for
LSZ240>244.
Small Craft Advisory until 11 AM EST Friday for LSZ245-246.
Gale Warning from 11 AM to 10 PM EST Friday for LSZ245-246-265-
266.
Small Craft Advisory from 7 AM Friday to 1 AM EST Saturday for
LSZ247-248.
Small Craft Advisory until 1 AM EST Friday for LSZ251.
Lake Michigan...
Small Craft Advisory until 1 PM EST Friday for LMZ221.
Small Craft Advisory until 4 PM EST Friday for LMZ248-250.
&&
$$
UPDATE...LC
SHORT TERM...GS
LONG TERM...Rolfson
AVIATION...LC
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Springfield MO
807 PM CST Thu Feb 8 2024
.KEY MESSAGES...
- Above average to near record temperatures continue through
Friday with highs in the 60s to near 70.
- There is a 20-30 percent chance of thunderstorms Friday night
east of Highway 65.
- Snow chances have increased Sunday night (50-80% chance)
however confidence in amounts remains low. Stay up on the
forecast going into the weekend.
&&
.UPDATE...
Issued at 805 PM CST Thu Feb 8 2024
We have cancelled the Red Flag Warning an hour early as humidity
values have recovered into the 35-45% range. Winds have also
decreased to below 15 mph.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 100 PM CST Thu Feb 8 2024
Current Conditions and Synoptic Pattern: Water vapor and upper
air analysis shows a complex pattern with a shortwave currently
moving through the area with a strong upper level jet extending
from the Pacific Ocean into the southern Plains. The mid level
ridge has moved east of the area. Additional shortwaves were
located across the southwest US. A strong surface low was
moving into Minnesota with a dry front currently stretching
south through the area. Moisture depth was lacking across the
area and skies were beginning to clear from west to east. The
strong pressure gradient and mixing down of a low level jet has
created very strong winds across the western part of the area
with 45-50mph gusts being measured thus far from Joplin to
Springfield to Osage Beach and point west.
850mb temps in the 8-10C across the area combined with the warm
start to the day and plenty of sunshine has allowed for temps to
warm well into the 60s to around 70. See the climate section for
record high potential today. Surface dewpoints in the 30s were
beginning to advect into the area from the southwest and we
expect RH values to drop into the 20-30 percent range this
afternoon. This combined with the winds will cause a significant
to locally extreme grass fire danger and the Red Flag Warning
remains in effect for the afternoon and evening.
Friday: Shortwave energy across the southwest will move
northeast into Kansas during the day with low pressure
developing. Southerly winds will continue however it will not be
nearly as windy as today with peak gusts of 25-30mph west of
Springfield. HREF data suggests an increase in mid/high clouds
from the south during the afternoon and evening. Until then,
plenty of sun and warm 850mb temps should allow for another very
warm day with highs again well into the 60s to near 70 per NBM
75th percentile guidance (performing well with temps lately).
Additional record highs are in jeopardy. Given the weaker winds,
the grass fire danger should not be as significant as today
however RH values may well drop into the 25-30 percent range
north of Springfield.
By Friday evening, the trough will be approaching the area with
a front and latest high res guidance, RAP and NAM suggesting an
increase in low level moisture (50-55 dewpoints) and elevated
instability. The 12z HREF has mean MU cape values near 500j/kg
east of Highway 65. Therefore if enough moisture is present then
some isolated to scattered thunderstorms could develop across
the eastern ozarks. There are a few high res models showing
storms developing as far west as the Kansas border so will need
to monitor for a westward extension of precip chances. Given
the struggles with model moisture lately, confidence remains low
in this scenario however will need to monitor it because there
will be plenty of wind shear for some small hail if
thunderstorms can form. Behind this system a cold front will
move through brining cooler temps.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 100 PM CST Thu Feb 8 2024
Saturday through Monday: Northerly winds, cooler air aloft and
clouds will keep high temps in the 50s but still above average
for the time of year. Ensembles continue to suggest that
shortwave energy will dive south out of western Canada and into
the southwest US Saturday and then attempting to close off as
it moves into Texas on Sunday. Looking at the potential paths
from the ensemble clusters shows growing consensus that this
upper low will then track south of the area Sunday night into
Monday however there are differences in timing.
