Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/26/23
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
459 PM MST Mon Dec 25 2023
...New AVIATION...
.SYNOPSIS...
Issued at 243 PM MST Mon Dec 25 2023
After another cold and mostly clear night, temperatures will warm
slightly Tuesday. Breezy to windy conditions are expected across
much of high terrain and their adjacent highlands. A few snow
flurries may grace the extreme northeast part of the state but
elsewhere will remain dry. Temperatures will continue warming most
areas Wednesday through the end of the week with dry conditions
prevailing. Winds will be generally light with occasional breezes
across portions of the central highlands and northeast New Mexico.
&&
.SHORT TERM...
(This evening through Tuesday night)
Issued at 243 PM MST Mon Dec 25 2023
Mostly dry and cooler than normal weather is expected tonight
through Tuesday night. Apparent temperatures over the Sangre de
Cristo mountains tonight could range from near -10 to -20 degrees
below zero.
Tracking and timing of the disturbances rotating around the
deepening upper low pressure system over the central plains states
will continue to be problematic during the short term. With this
package, one disturbance may impact the Sangre de Cristo mountains
into far northeast New Mexico late tonight and Tuesday morning,
bringing slight chances for light snow to the area but with little
to no accumulations. A second disturbance may follow Tuesday night
with somewhat better potential for meager snowfall.
The wind has been relatively tame so far today but could still gust
up a bit before sunset. Northwest winds aloft begin to strengthen
this evening and moreso during the overnight, impacting the western
and central high terrain. Guidance suggests some Wind Advisories
will be needed Tuesday in some of the usual northwest flow areas
such as the Central Highlands, but also potentially over some lower
terrain areas including Chaves County Plains. Can`t rule out a few
spots hitting High Wind criteria if the 18Z HRRR gust potential is
correct but that model also decreases wind speeds Tuesday afternoon.
Therefore the timing of the incoming disturbance could be a critical
factor, and will pass on issuing any wind highlights at this time.
&&
.LONG TERM...
(Wednesday through Sunday)
Issued at 243 PM MST Mon Dec 25 2023
The nearly stationary low pressure over the Great Plains will
finally begin pushing eastward on Wednesday. Brisk northerly winds
will take hold across portions of northeastern NM in the
disturbance`s exit as a stout jet max drapes itself over the
state. High pressure builds to our west and temperatures will
rebound a few to several degrees areawide thanks to the increase
in pressure heights. The highly amplified ridge will scoot slowly
eastward across the Desert Southwest through the end of the work
week, bringing generally tranquil conditions. Temperatures will
continue warming through Saturday, with all areas seeing near or
above average values. The next chance at precipitation may arrive
Sunday as a weak trough passes through the Intermountain West.
Forecast confidence is low but what precip could be seen would
favor the northern high terrain.
&&
.AVIATION...
(00Z TAFS)
Issued at 443 PM MST Mon Dec 25 2023
Northwest flow aloft will strengthen tonight mainly over the
central and southwest thirds of the forecast area, and also over
the northeast corner. This will cause surface winds to remain
breezy in many locations through much of the overnight hours, and
into Tuesday morning. Winds aloft and at the surface are forecast
to weaken some late Tuesday afternoon. A weak disturbance will
also clip northeast NM Tuesday morning, where/when periods of
light snow are expected with a risk of MVFR conditions as far
south as AXX, RTN, and CAO.
&&
.FIRE WEATHER...
Issued at 243 PM MST Mon Dec 25 2023
Critical fire weather conditions are not anticipated through the end
of this week. Gusty northwest to north winds on the back side of a
deepening upper low pressure system over the central plains states
are expected to impact especially the central mountain chain and
eastern New Mexico through Wednesday. The strongest winds with
greatest areal coverage of gusts to around 50 or 55 mph still
appears to occur Tuesday but minimum humidities are forecast to
remain near to above 20 percent. Areas of good to even excellent
ventilation rates Tuesday are expected to transition to widespread
poor rates Thursday through Sunday.
Patchy light snow may return over the Sangre de Cristo mountains and
portions of far northeast New Mexico late tonight and early Tuesday
then again Tuesday night with little to no accumulations.
Temperatures will remain below normal through Wednesday before
recovering to near normal or above for the rest of the week.
The upcoming weekend now appears to be dry, but forecast models have
been highly variable handling the energy moving into the CONUS from
west.
&&
.PRELIMINARY POINT TEMPS/POPS...
Farmington...................... 13 39 14 40 / 0 0 0 0
Dulce........................... 4 33 4 42 / 0 0 0 0
Cuba............................ 9 33 10 38 / 0 0 0 0
Gallup.......................... 8 41 9 44 / 0 0 0 0
El Morro........................ 7 38 9 42 / 0 0 0 0
Grants.......................... 10 42 10 44 / 0 0 0 0
Quemado......................... 12 38 10 43 / 0 0 0 0
Magdalena....................... 20 42 20 45 / 0 0 0 0
Datil........................... 15 37 15 43 / 0 0 0 0
Reserve......................... 13 45 13 52 / 0 0 0 0
Glenwood........................ 23 50 23 56 / 0 0 0 0
Chama........................... -2 28 4 39 / 0 0 0 0
Los Alamos...................... 14 35 17 39 / 0 0 0 0
Pecos........................... 11 36 17 42 / 0 0 0 0
Cerro/Questa.................... -1 29 4 36 / 0 5 5 0
Red River....................... -1 26 4 36 / 5 5 10 0
Angel Fire...................... -4 28 0 36 / 5 5 10 0
Taos............................ 3 31 6 38 / 0 0 5 0
Mora............................ 8 35 13 43 / 0 5 0 0
Espanola........................ 8 37 13 45 / 0 0 0 0
Santa Fe........................ 12 34 17 39 / 0 0 0 0
Santa Fe Airport................ 14 36 17 41 / 0 0 0 0
Albuquerque Foothills........... 19 39 21 44 / 0 0 0 0
Albuquerque Heights............. 22 42 23 45 / 0 0 0 0
Albuquerque Valley.............. 16 43 18 47 / 0 0 0 0
Albuquerque West Mesa........... 20 41 21 46 / 0 0 0 0
Belen........................... 21 46 20 46 / 0 0 0 0
Bernalillo...................... 19 41 20 46 / 0 0 0 0
Bosque Farms.................... 19 44 18 46 / 0 0 0 0
Corrales........................ 19 41 20 46 / 0 0 0 0
Los Lunas....................... 19 45 20 46 / 0 0 0 0
Placitas........................ 18 39 20 42 / 0 0 0 0
Rio Rancho...................... 20 41 21 45 / 0 0 0 0
Socorro......................... 24 48 23 49 / 0 0 0 0
Sandia Park/Cedar Crest......... 15 35 19 39 / 0 0 0 0
Tijeras......................... 17 37 19 41 / 0 0 0 0
Edgewood........................ 16 36 17 40 / 0 0 0 0
Moriarty/Estancia............... 14 38 15 42 / 0 0 0 0
Clines Corners.................. 14 34 17 40 / 0 0 0 0
Mountainair..................... 18 38 18 42 / 0 0 0 0
Gran Quivira.................... 20 39 19 44 / 0 0 0 0
Carrizozo....................... 25 44 24 50 / 0 0 0 0
Ruidoso......................... 22 39 24 46 / 0 0 0 0
Capulin......................... 9 35 19 39 / 0 10 20 0
Raton........................... 9 41 18 44 / 0 5 10 0
Springer........................ 11 41 17 46 / 0 5 5 0
Las Vegas....................... 13 40 18 44 / 0 5 0 0
Clayton......................... 19 42 25 46 / 0 5 10 0
Roy............................. 17 43 21 47 / 0 5 0 0
Conchas......................... 19 45 23 51 / 0 0 0 0
Santa Rosa...................... 22 46 24 48 / 0 0 0 0
Tucumcari....................... 19 47 22 51 / 0 0 0 0
Clovis.......................... 20 47 23 52 / 0 0 0 0
Portales........................ 21 48 23 53 / 0 0 0 0
Fort Sumner..................... 24 49 24 52 / 0 0 0 0
Roswell......................... 24 55 25 57 / 0 0 0 0
Picacho......................... 26 49 27 53 / 0 0 0 0
Elk............................. 25 47 25 52 / 0 0 0 0
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...99
LONG TERM....12
AVIATION...44
Area Forecast Discussion
National Weather Service La Crosse WI
600 PM CST Mon Dec 25 2023
.KEY MESSAGES...
- Rain persists tonight, into Tue morning, with small chances (20%)
continuing into Thu. Additional amounts upwards of 1/2".
- Record/near record warmth ending, but still relatively mild
through the end of December. Weekend trending dry, into the early
part of next week.
&&
.DISCUSSION...
Issued at 215 PM CST Mon Dec 25 2023
* RAIN CONTINUES TONIGHT - amounts upwards of 1/2" for some. Smaller
pcpn chances then into Thu (20%).
Band of rain slowly lifting north/northwest across the area this
afternoon, associated with a stacked low pressure system currently
churning over the central plains. A cold front hangs north-south
along far eastern MN into eastern IA. Quite a contrast in temps -
from the mid 30s in south-central MN to the lower 50s in southeast
MN.
The precipitation will continue to lift northwest with a wing of the
upper level energy. Short term guidance pushes the band north of I-
90 by 15z Tue, eeking northward of I-94 in the early afternoon. Temp
profiles continue to keep the pcpn type as rain. That said, RAP
bufkit soundings suggest a 1-3 hour window over southeast MN where
ice could be lost in the cloud and temps around freezing - making
freezing rain a possiblity. Short term blend holds this threat
around 20% and will opt to keep this in the forecast for now. As for
additional rain, amounts tonight through Tue morning from 1/4 to
1/2" on average. About a 30-50% that could push north of 1/2".
South of the band, cold air will be rotating around the low on Tue,
resulting in warmer high temps north of I-94 compared to south of
there. The colder air will also increase low level lapse rates and
suggests a little instability could develop. Some hints in a few of
the short term models there could be some breaks in cloud cover that
could/would further possible instability via sfc warming. RAP bufkit
soundings shows the cooling/increasing lapse rates, while also
holding onto enough saturation that a few showers would be possible.
Not great chances (~20%), but enough signals to warrant small
chances at least for northeast IA/southwest WI Tue afternoon. Upshot
here is if showers are realized, temp profiles would favor snow. Any
accumulation would be minimal and on grassy sfcs.
The low pressure system doesn`t have a lot of reason to get out of
the area too quickly with the upper level jet mostly under-cutting
it, but medium range guidance does shift it east/southeast moving
into Thu. A smattering of low end pcpn chances (20-30%) could
persist for some locations as bits of energy ripple around the low,
but most of the sensible weather impacts look to be a continuation
of the expansive cloud cover. A breakout into "full" clearing could
hold off until later Thursday night/Fri.
* TEMPERATURES INTO THE WEEKEND - cooler, but still above normal
As the upper level low slowly meanders eastward, colder air will be
wrapped in from the west/north. The GFS and EC then favor northwest
flow a loft for the rest of the week, with shortwave troughs/ridges
popping across the region. While the record/near record warmth of
the holiday will exit and colder Canadian air takes its place -
temps still look to hover 5 to 10 degrees above the late December
normals - with some fluctuations based on whether there is a ridge
or trough making its way across the upper mississippi river valley.
* PCPN CHANCES FOR SECOND HALF OF WEEK? small, with minimal
accumulations if they occur
Long range guidance continues to suggest a few upper level shortwave
troughs could/will drop southeast out of Canada, spinning across the
region this weekend into the early part of next week. Deterministic
GFS and EC, along with the bulk of the ensemble members, aren`t very
enthused with pcpn chances (roughly 10 to 20%). If any pcpn would
fall, QPF via the model blend keeps it at just a few hundreths of
the an inch (locally). Currently, trends favor keeping the bulk of
any pcpn threat and amounts northward. If more saturation can be
realized, chances will creep up, although amounts would still trend
on the light-side. Will roll with the model blend for now.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 600 PM CST Mon Dec 25 2023
Rain will continue into the overnight with occasional MVFR
visibility reductions. Trended KLSE predominantly towards MVFR
ceilings, but there is a window for IFR ceilings (45-55% chance)
from mid-evening through early morning. Higher probabilities
(60-80%) for IFR ceilings exist at KRST overnight, with a
period of LIFR possible. Winds could gust 20 to 30 kts at times
this evening, although the stable airmass may limit gusts,
especially at KLSE. Winds will shift southerly late tonight, and
guidance suggests gradually improving ceilings on Tuesday,
potentially to VFR for some areas by afternoon.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Rieck
AVIATION...JM
Area Forecast Discussion
National Weather Service Columbia SC
657 PM EST Mon Dec 25 2023
.SYNOPSIS...
Rain continues to be over the area through tonight, with rain
chances remaining fairly high into Tuesday night until a cold
front pushes through the region. Temperatures will remain above
normal into mid- week, but cooler conditions are expected late
this week and over the upcoming weekend following the passage of
a cold front.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Large closed upper low continues to spin over the Central
Plains with broad southwesterly flow across the southeastern
states. Surface high pressure remains anchored over New England
ridging into the Carolinas but is weakening and shifting
northeastward. Low level flow is from the southeast off the
Atlantic and there is currently strong isentropic lift over the
forecast area as the latest radar imagery shows widespread
rainfall along and north of the I-26 corridor. Further south the
precipitation is a bit more scattered.
Latest hi-res guidance suggests the strongest isentropic lift
will continue to be over the northern half of the forecast area
along and north of I-26 while scattered showers are expected in
the CSRA through the evening into overnight. After collaboration
with neighbors, decided to lower pops to chance in the CSRA
while maintaining likely/categorical pops across the rest of the
forecast area. Mesoanalysis shows instability continues to be
confined to central and southwest GA with a stable air mass in
place over our area so have removed thunder from the forecast
overnight. WV Imagery shows significant dry air in the mid
levels moving in from the west overnight which should also limit
deeper convection threat. Temperatures will be relatively
steady through the night with low dewpoint depressions and
widespread clouds and some rain. Lows generally expected in the
mid 50s to around 60 degrees.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
A frontal boundary will progress to the north and east of The
Midlands and CSRA Tuesday into Tuesday Night. The CAMS differ
on the timing of the exit of shower activity with the preferred
HRRR and NAM 3 km slower than the FV3. Mid level drier air
advects into the region on Tuesday which should destabilize the
atmosphere enough for a chance of thunderstorms. Precipitation
winds down Tuesday Night with total accumulations of 1 to 2
inches.
A closed H5 upper level low pressure system gradually
progresses into the Midwest and Ohio River Valley during the
middle of the week. The cooler air does not begin to filter into
the Southeast U.S. until Thursday, therefore Wednesday should
still be above normal temperature wise. Temperatures should be
near normal for late December on Thursday.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Below normal H5 heights will be over the Southeast U.S. through
Friday before a transition to a zonal flow aloft for the New
Years Weekend. Disturbances moving through the region should
be hard to time. The Northern Midlands and Pee Dee may be at a
slight risk for showers during this time period. Temperatures
are expected to be 5 to 10 degrees below normal.
The model ensembles differ quite a bit on forecast solutions for
the start of the New Year. There appears to be a blocking
pattern over the Western U.S. which impacts how the polar and
subtropical jet streams interact with each other across the
Eastern U.S. The models depict an upper trough affecting the
East Coast, however they have considerable differences on
pattern evolution, timing, and location.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Restrictions expected to dominate the TAF period.
Clouds and rain continue across the terminals as weak low pressure
moves south of the area. Satellite and radar imagery show the
thickest clouds and heaviest rain moving through CAE/CUB with some
rising cigs and vsbys as the rain move north of the area. Expect
this to be a short time period as easterly winds continue pushing
Atlantic moisture into the area which will bring cigs back to
IFR...possibly LIFR...from the early morning hours through the end
of the period as the system slowly crosses the region. With the rain
becoming more scattered have kept mention of VCSH at all terminals
through the end of the period and plan to handle any bands which
develop with a TEMPO group. Winds through the period will be
easterly at 10 knots or less.
EXTENDED AVIATION OUTLOOK...Restrictions possible through Tuesday
night as low pressure crosses the region with scattered showers.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1028 PM EST Mon Dec 25 2023
.SYNOPSIS...
Widespread rain continues across the area through Tuesday.
Thunderstorms are possible tonight into Tuesday. Colder weather
arrives Wednesday night into late week with snow possible across the
mountains.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 1016 PM Monday: The KGSP radar shows most of the precip
lifting north of a line from Toccoa to Anderson and Laurens,
with widespread coverage north of that line. Will cut back
the precip chances a bit over the Lakelands/lower Piedmont,
down into the good chance range, but not too much as continuing
moist southerly upslope could force new showers at any time. Have
seen a few lightning strikes over the western Upstate and the srn
mountains of NC in the past hour or two, validating our idea that
enough elevated CAPE would be present to support a few embedded
thunderstorms. Will obviously keep the slight chance mention
overnight based on that observation. Beyond that, we continue to
watch a band of precip with some heavier convective cells training
north/northeast across nrn GA. The HRRR points this activity toward
the western part of the fcst area into the pre-dawn hours, but for
now the heavier precip was moving more toward southeast TN/extreme
southwest NC. A few more tweaks have been made to the precip probs,
but otherwise we will stay the course.
Otherwise...a deep closed upper low continues to strengthen across
the Central Plains. As such, the low will make little eastward
progress over the next 36hrs as it slowly crawls from western KS
to northern MO. Latest surface analysis places an occluded sfc
low over nwrn IA with a new wave over srn IL, then cold front
draped in an arc through the MS Delta Region. Ahead of the front,
strong mass response to the deepening closed low has strengthened
a 40-50kt low-level jet that has pushed into the region along with
subsequent moisture transport. PWATs have surged to 1-1.4" within a
pronounced low-level ThetaE ridge. Slow progression of the synoptic
pattern will allow for waves of showers and a few thunderstorms to
develop and move across the area through the overnight hours and
into tomorrow morning. A plume of 300-800 J/kg of elevated MUCAPE
will also pivot into the area this evening along with rather steep
6.5-7.5 C/km mid-level lapse rates. This will allow for an uptick in
convection with heavier precipitation rates through the overnight.
By tomorrow morning, secondary surface cyclogenesis will likely
be underway across southern Georgia as upper divergence increases
in the left exit region of a subtropical jet extending along the
Gulf Coast. The low will likely slide along the coast to just
offshore with the potential for a cluster of coastal convection to
inhibit inland moisture flux. This still casts some uncertainty in
the forecast heading into tomorrow afternoon and evening as some
CAMs continue to fester training convection across the eastern two
thirds of the area while other are more progressive in clearing out
the deeper moisture and sliding any heavier rainfall rates off to
the east. At least some flooding threat could linger into tomorrow
afternoon, especially across the northern Blue Ridge Escarpment.
Overall, the highest event total rainfall will be along the
favorable upslope escarpment with 1-3" east of the mountains and
an inch or less in the downslope areas west of the Blue Ridge.
Temperatures will be quite mild through the period as dewpoints
rise into the 50s to near 60 with overnight lows upwards of 20
degrees above normal.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 130 PM Monday: Closed upper low over the Mid-MS Valley will
begin to progress eastward as it is shown opening up during the
short-term per deterministic guidance. The remnant frontal boundary
associated with the closed low shifts east of the CFWA, while a
surface low develops along the front and helps push the axis of deep
layer moisture to the northeast. As the closed low churns over the
east-central CONUS, drier air will filter in across the CFWA
Wednesday and Thursday. The core of the closed low will bring a
reinforcement of moisture and stout cold air aloft. Factor in weak
surface low riding underneath and northwest flow snow will begin to
set up along the NC/TN border late Thursday and Friday. The southern
stream jet will stretch along the Southeast Coast and allow the
closed low to gain a positive tilt. This will help to enhance
dynamical upper forcing as the low enters the region. Depending on
whether or not the upper low remains closed or opens up by the time
it reaches the area will determine if there will be enough support
for deformation banding to setup. In the latest runs of the
deterministic guidance, low-level thicknesses will become cold
enough for snow to form by Thursday night across the mountains.
Wouldn`t be surprised if some of this activity can break containment
east of the mountains, especially across the NC Piedmont overnight
Thursday and Friday. As a result, there may be portions of the CFWA
that receive their first flakes of the season. Still a lot of
uncertainties, but the overall synoptic setup and forcing for ascent
is definitely intriguing and we will need to continue to monitor the
upcoming trends. Best bet is for accumulating snow to begin at the
end of the forecast period in the higher elevations along the NC/TN
border, but still a lot of questions to be answered elsewhere.
Wednesday will be the last very warm day before the fropa occurs and
CAA sneaks in across the CFWA. Temperatures on Wednesday will
continue to run ~10 degrees above normal, with a dip to near-normal
values by Thursday and Thursday night.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 220 PM EST Monday: A progressive synoptic pattern will
be in store through the medium range. The flow will flatten out
over the weekend following the upper low lifting northeast of the
area. Ongoing northwest flow snow could persist into the weekend
as well, but limited available moisture will keep totals on the
lighter side. Otherwise, the forecast will remain quiet through
the weekend as we remain in a post-frontal regime. Expect good
diurnal swings over the weekend with lows slightly below normal
due to good radiational cooling conditions and highs near-normal
with good insolation. Interesting set up could take shape by
early next week as the GFS and ECMWF show a potent shortwave
trough digging into the area from the Midwest by D7. The could
allow the southern stream jet to activate and provide us our next
storm system. Details are way too far out for specific details,
but will be worth monitoring over the next week. There is some
support from ensembles, but still off in regards to timing and
location of the shortwave.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Widespread flight restrictions can be
expected thru the period, affecting all terminals. Most places
have already started the transition from MVFR to IFR as the
southeasterly upslope flow strengthens across the region. A
few VFR holes were noted, but are expected to close up in short
order. Guidance suggests that a widespread MVFR vis/IFR ceiling is
most likely, with an eventual progression to LIFR. There will be
some fluctuations, no doubt, but no attempt will be made as of yet
to nail them down. Winds will favor ESE from mid evening through
midday Tuesday. One main forecast problem will be the wind direction
at KCLT. The recent guidance favors keeping the ESE direction as
prevailing into Tuesday afternoon, so a change was made to the new
TAF accordingly. The guidance develops some weak instability up from
the south late Tuesday, so a chance of TSRA was included at KCLT.
Outlook: Restrictions may linger into Wednesday morning before
VFR finally returns. Precip and restrictions return again to the
mountains Thursday amd Friday, possibly spreading east across the
area Friday.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Flood Watch through Tuesday afternoon for GAZ010-017-018.
NC...Flood Watch through Tuesday afternoon for NCZ062>065-507>510.
Flood Watch through Wednesday morning for NCZ033-049-050-
501>506.
SC...Flood Watch through Tuesday afternoon for SCZ101>106-108.
&&
$$
SYNOPSIS...DEO
NEAR TERM...PM/TW
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...PM
Area Forecast Discussion
National Weather Service Louisville KY
827 PM EST Mon Dec 25 2023
.Forecast Update...
Issued at 827 PM EST Mon Dec 25 2023
Main forecast update this evening was to add fog/drizzle wording
for areas east of I-65 where low level moisture looks to linger
longest ahead of a frontal boundary. Some of the high-res guidance
takes visibilities down quite low in the early morning hours, and
forecast soundings in those areas show quite a bit of saturation in
the low levels of the atmosphere to support potential fog/drizzle.
Otherwise, rest of forecast is on track.
&&
.Short Term...(This evening through Tuesday)
Issued at 310 PM EST Mon Dec 25 2023
==============================================================
Key Messages:
- Low confidence for a few thunderstorms this afternoon for south-
central KY.
- Wind gusts relax this evening.
- Temperatures gradually fall tomorrow.
==============================================================
The primary widespread precip shield has shifted off to our north
and east since this morning, though some scattered shower activity
continues across central KY for this afternoon. GOES Vis imagery is
showing some minor breaks in the cloud deck across central Tennessee
and south-central Kentucky. These areas are seeing temps in the
upper 50s and low 60s, along with dewpoints in the upper 50s, and
continue to be where to watch if any destabilization can develop for
a storm or two to pop up. HRRR continues to be a bit more aggressive
than the other CAMs with instability over the next few hours. SPC
Mesoanalysis does depict 500 J/kg of SBCAPE nosing into central
Tennessee, but stops short of the KY/TN state line. RAP guidance
indicates this instability will be waning in the coming hours as CIN
increases, but it`s possible to have 100 J/kg nose into far south-
central Kentucky. Shear is very strong across the region due to the
LLJ overhead, which the VAD wind profiles have shown 40-50kts in the
3-4k ft layer. Low confidence continues for any gusty thunderstorm
development, but south-central Kentucky will be the most likely
place if we do see any develop.
Peak wind gusts so far have been in the 20-30 mph range, with
slightly higher wind gusts across western Kentucky. We only have
about 2 more hours of prime momentum transfer, so still can`t rule
out some gusty winds, but the trend has been to slightly lower wind
gusts for the rest of the afternoon.
For tonight and tomorrow, the upper low will wobble over eastern
Kansas and western Missouri, and the attendant sfc frontal boundary
will pass through the region from west to east. This will cut off
the precip chances from west to east for most of the area, but PoPs
will linger for the I-75 corridor, either as drizzle or light rain
with minor accumulations. Temps will range quite a bit depending on
where the front is. Low to mid 40s are expected for areas west of I-
65 since they will be post-frontal, but to the east of I-65,
counties could only get down to the low 50s due the WAA still out
ahead of the boundary. Due to the boundary cutting through the
region tonight and into tomorrow morning, expect a non-diurnal
temperature curve for tomorrow. Temps will gradually be falling
throughout the day.
.Long Term...(Tuesday night through Monday)
Issued at 320 PM EST Mon Dec 25 2023
==============================================================
Key Messages:
- Thursday and Friday, slightly below-average temperatures with
potential of wintry mix and measurable snow.
- Weekend, seasonable temperatures and dry conditions.
==============================================================
Synopsis...The first and most active half of the medium range begins
with broad upper trough and embedded closed low moving from the Mid
Mississippi Valley to the East Coast while pushing a weakening
occluded surface low/front across the lower Ohio Valley Thursday
into Friday. The aforementioned system will increase once again
precipitation chances for the region with an increasing possibility
of a wintry mix and spots of measurable snow. Conditions then settle
during the second half as the eastern edge of the West CONUS upper
ridge slowly moves into the region and the core of the negative
height anomalies depart to the North Atlantic, providing drier and
warmer conditions. However, a shortwave trough coming from Canada
will disturb the ridge late in the weekend into next week allowing a
cold front to move across the Ohio Valley Sunday night into Monday.
Model Evaluation/Confidence...Overall, model guidance has come into
better agreement with the upper low track as main deterministic
guidance depicts the system moving across the lower Ohio or
Tennessee Valleys Thursday into Friday. Nonetheless, there is still
fair disagreement on the exact low track and especially the center
structure and vorticity intensity. In this regards, the UKMET and
ECWMF feature a more loosely-organized upper low while the GFS and
CMC lie on the stronger and more compact side of the envelope. This
differences might provide some context on why the snowfall totals
for the UKMET/ECWMF are significantly lower and more spotty in
coverage than the CMC and GFS which looks higher and more
frontogenetically driven with banding swaths. Between the GFS and
CMC, the former concentrates impactful snowfall in an arc extending
across western KY and southern IN while the latter hosts scattered
accumulations across southern Indiana and central Kentucky. As for
ensemble guidance, more than half of the CMC/GFS/ECMWF members have
measurable snow in SDF, BWG, and LEX during the Thursday-Friday
period. Given the above elements, there is moderate to high
confidence in measurable snowfall/wintry-precip with low confidence
in exact amounts.
Wednesday...Although a couple of showers might be departing the area
through the east before sunrise, mostly dry conditions will prevail
as the upper low approaches the area. Expect weak and variable
surface winds ahead of the occluded low with increasing sky cover
through the afternoon and evening. Model soundings show top-down
saturation with plenty of dry air anchored in the low levels, so
will remain rain free except for a few droplets in the western side
of the CWA towards the evening.
Thursday - Friday...There is fair model spread with snowfall/wintry
mix location and amount during this period, as discussed in the
Model section above. The official forecast reflects best chances of
wintry precipitation overnight and during the early morning hours
towards the NW/W portion of the forecast area Wed night into
Thursday and to the south and east Thu night into Friday morning.
During daylight hours on Thursday, near-surface temperatures will be
above freezing which could cause precipitation to be cold rain or
even a mix of rain and graupel if low-level lapse rates and DGZ
saturation/lifting allow it. For Friday, model soundings show mid-
level dry air working from west to east that will diminish precip
chances Friday afternoon and evening. Note that if the heavier
GFS/CMC solutions do materialize, a change of p-type from liquid to
frozen can happen during the day via dynamic cooling in moderate to
heavy precipitation rates.
Weekend...Slow upper-level height rises and plenty of dry air in the
vertical profile will promote dry conditions during this period.
Temperature wise, a near steady trend will be in place with near-
steady readings as highs oscillate in the mid to upper 40s with
below-freezing lows in the upper 20s.
&&
.Aviation...(00Z TAF Issuance)
Issued at 601 PM EST Mon Dec 25 2023
Rain showers are slowly lifting out of the region this evening as a
large upper level system spins over the center of the CONUS. Drier
air will work in aloft, but low level moisture will linger, keeping
stratus in the region. The `deepest` low level moisture will be east
of I-65, where IFR cigs/vis will be possible along with
mist/drizzle. Along and west of the I-65 corridor, cigs will bounce
between VFR and MVFR levels before staying in the MVFR range after
midnight. Mist/Drizzle may develop in these areas but confidence is
low.
Low level moisture will slowly be scoured out of the region from
west to east tomorrow, and cigs/vis should transition to VFR levels
before the end of the forecast period for all but the LEX
terminal.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...DM
Short Term...CJP
Long Term...ALL
Aviation...DM
Area Forecast Discussion
National Weather Service St Louis MO
523 PM CST Mon Dec 25 2023
.KEY MESSAGES...
- Confidence continues to increase in periods of snow Tuesday
night at least through Wednesday night. Warm surface
temperatures are expected to minimize accumulations to less than
an inch mainly on grassy areas.
- Temperatures through the end of the week are expected to be
closer to seasonal normals.
&&
.SHORT TERM /THROUGH TUESDAY/...
(Through Late Tuesday Afternoon)
Issued at 313 PM CST Mon Dec 25 2023
A large upper level closed low is spinning over the Great Plains
this afternoon. The surface low, centered over northwest Iowa, is
pushing a cold front through southwest and south central Illinois at
this time. Drier air behind the front is shutting off precip as it
filters into the Mid Mississippi Valley. There may be an isolated
shower or two behind the front tonight, but for the most part
tonight and Tuesday should be dry. Temperatures behind the front
are falling quickly into the 40s, and lows tonight will likely drop
to near or slightly below freezing across most of the forecast area
for the first time in almost a week. Tuesday`s highs will be around
15 degrees cooler than today`s were ahead of the front. This
assumes there will be some breaks in the cloud cover tomorrow as
most guidance suggests. However, RAP soundings suggest there will
be a fairly thick layer of strato-cu persisting through the day. If
this is the case we`ll be somewhat cooler and many parts of the area
may not warm above 40 degrees.
Carney
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
(Tuesday Night through Next Monday)
Issued at 313 PM CST Mon Dec 25 2023
The closed low aloft will begin drifting east on Tuesday and then it
will turn to the southeast on Wednesday. The latest guidance shows
that it will take until Thursday morning before the center of the
low moves out of Missouri. Guidance also continues to show colder
temperatures aloft associated with the low, resulting in greater
potential for snow. Forecast soundings show moisture and lift in
the DGZ as the low moves into the area Tuesday night, and the GFS
and NAM show some moderate frontogenetical forcing, mainly ahead of
the low on Wednesday. This brings up the possibility of some
heavier precipitation bands rotating around the low, and the CAMs
bear this out, particularly the HRRR which is showing bands of
reflectivity in excess of 40dBZ on Wednesday. Temperatures are
still forecast to stay above freezing on Wednesday, but I leaned
heavily on the 25th percentile NBM for highs which keeps central and
northeast MO in the mid 30s, and upper 30s farther east. Since the
most intense precip looks like it will be during the day with
temperatures above freezing, we still don`t have much accumulation
in the forecast. However there`s still some chance for light
accumulations less than an inch on grassy surfaces during the night
time hours, late Tuesday night, and again Wednesday night.
Precipitation chances should wrap up late Thursday as the low shifts
southeast away from the area. Friday through next Monday continue
to look dry with near normal temperatures.
Carney
&&
.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 515 PM CST Mon Dec 25 2023
MVFR conditions continue to plague the bi-state region and will
persist through tonight. MVFR ceilings are expected to lift and
scatter beginning tomorrow morning though there is uncertainty
regarding how quickly. Guidance shows a swath of low-level
moisture wrapping back into central Missouri in the morning,
but the general scattering of clouds should keep MVFR
conditions at bay. Otherwise, gusts out of the southwest are
expected to diminish overnight before elevating again tomorrow
afternoon. Surface winds will back to southeasterly late in the
TAF period.
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
SHORT TERM...
LONG TERM...
AVIATION...Jaja
Area Forecast Discussion
National Weather Service Melbourne FL
1004 PM EST Mon Dec 25 2023
...New UPDATE, MARINE, AVIATION, HYDROLOGY, PREV DISCUSSION...
.UPDATE...
Issued at 957 PM EST Mon Dec 25 2023
Weak forcing has resulting in a fairly sloppy evolution of the low
pressure system approaching Florida. Latest surface analysis puts
the center of the low over the Florida panhandle, but the GFS has
been keying on yet another weak low/trough developing off the
southwest Florida coast, which is backed by KTBW radar imagery.
The GFS tracks this feature due east across South Florida, while
the HRRR lifts it north into and across central Florida, with the
other 00Z CAMs showing a similar scenario. So despite the lack of
activity across ECFL at the moment, forecast continues to call for
30-40 pct PoPs through the night as convection to the south lifts
into the area. Instability remains lacking with MUCAPE values 500
J/kg or less and shallow lapse rates, so keeping thunder out of
the forecast except over the Gulf Stream. Haven`t made any changes
to fog in the forecast at this time as SREF and HREF guidance
indicating less than 20 pct chance of visibilities below 1 mile,
so continuing to call for patchy fog along and north of I-4. That
said, winds have been trending lighter, so can`t rule out patchy
fog further south.
&&
.MARINE...
Issued at 957 PM EST Mon Dec 25 2023
Tonight...Poor to hazardous boating conditions continue across the
central Florida Atlantic waters as a weak low pressure system and
cold front approaches. Southerly winds range from 5-10 kts near
the Volusia coast to 15-20 kts near Stuart, and up to 25 kts well
offshore in the Gulf Stream. Seas 5-6 ft close to shore,and 6-8 ft
in the Gulf Stream. Isolated showers at lightning storms expected
to become scattered to numerous towards morning.
&&
.AVIATION...
(00Z TAFS)
Issued at 957 PM EST Mon Dec 25 2023
Expecting MVFR-IFR CIGs, and possibly VIS reductions to impact
inland terminals at some point tonight, but guidance has proven to
be too aggressive, so have backed off onset of impacts a couple
times with AMDs and the 00Z package this evening. Latest update
calls for MVFR CIGs to set in at inland terminals 04-05Z, and IFR
CIGs around 09Z. CIGs dropping to LIFR and VIS reductions will
also be possible if winds become light, which they`re currently
trending towards. Along the coast, MVFR CIGs also expected to set
in around 09Z and linger through the afternoon. Very low
confidence in location of convective development, so all terminals
carry VCSH and short-fused AMDs as showers develop can be
expected.
&&
.HYDROLOGY...
Issued at 957 PM EST Mon Dec 25 2023
The Saint Johns River at Astor is forecast to remain in Minor Flood
Stage as levels remain steady over the next couple days before
slowly falling mid week. Elsewhere along the Saint Johns River, the
forecast point above Lake Harney near Geneva will remain steady
while in Action Stage this week.
&&
.PREV DISCUSSION...
Issued at 957 PM EST Mon Dec 25 2023
Currently-Tonight... Not the best Christmas forecast with gloomy
conditions across east central Florida. However, on the plus side it
has been a little drier than anticipated, especially north of the
Treasure Coast. KTBW radar imagery shows isolated to scattered
stratiform precipitation moving northeast across central Florida
primarily over the Treasure Coast to Lake Okeechobee region, as
well as north of I-4. Analysis charts show a weakness in the
western Atlantic ridge to the northeast of Florida.
Meanwhile, a cold front is located upstream stretching across the
eastern Gulf of Mexico. Ahead of the front, scattered showers
with embedded lighting strikes are forecast as we head into the
late afternoon and early evening hours. Rain chances will dwindle
from southwest to northeast across east central Florida into the
overnight. Rain chances decrease to 15-30% west of I-95 after
midnight and remain near 50% at the coast. Southeast winds have
been a little lower than anticipated but gusts to 25mph remain
possible along the coast. Patchy fog is forecast along and to the
north of 1-4 overnight, within a few hours leading up to sunrise,
before diminishing by 9am. Low temperatures forecast to drop into
the low to upper 60s.
Tuesday... The aforementioned cold front will move across central
Florida Tuesday afternoon before reaching the local Atlantic
waters by the evening hours. Isolated to scattered showers are
forecast with isolated lightning storms over the Gulf Stream. The
greatest chance for rain will be along the coast (PoPs ~30-50%)
with lower chances inland west of I-95 (PoPs ~15-30%). Drier air
will filter in across Florida by the afternoon with partly to
mostly cloudy skies. Southeast winds around 10-15kts veer to the
west and decrease behind the front. Afternoon highs are forecast
to reach the mid to upper 70s.
Wednesday-Thursday...Low pressure aloft gradually shifts from the
central midwest into the southeast U.S. At the surface, a weak area
of low pressure moves off the northeast Florida coast early
Wednesday, lifting along the eastern seaboard into Thursday.
Coverage of showers returns early Thursday morning as a cold front
approaches east central Florida with rain chances ranging 20-50%
from north to south. Afternoon high temperatures in the low to mid
70s on Wednesday fall into the upper 60s Thursday. Low temperatures
in the mid to upper 50s Wednesday night cool Thursday night, widely
ranging the 40s. Slightly warmer across Okeechobee and the Treasure
Coast counties with low temperatures in the low 50s Thursday night.
Friday-Monday (modified previous)...2023 will end on a much colder
and drier note across the area, as a stronger cold front clears the
area by early Friday and then a reinforcing shot of colder air moves
through behind another strong front on Saturday. Current forecast
has highs as low as the mid 50s to low 60s on Fri-Sat, and then only
slightly rising through the New Year, from the low to mid 60s on
Sunday and mid to upper 60s across much of the region on New Year`s
Day. The coldest temperatures are forecast into Friday night and
Saturday night, with lows in the mid 30s to low 40s. New Year`s Eve
will also continue to be colder than normal, with lows in the upper
30s to mid 40s. While freezing temperatures are not currently
forecast across the region with this cold snap, trends will have to
be closely monitored through the week. Weakening NW flow into
Saturday night may allow for some isolated, normally colder spots,
mainly near to NW of I-4 to reach the freezing mark.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 63 75 60 73 / 40 30 10 0
MCO 66 76 62 72 / 30 30 10 10
MLB 65 78 61 74 / 40 40 10 10
VRB 68 79 60 76 / 40 40 10 10
LEE 63 74 60 71 / 30 20 0 0
SFB 65 76 61 73 / 40 30 0 0
ORL 66 76 63 73 / 30 30 0 10
FPR 68 79 61 76 / 50 40 10 10
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory until 1 AM EST Tuesday for AMZ552-555.
Small Craft Advisory until 10 AM EST Tuesday for AMZ570-572-575.
&&
$$
SHORT TERM...Haley
LONG TERM....Sedlock
AVIATION...Haley
Area Forecast Discussion
National Weather Service Marquette MI
756 PM EST Mon Dec 25 2023
.UPDATE...
Issued at 742 PM EST MON DEC 25 2023
Updated the forecast to include a Dense Fog Advisory for
Marquette and Baraga counties through 9 am Tuesday where
developing northeast upslope/onshore winds off Lake Superior will
enhance the dense fog potential given the very moist low to mid
40s dew points in place over the area. There could be some minor
improvement in visibilities after sunrise with increased
turbulent mixing from strengthening northeast winds and increasing
rain chances as a trough lifts up from the Midwest.
&&
.SHORT TERM...(Through Tonight)
Issued at 331 PM EST MON DEC 25 2023
Key Messages:
- Areas of fog persist tonight, locally dense at least thru the
evening hours.
- Patchy drizzle gives way to rain showers spreading into Upper MI,
mainly late tonight.
- Continued unseasonably warm/record breaking.
- For the third day in a row, a record high min temp to be set.
Current record high min temp for today (12/25) at the NWS site in
Negaunee Township is 31F set in 2019. Record high min temp for the
month of Dec likely to be set as well. Current record high min temp
for month of Dec is 41 set on Dec 2, 1982.
Water vapor imagery and RAP analysis show a large, closed mid-level
low centered over KS. Around this feature, a wide swath of shra is
wrapping from the SE States, across the Ohio Valley into the Upper
Mississippi Valley. To the n, shortwave trof is moving across Hudson
Bay. Sfc cold front associated with this feature extends from just s
of James Bay sw across Lake Superior, just to the e of the Keweenaw,
into nw WI. Shra ahead of this front that moved into roughly the nw
half of Upper MI last night/early this morning have been lifting
back to the n today as weak isentropic ascent is lifting n.
Otherwise, low clouds and fog have been dominating once again across
Upper MI with some locations with vis aob 1/2sm. However, the low
clouds are breaking up into portions of southern Upper MI per vis
satellite imagery and per obs at KMNM/KESC/KISQ. Temps remain
unseasonably warm/record breaking. Current readings are running
~15-25F degrees above normal, ranging from the mid 40s to around
50F.
Here at the Marquette NWS office in Negaunee Township, today is the
warmest Christmas on record. The high temp so far has been 47F,
breaking the previous record of 46F set in 1994. The min temp for
the day so far has been only 43F. It is quite unlikely that the temp
will fall to 41F before midnight tonight. If that is in fact the
case, today`s min temp will also be the highest min temp ever
recorded in the month of Dec at the NWS site in Negaunee Township.
Weather records here date back to 1961. Looking at other sites that
have long standing records back to the late 1800s/early 1900s,
today`s min temps will be rivaling record high min temps for the
month of Dec. For the month of Dec, record high min temps are:
-Ironwood (period of record (por) back to 1901) 44 set Dec 3,
1941/1951
-Houghton area (por back to 1887) 46 set Dec 4, 1941
-Iron Mountain (por back to 1899) 43 set Dec 3, 1951/1962
-City of Marquette (por back to 1857) 46 set Dec 4, 1941
-Munising, (por back to 1911) 46 set Dec 3, 1982
It`s also noteworthy that these monthly record high mins were set in
the first few days of Dec, and we`re putting these records in
jeopardy near the end of the month, deeper into the cold season,
when daily record high min temps at all sites are in the low/mid
30s F. The complete lack of snow cover across Upper MI and
surrounding area is playing a critical role in this warmth so late
in the month.
Shra wrapping around the aforementioned mid-level low will advance n
and ne tonight as occluded front bulges northward to the ne of the
sfc low over the Plains. Although the corridor of 850-700mb moisture
transport that lines up well with the current shra does weaken with
time, still expect the zone of northwestward moving -shra to
overspread the area from s to n, mainly late tonight thru Tue
morning. Fortunately, forcing is not strong as precipitable water
running 275-325pct of normal would support excessive rainfall in a
strongly forced environment. Prior to the main band of shra, isold
-shra may occasionally develop across the area, but it`s more likely
that patchy -dz will occur at times in areas where winds are
upsloping. Fog will likely expand in coverage again this evening,
and it will be locally dense. Some increase in ene winds overnight,
along with developing shra late will result in improving vis. Lowest
vis will become confined to areas that see upsloping with ene winds,
such as n central to nw Upper MI. Expect min temps ranging from 39-
44F tonight, ~15-20F above the normal max temps for this time of
year.
.LONG TERM...(Tuesday through Monday)
Issued at 242 PM EST MON DEC 25 2023
Key Messages:
- High temperatures around 20F above normal Tuesday with morning
rain tapering off from south to north
- Not as warm for the middle to end of the week but temperatures
remain above normal without any significant precipitation
Deterministic models and ensembles continue to be in fairly good
agreement through the end of the upcoming week. The sprawling cutoff
low over the central Plains will wobble slowly eastward, while the
massive positive 500 mb height anomaly holds serve over most of
Canada and portions of the northern tier of the CONUS. Ridging
quickly builds back into south-central Canada during the midweek,
preventing any incursions of much colder air or potential for
meaningful lake effect snow. Models do show some potential for
northern stream troughing to force its way into the upper Great
Lakes by next weekend, although this is still rather uncertain.
Diffluent region of the midlevel cutoff low circulation becomes
favorably positioned over the UP Tuesday morning, with a modest low-
level jet increasing moisture transport. PWAT values peak between
0.75-1.00 inches, which is +3 to +4 sigma per the NAEFS.
Fortunately, the midlevel dry slot pushes in from the south during
the afternoon and evening, and elevated instability is not expected,
which should limit longevity and intensity of rainfall. So,
widespread rain in the morning will taper to showers from south to
north through the afternoon and evening. It will be one more day of
temperatures near record values at WFO Marquette (record high 45 in
2003), with highs reaching the low to mid-40s. Cold advection will
occur from the south Tuesday night due to the very occluded system,
with lows finally getting perhaps a couple degrees below freezing in
the WI border counties. A few rain and snow showers may linger, but
no impacts are expected.
Wednesday into Thursday, low-level winds turn back northerly as the
surface low pressure reorganizes to our southeast. While a few rain
and snow showers may linger, temperatures aloft aren`t cold enough
for lake effect snow, and in fact, some sunshine may finally emerge
at times from the middle to the end of the week due to the building
midlevel ridge to our north. Temperatures during this period will be
cooler than what we have seen over the holiday weekend, but still
much warmer than normal with daytime highs likely getting above
freezing over the entire UP. Will maintain some chance PoPs (30-40%)
in the northerly lake effect belts for the upcoming New Year`s
weekend and temperatures easing back closer to normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 641 PM EST MON DEC 25 2023
Abundant low-level moisture continues to dominate, and with a
dissipating cold front settling across the area, low stratus/fog
will persist. While there may be -shra or -dz at times, better
chance of -shra will arrive later tonight into Tue morning as an
occluded front sweeps n into Upper MI. At IWD, LIFR to VLIFR
conditions tonight will give way to mostly IFR conditions on
Tuesday. At CMX, conditions mostly at airfield landing mins thru
Tue morning in an upslope easterly wind will improve to LIFR Tue
afternoon. Easterly winds will become gusty to around 25kt at CMX
later tonight thru Tue morning. At SAW, winds will shift to an
upslope ne direction this evening with conditions likely falling
back blo landing mins. Slight improvement should occur Tue
morning as -shra arrive with further improvement expected to IFR
late Tuesday as winds veer east-southeast.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 242 PM EST MON DEC 25 2023
Northeasterly winds will continue to ramp up this afternoon and
evening over the western half of the lake as a strong pressure
gradient develops between low pressure over the Upper Mississippi
Valley and high pressure building into southern Ontario. Model
forecast soundings suggest that cold air creeping in at lower levels
will allow some stronger winds to around 40 kt to mix to the
surface, especially over the western arm of the lake (between the
North Shore, Apostle Islands, and Twin Ports). There is about a 70%
chance of seeing gusts in excess of 40 kt in that area between about
7 pm this evening and 1 pm Tuesday. Further east, winds will be more
marginal between the Keweenaw and Isle Royale, but there is still
about a 60% chance of seeing gale force gusts there. Over the rest
of the eastern half of the lake, easterly winds will mainly gust in
the 25-30kt range, although a few of the higher observing platforms
may see gusts to near 35 kt at times.
Gales over the western half diminish Tuesday afternoon into Tuesday
evening. Northerly winds will remain elevated at times for the end
of the upcoming week into next weekend (20-25 kt), but potential for
gales continues to appear low (<20%) at this time.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Dense Fog Advisory until 9 AM EST Tuesday for MIZ004-005.
Lake Superior...
Gale Warning until 5 PM EST /4 PM CST/ Tuesday for LSZ162.
Gale Warning until 1 PM EST Tuesday for LSZ263.
Gale Warning until 10 AM EST Tuesday for LSZ264.
Lake Michigan...
None.
&&
$$
UPDATE...Voss
SHORT TERM...Rolfson
LONG TERM...Thompson
AVIATION...Voss
MARINE...Thompson
Area Forecast Discussion
National Weather Service Pocatello ID
229 PM MST Mon Dec 25 2023
.SHORT TERM...THIS AFTERNOON THROUGH TUESDAY NIGHT...
The pattern continues...very light, cold, NE flow down the Snake
Plain corridor with patchy nocturnal/AM freezing fog and low stratus
concerns under a synoptic ridge of high pressure. RH analysis
suggests tonight might be ever so SLIGHTLY drier than last night
(which featured only VERY localized fog), and both the HRRR and NBM
are less aggressive with fog development tonight, but to be safe we
continue to carry patchy freezing fog in the forecast for portions
of the Snake Plain, Arco Desert, Mud Lake, and Fremont County
corridor eastward into some valley locales between I-15 and the WY
border. Fog also tends to decrease immediately ahead of approaching
wx systems (which we have), but given no change in overall wind flow
and the fact that approaching clouds and precip should hold in the
far wrn CWA until sunrise Tue, don`t think this will have much of an
impact or guarantee no fog. We also made some forecast adjustments
to NBM low temps tonight based on trends the last 2 nights where
locales such as Stanley and the Soda Springs to Montpelier corridor
bottomed out colder than forecast.
Tue, a shortwave trough of low pressure (the aforementioned
approaching system) remains forecast to flatten/ride through the top
of the high pressure ridge, but models continue to offer solid
consensus in a steady weakening trend the further east this feature
tracks. In fact, looking at the 12z HREF suite, one can almost
visualize a wall existing from about Dubois to Pocatello where model-
simulated echoes coming in from the west "wash out" as this trough
tracks through. NBM probabilities of exceeding 1 inch of snow are
only 5-10% west of this "wall" (except 50-60% in the Sawtooths and
mntns around Stanley), and looking at a worst case/high-end scenario
represented by the NBM 95th percentile, we`re hard-pressed to find
more than a mntn peak or two that reach 3 inches (and certainly no
more than 1 inch in the ern Magic Valley/lower Snake Plain IF the
system over-performs), so we continue to anticipate this will be a
VERY low-impact system with clouds for everyone, a CHANCE of a light
snow shower anywhere, but best chance west of I-15. Expect steady
temps through Tue, before a warming trend begins. 01
.LONG TERM...WEDNESDAY THROUGH NEW YEAR`S DAY...
The middle and end of this week will be fairly dry. We have some
weakening "waves" that temporarily shift the ridge east...but
aren`t expected to produce much more than a few sprinkles or light
snow/flurries even up in the mountains. For New Year`s Eve and
Day, we are looking at a potential split flow pattern setting up.
The GFS, ECMWF and about 60% of cluster forecasts shows this for
Sunday. For Monday, the models and cluster forecasts are all over
the place. The GFS and ECMWF all have a decent ridge briefly
overhead. About 20% of the clusters show the ridge, 20% show split
flow remaining in place, with the rest showing the next storm
already along the coast. Even if we do get some moisture with that
storm, split flow usually doesn`t produce a ton for us...and that
is reflected in our Blend of Models with some light
precipitation. Temperatures will slowly climb throughout the
period. Keyes
&&
.AVIATION...
VFR weather is expected heading through tonight. A couple of
exceptions: patchy fog/stratus is still trying to hanging tight at
PIH early this afternoon. We should see that eventually going
away through the rest of the afternoon; low stratus moved into IDA
late this morning...is already beginning to erode and we should
see VFR weather returning later this afternoon as well. The next
wave moving into our area tomorrow will quickly weaken. We do have
a threat of VCSH/-SHSN at SUN and BYI tomorrow. The latest trends
quickly diminish a band of snow as it shifts east toward the
Snake Plain and eastern highlands. We should at least see low
clouds and some potential for VCSH at IDA, PIH and DIJ later
tomorrow. At the moment, we aren`t seeing anything worse than
MVFR. Keyes
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
739 PM MST Mon Dec 25 2023
.UPDATE...
Issued at 723 PM MST Mon Dec 25 2023
00Z high res model runs (HRRR and NamNest) are filtering in and
continue to show 2 rounds of snow spreading into northern El Paso
county. The first peaks between 5-10 AM with a lull shortly
thereafter. Then the second round spreads in between 4 PM and 11
PM. HRRR has less of a distinct break between these 2 rounds but
portrays generally the same idea. Have refined and boosted pops
for these periods.
