Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/10/24
Area Forecast Discussion
National Weather Service La Crosse WI
952 PM CST Mon Dec 9 2024
.KEY MESSAGES...
- Light precipitation (drizzle-10% to light snow north of hwy 20
60%). Snow showers developing later Tuesday night into
Wednesday (60%) with minor accumulations possible. Some
reduced visibilities with the snow showers during the
Wednesday morning commute through the evening commute.
- Much colder Tuesday night through Friday morning. Lowest wind
chills -15 to -25 Thursday morning.
- Warmer temperatures return for the weekend along with
increased precipitation chances (20 to 50% of rain/snow/wintry
mix).
&&
.DISCUSSION...
Issued at 246 PM CST Mon Dec 9 2024
Overview:
The latest subjective surface analysis shower a 998mb low centered
over the U.P. of Michigan with a gradual wind shift to the west and
northwest/cold front through Minnesota. At 20Z temperatures were in
the mid to upper 40s and OVS/PDC were around 50. Temperatures were
falling at RST and they were at 39 degrees behind the cold front.
Most gusts were 15 to 30 mph, however Preston was gusting from the
west at 38 mph. Latest water vapor satellite imagery, and heights,
show a 500mb closed low over Ontario Canada with a trough
extending southward across Minnesota into the Plains. A 500mb
ridge was noted off the West Coast. Latest WSR-88D radar showed
snow showers over northern Wisconsin into northern Minnesota.
Farther south into the warmer temperatures by STC, it was light
drizzle.
Through Thursday:
The shortwave trough will continue to swing through the region
tonight with the first wave of cold area spreading over the area.
Per RAP soundings, saturation becomes deep enough for light snow
north of highway 20 in north central WI. Some minor snow
accumulations of a tenth or south are expected. Farther south, there
may be a wintry mix of drizzle and flurries or a brief period of
freezing mist. Trace amounts are most likely. The RAP and to a
lesser extent the HRRR have patchy lower IFR ceilings behind the
front where some freezing mist could occur where the depth of the
cold air is not as large, but temperatures have fallen behind
freezing.
850mb temperatures started from 0 to +3 deg C at 12Z, however by 00Z
are forecast to drop to -6 to -8 deg C. Additional troughing moves
through Tuesday with the cold air deepening. Temperatures drop to -
9 to -12C, thus cannot rule out flurries. Highs Tuesday are
forecast to be below our normals of 30 to 35, in the 25 to 30 range
for most spots.
A stronger trough with a push of colder air moves in for Tuesday
night and continues Wednesday. Each day we have been increasing our
chance for snow showers, albeit amounts remain light. This activity
will be affecting commuters Wednesday morning, thus have included it
in our hazardous weather outlook. We monitor our snow squall
parameter in situations like this and we expect snow showers at this
time, but do not have the winds as strong as the last event or a
flash freeze forecast. Temperatures will be cold though with most
highs in the teens to lower 20s. Due to the small CAPE snow showers
could be vigorous at times. The HREF does have reduced visibilities
during the snow showers (HRRR less than 2mi, some of the others less
than .5mi), thus travelers should check conditions before they head
out Tuesday morning and throughout the day Wednesday. Minor
accumulations will be possible from a few tenths to an inch or two
toward Medford. Currently wind gusts are forecast to range from 25
to 35 mph
Bitter cold temperatures are still on track for Wednesday night
through Friday morning. Coldest wind chills are Thursday morning
from -15 to -25.
Extended:
The bitter cold temperatures are short-lived, but still remain below
normal for Friday. The thermal trough shifts east with a trough on
the West Coast Thursday moving into the Sierras and Rockies...the
develops further as it tracks into the Plains Friday. Channeled
flow aloft initially develops with an area of surface low pressure
organizing somewhere over the Plains into the Mid Mississippi
Valley. A week ripple in the flow could produce a band of light snow
somewhere over Iowa Thursday night. We are on the cooler side of
the next shortwave trough, but depending on the track...it will
bring up warmer temperatures northward. It is currently looking
like rain then transitioning to light snow farther north, however
there could be a wintry mix in between. The 09.00Z EC/GEFS/Canadian
ensembles have 5 to 25% probabilities for 1" or more of snow.
&&
.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 952 PM CST Mon Dec 9 2024
MVFR stratus prevails over the region throughout the overnight with
low-level saturation firmly in place. Winds will continue to
diminish throughout the TAF period as the surface pressure gradient
slowly lessens into the afternoon hours. The largest forecast
question after daybreak tomorrow will be if MVFR cigs will yield to
sct-bkn VFR cigs during the afternoon across portions of the area.
Currently seeing mixed signals across guidance with the recent NBH
guidance having high confidence at KRST (70-90%) to remain MVFR
throughout the entire forecast period. This is contrasted by some of
the CAMs which show some low-level drying in the RH fields. As a
result, have some lower probabilities (30-50%) for MVFR cigs at KLSE
during the afternoon in the NBH. Consequently, have generally
leaned into the probabilistic guidance for this TAF issuance
with a period of VFR (18z-00z) at KLSE and in the general
vicinity of the Mississippi River with MVFR elsewhere.
Otherwise, our next weather system moves into the region late
tomorrow evening with some chances (15-30% chance) for snow
showers from 03z to 06z generally west of the Mississippi River
with some MVFR vsbys possible.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Zapotocny
AVIATION...Naylor
Area Forecast Discussion
National Weather Service Cheyenne WY
733 PM MST Mon Dec 9 2024
.KEY MESSAGES...
- Scattered snow showers possible through this evening. Rapidly
changing conditions possible in showers.
- High Wind Watches and Warnings issued for the southeast
Wyoming wind prones Tuesday afternoon until Wednesday evening.
Wind gusts up to 65 MPH possible.
- Seasonably cool temperatures are expected to persist through
the remainder of the week into the weekend. Cannot rule the
potential for more light snowfall for the Mountains of SE
Wyoming on Friday along with gusty winds Saturday and Sunday.
&&
.UPDATE...
Issued at 728 PM MST Mon Dec 9 2024
Upgraded current High Wind headlines across the I-80 corridor
from watches to warnings. Guidance has continued to increase
high winds potentials across Arlington and the Summit, with the
NBM v4.2 Probability of Exceeding 48 knots have continued to
trend upwards with greater than 70% probabilities of hitting
strong winds across the upgraded zones. Combined with in-house
model guidance strongly suggesting strong winds and gradients at
both 850mb and 700mb greater than 60 meters, felt confident
enough to upgrade. Will hold off on Bordeaux where confidences
is not overly high for high wind criteria will be met and
elevated winds appear more likely.
&&
.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 154 PM MST Mon Dec 9 2024
Cloud cover continues to increase across the CWA this afternoon as a
cold front drops into the area from the north. With the frontal
passage, scattered snow showers are expected to develop this
afternoon. Snow showers will mainly be confined to Wyoming, however
would not be surprised to see some flakes in the northern Nebraska
panhandle. Will have to keep an eye on the snow showers this
afternoon, especially west of the Laramie Range. The RAP shows
about 100 J/kg of CAPE out in Carbon and Albany Counties by mid-
afternoon. Each new run of Hi-Res guidance that comes in shows
increasing values of the snow squall parameter. Although these
values are still moderate, the increased frontogenesis from the
cold front could lead to snow squalls this afternoon. The
limiting factor for squall development this afternoon will be
wind speeds. Guidance is not too keen on strong winds. However,
the HRRR is hinting at increased wind speeds within snow
showers. With these ingredients, would not be surprised to see a
snow squall or squall like shower or two. Shower activity will
wrap up this evening, but a stray shower could still be possible
overnight.
Another cold day is expected Tuesday as the upper-level trough that
brought the secondary cold front exits to the east. Expect
temperatures to be a few degrees below normal with highs in the
20s and 30s. Lingering cloud cover will add to the cold
temperatures, as well as the potential for a stray shower or
two, mainly east of the Interstate 25 corridor. High winds
return to the wind prones Tuesday evening. A strong surface high
will build over the Colorado Rockies with a strengthening
surface trough east of the Laramie Range. This will cause a
rather strong MSLP gradient to develop over and west of the
Laramie Range, leading to a gradient driven wind event. CAG-CPR
850 mb height gradients are also rather impressive, maxing out
at 80 meters late Tuesday night. 700 mb height gradients are
also within the range that would likely lead to high winds in
the Arlington/Elk Mountain zone. Winds aloft will be about 50 to
55 kts over the wind prones. Coupled with strong subsidence
over these areas and these winds will likely make it down to the
surface. In-house guidance is pinging the usual wind prones for
high winds with this coming event. It shows especially high
probabilities for the Arlington and Interstate 80
summit/foothills zones. As a result, did go ahead and issue a
High Wind Watch for these zones starting Tuesday afternoon and
continuing until Wednesday evening. Also issued a High Wind
Watch for Bordeaux, starting later Tuesday night and running
through mid-Wednesday afternoon.
High winds will continue into the day Wednesday, but gradually
weaken as gradients relax from a weak upper-level ridge over the
Great Basin. Winds will ease over the wind prones by the evening,
but blustery conditions can still be expected through Wednesday
night as winds aloft stay elevated. Aside from the wind, warmer and
drier conditions can be expected during the day Wednesday.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 154 PM MST Mon Dec 9 2024
The upper level pattern remains rather tranquil in terms of
precipitation for the High Plains of SE WY and Nebraska
panhandle through the remainder of the week into the weekend. A
couple of the deterministic models (ECMWF/GFS) are showing a
slight perturbation moving through northern Wyoming on Thursday
which may trigger a trigger a few snow snow showers along an
elevated boundary near the northern fringes of Converse and
Niobrara counties, but with limited moisture it most likely not
bring much more than a dusting of snowfall. Another open upper
level wave is progged to quickly transverse across the area late
Thursday night into Friday. This feature initially shows a
pretty good fetch of Pacific moisture moving into western
Wyoming on Thursday night with even a hint of higher than normal
PWAT`s for this time of year. However, this moisture quickly
dries out as it crosses the the higher terrain. It may be enough
to bring an inch or two to the Sierra Madre`s on Friday
morning, due to some favorable upslope flow. However, the
700-500mb flow begins to turn more towards the west Friday which
will tend to limit accumulations. Temperatures will also be a
tad cooler (5-10 deg) on Friday as a frontal boundary crosses
the area.
This weekend still looks rather dry with the potential for some
weak upper level ridging. This will all be factored on the strength
of the upper level trof along the west coast. As a result, we
will continue to lean toward the blends in keeping temperatures
seasonably cool.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 431 PM MST Mon Dec 9 2024
Cold front well south of Wyoming and Nebraska this afternoon
with a brick north to northeast wind behind the front. These
winds will ease over the next hour or so. Strong winds return
Tuesday across southeast Wyoming and Nebraska Panhandle with
gusts 35 plus knots. Will need to keep an eye on lower ceilings
tonight in these northeast winds. For now...will keep lower
ceilings out of the forecast. But may need to amend TAFs if they
do occur.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Watch from Tuesday evening through Wednesday
afternoon for WYZ106.
High Wind Warning from 2 PM Tuesday to 5 PM MST Wednesday for
WYZ110-116-117.
NE...None.
&&
$$
UPDATE...MRD
SHORT TERM...SF
LONG TERM...REC
AVIATION...GCC
Area Forecast Discussion
National Weather Service Des Moines IA
535 PM CST Mon Dec 9 2024
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
- Strong cold front arrives late Tuesday and Tuesday night. Snow
showers are expected with some potentially being intense which
could lead to rapidly deteriorating conditions in some areas.
- Cold Wednesday into Thursday with lows below zero over
northern Iowa Thursday morning. Wind chill values Wednesday
night and early Thursday may reach 10 to 20 below over the
north.
- Monitoring a system late in the week that may bring a wintry
mix to the region.
&&
.DISCUSSION...
Issued at 302 PM CST Mon Dec 9 2024
A cold front is now moving into northwest Iowa with falling
temperatures beginning to occur. Ahead of the boundary, temperatures
again surpassed guidance values with highs in Another
round of snow showers will impact the region Wed night; possibly
the low to mid 50s
over central and southeast Iowa. The cold front will continue to
move southeast through the state into tonight. Gusty winds have
topped 40 mph at times near the boundary. The gusty winds will
persist into this evening but the gusts should be below 40 mph and
more in the 25 to 35 mph range. A broad area of stratus is
descending from South Dakota and Minnesota and is now into far
northern Iowa. This stratus field should reach central Iowa with
less certainty further south towards the Missouri border. It is
possible. Numerous models still having issues with potential cloud
depth and low level saturation as the stratus moves into northern
Iowa. RAP profiles would suggest that a few flurries may occur
across northern Iowa and there have been flurries reported upstream
in Minnesota. This should be of little consequence though otherwise.
Low temperatures tonight should be in the low to mid 20s with the
clouds and boundary layer mixing helping keep temperatures "warmer"
despite the cold advection.
The primary weather event that is will have an impact on the state
is the strong cold front arrive late Tuesday into early Wednesday.
The main focus here is the potential for snow showers and perhaps
some intense snow showers that could reach snow squall intensity.
Low level CAPE values and low level vorticity would help fuel these
snow showers and the cold advection would allow a significant
portion of the cloud layer to fall to within the dendritic growth
zone (DGZ). In addition, there is a wind potential with mixed layer
winds approaching 35 to 40 kts. Snowfall amounts of 1-2 inches may
occur in narrowly banded areas with these snow showers with lesser
amounts elsewhere. If you are traveling Tuesday night, be aware of
the potential for quickly deteriorating conditions. This activity
will linger into southeast Iowa Wednesday morning before departing.
The cold is the other factor behind this boundary. Highs on
Wednesday will be in the teens and 20s. The coldest period will be
Wednesday night into Thursday. Low temperatures Thursday morning
will be below zero north to the single digits above zero south. Wind
chill values will be near 15 to 20 below zero over northern Iowa
also. Thursday will remain cold with highs near 10 above north to
20s south.
Finally the other potential weather impact is late week as an
overrunning event and possibly mixed precipitation event develops.
Deterministic models with the ensembles trending towards this
solution of warmer more moist air overrunning the colder air over
Iowa that could bring a wintry mix to the state. It is too early to
get into fine details this far out as expect a lot of adjustments
going forward given model accuracy in the winter beyond day 4. Will
maintain a rain/snow mix but if trends persist, will have to evolve
the forecast to including freezing rain and or sleet mention.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 535 PM CST Mon Dec 9 2024
Area of MVFR clouds moving southeast across region and likely
will affect all sites except OTM this period. Winds increasing
northwest 15 gust 25kt relaxing aft 12z. North sites FOD/ALO may
see brief break in MVFR 08-15z while MCW remains MVFR. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Donavon
AVIATION...REV
Area Forecast Discussion
National Weather Service Quad Cities IA IL
1001 PM CST Mon Dec 9 2024
.KEY MESSAGES...
- An arctic cold front will sweep through the area Wednesday
morning, leading to gusty northwest winds and scattered snow
showers. Some of the snow showers could become briefly
moderate to heavy.
- Temperatures steadily fall tonight through Thursday this week, with
the coldest conditions expected Wednesday night/Thursday
morning, with widespread wind chills in the negative single
digits and teens.
- Moderating temperatures are expected late in the week, along
with chances for rain and snow.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 205 PM CST Mon Dec 9 2024
All aboard the Temperature Coaster! Temperatures have hit their peak
this week Sunday and today and will begin their downhill slide
tonight as a weak, dry cold front sweeps through the area. The
large- scale synoptic pattern isn`t expected to change much
through the day Tuesday, as a pretty broad upper-level trough
has taken shape over the north-central CONUS today. The first of
two embedded impulses/fronts with this trough will move through
tonight. Temperatures tonight will be cold, but seasonal, with
lows in the lower 20s northwest to the middle 20s southeast.
Tuesday remains dry, but continued northwesterly flow maintains
seasonal conditions, with highs near 30 north to the middle 30s
south.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 205 PM CST Mon Dec 9 2024
The long-term begins with the well-advertised arctic cold front
diving through our region, the second of two fronts that will help
our temperatures plummet this week. Temperatures will fall even
further into Wednesday morning, with lows in the teens above zero
north to the lower 20s south. An accompanying PVA maxima with the
front will support a chance (30 to 50%) of snow showers as the
thermal profile suggests a saturated dendritic snow growth zone. It
is possible that some of these snow showers could become heavier in
nature, given fairly steep low-level lapse rates, enhanced low-level
FGEN forcing collocated with the PVA maxima, and even some modest
instability. Both the NAM and RAP guidance indicate a strong
pressure rise/isallobaric component behind the front, so that would
support some stronger snow showers capable of reducing visibilities,
which appears to coincide with the Wednesday morning commute time,
so something to keep a close eye on. Confidence remains lower for
snow squall potential as there doesn`t appear to be much support for
a flash freeze per the latest WSSI impact fields. Still, a burst of
snow isn`t out of the question with these snow showers, leading to
reduced visibilities, especially with northwest winds gusting to
around 25 to 35+ mph.
Signals continue to be bullish for a frigid Wednesday night, as both
the GEFS and EPS ensembles suggest 850 mb level temperatures to fall
around 15 to 20 degrees C below zero for most locations. The EPS
ensemble climatological percentiles for 850 mb temperatures place
these values near the bottom percentile of the climo! Additionally,
with these ensembles suggesting 850 mb temperatures around -18
degrees C at 00z/6 PM Wednesday, if these numbers come to fruition,
these would be near the daily minimum for this parameter per the SPC
sounding climatology. In short, it`s gonna get real cold Wednesday
night into Thursday AM. Forecast lows are in the single digits above
and below zero, and wind chills range from the negative single
digits south to around 15 to 20 degrees below zero north.
Temperatures do look to rebound, starting Friday and lasting through
the upcoming weekend, as a compact mid-level shortwave approaches
our region from the west. Latest guidance indicates that this system
could pack a wintry mix with it, mainly in the form of a rain and
snow mix. A few of the models suggest perhaps some freezing rain
potential, but confidence in this is very low, especially as the NBM
shows chances of measurable ice accretion only around 10 to 20
percent across the area, so not likely at all. High temperatures by
the weekend look to warm back up to the middle 30s to the lower
40s.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 950 PM CST Mon Dec 9 2024
A cold front continues to sweep into northwest Illinois tonight
with a MVFR stratus cloud deck between 1500 to 2500 ft building
into the area behind the the front. This MVFR cloud deck is
slow moving and will approach KMLI and KBRL between 10 to 12
UTC. Ceilings are forecast to lift after 15 UTC from west to
east and clear KBRL by 20 UTC. In addition to the MVFR ceilings,
northwest winds behind the front will increase to 10 to 15
knots with gusts up to 25 knots. Winds will diminish through the
day.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Schultz
LONG TERM...Schultz/Uttech
AVIATION...Cousins
Area Forecast Discussion
National Weather Service Goodland KS
425 PM MST Mon Dec 9 2024
.KEY MESSAGES...
- 15-20% chance of quick but intense snow showers across the
northeast part of the area Tuesday afternoon.
- A brief warm up on Wednesday is then followed by near normal
temperatures into the weekend along with dry conditions.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 105 PM MST Mon Dec 9 2024
Cold air advection is working into the area in wake of a cold front.
Increasing mid level moisture this morning is leading to an
increase in cloudiness that will be the theme for the remainder
of the day that will make it difficult to warm up much more than
what it already has. Breezy northwest winds up to 35 mph are
forecasted for mainly eastern portions of the area where the
nose of an 850mb jet is forecast to reside but will quickly wane
mid afternoon; elsewhere gusts around 25-30 mph are forecast.
Light snow potential continues across Kit Carson and Cheyenne
county Colorado this afternoon along a 700mb frontogenesis
(FGEN) band. Drier air at the surface will mitigate the overall
snow potential but a dusting of new snow fall through the
afternoon does remain possible. Overnight cold air advection
will continue leading to overnight lows currently forecast in
the teens. Guidance wants to go higher on lows in the mid 20s
for what I`m assuming is due to the cloud cover and continued
winds around 10 mph which would promote continuously mixing but
with the cold air advection continuing I`m opting for the
colder end of guidance.
Tuesday, clouds are forecast to dissipate during the morning
hours as dry mid level air briefly moves in but are forecast to
redevelop during the early afternoon hours. A quick moving
shortwave through the afternoon will traverse the area resulting
in an increase in mid level moisture again. An 850mb FGEN
boundary is forecast to be present from Red Willow county up
into central Nebraska and then will move to the southeast across
Norton and Graham and potentially clipping Decatur county.
Along this boundary there may be the potential (15-20%) for
brief but intense bursts of snow that would reduce visibility to
a mile or less. This is supported by the FGEN band for lift,
along with additional isentropic lift support in the 285K level.
The RAP also shows a period of negative EPV* (which is a
measurement of instability) values that would also support the
heavy snow potential. Forecast soundings also show steep 0-3km
lapse rates of 8.0 to 8.5C/km which again shows the unstable
nature of atmospheric profile along with 5-10 j/kg of mixed
layer CAPE. Winds will also be breezy to gusty throughout the
entire day gusting to around 35-40 mph which may also lead to
some blowing snow as it is falling. A wet snow is however
forecasted which would limit the potential of snow getting
re-lofted again after it has fallen. Overall my confidence is
around 15-20% for this to occur but would be higher if the
sources of lift were stronger. Should the snow occur snow
accumulation of a quick dusting to an inch may be possible which
may lead to a period of hazardous travel conditions due to
reduction in visibility of less than a mile and roadways may
become slick as a Nebraska Department of Roads site near
Trenton, Nebraska has road temperatures currently in the upper
30s. The other part to note is that the current forecast time
for this to occur is from 2-5pm CT which may interfere with
schools releasing for the day. Again the potential for this is
conditional but is worth mentioning given the potential
impacts. Given the conditional nature of this please continue to
check back for the most up to date forecast.
High temperatures for the Tuesday have increased some due to
the forecasted lack of cloud cover across the area into the
upper 40s to mid 40s, however 850mb temperatures remain low in
the zero to two below range so should cloud cover linger then
temperatures would end up cooler than currently forecast.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 105 PM MST Mon Dec 9 2024
The start of the extended period on Wednesday will see a brief warm
up into the 50s for most as northwest flow returns. Some mid level
clouds may be present during the morning hours as mid level
moisture increases but at this time no obvious signs of lift to
promote any precipitation. The GFS has taken the side of the
ECMWF and is promoting more of a pattern change to a more
progressive shortwave pattern through the duration of the
extended period. The potential may be there for more active
weather if it is in the form of precipitation or wind which will
be reliant on the exact postponing and path of these
shortwaves. The positioning will also be key to if there will
be any moisture in place for precipitation to form as well. So
overall will be leaving the forecast dry but as these waves
approach and get better sampled then confidence would tend to
increase one way or the other.
As for temperatures, GEFS ensemble members are in relatively decent
agreement in either a lobe of cold, arctic air breaking off or the
cold air wrapping around back into the region on Thursday and
Friday. As a result have trended high temperatures down a few
degrees into the upper 30s to mid 40s. From the weekend on into
next week due to the progressive nature of the pattern a fairly
oscillating nature to the temperatures can be expected with
brief warm up periods and brief cool down periods. At this time
high temperatures are forecast mainly in the 50s along with low
temperatures in the 20s.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 422 PM MST Mon Dec 9 2024
For KGLD & KMCK... VFR conditions are forecast for both
terminals through the period. Keep an eye on future forecasts
as there is a 15% chance for some isolated snow showers both
between 03-10Z and 18-00Z. Otherwise, varying skies cover around
7500 to 15000ft is forecast for most of the period. Winds should
lighten to around 10 kts for the first 12 hours, then pick up to
20 kts with gusts to 30 kts from 16-23Z.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
SHORT TERM...Trigg
LONG TERM...Trigg
AVIATION...KAK
Area Forecast Discussion
National Weather Service Gray ME
1100 PM EST Mon Dec 9 2024
.SYNOPSIS...
Precipitation breaks out tonight starting as rain, snow, or a
mix. Snow and mix will taper off late tonight and change over to
freezing rain or drizzle for large parts of the forecast area.
This freezing precipitation may linger through the commute on
Tuesday. A very brief break late Tuesday afternoon will give way
to a much stronger storm Wednesday and Wednesday night that
brings heavy rainfall and potentially strong winds to parts of
the area. High pressure returns late in the week and lasts into
next weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
11 PM Update...Surface low pressure is presently analyzed over
Martha`s Vineyard and is forecast to deepen slightly as it
tracks east of Cape Cod over the next couple of hours. The back
edge of the steady precipitation is advancing ENE through Carrol
County and the NH/ME border with mainly snow remaining the
dominant precipitation type. The back edge of this snow will
move east of PWM around 2 AM and the Mid Coast around 6 AM. As
the surface low tracks ENE colder air will advect southwestward
with even portions of far SE NH dropping below freezing.
However, surface observations west of the back edge of
precipitation in NH indicate that no precipitation (including
freezing drizzle) is occuring, while drizzle is being reported
in Albany, NY with a temperature of 35F. For this update have
focused on temperatures, PoPs, and trended ice amounts down
taking into account the lack of freezing drizzle materializing
at this hour. That said, BUFKIT soundings continue to show
decent lift through saturated low levels with drying aloft in
the DGZ indicating that freezing drizzle will remain possible
tonight into tomorrow morning. Therefore have not made any
changes to the going Winter Weather Advisory for slick travel
through the morning commute.
725 PM Update...Latest observations and recent runs of the HRRR
suggest the going forecast through tonight is in good shape.
Snow reports have generally come in around 1-2 inches across
south-central into interior SW Maine with temperatures warm
enough for mainly rain across southern NH. Steady precipitation
will transition to drizzle across southern NH around midnight
and to freezing drizzle from SW to NE across central NH into
Maine after midnight. Have mainly made minor tweaks to the
forecast to incorporate the latest observations.
Previously...
Impacts and Key Messages:
* Slippery travel possible Monday night as light snow and light
freezing rain accumulate on surfaces
Precipitation is just starting to break out across southwestern
New Hampshire at this hour and will continue to push eastward.
To start it will be rain, snow, or a rain/snow mix. It is not
until around midnight that the warm nose begins to push in and
we start to see the threat of freezing rain, again beginning in
southwestern New Hampshire. Elsewhere, it looks to start as
snow. Steady snow will push through overnight, but begin to
taper off heading toward Tuesday morning as warm air aloft
continues to push north and change the precipitation type. With
poor snow ratios and a small accumulation window, expect 1 to 3
inches outside of southern New Hampshire, with lower end amounts
where the change over happens early, and higher end where it
stays snow the longest. The upper levels begin to dry out so as
the freezing rain moves north, rates will likely be decreasing
and it will be more in the way of freezing drizzle heading
toward sunrise.
With temperatures making it up into the mid 40s in Rockingham
and Eastern Hillsborough counties today, I have gone with the
thinking of the previous shift in leaving these areas out of the
Winter Weather Advisories. Even if there is a brief period of
freezing drizzle to start, road temperatures likely stay just
warm enough to not cause major issues. The only exception may be
the northern triangle of Rockingham County (Candia, Nottingham,
Northwood) as temperatures will be a little colder there.
&&
.SHORT TERM /TUESDAY NIGHT/...
Impacts and Key Messages:
* Slippery travel possible during the morning commute as light
freezing drizzle continues
As usual with cold air damming, it`s not likely to budge. I
blended in some colder guidance for temperatures tomorrow, so
expect areas of freezing drizzle to stick around most of the
day. Southern New Hampshire and the Maine coastline will switch
over to plain drizzle as the afternoon goes on. With all this
being said, rates and the accumulation window for the freezing
rain/drizzle support accumulations from a trace to a tenth of an
inch. Again, the low end amounts will be where the changeover
to plain drizzle happens quickly (southern zones) or
precipitation stays mostly snow (Northern zones). The high end
amounts will be in the foothills where the freezing drizzle will
hang on the longest.
Starting around midnight Wednesday is when we will begin to see
the steadier rain from the next system moving in to New
Hampshire, and pushing eastward overnight. There may be a very
brief period of freezing rain on the front end of this in the
foothills and northwestern Maine, but the higher rates will help
to quickly mix down the warmer temperatures and switch everyone
over to plain rain by Wedensday morning. More details on the
impacts of the that system will be in the long term section
below.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Overview...
A strong storm moves through New England Wednesday and
Wednesday night with heavy rainfall and potentially damaging
winds. The storm moves away Thursday. Cooler air returns for the
end of the week and next weekend with a strong high pressure
center building into New England.
Details...
Low pressure continues to deepen as it moves through the Mid
Atlantic on Wednesday. A steady soaking rain continues Wednesday
morning, with pockets of freezing rain continuing until about mid
morning across the northern valleys. Ice accretion won`t be
efficient with the heavier rainfall rates, so ice amounts are
not expected to be as high as some of the raw models guidance is
showing. However, slick travel will continue on untreated
surfaces across the north through Wednesday morning. Elsewhere,
steady rain continues through the day on Wednesday. The rain may
become more broken and periodic on the warm side of the coastal
front by the afternoon hours, but remain steady inland.
Rain will be heavy at times, with a widespread 2-3 inches
expected. Locally higher amounts are also likely, especially
along the southeast facing higher terrain through the mountains
and foothills of New Hampshire and western Maine. An area of
heavier rainfall rates is also likely to set up on the colder
side of the coastal front, slowly transiting inland through the
day on Wednesday as warmer air pushes in. Further details on the
rainfall and flooding potential can be found in the Hydrology
section.
Strong to damaging winds continue to be another concern,
particularly along the MidCoast and through the Kennebec valley
region in central Maine. A strong southerly LLJ of around 90kt
at 850mb develops Wednesday evening ahead of the front. Just how
quickly this organizes continues to be the greatest factor in
determining the wind speeds, with chances for the strongest
winds gradually increasing further east. The wind forecast has
been increased with this update, with generally 40-50 mph gusts
expected along much of the coastline and into central Maine.
There is still room for this wind forecast to trend upward. A
track further west and a more quickly strengthening LLJ would
push wind speeds higher, but for now we`ll continue to hold off
on leaning too far toward the higher end scenarios.
The storm system moves through Wednesday night, with precip
quickly shutting off with the passage of the cold front after
midnight. Upslope showers change to snow showers as colder air
pours back into the area. Relatively cooler air returns for
Thursday, with seasonably cool air returning by Friday. High
pressure builds in from Friday through the weekend, with
seasonable temperatures continuing.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
Short Term...Ceilings and visibilities will quickly be trending
down to IFR tonight as snow and mix breaks out across the area.
Unfortunately, there won`t be much improvement tomorrow as
ceilings stay low and -DZ/-FRDZ stick around for much of the day
and then steady rain moves in Tuesday night. Coastal terminals
may see a brief period of gusts up to 20kts with the onset of
precipitation.
Long Term...Heavy rain is likely at all terminals on Wednesday
and Wednesday night, with strong southerly wind gusts of 30-40kt
likely along the coast Wednesday afternoon and Wednesday night.
MVFR to IFR ceilings are likely. Drier conditions return
Thursday, with MVFR ceilings possible at HIE in upslope flow.
High pressure brings mainly VFR conditions by the end of the
week.
&&
.MARINE...
Short Term...Northwesterly wind gusts will increase to 25-30kts
tonight as a weak system moves through the area. There looks to
be a brief period of sub-SCA conditions Tuesday afternoon and
night, but winds will shift southeasterly and increase again
heading into Wednesday morning as a stronger system approaches
the waters. Seas will begin to build during that time as well.
Long Term...A developing storm center moves up the East Coast
on Wednesday, tracking west of the waters Wednesday night. Gale
to possibly storm force winds are likely Wednesday afternoon and
Wednesday night. Westerly gales are possible behind the storm
into Thursday, with high pressure building across the waters by
late in the week.
&&
.HYDROLOGY...
A soaking rain event is on track for the region on Wednesday.
Flash flooding, ice jam flooding, and river flooding is
possible. Best estimates of rainfall are between 2-3", but could
be higher based on a band of higher rain that could fall near
the foothills. A meltout of snow will occur in southern ME and
NH, and a near melt out in the foothills. The snowpack in the
mountains will hold. This will slow the runoff and limit the
flood potential in this region, however any rises on area
streams could move ice raising concerns for ice jams. The total
runoff will be around 2.5-4", highest likely in the lower Andro
and Kennebec Valleys where the warmer temps will last longest.
The heaviest rainfall Wednesday night could result in rapid
stream rises particularly for small tributaries. The mainstem
rivers should show a slower and less robust response. At this
time minor to moderate river flooding is possible with a lesser
risk in the mountains apart from ice jam issues. Major river
flooding is not anticipated at this time, however should the
storm track further west than the current projections it could
support worse conditions. Questions have been raised about this
event in comparison to last December. This flood will NOT have
the severity of December 2023. There is more storage for runoff
with low stream levels across most of the region, the storm will
be more progressive, and the snowmelt from the mountains will
be less.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 4 PM EST Tuesday for MEZ007>009-
012>014-018>022-033.
Winter Weather Advisory until 10 AM EST Tuesday for MEZ023>028.
NH...Winter Weather Advisory until 4 PM EST Tuesday for NHZ004-006-
009.
Winter Weather Advisory until 10 AM EST Tuesday for NHZ001>003-
005-007-008-010-011-015.
MARINE...Small Craft Advisory until noon EST Tuesday for ANZ150-152-154.
Storm Watch from Wednesday afternoon through Thursday morning
for ANZ150>154.
&&
$$
NEAR TERM...Baron/Schroeter
SHORT TERM...Baron
LONG TERM...Clair
Area Forecast Discussion
National Weather Service Marquette MI
650 PM EST Mon Dec 9 2024
.KEY MESSAGES...
- Lake effect snow develops tonight into western Upper MI. Up
to 3 to 5 inches of snow expected across western Gogebic
County into the Porcupine Mtns, leading to hazardous travel
conditions.
- Several inches of very fluffy lake enhanced/effect snow is
expected to fall over the northwest to north-northwest wind
snow belts Tuesday through Thursday.
- A Winter Storm Watch is in effect for Gogebic, Ontonagon,
Houghton, Keweenaw, Baraga, Marquette, and Alger counties from
late Tuesday night through late Wednesday. Very difficult
travel due to quickly accumulating snowfall and reduced
visibilities down to a quarter mile or less is possible.
- A return to below normal temperatures is expected by the
middle of this week, with the coldest time period being
Thursday and Thursday night. But, above normal temperatures
look to return by late this weekend into early next week.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 401 PM EST Mon Dec 9 2024
Water vapor imagery and RAP analysis show a shortwave trof moving
over the Upper Mississippi Valley. Pair of sfc lows that were
present 24hrs ago, one over se Saskatchewan and the other over
eastern SD, have transitioned to a consolidating low pres over
western Lake Superior, now just nw of the Keweenaw. Sfc trof extends
from the low into eastern Upper MI. Drier air arriving on westerly
winds behind the trof have helped scour out some of the low
cloudiness into southern Upper MI, especially where the flow is
downsloping. Skies have become sunny across much of Menominee
County. Current temps are above freezing across the fcst area,
ranging thru the 30s, but where some sun is appearing, temps have
risen into the 40s F. It`s currently 50F at Menominee.
A vort max evident in water vapor imagery over far nw WI is aiding
an area of -shsnra that is now moving into far western Upper MI. So,
expect -shsnra to expand into western Upper MI over the next few
hrs. Low pres currently w of the Keweenaw will exit eastern Lake
Superior during the evening. Trailing cold front will drop across
western Upper MI this evening, and models show rather strong low-
level convergence setting up into western Gogebic County. With 850mb
temps slowly falling, expect lake enhanced snow to pick up there
during the evening. The convergence weakens overnight, but with
850mb temps continuing to fall, settling to around -12C by 12z,
conditions will become increasingly supportive of LES under nw flow.
Initially in the evening during the period of developing lake
enhanced snow, the DGZ is mostly above the upward motion. So, snow
to water ratios will be on the lower side, resulting in snow that is
more dense. Overnight, as the column cools, snow to water ratios
will increase for a change to a little fluffier snow. With the
changing snow characteristics, snow accumulations are more
challenging. Will continue to carry snow accumulations of ~3-5
inches in the area from Ironwood to Wakefield n into the Porcupine
Mtns. Elsewhere across the w, only expect 1-2 to isolated 3 inches
of snow by sunrise on Tue. To the e, by 12z Tue, 850mb temps will
have fallen to around -8C, just to the point of supporting LES by
that time. So don`t expect much more than some isold to sct -shsn
developing tonight in the cyclonic flow in the wake of the low pres
exiting the lake.
&&
.LONG TERM /TUESDAY THROUGH MONDAY/...
Issued at 401 PM EST Mon Dec 9 2024
Arctic air dominates the mid week as temperatures become below to
well below normal Tuesday to Friday. The Arctic air mass will bring
several inches of fluffy lake enhanced/effect snow across the
northwest to north-northwest wind snow belts Tuesday through
Thursday before ending on Friday; there is concern for heavy lake
enhanced snowfall and patchy blowing snow across the north late
Tuesday night to late Wednesday. Therefore, a Winter Storm Watch
has been issued to alert the public and our partners to this
possibility. Temperatures trend back up this weekend and become
above normal once again by early next week as air from the Gulf
tries to fight its way into the Upper Peninsula from the southwest.
Additional details follow below.
Expect lake effect snowfall over the northwest wind snow belts
Tuesday as it finally starts to pick up over the east half during
the morning hours while cold air advection continues to increase
delta-Ts over Lake Superior to the mid teens over the east to around
20C over the west. The delta-Ts continue to increase throughout the
day and overnight hours as cold air advection continues across the
area, allowing the snow showers to intensify with time.
As a Manitoba Mauler low drops down into the Upper Midwest and later
the Great Lakes region by Wednesday, expect the lake effect snow to
become lake enhanced across the northwest to north-northwest snow
belts as the low approaches. As this occurs, we could have a surface
low that develops over eastern Lake Superior. Should this low
appear, expect convergent winds to create a robust lake enhanced
band of snowfall capable of 1+ inches of fluffy snowfall per hour.
While it is probable (50-70% chance) that this convergent band forms
Wednesday, details are still uncertain as to where this band will
form. Regardless, with the threat of the convergent band and patchy
blowing snow decreasing visibilities near the lakeshore Wednesday,
decided to hoist up a Winter Storm Watch for Marquette and Alger
counties. In addition to the north central, the west is also
expecting increasing moisture flux over the northwest wind snow
belts too beginning late Tuesday night. With the DGZ falling to the
sfc with time, expect high 20+:1 SLR snowfall to begin ramping up to
moderate to heavy snowfall rates after midnight. In addition, with
winds gusting up to 30 mph near the lakeshore, some patchy blowing
snow, in addition to the high snowfall rates, could possibly
significantly drop visibilities down to below a quarter mile or less
at times. Therefore, a Winter Storm Watch has been issued for
Gogebic and Ontonagon counties starting at midnight CST, and for
Houghton, Baraga, and Keweenaw counties starting at 7 AM EST.