The potential track of this system would favor accumulating
snowfall across the area as we remain on the northerly/colder
side of this system, especially if the 850mb low track remains
south and east of the area. Majority of ensembles suggest that
rain starts out across the area Sunday and then switches to snow
Sunday night as colder air wraps into the storm with a
band/swath of accumulating snow on the north side of the system
during the Sunday night and Monday morning time frame. The NBM
and a majority of the ensembles currently have a 50-70% chance
of at least one inch of snowfall with this system. The ECMWF
Extreme Forecast Index is also beginning to show a corridor of
higher snowfall in or near the area. Be cautious with snowfall
model output at this time range as the deterministic models are
currently showing much higher accumulation potential than its
own ensemble means. One limiting factor will be the warm temps
preceding this system. Overall the trend over the last 24 hours
has been an increase in snow potential and the Probabilistic
Winter Storm Severity Index now has 40-70 percent chances for at
least some winter weather impacts with this system. Stay up on
the forecast over the next few days as we get a better sample on
this storm.
Tuesday and Wednesday: A zonal to slightly northwest flow aloft
will persist with NBM suggesting temps climbing back above
average (highs at least near 50) and precip chances below 20
percent.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 457 PM CST Thu Feb 8 2024
VFR conditions will continue through Friday with a few passing
high clouds.
Southwest surface winds will quickly decrease this evening
after sunset. Gusts to 30 knots will continue through 01Z.
A period of low level wind shear will develop from this evening
through sunrise as a low level jet stream strengthens across
the Mid-Mississippi Valley.
Surface winds will then increase out of the south to southwest
again late Friday morning with gusts exceeding 20 knots in the
afternoon.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
KS...None.
MO...None.
&&
$$
UPDATE...Schaumann
SHORT TERM...Burchfield
LONG TERM...Burchfield
AVIATION...Schaumann
Area Forecast Discussion
National Weather Service Salt Lake City UT
419 PM MST Thu Feb 8 2024
.SYNOPSIS...An additional push of moisture will keep showers of
valley rain and mountain snow around through Saturday, with cold
air dropping snow levels statewide tonight. Dry conditions return
by the back half of the weekend through next week with
temperatures running slightly below normal.
&&
.SHORT TERM (Through 12Z Saturday)...A lifting trough continues to
slowly transit southern Utah this evening and overnight, with a
tight circulation around the center of low pressure presenting on
mid-level water vapor imagery. Notable is the amount of moisture
in the column along the feature`s northeastern edge, and with
favorable southerly/upslope flow, is forecast to be a productive
precipitation event overnight, especially across the northern
portions of the Grand Staircase and area mountains. While some
initial uncertainty in precipitation type exists, the entirety of
the ensemble trends quickly towards snow as snow levels crash to
the surface with sustained cold advection through the overnight
hours.
A few areas of note: St. George presents with a 15% chance
of snowfall in the early morning and late evening Friday, but near
0% chance of accumulation. Escalante and Hanksville both carry a
high probability of at least 1" of snow accumulation, but little
chance of higher amounts. The spread is greater across the San
Rafael Swell and eastern valleys, where 3-5" of snowfall are
possible, dependent on the strength of deformation band driven
snowfall in the area. Higher portions of I-70 may be impacted by
periods of heavy snowfall into the early morning as a result.
Lastly, SR-10 through Castle Country, while not in an advisory,
still has a 25% chance of exceeding 4-6" of snowfall by Friday
night - that said, a switch to west/northwesterly flow should
lead to downslope warming and drying, ultimately limiting amounts.
Along the Wasatch Front, the potential for impacts to the morning
commute exists, though as a fringe probability at this time.