Otherwise, still looks like the peak of the damaging gusts favor
the 5 AM to Noon timeframe, especially for locations to the
northeast of KCOS...though 50 mph gusts will continue through the
afternoon even as snow lulls for a brief period. This will keep
blowing snow and blizzard conditions going through the full
duration of the blizzard warning. There is some potential that
that the Blizzard Warnings may need to be extended past midnight
and through the early morning hours on Wednesday. Not enough of
the 00z runs have come in to bring this clarity on this yet...but
some high res members are suggesting this possibility. Main
change to grids was to cool down MaxT grids a few degrees across
northern portions of the plains and to refine/increase pops to
reflect the likelihood for those 2 windows of heavier snow across
northern El Paso county. Still looks like Colorado Springs will be
in the downslope shadow of the Palmer Divide with snowfall
amounts dwindling quickly with southern extent through the city.
Most areas may see a Trace to an inch across northern portions of
the city as compared to the 2 to 6 inches with locally higher
amounts across northern El Paso county. -KT
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 244 PM MST Mon Dec 25 2023
Key Messages:
- Highly impactful winter weather expected over the Palmer
Divide and Teller County tonight through Tuesday. Blizzard warning
issued for the Palmer with a Winter Weather Advisory for Teller.
- Strong northwest winds will set in across the eastern plains
tonight, with potentially damaging winds over El Paso County and
strong gusts elsewhere.
Currently, a potent upper-level low pressure system continues to
spin and wrap up to the east of our area. Over the next 24 hours or
so, this low will continue to intensify and meander a few miles to
the west, bringing an extra round of impactful winter weather to
parts of our area.
Things will start to ramp up later tonight, largely after Midnight,
with moisture and strong north-northwesterly winds beginning to
encroach on the Palmer Divide. Sustained winds around 25-35 mph will
move in, kicking up existing snow on the ground and resulting in
widespread visibility issues. These winds will only increase through
the night and into Tuesday morning, with sustained winds closer to
40 mph or more and gusts upwards of 50-60 mph. While this occurs,
wrap-around moisture from the upper low will bring upsloping winds
and additional snowfall to the Palmer Divide, with anticipated
snowfall totals increasing noticeably since yesterday. While models
do vary on the southward extent of the snow, likely due to the
influence of downsloping over parts of southern El Paso County,
there should be a fairly steep gradient. In general, northern parts
of the Palmer Divide will receive 3-7 inches by Tuesday evening. The
higher amounts in that range will be higher up on the divide, closer
to Monument Hill, while areas downslope will likely only see 1-3 on
average. Little snow is expected south of that at this point, with
around an inch in parts of southern El Paso County. Meanwhile,
upslope into Teller County will net 3-6 inches with overall weaker
but still potentially impactful winds.
High-res model guidance and ensemble data has been in good agreement
today on the placement and intensity of both wind and precipitation
forecast, with the only main uncertainty being the southern extent
of precipitation over the Palmer, and parts of Kiowa and Crowley
Counties. In general, those two counties, while right on the edge of
more impactful conditions, have not been meeting any Watch or
Warning criteria. Have not hoisted anything out there at this time,
as precipitation should be minimal and winds should be below
thresholds. Conditions will be closely monitored for changes in
future model runs. Meanwhile, over Teller County and Pikes Peak, a
Winter Weather Advisory has been issued for modest snow amounts and
impactful winds. Blowing snow and reductions to visibility across
the area will be possible. Finally, given the strong to potentially
damaging winds and improved snowfall totals for tonight and Tuesday,
we have decided to hoist a Blizzard Warning for the Palmer Divide
through Tuesday evening. Limited to zero visibility, bitter cold,
and quickly accumulating and drifting snow will be expected across
the area. Travel and exposure to the outside should be avoided, with
dangerous travel conditions and wind chills below zero anticipated.
Though the strongest winds will be confined to the east side of the
county (with wind gusts of 60 mph or more), the entire zone will see
consistent gusts of over 35 mph well into tomorrow. In that same
vein, have continued the High Wind Warning for southern El Paso as
well, though they are currently expected to see very little snow.
Snowfall will begin to wane Tuesday afternoon, while gusty winds are
expected to continue into the evening hours.
Some blowing snow will also be possible across our southeast
plains as moisture wraps around the back of the low to our
southeast, with gusts around 30-40 mph possible along with up to
an inch of snow. Some travel impacts are expected here as well,
though a bit more short-lived than up north given the relatively
warmer temperatures.
Overnight lows tonight, without any wind chill, will mainly sit in
the teens to low-20s over the plains and negative single digits over
the valleys. However, as the winds set in over the plains the actual
temps will be much colder. For Tuesday, highs will depend on snow
and cloud cover, but in general we can expect to see 40s over most
of the plains and 30s over both the valleys and areas with snow
cover.
.LONG TERM...(Tuesday night through Monday)
Issued at 244 PM MST Mon Dec 25 2023
Key Messages:
- Blizzard conditions are possible from strong winds and blowing
snow Tuesday night for the Palmer Divide with winds diminishing
early in the day on Wednesday.
- A quieter stretch of dry weather is expected mid-week and into
the weekend.
Tuesday Night into Wednesday...
There is a GFS/NAM/ECMWF model agreement that a strong closed upper
low will be sliding from eastern Kansas across Kansas City, Missouri
and into the Missouri Valley. At the surface, a tightened pressure
gradient will still be in place between a strong area of high
pressure centered over the UT-CO border and the surface low in
Missouri. This will allow for blustery, windy conditions to continue
early on Wednesday from El Paso County eastward with cloud coverage
increasing closer to the upper low across the eastern Plains. With
some fresh snow for northern El Paso County, blowing snow and
blizzard conditions could be continuing early Tuesday night with
winds decreasing and visibility improving early in the day on
Wednesday for the Palmer Divide. Otherwise, further westward, the
high will dominate with light winds and abundant sunshine expected
for areas west of the Front Range, Wet Mountains, and Sangre de
Cristos.
For temperatures the forecast is closest to the National Blend of
Models (NBM). A cold night is expected west of the Front Range with
more radiational cooling closer to the high. Lows will range from
the mid 20s in the eastern Plains to the single digits for the
higher terrain and mountain valleys to the negative single digits in
the San Luis Valley. Highs will range from the mid to upper 40s east
of the Front Range across the eastern Plains to the lower to mid 30s
in the San Luis Valley to the teens and 20s across higher terrain.
Wednesday Night through Monday...
GFS/Canadian Ensemble solutions indicate that an upper low will
shift well east of the area and an upper ridge axis will move
eastward from Nevada. The ECMWF Ensemble mean is mostly in
agreement until the weekend into early next week when it pair of
closed low into Sierra Nevadas and the Upper Midwest, shunting the
ridge. Regardless, high pressure should dominate the region
through this period with the area staying dry for the majority.
Temperatures through this period will be near seasonal normal
values. Highs will range from the lower 50s for the eastern Plains
to the mid 30s for the San Luis Valley to the 20s for higher
terrain. Lows will range from the upper teens to lower 20s for the
eastern Plains to the lower teens for higher terrain to near zero
for the San Luis Valley.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 244 PM MST Mon Dec 25 2023
VFR conditions will prevail across the terminals through the TAF
period. The biggest aviation impact of note through this period
will be winds picking up early Tuesday at KCOS and by late
morning Tuesday for KPUB. Northerly winds today at 10-15kts can
be expected at KPUB/KCOS. Overnight, winds will become
northwesterly and increase to 20kts with gusts to 30kts at KCOS,
increasing to 25kts with gusts to 40kts there by 15Z on Tuesday.
KPUB will see northerly winds increase to 15kts with gusts to
25kts by 15Z on Tuesday. At KALS, winds will be light and more
variable through the TAF period.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 2 AM to 3 PM MST Tuesday for COZ081-
082.
Blizzard Warning from 2 AM Tuesday to midnight MST Tuesday night
for COZ084.
High Wind Warning from 2 AM to 3 PM MST Tuesday for COZ085.
&&
$$
UPDATE...KT
SHORT TERM...GARBEROGLIO
LONG TERM...WOODRUM
AVIATION...WOODRUM