Snowfall is expected to exceed one inch per hour in the heaviest
bands late Tuesday to late Wednesday. As the low pulls away
Wednesday night into Thursday, expect the transition back to pure
lake effect snow as winds back to the northwest and eventually west
with time. Nevertheless, some moderate snowfall could still be seen
in the west-northwest snow belts late Wednesday night into Thursday,
and headlines may need to be extended/added to account for this. The
last of the lake effect snow looks to end Friday as warmer air
starts to fight its way into the region. However, that`s not before
well below normal temperatures take hold over the area by this mid
week, with Thursday and Thursday night having the coldest
temperatures; it`s very possible that the interior west fails to get
above 0F, as the European ensemble shows a 50 to near 100% chance of
this occurring (highest chances near the Wisconsin border).
Thankfully, we will see a warming trend beginning this Friday...
As we move into this upcoming weekend, temperatures will warm from
below normal by this Friday to above normal by early next week. It
does appear that a shortwave low could possibly move over us this
weekend and bring additional precipitation over us. However, given
the model spread nearly a week out, confidence in the timing of the
shortwave low as well as the precipitation type associated with it
is low. I would keep an eye out for some wet snowfall chances across
the area as the deterministic European has trended a potential
shortwave low further south, bringing it through southern Lake
Michigan instead of northern Lake Michigan or even northern Ontario
(the southerly track would keep us cooler for longer). However, this
could be nothing more than wishful thinking for more snowfall across
our area. Moving into early next week, expect to see some snow melt
across our area as high temperatures get above freezing.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 648 PM EST Mon Dec 9 2024
An area of low pressure over Lake Superior will continue to
move to the northeast tonight, bringing winds from the WNW
across the area. At IWD, snow showers will develop this evening
bringing LIFR conditions. Conditions at IWD will improve to
MVFR Tue morning, but IFR remains possible with passing snow
showers. At CMX, LIFR conditions will continue this evening with
the snow showers. After midnight conditions will improve to
IFR, with continued improvement to MVFR overnight. While MVFR
will continue thru the end of the fcst period at CMX, some brief
periods of IFR are possible with passing snow showers. At SAW,
MVFR will prevail for the remainder of the fcst period. Flow
will not be favorable for snow showers at SAW, but can`t rule
some flurries tonight thru Tue morning.
&&
.MARINE...
Issued at 401 PM EST Mon Dec 9 2024
Winds are progressively becoming north and eventually northwest
behind the low traveling through Lake Superior now the rest of this
afternoon into tonight, increasing to 20 to 30 knots with a few gale
force gusts to 35 kt possible at times around the low`s center. As
the low continues to move away from Lake Superior late tonight,
expect the northwest winds to calm to around 20 knots Tuesday.
However, expect the winds to pick up once again from the north and
north-northwest Wednesday to 20 to 30 knots, with gales up to 35
knots possible as a low drops from Manitoba through the Upper
Midwest into the Great Lakes region (the European ensemble shows a
50 to around 90% chance of gales to 34 knots from Wednesday through
Thursday). In addition to the strong winds, moderate to possibly
heavy freezing spray looks to move over Lake Superior Wednesday
through Thursday; I would not be surprised if eventually we had to
hoist up a Heavy Freezing Spray Warning for most of the open lake
given we have yet to include many of the higher resolution models.
As the low moves away, expect the winds to become northwesterly,
before weakening to 20 knots or less by Friday morning as warmer air
tries to advect in from the southwest. The lighter winds are
currently projected to continue into this weekend, but we may see a
nearby shortwave low increase them before early next week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Storm Watch from Wednesday morning through late
Wednesday night for MIZ001-003>006-084.
Winter Storm Watch from late Tuesday night through late
Wednesday night for MIZ002-009.
Winter Weather Advisory until 6 AM CST Tuesday for MIZ009.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...TAP
AVIATION...RM
MARINE...TAP
Area Forecast Discussion
National Weather Service Tallahassee FL
918 PM EST Mon Dec 9 2024
...New UPDATE...
.UPDATE...
Issued at 915 PM EST Mon Dec 9 2024
No significant changes made to the forecast this evening. Light
to moderate rain showers will continue for our SE AL and west-
central GA counties tonight.
&&
.NEAR TERM...
(Through Tuesday)
Issued at 304 PM EST Mon Dec 9 2024
Perturbations aloft attendant to a dampening upper shortwave across
the MS Valley will continue to make for warm/humid, cloudy
conditions with periods of on & off showers tonight through
tomorrow. Afternoon radar shows an extensive area of rain, mostly
stratiform, marching east over the region. We have been observing
embedded isolated rotating cells near the FL/AL border in a
localized favorable corridor of instability amidst strong deep-layer
shear. This activity bears watching for any potential quick spin ups
and/or gusty winds.
The best rain chances (heavy at times) reside in the NW portion of
the Tri-State area during the near-term period, in line with the Day
1 Marginal Risk (level 1 of 4, at least 5% probability) for
Excessive Rainfall. However, some refinements to overnight PoP may
be needed if the axis of precipitation shifts more south or SE than
forecast. Expect unseasonably warm low temperatures ranging from mid
60s to upper 50s. The potential for patchy fog also exists in the FL
Big Bend into parts of SW GA.
For tomorrow, look for additional rounds of convection to get tugged
northward in semi-broken bands or clusters capable of heavy rain,
gusty winds, and perhaps a brief tornado. Intermittent lulls are
possible, for which the 18Z HRRR suggests at SE AL and the FL
Panhandle & Eastern Big Bend. Widespread highs in the mid/upper 70s
are forecast given the warm airmass in place. It appears the peak of
this wet weather event holds off until the short-term period.
&&
.SHORT TERM...
(Tuesday night through Wednesday)
Issued at 304 PM EST Mon Dec 9 2024
An extensive upper trough swinging down the Deep South acts as the
kicker system of a stagnant frontal boundary while also providing
renewed forcing for showers & thunderstorms late Tuesday/early
Wednesday. Hi-res guidance has more robust convective coverage after
0Z Wednesday as the associated front tracks eastward through the Tri-
State area. It is during this time that the best potential for
isolated nuisance/flash flooding and/or severe weather should exist.
The former is of greater concern given the set up for training
storms amidst an anomalously moist airmass.
A Slight Risk (level 1 of 4, at least 15% probability) for Excessive
Rainfall extends down into the Wiregrass & SE AL with a Marginal
(level 1 of 4) covering all but the easternmost FL Big Bend. See the
hydrology section below for more details. As for severe weather, the
environment will be somewhat favorable thanks to ample wind shear, a
30-35-kt low-level jet, and some instability to work with. The
latter is a limiting factor, especially if thick cloud cover
persists. A Marginal Risk (level 1 of 5) is maintained by the SPC
roughly along/NW of a Tifton-Bainbridge-Panama City line where 5%
wind & 2% tornado probabilities are in place. Any damaging gust or
spin up is likely to be isolated and short duration.
Frontal passage occurs Wednesday morning-afternoon with rapidly
clearing skies from west to east as breezy cP air filters in from
the NW. Expect chilly conditions to close out the work week. Highs
Wednesday range from mid 50s to upper 60s, then turning much
cooler Wednesday night into Thursday.
&&
.LONG TERM...
(Wednesday night through Sunday)
Issued at 304 PM EST Mon Dec 9 2024
Once the cold front passes through the area, temperatures dive
quickly downward with a light freeze possible across much of the
area both Wednesday and Thursday nights. We don`t really see a
night that is ideal for radiational cooling as high pressure
quickly moves to the north of our area during the day Thursday.
Thus, winds will stay just above calm, keeping things slightly
mixed. This does bring in some concern for wind chills, however,
as wind chills drop off into the mid 20s to lower 30s area-wide.
We`re not currently meeting our Cold Weather Advisory criteria at
the moment, but it`s something we`ll have to monitor. Highs
Thursday afternoon will only top out in the mid to upper 50s. A
weak shortwave also helps spread some upper-level clouds across
our region Thursday night, further limiting our potential for
radiational cooling.
A warming trend ensues late week into the weekend ahead of our
next cold front moving through on Sunday. This front appears
rather weak, though we do get some moisture return ahead of it.
Upper-level support remains well to our north, giving us only
low-end chances (20-40%) of rain showers Saturday night into
Sunday. Highs will return to the 60s and 70s with lows in the 40s
and 50s.
&&
.AVIATION...
(00Z TAFS)
Issued at 643 PM EST Mon Dec 9 2024
Overcast conditions across the region are currently impacting
area terminals. For now rain coverage has decreased and is mostly
confined across DHN and ABY. As a cold front approaches from the
west we`ll see rain chances increase throughout tomorrow.
Initially impacting ECP/DHN around daybreak, rain will then
spread eastward. MVFR to IFR conditions are expected throughout
the TAF period as lowering cigs and vsbys impact terminals.
There`s a chance ECP and DHN see VCTS tomorrow afternoon when
instability is highest.
&&
.MARINE...
Issued at 304 PM EST Mon Dec 9 2024
A tightening pressure gradient along and behind the cold front
Tuesday night into Wednesday will result in the potential for gale
force winds, mainly in gusts. However, the marine MOS guidance
suggests that sustained gale-force winds cannot be ruled out over
the western waters. Given this and much of the model consensus
showing the possibility of gale force gusts, have issued a Gale
Watch for our western waters.
From CWF Synopsis... Southerly winds ahead of a cold front will
persist through Tuesday, increasing to advisory-level late Tuesday
night. Showers and a few thunderstorms are likely ahead of the
front. Behind the front on Wednesday, winds will shift out of the
north to northwest with gale force gusts over the western waters.
Winds over the eastern waters will likely be advisory level, but
can`t rule out some gale force gusts. Seas will build to 6 to 9
feet over the waters. Winds and seas will subside late in the week
as the pressure gradient relaxes.
&&
.FIRE WEATHER...
Issued at 304 PM EST Mon Dec 9 2024
Wetting rains will continue to spread across the region Tuesday
with the best potential being Tuesday night into Wednesday
morning. Multiple rounds of scattered showers are expected with a
few embedded thunderstorms possible. Showers and thunderstorms are
expected to come to an end Wednesday afternoon. Winds will shift
from southerly/southwesterly during the morning hours to
northwesterly as the cold front makes its way through Wednesday.
Transport winds will increase to 25-30 mph Wednesday and will
begin to subside during the evening hours. Dispersions will be
high across the region during the afternoon on Wednesday.
Behind the cold front, drier and cooler air will usher in with
gentle northwest breezes.
&&
.HYDROLOGY...
Issued at 304 PM EST Mon Dec 9 2024
Locally heavy rainfall will be possible through Wednesday as a
cold front slowly approaches the area before getting a larger push
out of the area Wednesday. Widespread rainfall totals of 2 to 4
inches are expected along and west of the Apalachicola and Flint
Rivers. The reasonable worst case rainfall (10% chance of
exceeding) is about 4-5 inches in these areas. Rainfall totals
drop off quickly to the south and east. Flash flooding is
possible as flash flood guidance is about 2.5 to 3.5 inches in one
hour or 3 to 4.5 inches within 3 hours. The Weather Prediction
Center has outlined southeast Alabama and adjacent parts of
southwest Georgia in a Slight Risk of excessive rainfall (level 2
of 4) with the rest of southwest Georgia into the Florida
Panhandle and western Big Bend in a Marginal Risk (level 1 of 4).
This rainfall will cause some rises on area rivers, such as the
Pea, Choctawhatchee, Kinchafoonee, and Muckalee; but NAEFS
guidance is in agreement that the rivers should remain at or below
action stage. This is due to the rather dry antecedent conditions
leading to low river levels. The HEFS is a bit more bullish with
showing some possibility of minor flooding along these rivers.
However, this incorporates the rainfall totals that are higher
than our current reasonable worst case scenario.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 62 74 59 61 / 20 20 80 100
Panama City 66 75 57 59 / 30 50 90 90
Dothan 64 74 52 56 / 90 70 100 60
Albany 61 75 57 58 / 80 50 100 100
Valdosta 59 79 63 63 / 20 10 70 90
Cross City 56 79 64 68 / 0 0 50 70
Apalachicola 64 73 61 65 / 10 20 90 90
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Thursday afternoon for FLZ108-112-
114-115.
GA...None.
AL...None.
GM...Gale Watch from late Tuesday night through Wednesday afternoon
for GMZ750-752-770-772.
&&
$$
NEAR TERM...IG3
SHORT TERM...IG3
LONG TERM....Young
AVIATION...Oliver
MARINE...Young
FIRE WEATHER...Montgomery
HYDROLOGY...Young