While the probability of trace amounts of snowfall accumulating on
all surfaces Friday morning is very high (near 100%), the chance
of 1-2" is less than 25%, and entirely dependent on the
development of more convective type snow showers under the cold
core of the broader trough. So far, seeing the HRRR key in on
these showers developing somewhere between Ogden and Salt Lake
through the morning commute hours. Will continue to evaluate newer
output from the CAMs overnight and keep shaping the messaging with
the latest.
By Friday afternoon, a shift to more orographic showers and
scattered convection will see greater chances for graupel mixing
in with snow showers across especially northern Utah, and
continued orographic snow showers tapering off in intensity
through Friday night, ending as much drier air and subsidence in
the mid-levels sets in Saturday morning.
.LONG TERM (After 12Z Saturday)...The back end of an upper trough
bringing impacts across will begin to phase out of the forecast
area through the day on Saturday, allowing precipitation to
gradually taper off through the afternoon and evening hours. Up
until then, however, lingering snowfall over the central and
southern Utah will prevail through the morning. Additional snow
accumulations from these snow showers are expected to be generally
light, with additional accumulations up to 2 inches in the
mountainous terrain. Valley areas could also see upwards of 1 inch
of additional accumulation. The post-frontal environment will
bring both cold temperatures across the forecast area as well as a
deep northerly flow. Northerly flow will help with thermal
packing along the Cedar City area mountains, helping to develop a
surface pressure gradient between Cedar City and St. George. This
gradient combined with aligned northerly flows across southern
Utah will help to generate locally stronger winds along the I-15
corridor between Cedar City and St. George. At this current time,
there is a 25% chance that peak wind gusts exceed 40 kts overnight
Saturday/ early morning Sunday.
After Sunday morning however, potential for significant weather
across the forecast area decreases substantially as a ridge of high
pressure builds back into the region. Quickly stabilizing conditions
and lack of lower level moisture will help to bring dry conditions
areawide. Some of the coldest morning low temperatures are expected
on Sunday, however, an overall warming trend will establish as
temperatures warm overhead. There is a bit of uncertainty heading
through the remainder of the week with whether or not a series of
troughs across the PacNW region will contain enough energy to break
down the ridge and produce precipitation in northern Utah. Ensemble
guidance is overall supportive of the ridge holding strong and
maintaining a dry forecast over the area. That said, there are still
about 10-30% of members from the EPS and GEFS that produce
measurable precipitation over the northern Utah mountains between
early Tuesday through Friday (threshold set to 0.01). When
increasing precipitation thresholds to QPF > 0.1 inches,
probabilities are generally 0-20%, and 0% for QPF > 0.5 inches. So
while precipitation may be possible with the aforementioned series
of troughs, impacts of any potential precipitation is expected to be
low.
&&
.AVIATION...KSLC...Occasional period of MVFR conditions are forecast
tonight resulting from scattered rain and snow showers. Otherwise,
mid and low level cloud decks will prevail until early this evening
before briefly improving to VFR conditions through approx 08z.
Lowered ceilings are then expected to return through tomorrow
morning. There is potential for fog development as well but
confidence is not high enough to place it in the TAF yet.
.REST OF UTAH AND SOUTHWEST WYOMING...A variety of conditions this
evening and through tomorrow resulting from widespread scattered
rain and snow showers. Impacts that would lower visibility are
likely to be short lived especially in northern Utah and southwest
Wyoming terminals. Southern Utah terminals have increased potential
for seeing longer lived snow showers and thus longer periods of
MVFR/IFR conditions. By tomorrow afternoon, VFR conditions are
expected for terminals.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Storm Warning until 5 AM MST Friday for UTZ113-117-125.
Winter Weather Advisory until 8 AM MST Friday for UTZ116-121.
Winter Weather Advisory until 5 PM MST this afternoon for UTZ127.
WY...None.
&&
$$
Wessler/Webber/NDeSmet
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity