Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/22/23
Area Forecast Discussion
National Weather Service Boston/Norton MA
706 PM EST Tue Feb 21 2023
.SYNOPSIS...
Another weak low tracks across northern New England this
evening, bringing a brief period of light rain and snow to the
area. Weak high pressure delivers mainly dry, seasonably cool
weather Wednesday. A warm front likely brings a wintry mix of
precipitation Wednesday night into Thursday night. Then bitter
cold arrives later Friday into early Saturday. Snow showers
possible Sunday. More wet weather possible early next week
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Overall forecast remained on track this evening. Did tweak the
precipitation timing based on the latest runs of the
NationalBlend and time-lagged HRRR ensemble. Expecting
precipitation to end from west to east between now and 1 AM.
Still thinking only minor accumulations of either rain or snow.
Brought temperatures back in line with observed trends.
Previous Discussion...
After a brief respite from the wet weather we continue our
relatively active week of weather with a quick hitting light
snow/rain event this evening into the early overnight hours. As
this morning`s low pressure center moves further offshore
another low begins to move from the eastern Great Lakes into
southern Quebec while at the mid levels a weak shortwave
disturbance lifts from eastern New York through New England.
This, together with the low`s passing cold front will provide
the necessary forcing for ascent to squeeze out some meager rain
and snowfall. While some of the more recent high resolution
guidance indicates the chance for widely scattered showers this
afternoon the more appreciable showers arrive ahead of the cold
front which should be knocking on the door of western MA and CT
between 7 and 9 PM, reaching eastern MA around midnight. The
showers themselves will lead the front, entering western MA
closer to 3 to 5 PM and eastern MA by 6 to 8 PM. Precip exits
west to east and will be out of southern New England by
midnight. Given surface temperatures above freezing for much of
the region this will be another elevation based snow event with
the best chance of light snow in the Berkshires and Worcester
Hills; even so, with the meager moisture available ahead of the
front (PWATs <0.45") giving a few hundredths to a few tenth of
an inch of liquid precipitation, and with the bulk of the precip
moving through during the afternoon/evening hours (more
marginal temperatures) snowfall accumulations are expected to be
minor, generally up to 1 to 2 inches. The METRo Roadcast
projects road temperatures in northern MA not falling below
freezing until closer to midnight, after the precip has ended,
so we expect any accumulation to be mainly on grassy surfaces
rather than roads. The best shot of seeing 3+ inches on the
grass will be for the typical jackpot areas in the northern
slopes of the Berkshires but it is a low probability. By
midnight the cold front has ushered in much colder and drier
air, bringing precip to an end and low temperatures down into
the 20s-low 30s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
Our active and progressive weather pattern continues during this
period as we see a ridge of high pressure briefly bring a quiet
and dry period of weather for Wednesday before another winter
weather system arrives Wednesday night. This storm starts as a
low pressure over the Midwest Wednesday afternoon before it
moves into NY/PA Wednesday night, generating a secondary low
along the frontal boundary off the mid Atlantic coast overnight
into Thursday.
Precipitation arrives in western MA and CT after sunset
Wednesday associated with the warm front extending from the
parent low. Given this timing we`re not expecting an impact to
the Wednesday evening commute. Temperatures through the column
may be initially cold enough for this to start off as snow for
some, though there remains much uncertainty as to the
timing/details of this dynamic mixed precipitation event. There
is high confidence in a stout warm nose around 800 mb which will
produce sleet and freezing rain, eventually changing to rain.
The low confidence comes with how quickly that warm nose moves
in. The faster guidance would allow very little time for any
snow, while the slower global guidance keeps precipitation as
snow for several hours before flipping over. We are just getting
into the window of the higher resolution guidance, and for now
we`ll stick with a blend of the two solutions, with some minimal
snowfall accumulations at the onset, northwest of the I-95
corridor, then flipping to sleet and freezing rain. Best shot at
a few inches of snow will be for northern MA. Of greater
concern for travel interests during Thursday morning`s commute
will be the icy precipitation (sleet/freezing rain). For areas
south and east of I- 95 a mostly rain solution is favored.
Eventually the dry slot moves overhead Thursday morning bringing
an end to precipitation by afternoon. After widespread highs in
the 40s on Wednesday we`ll be cooler for most on Thursday.
Given the path of the low, it will direct cold
north/northeasterly flow into southern New England as it passes
on Thursday so the warmest part of the day will be early, with
colder air funneling in during the afternoon. Highs will be
coldest in northern MA and warmest along the south coast.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Highlights...
* A wintry mix expected to end Thursday night, yielding slippery
travel, especially across northern MA
* Brief cold blast Friday afternoon into Saturday morning, with wind
chills below zero Friday night
* Becoming more likely that a low pressure remains too far offshore
to provide much of an impact this weekend.
* Another low pressure may provide a round of rain and/or snow early
next week
Active mid level synoptic pattern should become more zonal late this
week, with a preferred storm track to our south and offshore. The
amplitude of any longwave troughs or ridges is minimal, at least
into this weekend. The pattern looks to become more amplified into
early next week. Do not have a lot of confidence in the details, as
the spread amongst the guidance members is fairly large. We have
some time to iron out those wrinkles since it is a Day 6-7 forecast.
At the surface, a low pressure moves away from our region Thursday
night into Friday, bringing an end to our wintry mix. This is
followed by a large high pressure moving from central Canada. This
will mean a significant cooldown, especially Friday afternoon into
Saturday morning. While not as cold as our brief arctic outbreak in
early February, it will be noticeably colder than we have been. This
high pressure should make it more likely for a low pressure to
remain farther offshore this weekend. As mentioned above, still
watching the track of a low pressure early next week. The exact
timing will play a significant role in determining the amount of
colder air still present across southern New England, which in turn
will determine how much snow or ice we could see. At this moment,
thinking more of a snow-to-rain scenario Monday into Tuesday. The
NationalBlend modeled this well.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight...Moderate confidence.
Quick-hitting -SHRASN, ending from west to east between 02-06Z.
Minor accumulations of SN possible at ORH. Expecting -RA
elsewhere, but can`t rule out some brief -SN at other western
MA/CT terminals. S/SE winds generally less than 15 kt. IFR/MVFR
improving to VFR as precipitation comes to an end by 08Z.
Stronger NW winds develop behind a passing cold front with
isolated gusts 20-30 kt possible, mainly for south coastal
terminals.
Wednesday...High confidence.
VFR, trending to low end VFR by late afternoon. NW wind becoming
SW 10 kt.
Wednesday night...Low confidence.
VFR becoming IFR/LIFR by 06Z with arrival of mixed
precipitation. Confidence on precip type is low but for interior
terminals a SN to IP/FZRA to RA transition is likely between 0Z
and 12Z. Light winds out of the south become easterly.
KBOS Terminal...Moderate confidence in TAF.
KBDL Terminal...High confidence in TAF. Expecting precipitation
tonight to fall as RA given warm surface temperatures.
Outlook /Thursday Night through Sunday/...
Thursday Night: MVFR/IFR conditions possible. Strong winds with
areas of gusts up to 45 kt. Chance RA, chance FZRA.
Friday: VFR. Strong winds with gusts up to 50 kt. Slight chance
FZRA.
Friday Night: VFR. Windy with gusts up to 35 kt.
Saturday: VFR. Breezy. Slight chance SN.
Saturday Night: VFR. Chance SN.
Sunday: Mainly VFR, with local MVFR possible. Breezy. Chance
SN, chance RA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight: High confidence.
E/ESE winds shift to the W/NW behind a passing cold front.
Gusty, with winds between 20-30kt possible. SCA goes into
effect 00z this evening.
Wednesday: High confidence.
Dry. WNW wind becomes SW late as winds diminish, SCA continues
for waves greater than 5 ft.
Wednesday night...High confidence.
Winds becoming SE and increasing to 15 to 20 kts gusting 20 to
25 kts by sunrise. Seas increasing to 2 to 4 ft.
Outlook /Thursday Night through Sunday/...
Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 7 ft. Chance of rain,
chance of freezing rain.
Friday: Moderate risk for gale force winds with gusts up to
45 kt. Rough seas up to 9 ft. Chance of snow.
Friday Night: Low risk for gale force winds with gusts up to
35 kt. Areas of rough seas.
Saturday: Winds less than 25 kt. Local rough seas. Slight
chance of snow.
Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of snow.
Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain, chance of snow.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 11 PM this evening to 7 AM EST
Wednesday for ANZ231>235-237-251.
Small Craft Advisory until 1 PM EST Wednesday for ANZ250-
254>256.
&&
$$
SYNOPSIS...Belk/BW
NEAR TERM...Belk/BW
SHORT TERM...BW
LONG TERM...Belk
AVIATION...Belk/BW
MARINE...Belk/BW
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
934 PM CST Tue Feb 21 2023
...New UPDATE...
.UPDATE...
Issued at 915 PM CST Tue Feb 21 2023
Winds across the southern Coastal Bend have decreased below
advisory levels, but remain strong. Have let the Wind Advisory
expire at 9 PM as winds should generally remain at 20 to 25 mph
with occasional gusts to 35 mph overnight. VAD Wind Profile
indicated 35 knot winds around 2kft and models prog a LLJ to
increase to 45-50 knots by 06Z. The RAP and HRRR show wind gusts
around 45kt across interior portions of S TX overnight. However,
models also indicate sustained winds of only 20-25kts. Am not so
sure a 45kt LLJ will fully mix to the surface with lapse rates
less than 4C/km. Gusts of 30-35mph look more likely to occur.
&&
.SHORT TERM...
(Tonight through Wednesday night)
Issued at 355 PM CST Tue Feb 21 2023
As has been the case the last several days, temperatures and wind
speeds have outperformed guidance. Southerly winds have increased
to advisory levels over the southern Coastal Bend. A Wind Advisory
is in effect until 9 PM this evening. NBM shows wind gusts may be
near advisory levels over portions of the Brush Country later
tonight. Windy conditions will occur across all of south Texas as
the low level jet increases to 45-50 knots this evening and shift
eastward toward the coast by daybreak. Sea fog persisted much
longer than expected today. Expect wind speeds will inhibit dense
fog formation tonight, but with warm moist air (dewpoints in the
upper 60s) moving across cool water temperatures could lead to
fog formation again later tonight.
Surface trough/dryline is still on track to move through south
Texas Wednesday as the upper level short wave trough moves to the
northeast. With dry air mass and westerly surface winds, could see
temperatures soar to near record levels. Went slightly above NBM
guidance for highs. Record at LRD looks to be in jeopardy and CRP
will be close. Afternoon RH levels will fall to 15 percent Brush
Country to 25 percent inland Coastal Bend. But the wind speeds
fall off by the afternoon, so only expecting near elevated fire
danger conditions over the Brush Country in the afternoon.
Onshore flow will bring boundary layer moisture back into the
region Wednesday night. With warm air moving across the cool shelf
waters, expect advection fog to occur along the coast and move
inland into the coastal plains after midnight.
&&
.LONG TERM...
(Thursday through next Monday)
Issued at 355 PM CST Tue Feb 21 2023
The GFS/NAM/ECMWF generally agree that an upper level disturbance
will lift northeastward across the northern Plains/Great Lakes
Thursday, while an upper ridge builds over the Gulf of Mexico. The
upper pattern is predicted to become quasi-zonal Friday, except for
the western CONUS as an upper disturbance approaches the West Coast.
The GFS/ECMWF are generally consistent with the position/timing of
this system, moving it across the southwestern CONUS/TX Sunday
night/Monday. The foregoing upper pattern is expected to support
onshore flow Thursday through Sunday, with PWAT values near/above
normal. Based on the GFS soundings at select locations, radiation
fog may occur early Thursday morning over the coastal plains, along
with advection fog over the bays/nearshore waters when considering
the predicted surface dew point temperatures related to current SST
values. (Caveat, advection may be limited owing to weak flow).
Deeper moist layer may preclude radiation fog early Friday morning.
In response to an earlier upper disturbance expect to move across
the U.S./Canada border in the Short Term, a frontal boundary is
predicted to enter TX and stall just north of the CWA Friday, then
lift northward Saturday. Unsure whether precipitation will occur
Friday over the northern CWA. Convection not expected Saturday/
Sunday owing near zero CAPE/significant CIN, and no significant
forcing. In response to the second upper disturbance, a frontal
boundary/dry line is predicted to move across the CWA Monday. Given
the expected lack of significant CAPE, and significant CIN in
advance of the boundary, unsure whether convection will occur
along the boundary. Decided to increase maximum temperatures
Monday, as NWP models may not account for greater adiabatic
compressional heating.
&&
.AVIATION...
(00Z TAFS)
Issued at 531 PM CST Tue Feb 21 2023
Main concern tonight will be winds and low level wind shear. A
50kt low level jet is expected to develop this evening initially
across the Brush Country then shifting east toward the coast
through early Wednesday morning. Some of this energy will continue
to mix to the surface, maintaining strong southerly winds with
gusts around 35kt, especially for CRP TAF site, through the
overnight hours. A boundary will move into the Brush Country
between 11Z-13Z, and reaching the coast between 15Z-18Z. As the
boundary moves east across S TX, winds will relax and shift to the
southwest then west. The boundary is expected to stall close to
the coast, then retreat westward as the sea breeze kicks in. This
will shift winds back to the south across CRP by late afternoon
and eventually all of S TX Wed evening. Winds will be much lighter
Wednesday night. VFR conditions are expected through this evening,
then MVFR conditions are expected across ALI, CRP and VCT by late
evening then improving to VFR as the boundary brings drier air to
the area.
&&
.MARINE...
Issued at 355 PM CST Tue Feb 21 2023
Moderate to strong onshore flow will increase to strong to very
strong after midnight and continue through Wednesday morning. Some
gusts to near gale force will be possible mainly over the offshore
waters but could occur over the southern bays into this evening.
Winds will decrease to moderate Wednesday afternoon but seas will
remain elevated over the offshore waters into Wednesday evening.
Patchy to areas of fog will be possible over the bays and near
shore waters tonight and again Wednesday night.
Advection fog may occur over the bays/nearshore coastal waters
Thursday morning, however onshore flow may be too weak for advection
fog. Greater onshore flow and expectation that surface dew points
will exceed SST values suggest at least patchy advection fog Friday
morning. Unsure whether surface dew point temperatures will exceed
SST values and thus will not predict advection fog for Saturday
morning. Persistent onshore flow and above normal moisture (based on
the PWAT metric) predicted to occur Friday through Sunday.
Moderate/strong south flow predicted for Sunday night, as an upper
level disturbance approaches the region. A frontal boundary is
expected to move offshore Monday. Unsure whether the boundary will
trigger convection, and also unsure whether strong offshore flow
will occur after boundary passage (colder air will not follow this
boundary).
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 68 90 66 84 / 10 0 0 0
Victoria 67 87 65 82 / 0 0 0 0
Laredo 67 97 64 91 / 0 0 0 0
Alice 67 94 65 87 / 10 0 0 0
Rockport 67 83 66 76 / 0 0 0 0
Cotulla 64 95 60 89 / 0 0 0 0
Kingsville 68 94 66 87 / 10 0 0 0
Navy Corpus 67 84 67 75 / 10 10 0 0
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory until 10 AM CST Wednesday for GMZ231-232.
Small Craft Advisory until 10 AM CST Wednesday for GMZ236-237.
Small Craft Advisory until 6 PM CST Wednesday for GMZ250-255.
Small Craft Advisory until 9 PM CST Wednesday for GMZ270-275.
&&
$$
SHORT TERM...TE/81
LONG TERM....WC
AVIATION...TE
Area Forecast Discussion
National Weather Service Cheyenne WY
708 PM MST Tue Feb 21 2023
.UPDATE...
Issued at 704 PM MST Tue Feb 21 2023
Made a quick update to tonight`s forecast package with the arctic
portion of the front coming in a little quicker, so updated temps
and dewpoints with Chadron dropping from 36 degrees to 17 degrees
in about 30 minutes earlier this evening. Current forecast through
tonight looks on track and will continue to monitor trends in
snowfall rates as well as wind speeds in the event that Blizzard
Warnings need to be extended.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 400 PM MST Tue Feb 21 2023
The anticipated major winter storm for portions of our area is
beginning across portions of Southeast Wyoming and the Nebraska
panhandle. While the forecast is largely on track, there have been a
few minor but important changes with this update. The highlights are
as follows:
* A very high impact event is still on track for northern Carbon
county, with snowfall accumulation in the 12 to 20 inch range and
blizzard conditions expected to begin tonight.
* A northward shift in recent model guidance has resulted in
slightly reduced forecast snow totals for those along and south of
a Laramie to Alliance line. Impactful snow is still expected, but
totals have decreased slightly.
* Dangerously cold wind chills are expected behind this arctic
front. Apparent temperatures between -25 and -40F are likely for
the majority of the forecast area Wednesday night into Thursday
morning. A Wind Chill Watch has been issued.
Currently, our area is under moist WSW flow aloft ahead of a potent
trough rapidly digging into the west coast at this hour. The
downstream branch of the trough is leading towards falling pressures
over southwest Wyoming and northeast Utah as the lower atmospheric
low pressure center starts to develop. Meanwhile at the surface, the
arctic high is pushing southward. The combination of those two
effects is rapidly reducing (and eventually reversing) the cross-
barrier pressure gradient. Thus, the strong westerly winds have
waned this afternoon after a very windy morning. Can`t rule out a
quick burst of winds right before the front pushes through, but
after that winds are expected to reverse. The cold front has already
pushed into our northern counties, with Douglas reporting north
winds, a temperature of 32, and light snow. Bitter cold temperatures
are lagging behind the initial wind shift a little bit (still
appears to be north of Rapid City at this time), but arctic air is
still expected to reach the Colorado border by shortly after
midnight. Snow has already begin in Carbon county per radar and
webcams, but the blizzard conditions will likely hold off for a few
more hours until the reverse gradients set up and initiate
northeasterly winds. Further east, some light echos are showing up
over the North Platte River Valley, with Scottsbluff reporting light
rain for the last two hours or so. Some areas getting wet may see a
flash freeze and icy conditions when the front passes through this
evening and rain flips to snow quickly.
Over the next 12 hours, the storm is expected to evolve rapidly. The
upper level low will dig deep into the southwest this evening, and
support low level cyclogenesis over central Utah. This progression
has been the main source of the forecast uncertainty with this
update. The 12z suite of hires models came in with a significant
northward shift in precipitation, cutting down on totals for
southern and eastern portions of the forecast area, while the global
models still held strong with the higher end of the forecast.
Digging into the details producing this difference, it could be seen
that this change resulted from the positioning and strength of the
low pressure center. The RAP model earlier was showing the 700-mb
low positioned over SW Wyoming at 12z tomorrow, while the GFS was
holding consistent with this feature over central Utah. The ECMWF
and NAM were somewhere in between. This RAP solution then had a less
amplified low, leading to southwesterly flow in the 600 to 800-mb
level, rather than SSE flow. Such wind direction would be less
effective isentropic lift and theta-e advection working into the I-
80 corridor near and east of Laramie. This presents a compelling
failure mode that would result in the lower end of totals being
realized in southern and eastern portions of the area (but would NOT
affect totals in areas such as Rawlins, Wheatland, and Chadron). To
account for these trends, amounts were trimmed slightly on the
southern fringe. Did drop totals more significantly in Laramie,
because a lack of dynamic lift aloft would result in much less snow,
since orographics are very unfavorable there. Still looking at the
low end of warning criteria for these zones, but a further northward
shift could put that in jeopardy. However, 18z hires model trends
have ended this northward shift, and even wobbled slightly further
south, putting our official forecast that split the difference
between the 12z global models and hires models in a good position.
Further north and west, the forecast is still looking largely on
track. Northern Carbon county from Elk Mountain to Rawlins still
looks like it will see the most significant impacts. Model QPF means
remain around 0.8 to 1.2, which supports the current forecast of 12-
20 inches of snow with locally higher amounts possible. Strong winds
developing under impressive reverse pressure gradients are likely to
produce gusty winds of 40 to 50 mph and blizzard conditions in this
area. Significant blowing/drifting snow will compound the impacts.
The heavy snowfall rates will be partially attributed to the strong
frontogenesis predicted in this area, as the low-level front gets
hung up on the mountains to the south. Models remain consistent in
keeping this forcing over the area, which would lead to heavy banded
snowfall. There is some variability in the exact location of the
heavy band, which will likely be the difference between the lower
and higher end totals described above. Heading over the the high
plains north of the region of greater uncertainty described above,
the isentropic lift and theta-e advection will be positioned well to
still produce substantial lift and precipitation. Snow totals
look on track here, but the piece of uncertainty going forward is
the potential for blizzard conditions. There may be a period of
winds reaching blizzard criteria along a band stretching across
Niobrara county, northeast Goshen county, and just north of the
North Platte River valley, and points northeastward. Don`t have
the confidence at this time to upgrade to a blizzard warning due
to uncertainty regarding now persistent these winds will be able
to get, but will need to keep a close eye on wind and visibility
trends as a potential upgrade could be needed. Regardless, winds
will be enough to produce significant blowing/drifting snow
through Wednesday morning, but we do thing winds should come down
Wednesday afternoon. Another thing to watch for Wednesday is the
potential for some convectively enhanced snow showers in the
afternoon. Most guidance is showing steep lapse rates and some
elevated instability on top of the bitter cold surface inversion.
Thus, snow activity after midday Wednesday could take on more
spotty, convective characteristics. Winds in the 600-800mb layer
are expected to turn more westerly after 00z Wednesday, which will
start to advect in drier air and bring an end to the snowfall
totals.
The forecast also remains on track for another significant cold air
intrusion. Expecting almost the entire area except the higher
terrain in the SW part of the forecast area to be below 10F by
daybreak, and temperatures will only drop further through the day.
Most will stay in the single digits above to single digits below
during the daytime hours, with apparent temperatures between -20F
and -25F even during the day. There is still strong model consensus
for overnight lows in the -10 to -20F range Thursday morning. Even
with just a little bit of wind, this would be enough to produce wind
chills below -30F, so decided to issue a Wind Chill Watch for
Wednesday night through Thursday morning. Weak warm air advection
resumes Thursday, so the higher terrain should warm quickly (with
breezy conditions likely leading to more blowing snow concerns), but
the high plains will probably remain very chilly.
.LONG TERM...(Thursday night through Tuesday)
Issued at 400 PM MST Tue Feb 21 2023
The progressive large scale pattern will continue through the long
term. The flow aloft splits Friday, with a southern stream upper low
moving through CA/NV, the Four Corners and south central Plains this
weekend into Monday. Shortwave energy in the northern stream dampens
out, with a weak ridge shifting east ahead of the next Pacific upper
trough Monday. This trough gets absorbed by a more dominant upper
ridge, deamplifying Tuesday as a deeper upper trough takes shape
over the western CONUS.
Main concern for Friday through Saturday will be the resumption of
strong winds for the I-25/I-80 wind-prone zones. The 12Z in-house
random forest probabilities for high winds are around 40 percent,
with gusts falling just short of 58 MPH. Another byproduct of the
winds will be blowing/drifting of the newly fallen snow. Travel will
be impacted with the possibility of ground blizzard conditions. Winds
diminish Saturday night and Sunday, then strengthen Sunday night and
Monday. Probabilities for high winds along the I-80 corridor from
Rawlins to Buford are 60-65 percent with gusts up to 65 MPH.
There will be some Pacific moisture interacting with a passing
shortwave and orographic lift Friday to produce snow showers along
and west of the Laramie Range. One to three inches of snow will be
possible over the Snowies/Sierra Madres. Saturday will be dry, with
the next chance of mountain snow showers Sunday/Sunday night and
Tuesday with the passage of additional shortwaves.
Temperatures moderate from the 20s/30s Friday to the 30s/40s
Saturday and Sunday. Temperatures cool slightly Monday following a
frontal passage, then moderate once again Tuesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 423 PM MST Tue Feb 21 2023
Wyoming TAFS...A strong cold front will move across the terminals
around mid evening with winds becoming north and northeast and
widespread snow developing by late evening with IFR ceilings and
visibilities continuing through the period.
Nebraska TAFS...A strong cold front will sweep across the
terminals this evening with winds becoming northeast. Widespread
snow will develop behind the cold front late this evening
producing IFR ceilings and visibilities through the period.
&&
.FIRE WEATHER...
Issued at 227 AM MST Tue Feb 21 2023
Fire weather concerns will not be present for the next several days
as a strong cold front and accumulating snowfall occurs across the
region.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Warning until 5 AM MST Thursday for WYZ101>103-
106>108-111>114.
Wind Chill Watch from Wednesday afternoon through Thursday
morning for WYZ101>110-115>119.
Winter Storm Warning until 5 AM MST Thursday for WYZ116>119.
Winter Weather Advisory from 11 PM this evening to 5 AM MST
Thursday for WYZ115.
Blizzard Warning until 5 AM MST Thursday for WYZ104-105-109-110.
NE...Winter Storm Warning until 5 AM MST Thursday for NEZ002-003-095-
096.
Wind Chill Watch from Wednesday afternoon through Thursday
morning for NEZ002-003-019>021-054-055-095-096.
Winter Storm Warning until 5 AM MST Thursday for NEZ019>021-054.
Winter Weather Advisory from 11 PM this evening to 5 AM MST
Thursday for NEZ055.
&&
$$
UPDATE...TJT
SHORT TERM...MN
LONG TERM...MAJ
AVIATION...RUBIN
FIRE WEATHER...BW
Area Forecast Discussion
National Weather Service Des Moines IA
603 PM CST Tue Feb 21 2023
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Tuesday/
Issued at 309 PM CST Tue Feb 21 2023
Key Messages:
-Significant Winter Storm with heavy snow north to ice and sleet
into central Iowa tomorrow into Thursday
-Breezy northwest winds on Thursday
Discussion:
An elongated wave across the upper midwest has brought snow to
Minnesota and skimmed across far northern Iowa this afternoon. While
accumulations have remained fairly light, brief reductions in
visibility to a mile or less have occurred. At the same time,
temperatures have under performed today by several degrees as east
southeast winds provide an unfavorable trajectory for much warming
today.
The large, much talked about, system of note will make its presence
known beginning tomorrow morning. Deep moisture transport out of the
south phases with the northerly elongated wave as the surface low
bottoms out across the central plains. What does this mean for Iowa?
Let`s take this in phases. Rain will initially move into southern
Iowa early Wednesday morning and expand into central Iowa. As
temperatures near freezing are encountered, a transition to freezing
rain is expected, generally in the vicinity of the interstate 80
corridor. Further north towards the highway 30 to highway 20
corridor sleet is also anticipated. And finally, far northern Iowa
will see mainly snow, with potentially heavy accumulations along the
Iowa-Minnesota border.
The primary cause of this precipitation type transition is a nose of
warm air easily identified on a cross section across Iowa. as the
depth of the surface cold layer deepens to the north and the warm
layer cools, we see that transition from rain to freezing rain to
sleet to all snow. There are a few variables which will influence
just how much ice accumulates and where. High rain rates mean more
chance for runoff and thus less ice accumulation. Keep in mind that
a degree or two change in temperature, at the surface or aloft,
could make an impactful difference in the forecast. A few convective
elements are possible within this as well, with that additional lift
within cells that would contribute to more sleet and less freezing
rain. Across the models, the GFS tends to be slightly further south
with the wintry mix of ice and sleet nearer the interstate 80
corridor compared to the Euro which is further north closer to the
highway 30 corridor. In the hi-res world, the HRRR and RAP tend to
agree with a similar northerly track with the wintry mix, while the
HREF is more robust south of there. These are distances of 20 to 30
miles with potential significant impacts, as accumulations of a
quarter inch or more of freezing rain is possible.
Winds will remain breezy on Wednesday but increase further on
Thursday as the system departs. Breezy winds across northern Iowa on
Wednesday into Thursday will contribute to reduced visibility as
times. Any winds in areas with ice accumulations could contribute to
possibilities for tree damage and power outages. As winds increase
across southern Iowa on Thursday, gusts nearing 40+ mph are possible
and a wind advisory may be needed.
Lastly, there is a chance that the narrow warm sector reaching into
far southern Iowa could result in a few thunderstorms with elevated
CAPE of 100-300 J/kg. The primary severe risk is south of the area
into Missouri.
Much colder air will filter in behind the system and temperatures
will drop below zero across much of Iowa into Friday morning. With
breezy winds, wind chill will be well below zero and the need for a
wind chill headline cannot be ruled out across parts of northern to
northwest Iowa.
&&
.AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/
Issued at 600 PM CST Tue Feb 21 2023
VFR conditions will prevail during the first portions of the TAF
period, then quickly degrade into MVFR/IFR and even possible LIFR
from ceilings and visibilities. Conditions will be driven by
periods of SN/PL/FZRA/RA from north to south across the sites.
Concurrent with the precipitation will be gusty NE winds,
especially across northern sites KFOD/KMCW/KALO where gusts will
be up in the 30s kts during the latter half of the period.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 9 AM Wednesday to 6 PM CST Thursday
for IAZ004>007-015>017-023>025.
Ice Storm Warning from 9 AM Wednesday to 6 PM CST Thursday for
IAZ026>028-037>039.
Winter Weather Advisory from 9 AM Wednesday to 6 PM CST Thursday
for IAZ033>036-044>050-057>062-070>072.
&&
$$
DISCUSSION...Hagenhoff
AVIATION...Curtis
Area Forecast Discussion
National Weather Service Grand Forks ND
939 PM CST Tue Feb 21 2023
.UPDATE...
Issued at 939 PM CST Tue Feb 21 2023
Light snow band continue to sag further south, and the first round
of precipitation should push out of our area sometime after
midnight. Snow will begin to move back in by tomorrow afternoon
for the second round. Across the northern counties, skies have
already cleared out and wind chills are below -25 in many areas.
However, expecting temps and wind chills to get even colder, and
the wind chill warning and advisory headlines start very soon.
Will leave headlines as they are for now.
UPDATE Issued at 544 PM CST Tue Feb 21 2023
Decent snow coming down across our southern counties with 3 inches
so far in Lidgerwood. Radar has the snow band starting to weaken a
bit, but adjusted POPs for current trends. Overall forecast seems
on track for the time being and no changes planned for headlines.
&&
.SHORT TERM...(This afternoon through Tonight)
Issued at 214 PM CST Tue Feb 21 2023
Key Messages:
-Winter weather impacts remain likely through the afternoon/evening
hours across southeastern North Dakota into west central Minnesota.
-Cold, well below zero temperatures and gusty winds will lead to
dangerously cold wind chills overnight into Wednesday morning.
Discussion...
As of this afternoon, a midlevel convergent zone was noted on latest
RAP mesoanalysis. This correlates well with a region of 700 hPa
frontogenesis, which is leading to an area of snowfall across
southeastern North Dakota into west central Minnesota. The heaviest
snowfall rates are tied to the frontogenesis region, which is
generally located near the border of the Dakotas. Regardless,
transient periods of moderate to heavy snow have been observed with
these frontogenetical bands. Upstream visibility reductions down to
1/4 mile at times have been reported underneath the heaviest bands
of snow. Additional snowfall amounts of 1 to 4 inches will be
possible as this system moves through. Given the overall transient
forcing for ascent, anticipating this to be a quick moving system,
with snowfall chances decreasing rapidly as we move into the evening
hours. As snowfall chances diminish tonight, skies are expected to
clear over at least the northern half of the forecast area, leading
to another cold night ahead. Especially where clearing works in,
temperatures should be able to drop quickly back below zero. With
increasing winds also expected overnight, wind chill values in the -
30s to -40s will be possible, with a few -50s not out of the
question.
.LONG TERM...(Wednesday Morning through Tuesday)
Issued at 214 PM CST Tue Feb 21 2023
...MAJOR WINTER IMPACTS TOMORROW AND THURSDAY...
KEY MESSAGES
1. Blizzard conditions will develop from south to north during the
day Wednesday up to the Highway 200 Corridor.
2. Heavy accumulating snow from southeast North Dakota through
Wadena County of 6 to 10 inches, with areas approaching a foot.
3. Accumulating snowfall between 2 and 6 inches mainly south of
Highway 200.
4. Dangerous wind chills approaching 50-below at times will occur
through at least Thursday.
5. Travel will be life-threatening to those stranded, especially
in southeastern North Dakota and west-central Minnesota where
snowfall accumulations may exceed 8" with significant drifts and
dangerous wind chills.
DISCUSSION...
The well-advertised winter storm is on our doorstep. Satellite
analysis indicates our twin-headed lows spinning over the Baja of
California and the Pacific Northwest respectively. As these
continue to push eastward overnight tonight, a coupled jet is
expected to develop over the midwest. This will allow for strong
surface cyclogenesis tomorrow. With most guidance spitting out a
minimum pressure approaching 990mb sandwiched with a 1040mb high
over the Yukon and western Alberta, a gradient wind response will
develop over the CWA. BUFKIT momentum transfers indicate the
potential for winds to approach 25-30 knots assuming maximum
momentum transfer. However, with limited cold air advection to
punch down those max winds, the general thought here is that winds
will be much less than the max momentum transfer (by between 5-8
knots). While current snowpack is VERY blowable, winds should be
limited enough overnight that impacts will remain relatively
isolated and minor. Blowing snow probabilities within this
timeframe through 3 PM tomorrow are in the 10-20% range due to the
limited winds.
Conditions will deteriorate very quickly as snowfall arrives to
the southern Red River Valley after noon tomorrow. Blowing snow
probabilities with mostly stable winds between 20 and 25 knots
combined with the falling snow spit out probabilities approaching
100, particularly after sunset Wednesday through Thursday morning.
With the current blowability of snow, significant drifting will Not worth putting out
an advisory headline for a few hours. develop across southeast
North Dakota through west-central Minnesota into Wadena. Combine
this with the long duration of the snowfall and the high
predictability in warm air advection, there is high confidence in
the snowfall ranges across the entire region. Higher totals
exceeding 8 inches remain possible in southeastern North Dakota
and west-central Minnesota (30-60% probability, increasing
southward).
Regardless of the snow totals that are experienced, the winds will
be there for blizzard conditions within the blizzard warning. We
know there will be falling snowfall combined with the elevated
winds to create a prolonged period of blizzard conditions.
Conditions will be especially significant in the tri-state area
where significant snowfall accumulations approaching a foot with
the winds will create the potential for significant drifting. For
this reason, the expectation is for the worst conditions to be
felt in southeastern ND and WC MN. Very difficult to impossible
travel conditions will occur in these regions. Combine these with
the dangerous wind chills approaching 35 and 45 below, travel will
be life-threatening to those stranded. Further north, blizzard
conditions will impact the area despite the limited accumulation
potential. Falling snow and winds will create whiteout conditions
up to the Highway 200 corridor. Areas of blowing snow may exist
outside of these areas, however blowing snow impacts should remain
limited due to limited wind speeds and lack of falling snow.
Wind chill impacts of at least 30-below will impact most of the
area at some point between tonight through Thursday afternoon.
Conditions for travel should improve as winds diminish Thursday
afternoon. Impacts look to remain limited to wind chills through
the rest of the work week, with gradually warming temperatures
towards the end of the period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 544 PM CST Tue Feb 21 2023
Light snow impacting KFAR has brought vis down to 1-2SM at times,
but ceilings there and conditions at all other sites are VFR. With
dry air coming in from the north think that conditions will be
mostly VFR for much of the period until winds increase and we
start to get lower visibility from blowing snow tomorrow
afternoon. Winds will stay mostly in the 350 to 020 range for most
of the period, picking up in speed with gusts over 25 kts by
Wednesday afternoon at least for the ND airports.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Wind Chill Warning until noon CST Thursday for NDZ006>008-
014>016-024-026-027-054.
Blizzard Warning from 6 PM Wednesday to noon CST Thursday for
NDZ028>030-038-039.
Winter Weather Advisory until 6 PM CST Wednesday for NDZ038-039.
Winter Weather Advisory until 3 PM CST Wednesday for NDZ049-052-
053.
Blizzard Warning from 3 PM Wednesday to noon CST Thursday for
NDZ049-052-053.
Wind Chill Warning until 6 PM CST Wednesday for NDZ028>030.
MN...Wind Chill Warning until noon CST Thursday for MNZ001-004-007.
Wind Chill Advisory until 6 PM CST Wednesday for MNZ002-022-023.
Blizzard Warning from 6 PM Wednesday to noon CST Thursday for
MNZ002-003.
Winter Weather Advisory until 6 PM CST Wednesday for MNZ003.
Wind Chill Advisory until noon CST Thursday for MNZ005-006-008-
009-013>017.
Winter Weather Advisory from 6 PM Wednesday to noon CST Thursday
for MNZ022>024.
Winter Weather Advisory until noon CST Thursday for MNZ027-028.
Winter Weather Advisory until 3 PM CST Wednesday for MNZ029>032-
040.
Blizzard Warning from 3 PM Wednesday to noon CST Thursday for
MNZ029-030-040.
Winter Storm Warning from 3 PM Wednesday to noon CST Thursday
for MNZ031-032.
&&
$$
UPDATE...JR
SHORT TERM...Rick
LONG TERM...Perroux
AVIATION...JR
Area Forecast Discussion
National Weather Service Green Bay WI
830 PM CST Tue Feb 21 2023
New Information added to update section
.UPDATE...
Issued at 829 PM CST Tue Feb 21 2023
The latest RAP analysis and satellite/radar imagery show a
deformation zone extending across central Minnesota and northern
Wisconsin this evening. 800-700mb frontogenesis south of this axis
is helping to generate a swath of snow, which has been spreading
east across western and central WI this evening, and reaching the
Oshkosh area at around 8 pm. The snow has yet to reach north of
HWY 29 and east of US 51, thanks to residual dry air below 800mb.
However, mesoanalysis is showing low level saturation spreading
east into north-central WI and think snow will start to reach the
surface over the northwoods shortly. But with the slower start,
trended downward with snowfall amounts across far northern WI.
This may mean that the northern tier of counties within the winter
weather advisory will struggle to reach 3". Otherwise, a snowfall
axis of 3-5" south of HWY 29 is looking good so far this evening.
No changes to the winter weather advisory for tonight.
&&
.SHORT TERM...Tonight and Wednesday
Issued at 243 PM CST Tue Feb 21 2023
Headline changes include an eastward expansion of tonight`s
Winter Weather Advisory, an upgrade of the Winter Storm Watch to a
Warning, with an earlier start time over our southern counties.
Lake-induced low clouds lingered across northern WI, as mid/high
clouds quickly approached from the west. The regional radar mosaic
showed snow moving into eastern MN.
Strong frontogenesis, 850/700 mb warm air advection and the RRQ
of an upper level jet will overspread the forecast area during the
late afternoon and evening, causing light to occasionally moderate
snow to develop, then continue through the night. With a cold air
mass and deep dendritic growth zone in place, expect a widespread
powdery accumulation of 3 to 5 inches across roughly the southern
2/3rds of the forecast area. Have expanded the Winter Weather
Advisory eastward into Oconto, southern Marinette and Door counties.
The snow should diminish Wednesday morning, but models show a
quicker return of significant snow accumulations into central and
east central WI during the afternoon, as strong mid-level
WAA/isentropic lift arrives. Northeast winds will increase during
the day, and gust to 25 to 35 mph north, and 35 to 45 mph south
in the afternoon. Considerable blowing or drifting snow is
expected, especially in opens areas of central WI, the Fox Valley
and lakeshore. The Watch has been upgraded to a Warning, and
the start time has been tiered from noon in our southernmost
counties to 6 pm in northern WI.
.LONG TERM...Wednesday Night Through Tuesday
Issued at 243 PM CST Tue Feb 21 2023
The main focus of the extended period will be the resolution of
the winter storm passing over the area from the middle of the week
through Thursday.
Wednesday night through Thursday...
The winter storm will be ongoing over the beginning of the
extended period as the surface low lifts out of the Central Plains
and into Iowa through the overnight. The associated warm front
will lift towards the southern Wisconsin border during this
period, bringing overrunning warm air and moisture well into
Wisconsin. As a result, a fairly tight baroclinic zone will be
over southern Wisconsin with strong FGEN forcing north of this
area in central and northern Wisconsin. Upper level support will
not be lacking during this period either, as a pair of upper jets
rotate over the region. Snow fall rates will likely be high at
times, with rates up to an inch an hour not unlikely through
Thursday morning. Added to this, wind gusts will range from 30 to
45 mph at times, creating near whiteout conditions overnight. As
the surface system departs northeastwards towards lower Michigan
Canada Thursday morning, the most intense snowfall will lift into
northern WI. By the early afternoon, overall intensity will be
headed downwards, with gradually diminishing winds and snowfall.
That said, snow will likely become more fluffier as the day wears
and colder air wraps into the region. This could keep a prolonged
period of lower visibility in place into Thursday afternoon as the
newest snow remains more prone to blowing and drifting despite
the slowly decreasing wind gusts. All is said and done, snowfall
totals from Wednesday night through Thursday afternoon are
expected to be between 5-10 inches south of a line from Wisconsin
Rapids to Oconto, and 10-15 north of this line. Given the wind
during this period, measuring will be fairly difficult as there
will likely be marked difference between open areas and the
tallest drifts.
Thursday night and Friday...
Any remaining light snow will move out of the region Thursday
evening and overnight. A fairly cold and dry airmass will be in
place through the surface for this period, creating a fairly cold
night for the region. Friday morning wind chill values across
portions of central to north-central will likely be in the 10 to
20 below zero range. That said, WAA will pick up again over the
day Friday but moisture will likely be insufficient to produce any
precipitation during the day. By the early evening and early
overnight, models do produce sporadic chance pops across the area,
but the overall impact will likely be low. Stuck to blended
guidance for this period.
Rest of the forecast...The weekend will see moderating
temperatures, with highs gradually headed back into the 30s to
lower 40s by Monday. The next active weather system could arrive
early next week, but given the temperatures in the forecast,
currently would expected primarily rain as the dominant p-type.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 542 PM CST Tue Feb 21 2023
- A large area of snow will spread across the region from west
to east through 9 pm. Widespread IFR visibilities and MVFR
ceilings can be expected in the snow through late tonight.
Local reductions of visibilities to LIFR are possible. Several
inches of dry snow are likely.
- The snow may diminish somewhat Wednesday morning, but will
intensify from south to north during the afternoon as a winter
storm approaches from the Southern Plains.
- Northeast winds will be increasing through the day. Gusts of 30
to 40 mph are likely during the afternoon. The gusty winds
combined with the new snow will lead to reduced visibilities in
blowing snow.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 6 PM Wednesday to 6 PM CST Thursday
for WIZ005-010>013-018-019-021-073.
Winter Weather Advisory until 9 AM CST Wednesday for WIZ018>022-
030-031-035>040-045-048>050-073-074.
Winter Storm Warning from 3 PM Wednesday to 6 PM CST Thursday
for WIZ020-022-030-031-035>040-074.
Winter Storm Warning from noon Wednesday to 6 PM CST Thursday
for WIZ045-048>050.
&&
$$
UPDATE.........MPC
SHORT TERM.....Kieckbusch
LONG TERM......Uhlmann
AVIATION.......MPC
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1028 PM EST Tue Feb 21 2023
.SYNOPSIS...
A warm front will lift north of our area on Wednesday with
temperatures continuing to warm. A strong upper level ridge will
dominate our weather through Thursday with daily and perhaps even
monthly record highs expected to be broken. Another cold front will
pass Friday, with chilly and damp weather looking likely on Saturday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 1030 PM EST Tuesday: Warm frontal activation is being depicted
based on current dewpoint and wind observations and where very
isolated showers have developed, with 50s in the southern half of
the CFWA, while 30s still reside along the I-40 corridor. No major
changes to the overall forecast as it remains on track. Updated
temperatures and PoPs based on model trends and current
observations.
Otherwise, quasi-zonal flow will persist across much of the East
through the near term, cyclogenesis is underway in the lee of the
Rockies in response to height falls emanating from the western
Conus. This will activate the broad baroclinic zone across the
Southeast tonight into early Wed, with resultant weak warm front
expected to lift across our CWA during that time frame. Some high
resolution guidance...in particular the HRRR develop scattered
showers across the area beginning this evening, with some support
from this from some traditional guidance sources. Overall, there is
enough of a signal there to warrant 20-30 PoPs across much of the
forecast area tonight. While statistical guidance signals are mixed,
some fog...possibly locally dense could develop in the vicinity of
the warm front, but this will at least partly depend upon how
much...if any...precip falls. Min temps will remain well above
climo...right around where highs should be for the time of year.
Warm front is expected to lift north of the area by late Wed
morning, bringing an end to shower chances. Some guidance, in
particular the NAM tends to saturate the low level air mass in
response to light precip...developing a bit of an situ cold air
damming scenario over the I-40 corridor. This seems somewhat
dubious, and the NAM appears to be overproducing precip to some
extent, but it does create a bit of uncertainty re: Wed max temps,
especially across northern zones. Nevertheless, the most likely
outcome is another day of well-above normal max temps, with
mid-to-upper 70s likely along and southeast of I-85, and lower 70s
across the mtn valleys and I-40 corridor.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 121 PM EST Tuesday: The short term portion of the forecast
period will be dominated by an anomalously strong sub-tropical ridge
centered over far southern Florida. Latest guidance continues to
indicate a 597dam H5 height contour with anomalous heights in the
99th percentile for late February extending well into the Carolinas
and northeast Georgia. A weakening shortwave trough lifting through
the Ohio Valley will drag a weak boundary/convergence zone into the
Appalachians tomorrow night into Thursday morning. Isolated to
scattered showers are expected across the mountains, but upper
forcing quickly lifting away and rising heights will keep this
activity confined to the high terrain during the morning hours. The
main focus will be temperatures on Thursday, which will flirt with
all time February highs at many locations. Forecast confidence has
decreased slightly as morning low stratus could delay warming. Cloud
cover will eventually lift and scatter, but exactly how long that
takes remains to be seen. Regardless, at least partly cloudy skies
should be common by late morning to early afternoon which should
still support afternoon highs climbing into the low 80s east of the
mountains within a deeply mixed boundary layer. Mountain valleys
will likely see highs top out in the mid to upper 70s with 60s
across the highest terrain. Both morning low temperatures and
afternoon highs will be running 20-25 degrees above average.
Previously mentioned deep mixing will also support breezy
conditions, but current forecast gusts are expected to remain below
wind advisory criteria at this time.
A better defined shortwave trough lifting through the Great Lakes
region on Thursday will send a surface cold front through the area
Thursday night into Friday morning. The arrival of a cooler and
drier airmass will help knock temperatures down to where records
won`t be in jeopardy, but temperatures will still be above normal.
The frontal boundary will likely stall just to our south as it
becomes oriented parallel to westerlies on the poleward side of the
sub-tropical ridge. Spokes of DPVA embedded within the upper flow
along with ascent from upper jet dynamics will help instigate
precipitation along and north of the frontal boundary on Friday.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 203 PM EST Tuesday: Rain will peak in coverage Friday night
through Saturday as a subtle shortwave trough slides through the
region. A transient surface high shifting across New England will
support a hybrid/insitu CAD wedge as well with a damp/cool day in
store for most, especially across the North Carolina counties.
Temperatures will likely be several degrees below average, which
will be quite a pattern change from the warmth on Thursday. Westerly
downslope flow and drying will quickly clear out precipitation by
Sunday morning with only a few showers lingering along the Tennessee
border. This will allow for temperatures to quickly return to above
average on Sunday with highs in the low 50s to 60s for the mountains
and upper 60s to low 70s to the east.
Heading into early next week, guidance is in good agreement on a
compact negatively tilted trough ejecting out of the Desert
Southwest on Sunday and lifting through the Lower Mississippi Valley
and into Ohio on Monday. While guidance agrees on the presence of a
wave, there are differences in regards to track and strength and any
corresponding sensible weather impacts to the area. The GFS solution
is the most aggressive with a potent wave and a strongly forced QLCS
entering our western zones Monday evening, although quality of
moisture return and subsequent instability looks meager at best. The
ECMWF/CMC/ICON solutions have a weaker wave with the strongest
height/pressure falls brushing by the area to the north and mainly a
weak band of showers moving into the mountains. Kept the forecast in
line with the national model blend for now until guidance comes into
better agreement with the evolution of the wave.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: VFR w/ mainly SCT/BKN high clouds are
expected to persist through at least this evening. Winds have
diminished to 5 kts or less this evening before increasing to 10-15
kts during late morning/early afternoon Wed. Otherwise, low level
moisture is expected to return from the SW overnight in association
with a developing/weak cold front. This will bring shower chances...
mainly to the upstate SC terminals and KCLT, warranting VCSH at
those sites. Cig restrictions are also expected to develop toward
sunrise Wed, with MVFR cigs becoming likely at most sites, and IFR
well within the realm of possibility. Cigs should at least begin to
improve by the end of this forecast cycle. Fog could pose a problem
if the warm front sets up shop within the vicinity of the terminals
around daybreak Wednesday, but confidence is too low for a mention
in the latest TAF update, but will continue to monitor trends.
Outlook: Weak frontal boundaries will linger in or near the region
for much of the week, leading to occasional unsettled weather.
Periodic restrictions are possible due to low clouds and/or
precipitation at times during the latter half of the week.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...CAC/JDL
SHORT TERM...TW
LONG TERM...TW
AVIATION...CAC/JDL
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1013 PM EST Tue Feb 21 2023
.SYNOPSIS...
Showers and strong winds are forecast to develop tonight through
Wednesday night as low pressure tracks to the Great Lakes. Strong
winds are expected again on Thursday in the vicinity of a cold
front trailing the Great Lakes low. Colder temperatures and dry
weather follow the front for Friday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Evening update...
A few minor adjustments to the forecast this evening most of
which was in an attempt to sharpen up the forecast (PoP, wind gusts,
temps/dewpoints) based on latest guidance increasing confidence.
For PoPs this evening, increased to 80-90% as the elevated
activity spreads northeast overnight. Elevated CAPE and strong
flow likely yields some hail with the strongest activity. Can`t
rule out a few special weather statements during the early
morning hours.
With more high- resolution guidance coming in, a much stronger
temperature gradient (15-20 degrees within a few counties north
to south) looks to exist along the frontal boundary tomorrow as
it slowly moves northward. Also timed the strongest wind gusts
for locations south of the front during the afternoon. Not
expecting strong wind gusts to mix down elsewhere. The one
component that did not make it into the forecast due to the
uncertainty is the potential for fog along and ahead of the
frontal boundary during the morning and early afternoon hours.
HRRR guidance has been consistent with the signal for it
occurring, but rather sporadic with timing and intensity.
Final adjustment was to slow the advancement of strongest wind
gusts and decrease overall wind potential north of the boundary.
Still think the strongest winds will be dependent on the
northward position of the front and how efficient clearing
ultimately is. Wind gusts remain near wind advisory over the
currently advised area so will make no changes to it.
Afternoon discussion...(issued 330 PM)
Persistently strong winds this afternoon will diminish for a
few hours this evening as high pressure builds in briefly.
Issued SPS to highlight gusts around 40 mph through 4 pm along
and north of I-70.
For tonight, the surface high will be east of the area by 10 pm,
while a warm front containing a band of isentropic lift moves
in ahead of low pressure. Showers are forecast to overspread the
area from south to north following the movement of the warm
front. Thunderstorms will also be possible from an environment
containing ample elevated CAPE and potent winds aloft.
Under those very strong wind fields aloft, gusty winds will mix
to the surface south of the warm front, leading to some gusts
over 20 knots by 6 am. This will cause low temperatures to be
around midnight in the mid 30s north to mid 40s south, with
readings rising toward daybreak in mixing and warm advection.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
Warm front with showers will be moving to Northern Ohio on
Wednesday, leaving the ILN area in the well mixed warm sector.
Mainly dry and windy conditions are expected as a very strong
low level jet is mixed closer to the ground. Have issued a wind
advisory for the west half of the FA starting at 11 am, with
expansion farther east possible depending on later guidance.
Much above normal temperatures can be expected, with the high at
CVG around the daily record of 71. Readings as high as the mid
70s are forecast for southeast counties, while northern
locations may be limited to the 60s.
For Wednesday night, another band of showers and possible
thunderstorms is forecast to swing across the area from west to
east, containing more strong wind gusts. Therefore, the wind
advisory remains in effect until 1 am Thursday. Drier air and
somewhat lower wind speeds arrive later Wednesday night in the
rapidly progressing weather pattern.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
On Thursday morning, an area of surface low pressure will be
moving ENE into the southern Great Lakes. The Ohio Valley will
be well in the warm sector of this system on Thursday, with
strong theta-e advection on deep- layer southwesterly flow. Even
with the warm advection pattern, there is decent model
agreement on a well mixed boundary layer, and wind gusts of
35-45 MPH appear likely. Definitely a chance of getting into
advisory criteria (46 MPH or greater) on Thursday, particularly
in the northern half of the forecast area. Temperatures are
another item of note for Thursday, with values forecast to be
near records. The standing record high temperatures for Thursday
(Feb 23) are as follows.
Cincinnati 72 in 1996 and 1985
Dayton 70 in 2017
Columbus 72 in 2017
One thing not being mentioned for Thursday is precipitation, as it
looks like any warm advection precipitation should be clearing the
area by morning, and forcing appears to remain north of the area
beyond then. A cold front Thursday afternoon and evening will be
running into very dry air, and is unlikely to produce any
precipitation.
Behind the cold front, Friday looks like the coolest day of the
extended period, with highs in the 30s to 40s. An active pattern
will continue beyond then, with a weak wave producing some light
precipitation on Saturday morning. Based on temperature profiles,
some light wintry mix appears possible, but confidence in any
specific precipitation type remains low. The greatest forcing
appears likely to remain south of the region.
Another strong low pressure system appears likely to move through
the Great Lakes and Ohio Valley regions on Monday into Tuesday of
next week. While confidence is low in any specifics, a period of
warmer temperatures heading into Monday is almost certain, and some
windy conditions will yet again be possible.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Complex TAF over the next 24-30 hours with multiple factors
resulting in restrictions across the area.
Quiet start to the period still expected as mid-level clouds
increase and winds decrease. Between 04-06Z, scattered showers
begin to develop and gradually increase in coverage. Still
expect some thunderstorm activity with this elevated activity,
however, location and duration decreased confidence enough to
avoid a mention in the 00Z TAF. After several hours of showers,
MVFR CIGs become more likely ~10Z with more widespread MVFR and
IFR CIGs developing through 12-15Z. Heavier downpours will lead
to MVFR restrictions at times. Additionally, MVFR to IFR BR is
possible along the front for a couple hours as it moves slowly
northward. Visibility restrictions due to FG are more uncertain
with time and space, but with the low- level convergence along
the front, it does remain a possibility.
Surface flow is east-southeasterly through 14Z, but flow will
become more southwesterly as the front pushes north after 14Z,
affecting CVG/LUK first (~16Z), then ILN (~18Z), and DAY/CMH/LCK
(~20Z-21Z) last. LLWS will be strongest and more persistent
north of the surface boundary due to the lower winds. South of
the boundary, wind gusts between 30-35 knots will be more likely
as the strong low level winds are felt at the surface
(decreasing LLWS impacts). These conditions associated with the
boundary move north between 15Z-20Z. By 21Z, all sites should
be experiencing southerly flow and improved CIGs/VIS.
Improvement in CIGs are temporary between 20-24Z with northern
sites (DAY, CMH, LCK) least likely to see a complete break in
restrictions.
Another band of showers and perhaps a few strong wind gusts
between 25-40 knots moves through the are between 00Z-04Z
Thursday. MVFR CIGs/VIS also possible with this period of
activity.
.OUTLOOK...Wind gusts up to 45 knots are possible on Thursday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Wind Advisory from 11 AM Wednesday to 1 AM EST Thursday for
OHZ060>062-070>072-077>079.
KY...Wind Advisory from 11 AM Wednesday to 1 AM EST Thursday for
KYZ089>098.
IN...Wind Advisory from 11 AM Wednesday to 1 AM EST Thursday for
INZ050-058-059-066-073>075-080.
&&
$$
SYNOPSIS...Coniglio
NEAR TERM...Coniglio/McGinnis
SHORT TERM...Coniglio
LONG TERM...Hatzos
AVIATION...McGinnis
Area Forecast Discussion
National Weather Service Jacksonville FL
838 PM EST Tue Feb 21 2023
...New UPDATE...
.UPDATE...
Issued at 835 PM EST Tue Feb 21 2023
Current forecast was on track. A 1019 mb surface high pressure
was analyzed off the southwest coast of FL, with our local flow
remaining southwest in the low levels. Dewpoints are in the lower
60s with temps in the 70s. Latest satellite imagery shows mainly
broken coverage of high clouds, and the beginning stages of low
stratus forming over the FL Big Bend area per latest GOES fog
channel. Ceilings there are about 900 ft but visibility is still
good. With time tonight, the low ceilings will spread east to
northeast and visibilities will drop to less than 5 miles at
times after midnight, with areas of dense fog possible at or below
half a mile. The dense fog chances are greatest, generally from
the I-75 and I-10 corridors southward, with some enhanced
probabilities spread out southeastward toward Clay, Putnam,
southern St Johns and Flagler. This is where the boundary layer
winds are weakest. The wind flow may be light enough for some fog
and low clouds to push into the nearshore northeast FL coastal
waters as well. With the clouds and the south-southwest flow, low
temps will again be above normal in the upper 50s to around 60.
For the marine forecast update, not much change other than to
tweak seas a bit down for tonight, and include some patchy fog
wording for Wednesday morning.
&&
.SYNOPSIS...
Issued at 512 PM EST Tue Feb 21 2023
Late afternoon surface analysis depicts weakening high pressure
(1019 millibars) centered over southeast FL. Meanwhile, a frontal
boundary that extends from the Ozarks eastward across the
Tennessee Valley and the Carolinas was in the process of stalling.
Aloft...stout ridging centered over western Cuba continues to
direct shortwave energy eastward from the Upper Mississippi Valley
across the Great Lakes and New England. Meanwhile, cutoff
troughing spinning over Baja California and the Desert Southwest
was poised to pivot northeastward. A stratus deck that resided
south of the Interstate 10 corridor this morning has since lifted
to a cumulus and stratocumulus deck, while the southern edge of a
cirrus shield that was streaming across the southeastern states
has also invaded our skies. A tight pressure gradient continues
across our area, resulting in breezy west-southwesterly winds
area-wide that has allowed temperatures to soar into the 80s all
the way to coastal locations this afternoon. A few occasional
sprinkles have been noted this afternoon beneath a slightly
thicker stratocumulus field over the northern Suwannee Valley and
inland southeast GA. Temperatures climbed to the upper 70s and
lower 80s this afternoon region-wide despite the multi-layered
cloud cover in place across our area. Dewpoints have risen to the
upper 50s and lower 60s at most locations.
&&
.NEAR TERM...
(Tonight and Wednesday)
Issued at 512 PM EST Tue Feb 21 2023
High pressure will continue to shift eastward, merging with a
larger Atlantic ridge that resides to the south and southwest of
Bermuda by Wednesday afternoon. This evolution of the weather
pattern should allow our local pressure gradient to gradually
loosen overnight, setting the stage for a round of low stratus
ceilings and dense fog to overspread our area from southwest to
northeast overnight through the early morning hours on Wednesday
as mid and high altitude cloudiness decreases later this evening.
Low level southwesterly winds may remain elevated just enough for
less fog coverage over southeast GA, with low stratus ceilings
expected to overspread areas north of I-10 during the predawn
hours. Dense fog is are more likely for locations south of the
I-10 corridor, with stratus initially advecting northeastward from
Apalachee Bay and the FL Big Bend/Nature Coast shortly after
midnight, with fog potentially reaching the I-95 corridor in
northeast FL before sunrise. Lows will only fall to the upper 50s
and lower 60s at most locations.
Ridging aloft will continue to build northward over our region on
Wednesday, with rising heights aloft and prevailing southerly low
level flow resulting in the first of several days in a row of near
record high temperatures (see Climate Section below for details).
Fog and low stratus will erode from southeast to northwest during
the mid and late morning hours, with mostly sunny skies by early
afternoon boosting highs to the mid and upper 80s at most inland
locations. Our local pressure gradient should remain just loose
enough for the Atlantic sea breeze boundary to develop and move
onshore during the mid to late afternoon hours, which should keep
coastal highs mostly in the lower 80s.
&&
.SHORT TERM...
(Wednesday Night through Thursday Night)
Issued at 512 PM EST Tue Feb 21 2023
Stout ridging aloft will deflect the aforementioned cutoff trough
currently residing over the Desert Southwest quickly
northeastward, with this trough filling as it accelerates across
the Ozarks, Tennessee and Ohio Valleys. This trough will subtly
change our low level winds from southerly to southwesterly on
Wednesday night and Thursday. Another round of widespread stratus
and potentially dense fog will again advect across our area during
the predawn and early morning hours on Thursday, with inland areas
west of the I-95 corridor more favored for dense fog potential.
Lows on Wednesday night will remain in the lower 60s at most
locations, with highs on Thursday soaring to the upper 80s at
inland locations, with coastal highs climbing to the low and mid
80s. SREF probabilities for fog and low stratus ceilings remain
rather high for late Thursday night and Friday morning, and lows
will again only fall to the 60-65 degree range at most locations.
&&
.LONG TERM...
(Friday through Monday)
Issued at 512 PM EST Tue Feb 21 2023
Stout ridging in place over the FL peninsula on Friday will
gradually flatten and will begin retrograding slowly westward
across the Gulf of Mexico, allowing a weakening cold front to push
across southeast GA on Friday afternoon and evening. Support aloft
for this front will be minimal, with only isolated showers
possible ahead of this boundary on Friday afternoon and evening,
mainly for locations north of Waycross in southeast GA. Near record
warmth will otherwise continue on Friday, as inland highs again
soaring to the mid and upper 80s, while an afternoon sea breeze
keeps coastal highs in the lower 80s. The front will stall near
the FL/GA border by late Friday night, Lows will continue to
range from 60-65 degrees.
Strong high pressure building over New England on Friday in the
wake of this frontal boundary will quickly weaken as it slides
southeastward and off the Mid-Atlantic coast by Saturday night.
This feature will briefly wedge down the southeastern seaboard on
Saturday, with onshore winds developing, keeping coastal highs in
the 70s for locations north of St. Augustine. Inland highs on
Saturday will cool slightly to the lower 80s for inland southeast
GA, while unseasonably warm weather continues for northeast and
north central FL, where highs will again reach the mid to upper
80s. Breezy southwesterly winds will again develop on Sunday as
the front lifts back to the north as a warm front, with highs
again climbing well into the 80s area-wide on Sunday and Monday
ahead of an approaching cold front that should enter the
southeastern states towards Monday evening. Lows will continue to
run well above average, with upper 50s and lower 60s continuing
into early next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 645 PM EST Tue Feb 21 2023
VFR this evening with FEW-SCT cumulus and high clouds. Fairly
moist, southwest flow and overnight cooling will lead to some low
clouds overnight. First site to be affected should be GNV then VQQ
with the flow off the Gulf of Mexico bringing clouds to the
inland northeast FL area. Confidence in low clouds forming is
high, but details on the extent and duration is more uncertain,
with the HRRR model suggesting the IFR and potential LIFR will
oscillate to some extent early in the morning hours, though less
so at GNV. Overall, slightly lower chance of LIFR and IFR for
JAX/CRG/SSI, but still higher confidence in at least IFR CIGS at
these locations. Lowest vsby looks to be around VQQ, GNV, and SGJ.
Cig/vsby conditions should improve between 14z-16z, with VFR
clouds after 16z. Sfc winds will be light southwest tonight, and
then become south-southwest 6-12 kt on Tuesday after 15z, with
some gusts to about 20 kt Tuesday aftn. Slight backing of winds
expected for SGJ and SSI due to the aftn sea breeze.
&&
.MARINE...
Issued at 512 PM EST Tue Feb 21 2023
High pressure centered over southeast Florida will shift eastward
tonight, moving east of the Bahamas by Wednesday morning. Breezy
west southwesterly winds sustained around 15 knots this evening
will gradually diminish after midnight. Seas will subside to 2-3
feet both near shore and offshore overnight. Prevailing winds
will become southerly on Wednesday and Thursday, with an evening
wind surge expected offshore on Wednesday evening. Speeds should
reach Caution levels of 15-20 knots offshore before diminishing
after midnight, resulting in seas briefly building to 3-5 feet.
A weakening cold front will then approach our local waters on
Friday evening. This boundary will likely stall over the northeast
Florida waters by late Friday night and Saturday before lifting
northeastward as a warm front on Saturday night. Winds will
briefly become onshore on Friday night and Saturday, shifting to
southerly and then southwesterly late in the upcoming weekend
through Monday. A longer period northeasterly ocean swell will
arrive over our waters this weekend, likely resulting in seas
building to 3-5 feet both near shore and offshore. A cold front
is then expected to approach our local waters next Tuesday,
accompanied by scattered showers.
Rip Current Risk: Breezy south-southeasterly winds developing
behind an inland moving Atlantic sea breeze boundary on Wednesday
afternoon may create a low-end moderate risk at the northeast FL
beaches. Prevailing south-southwesterly winds should keep the risk
low at area beaches on Thursday and Friday.
&&
.FIRE WEATHER...
Issued at 512 PM EST Tue Feb 21 2023
Gusty west-southwesterly surface and transport winds will
gradually subside overnight, but transport speeds will remain
sustained at 5-10 mph, keeping nighttime dispersion values
slightly elevated. Surface and transport winds will then shift to
southerly after sunrise on Wednesday, with breezy conditions
developing during the mid-morning hours as low clouds and fog
dissipate. These breezy conditions will create good dispersion
values area-wide, with some marginally high values possible for
areas along the U.S. Highway 301 corridor during the afternoon
hours. The Atlantic sea breeze will develop and move onshore at
coastal locations during the afternoon, resulting in breezy
southeasterly surface winds for locations east of I-95. Breezy
southwesterly surface and transport winds are expected after
sunrise on Thursday, creating good daytime dispersion values area-
wide again. Lighter west to west-northwesterly surface and
transport winds are forecast on Friday.
&&
.HYDROLOGY...
Issued at 512 PM EST Tue Feb 21 2023
Water levels along the Alapaha River near the Statenville gauge
will crest in a minor flood on Wednesday, followed by water
levels falling below flood stage by early Friday morning.
Otherwise, minor flooding will continue through Thursday along
upper portions of the Altamaha River. Minor flooding will also
continue through the upcoming weekend along lower portions of the
Satilla River near the Atkinson gauge.
&&
.CLIMATE...
Issued at 512 PM EST Tue Feb 21 2023
Daily record high temperatures from Wednesday through
Friday at our designated climate sites:
Wed 2/22 Thurs 2/23 Fri 2/24 Sat 2/25 Sun 2/26
--------------------------------------------------------
Jacksonville 87/2019 85/1962 88/1962 87/2022 88/1962
Gainesville 88/2019 91/2019 88/1962 82/2022 88/1971
Alma, GA 84/2019 84/2018 85/2018 83/2001 82/1996
St. Simons Island 81/2011 82/2012 84/2012 80/2022 83/1972
Craig Airport 86/2019 85/2012 86/2012 85/2018 85/2018
All-time records for the month of February at our
designated climate sites:
Jacksonville 89 2/13/2020
Gainesville 91 2/23/2019
Alma, GA 87 2/21/2018
St. Simons Island 85 2/28/1962
Craig Airport 87 2/18/2021
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 60 85 62 86 / 0 0 0 0
SSI 60 80 62 81 / 0 0 0 0
JAX 59 86 61 88 / 0 0 0 0
SGJ 60 83 62 84 / 0 0 0 0
GNV 58 86 60 86 / 0 0 0 0
OCF 58 87 60 87 / 0 0 0 0
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
540 PM CST Tue Feb 21 2023
...Aviation Update...
.SYNOPSIS...
Issued at 347 PM CST Tue Feb 21 2023
H5 analysis from this morning has a very active pattern
across the CONUS and Canada. Starting in the west, closed low
pressure was located along the Baja California coast. A strong
shortwave trough was located off the coast of British Columbia.
Several embedded shortwaves extended east southeast of this feature
into Washington State, Montana, northern Wyoming and the Dakotas.
Further east, closed low pressure was located over Hudson Bay. A
shortwave trough extended from south central Ontario into the upper
Ohio Valley. At the surface, low pressure was located over
northwestern South Dakota. A warm front extended east southeast of
this feature into far northeastern Nebraska. A surface trough
extended south of this low into eastern Colorado. Along and north of
the warm front, bitter cold temperatures were noted along with
ongoing snowfall. South of the front, winds were southerly this
afternoon and 2 PM CT readings were in the middle 30s to middle 40s.
Key Messages:
- A winter storm is likely tonight through Thursday morning across
the central Sandhills, north central Nebraska and the eastern
Nebraska Panhandle.
- Bitter cold wind chills are likely Thursday morning and may
approach 40 below zero in some areas.
- Another storm may impact the area Sunday night into Monday, with
the possibility of rain/snow and strong winds.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 347 PM CST Tue Feb 21 2023
A strong arctic cold front will track through the area tonight,
clearing the forecast area by 12z Wednesday. Behind the front, mid
level warm air advection will spread from Wyoming into western
and north central Nebraska overnight into Wednesday. Light snow
will develop overnight in the northwest and spread south into the
western and central Sandhills and north central Nebraska.
Persistent light to moderate snow will continue during the day on
Wednesday as mid level warm air advection continues. Across
southwestern Nebraska, very light snow will develop later on
Wednesday. Accumulations south of a line from Grant, to North
Platte to Broken Bow will be very light Wednesday with
accumulations in these areas generally under an inch. Snowfall
rates will then increase Wednesday evening from southwestern into
central and north central Nebraska as a strong mid level
disturbance approaches the area from the southwest. Snow totals
trended down in southwestern Nebraska with the inherited forecast
this morning and this forecast cycle`s WPC QPF numbers were half
of the pvs. forecast from overnight. For LBF, the WPC numbers
were around 0.12 inches which was below the inherited forecast
(~0.20 inches) and well below the ensemble means from the GFS and
EC solns (~0.25-0.30 inches). The latest NAM12 and HRRR solns did
work in more mid level drying in association with the Wednesday
evening shortwave, which did lead to lower QPF`s for these solns.
This resulted in the lower model blend QPF with this forecast
cycle. With this package, went ahead and lowered QPF slightly from
the ensemble forecasts, but not nearly as low as the WPC
forecast. This yielded snow totals on the order of 1 to 4 inches
in the advisory area and 4 to 12 inches in the warning area.
Strong cold air advection tonight through the first half of
Wednesday, will facilitate gusty northerly winds with this system.
A secondary shot of gusty winds will arrive Wednesday evening
into Thursday as strong surface low pressure tracks along the
arctic front from southern Kansas into northwestern Missouri. The
combination of winds and bitterly cold temperatures of -5 to -15
degrees will push wind chills to -25 to -40 by Thursday morning.
Current winter headlines for snow and blowing snow run until 12z
Thursday morning. Will possibly need to extend a winter storm
warning for the northeastern zones to noon Thursday, given the
blowing snow threat. For the entire forecast area, wind chill
headlines will eventually be piggy backed on existing winter
headlines. Until timing becomes more certain and the blowing snow
threat is better handled, will hold off on any wind chill
headlines with this package.
.LONG TERM...(Thursday through Tuesday)
Issued at 347 PM CST Tue Feb 21 2023
Surface high pressure (~1040+ MB) will build into the eastern
Dakotas Thursday night. Winds will be much lighter Friday morning,
however temps may end up being colder, particularly over the
northeastern forecast area in closer proximity to the high. As for
wind chills, even with the lighter winds, they will bottom out in
the -20 to -30 degree range.
A weak mid level disturbance will ride east of the Rockies Thursday
night into Friday. Decent mid level warm air advection will
overspread the central and southern Plains Thursday night into
Friday. However, moisture will be limited in the wake of the
Wednesday weather system. The latest EC soln does generate some
light precipitation in eastern Nebraska. The latest NBM does have
some limited pops in eastern Nebraska and this appears plausible
based on the latest EC and GFS solns. Warmer temperatures will
return to the area Saturday and Sunday with highs in the 40s.
A strong upper level low will approach the central and southern
plains from the Four Corners Sunday. Low pressure will rapidly
deepen over eastern Colorado Sunday with strong southerly winds
increasing into the afternoon hours. Low level moisture advection
will increase quickly from Kansas into central and eastern Nebraska
with EC and GFS surface dew points reaching the upper 30s to mid 40s
by 00z Sunday. Further south, convection may fire across western
Kansas INVOF the dryline and surface warm front. As this convection
races northward into Nebraska, we may see rain over snow covered
areas. This could lead to some runoff issues, particularly in the
eastern half of the forecast area. We will need to monitor this
closely over the next few days, as there could be an increased
threat for flooding issues if rainfall rates and rain duration are
high enough over snow covered-frozen ground. With respect to
severe storms, the latest day 6 SPC outlook has a 15 percent
severe risk right up to the NE/KS border (south central Nebraska).
If this remains in place, feel the threat for showers embedded
thunderstorms will increase for the eastern forecast area. Right
now, will leave out the mention of thunder with this forecast
package. One aspect with this storm system which seems fairly
certain is the wind potential. Both the EC and GFS solns, develop
a sub 985mb low over Kansas, approaching 980mb as it lifts east
Sunday night. This would lead to very strong winds on the back
side of this system Sunday night into Monday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 539 PM CST Tue Feb 21 2023
MVFR/IFR/local LIFR ceilings and vsbys are likely overnight and
Wednesday. This flight concern will commence with the passage of
an arctic cold front moving steadily south through the cntl high
Plains. IFR/LIFR is expected to become widespread along and north
of highway 20 where snow is most likely to occur.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from midnight CST /11 PM MST/ tonight to 6
AM CST /5 AM MST/ Thursday for NEZ004>010-022>029-035>037-056-
057-094.
Winter Weather Advisory from midnight CST /11 PM MST/ tonight to
6 AM CST /5 AM MST/ Thursday for NEZ038-058-059-069>071.
&&
$$
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
908 PM CST Tue Feb 21 2023
.UPDATE...
Issued at 905 PM CST Tue Feb 21 2023
We will not be making any big changes to the forecast this evening
given the lack of observational evidence to steer the ship on a
different course, though it is a challenging forecast as we head
into Wednesday. It`s pretty tough to ignore some of the earlier
guidance from our freezing rain accumulation models putting out
some significant ice accumulations coupled with a decent winds,
and also a signal in some recent CAM runs of even some icing
potential into the Chicago metro area with the first precipitation
surge in the morning.
But looking at the big picture, temperatures have been holding
steady this evening across the area even as dewpoints rise.
Forecast soundings depict a fairly warm layer aloft will be
advecting in later tonight and tomorrow. Meanwhile, the low level
cold layer does not appear to be deep enough to support too much
in the way of sleet. Without a significant surge of cold air, we
will need some wet-bulbing to bring temperatures down over the
metro area. The debate is still on as to how much precipitation
will be occurring into the colder air mass in the morning hours,
latest RAP runs and 0z NAM really not that aggressive with the
northern extent of heavier precipitation.
The heavier rates will becoming in as the warm nose surges farther
northward. Our northern tier of counties remain in a precarious
position, but at this distance confidence in more impactful ice
accumulations is not high enough to steer towards a warning until
our midnight shift gets a chance to watch the evolving
observational trends and new 0z guidance.
KMD
&&
.SHORT TERM...
Issued at 315 PM CST Tue Feb 21 2023
Through Wednesday night...
Key Forecast Messages and Concerns:
* Wintry Mix With Accumulating Ice and Sleet on Wednesday:
Winter Weather Advisory issued for areas north of I-88 6 AM
Wednesday-6 AM Thursday, with exception of DuPage and northern
Cook where confidence is lower in any ice accumulations. Greatest
concern for state line counties where ice accumulations of greater
than 1/4 inch are distinctly possible and we do have some
localized accums up near 0.3".
There are competing factors tomorrow and tomorrow night regarding
surface temperatures of 32F or lower being realized, accretion
efficiency during the highest precip rates Wednesday afternoon,
and the mild antecedent conditions plausibly supporting a scenario
in which ice accums and impacts are lower. However, on the other
hand, can`t ignore the signal from the 12z and new 18z operational
models, plus the 12z HREF mean. The overall trend today was for
near or below freezing temps to have a farther south footprint.
Contemplated going to an Ice Storm Warning for the WI state line
counties, but given the concerns about less ice and lower impacts,
opted for advisory issuance.
The earlier precipitation onset Wednesday morning is now more
likely to overlap with temps being near or a bit below freezing
near and north of I-88, again with higher confidence well inland
of the lake. This was part of the reasoning for including Ogle,
DeKalb, and Kane Counties in the WWA. It`s quite possible impacts
are limited Wednesday morning and then temps warm above freezing,
but admittedly confidence is low in the exact 2m temps. Then on
Wednesday evening when precip rates diminish, the winds will shift
to more northeast or north-northeast from east-northeast during
the day. This could allow for some colder air to bleed south and
renewed ice accums down closer to I-88 corridor if plain rain is
observed Wednesday afternoon.
Given the warm antecedent conditions, any road impacts may be
relegated to elevated surfaces until Wednesday evening when
accretion rates may improve. For the state line counties, the
threat for accums up to 1/4" or a bit more does introduce a higher
threat for tree damage, ice accums on powerlines, and power
outages, also taking into account the northeasterly winds gusting
up to 35 mph. Finally, yet another potential "fly in the
ointment" is accumulating sleet, owing to likely embedded
convective elements, plus low level cold wedging (with model
variance on magnitude of this). Should sleet overperform, there is
a threat for accums nearing 1/2" closer to the WI state line.
Given all of the counteracting points of uncertainty tomorrow,
despite plausible threat for more widespread ice accums greater
than 1/4" along WI state line, opted with this issuance for the
WWA and will let midnight shift consider whether an upgrade to Ice
Storm Warning is warranted.
* Heavy Rainfall and Embedded Thunderstorm Threat on Wednesday:
The 350-400% of normal PWAT plume potentially upwards of 1.3" (at
or above Feb max for ILX) will surge northward on Wednesday
amidst strong large scale ascent from upper jet dynamics and a
stout positively tilted mid-level short-wave and speed max. This
will be juxtaposed with a potent low-mid level baroclinic zone
draped across the region. Finally, the anomalous warmth
associated with the moist plume can be expected to steepen lapse
rates enough for isolated to scattered embedded thunderstorms mid
day Wednesday through early evening, particularly near and south
of I-88/290.
Due to the above factors, rainfall, heavy at times, is expected
on Wednesday afternoon across most of northeast Illinois and
northwest Indiana. Local areas may receive rainfall heavy enough
to cause river rises, widespread ponding of water, and localized
flooding. 6-hour rainfall amounts of 1 to 1.5" are forecast in the
heaviest swath from noon to 6pm on Wednesday. While a slight
southward shift was noted in the 12z guidance and ensemble means,
the threat for very heavy rainfall does extend into the southeast
1/2 or so of the Chicago metro and points south and southeast.
The 12z HREF probability matched mean indicates threat for a
localized corridor of 2-3" amounts, though confidence is lower end
in occurrence and the exact location of this localized corridor of
heavy rain. Latest trends suggest relative threat zone for this
corridor of higher amounts is near and southeast of I-55 down to
the US-24 corridor (and we do have isolated spots of just above 2"
event total QPF in the gridded forecast).
Soil moisture ranges from near average in east central Illinois to
above average in northern Illinois. Most area soils have no
remaining frost depth except for the headwaters of the Fox and Rock
rivers in southern Wisconsin. All snow cover has melted due to
recent mild temperatures. The lack of snow cover and frozen soils
may somewhat reduce the risk of more impactful flooding, but this
may be balanced out by the expected heavy rainfall rates, elevated
soil moisture, and lack of evapotranspiration. The current
forecast of 1 to 2 inches of rainfall would likely cause several
area rivers, including the Little Calumet, Kankakee, Iroquois,
Fox, and Illinois, to near or exceed bankfull levels.
With the off the charts moisture parameters, but key points of
uncertainty (exact location of heaviest rainfall; shorter duration
of heavy rates; possibility of true warm sector convection
robbing some of the moisture transport; and lack of river ice and
frozen grounds), opted to re-issue the ESF focused south of I-88.
May need to consider a targeted Flood Watch if confidence
increases in the 2-3" rainfall corridor through Wednesday
afternoon, which would increase the chance of more than minor
flooding/road ponding type impacts, as 6-hour flash flood guidance
is around 2".
* Threat for localized thunderstorm wind damage Wednesday in parts
of central Illinois into central Indiana:
The warm sector south of the sharpening warm front east of
developing low pressure on Wednesday will be characterized by
temperatures of 55-60F and dew points into the 50s. HREF CAM
guidance depicted a scenario in which small convective segments
aided by gravity wave propagation may yield localized corridors of
damaging winds. Confidence is low in how far north this threat
will extend, with south of US-24 currently the area of greater
concern. SPC did expand the day 2 "marginal" (level 1 of 5) risk
to include parts of central IL into IN. Officially this clips
southern Ford County. This will certainly be something to monitor,
plus low CAPE, high shear cold season set-ups also bare close
monitoring for brief fast-moving tornadoes.
Castro
&&
.LONG TERM...
Issued at 253 PM CST Tue Feb 21 2023
Thursday through Tuesday...
By Thursday morning, the storm will have just about cleared the
area. A secondary low pushing across the CWA is expected to have
some stratiform precip riding its northern flank, some of which may
fall on the northern part of the area through the morning. With very
shallow saturation, any precip that does fall should be very light.
Thermal profiles from forecast soundings would suggest primarily
rain, though some snow may get mixed in there if we can saturate
deep enough to introduce some cloud ice.
Otherwise, Thursday will likely be dry across most of the area.
Once that center of low pressure passes off to the northeast, a
tight surface pressure gradient and a stout low level jet moving
over will drive winds up through the morning. Late morning through
early afternoon looks to be the timeframe of the strongest winds
when we could be gusting upwards of 40+ kt. The depth of the
mixing layer is in fairly good agreement, as are the steep lapse
rates through the mixed layer suggesting efficient mixing down of
winds through the channel. The strength of the LLJ is where most
of our discrepancies are rooted with guidance throwing up anywhere
from 35 to 55 kt at 925mb. There appears to be good clustering of
models around the 40 kt range. Additionally, it appears models
have been on a modest downward trend for Thursday`s winds since
yesterday`s 00Z runs. Gusts will slowly creep down through the
evening and overnight.
A high nearing the area to the northwest will drive some cooler air
in here for Thursday night and Friday. Lows early Friday morning are
forecast in the teens with morning wind chills as low as a few
degrees below zero near the IL/WI stateline to single digits across
most of the CWA. Highs on Friday look to be capped in the middle 20s
to lower 30s. Friday evening and night, a low amplitude shortwave
will interact with ample low and mid level moisture to provide a
chance for a few light snow showers. Both the GFS and Euro are
throwing up a few tenths of an inch of accumulation. Veering winds
through Friday night will result in efficient low level WAA heading
into Saturday pulling Saturday afternoon highs into the upper 30s
and 40s. This warming trend will continue through the weekend with a
ridge building aloft Sunday into Sunday night. Highs on Monday look
like upper 40s in the north to near 60 degrees in the far southern
CWA.
On Monday, behind the aforementioned ridge, a trough will be
swinging into the Midwest that looks to drop another healthy storm
system. The GFS is the most aggressive with this trough actually
resolving an upper low whereas the Euro and Canadian like the idea
of a low-amplitude, negatively-tilted trough. Nonetheless, all three
models place a speedy jet max on the trough`s leeward side whose
nose moves right across central IL and resolve a widespread rain
event for Monday. An early thunderstorm threat also exists with
guidance throwing up a couple of hundred joules of CAPE. If the Euro
and Canadian`s negative tilt plays out, resultant steep lapse rates
carry the thunderstorm chances even further. However, while there`s
surprisingly good agreement on this potential storm system, it`s
still far too early to get excited about any thunder chances.
Doom
&&
.AVIATION...
For the 00Z TAFs...
547 PM...Primary forecast concerns include...
Freezing rain Wednesday northwest IL, including RFD.
Lifr, possible vlifr, cigs/vis Wednesday/Wednesday evening.
Strong/gusty northeast winds Wednesday/Wednesday night.
Light winds to start will become easterly over the next few hours
with speeds increasing to 10-15kts tonight with gusts into the 20
kt range possible by the predawn hours. Winds will turn northeast
Wednesday morning with gusts increasing into the mid/upper 20kt
range. Winds are expected to remain northeast for the terminals
into Wednesday night, though speeds/gusts will likely slowly
diminish Wednesday evening.
Light rain is expected to spread across northern IL around/just
after daybreak Wednesday morning. There is some concern for a
brief period of freezing rain/sleet when this precip begins,
especially for ORD/DPA. Confidence is fairly low and for now have
maintained liquid rain. Rain will continue through late Wednesday
afternoon and the rain may be heavy at times, especially for MDW
and GYY. There may also be a few thunderstorms, especially south
of the terminals and confidence for thunder at MDW/GYY is too low
to include in this forecast. The rain is expected to taper off to
showers or drizzle early Wednesday evening.
At RFD, precip is expected to start as freezing rain and its
likely freezing rain will continue through much of the afternoon
with perhaps light rain or drizzle as the precipitation ends,
though light freezing rain or light freezing drizzle may continue
into Wednesday evening. There may also some sleet mixed in at
times at RFD, but confidence is also low.
Cigs will remain vfr until the precipitation arrives and then cigs
are expected to quickly lower through mvfr, then ifr with lifr and
possibly lifr cigs expected Wednesday afternoon into Wednesday
evening. cms
&&
.MARINE...Updated at 358 PM CST Tue Feb 21 2023
Hazardous east-northeast winds and associated waves will develop
tonight into Wednesday north of a developing low pressure system.
Brisk northeast winds may flirt with gales over parts of the
Illinois nearshore late Wednesday-Wednesday evening, though
confidence remained too low for watch issuance. Then on Thursday,
there`s increasing confidence in and likelihood of gale force
gusts up to 40 kt as secondary low pressure quickly lifts to the
northeast. A Gale Watch was issued for this period (in effect from
9 AM to 9 PM Thursday for the entire IL/IN nearshore), with the
highest speeds/gusts mid day Thursday through early Thursday evening.
KJB/Ogorek/Castro
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Winter Weather Advisory...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ011-ILZ012...6 AM Wednesday to 6 AM Thursday.
IN...None.
LM...Gale Watch...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...9 AM
Thursday to 9 PM Thursday.
Small Craft Advisory...LMZ740-LMZ741-LMZ742...midnight Wednesday
to 3 AM Thursday.
Small Craft Advisory...LMZ743-LMZ744-LMZ745...midnight Wednesday
to 9 PM Wednesday.
&&
$$
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Area Forecast Discussion
National Weather Service Melbourne FL
908 PM EST Tue Feb 21 2023
...New UPDATE, MARINE, AVIATION, PREVIOUS DISCUSSION...
.UPDATE...
Through tonight...What little diurnal SCU formed this afternoon
rapidly dissipated around sunset, leaving thin high clouds to
stream overhead, much like last night. With the surface and low
level ridges starting to creep northward, conditions appear a
little more favorable for fog to form over the peninsula. We`lll
likely see it initially to our west, spreading east in prevailing
west low level-flow. Inherited forecast has this trend well in
hand. made some cosmetic changes to the grids (mainly sky cover),
but nothing that would require a ZFP update.
&&
.MARINE...
Issued at 908 PM EST Tue Feb 21 2023
Tonight...West winds will slowly back to SW overnight as the
surface ridge axis lifts north toward Lake O and the adjacent
Atlantic. Speeds AOB 10kt, seas 1-2ft near shore/2-3ft offshore.
&&
.AVIATION...
(00Z TAFS)
Issued at 908 PM EST Tue Feb 21 2023
Little change to the afternoon package showing developing of fog
stratus. Some "pessimistic" adjustments toward prevailing
IFR/LIFR may become warranted later tonight, as the HRRR continues
to show, We`ll see if this is a function of its overaggressive
bias with low VSBYs, however there is better support from MOS
guidance for dense fog compared to last night.
&&
.PREV DISCUSSION...
Issued at 237 PM EST Tue Feb 21 2023
...Near Record Warmth for the Next Several Days...
Wednesday...Mid-level high pressure ridge will dominate the local
area, which will produce strong subsidence aloft, leading to dry
conditions and warm-hot afternoon temps. Highs will be near records,
mainly across the interior due to the sea breeze providing some
relief for coastal areas. Afternoon highs will be in the upper 80s
west of I-95, and mid 80s near the coast with plenty of sunshine
through the day. However, upper 80s would occur inland from the
barrier islands should the sea breeze be slower to form/push inland.
Wed Night-Tue...Very warm and dry conditions will prevail across the
area through the next several days, as mid-level ridge dominates the
weather pattern across Florida. Highs will be near record values,
mainly across the interior, as highs reach the U80s each day, and
even near the 90 degree mark on Thu. At the coast, highs will
generally range from the L-M80s as the sea breeze should form each
afternoon and provide some relief. However, U80s are not out of the
question for coastal locations (excluding the barrier islands)
should the sea breeze be slower to move inland, which could be the
case on Wed-Thu.
The NBM has backed off some on showing highs reaching the 90-degree
mark across the interior into late week and weekend, except on Thu.
MOS guidance also keeps max temps below this threshold as well, but
has also been a little too low compared to observed values the past
couple of days. However, should highs reach 90 degrees or L90s, this
will not only break daily record highs but also threaten record
highs for the month and Winter Season (see climate section below for
values).
Temperatures will remain mild, with overnight lows in the L-M60s,
potentially falling into the U50s for some areas on Sat and Sun
nights. However, no daily warm minimum temperature records look to
be reached.
&&
.MARINE...
Issued at 237 PM EST Tue Feb 21 2023
Wednesday...Generally good boating conditions. West winds will
back during the afternoon as the sea breeze develops with winds
generally 10-15kt. Seas 2-3ft.
Wed Night-Sun...High pressure over the west Atlc will allow winds to
become more southerly over the waters thru Thu, generally around 10-
15 kts, except up to 15-20 kts Wed night. Winds diminish to 5-10 kts
and become a little more variable in direction Fri before becoming
more S/SE on Sat as a weak back door front nears the offshore
waters. Seas will range from 1-3 ft, except up to 4 ft offshore Wed
night.
&&
.FIRE WEATHER...
Issued at 237 PM EST Tue Feb 21 2023
High pressure will continue to dominate the local
weather this week, which will lead to no mentionable rain chances
and warming temperatures. Near record highs will be possible this
aftn along the east coast, then focusing on the interior later in
the week. Min RH values will remain above critical levels, but the
extended heat and dryness should start to increase wildfire
potential. Dispersion values will be Very Good this aftn and Wed.
&&
.CLIMATE...
Issued at 237 PM EST Tue Feb 21 2023
Near record highs are expected over the next several days,
especially along the coast this aftn, and then focused across the
interior from Wed-Sat. Highs near the 90 degree mark are possible
across the interior from mid-week into this weekend, especially on
Thu, which could tie or potentially break record highs for the month
and even the Winter Season!
Daily Record Highs For the Next 5 Days (Through the 2/25):
21ST 22ND 23RD 24TH 25TH
LOC HI-MAX HI-MAX HI-MAX HI-MAX HI-MAX
DAB 87 1989 87 1962 87 2013 88 2012 87 2022
LEE 87 2018 89 1991 87 2019 87 2012 88 2022
SFB 87 2003 88 2003 88 2019 89 2012 89 1962
MCO 88 1989 88 2003 89 2013 90 1962 90 1962
MLB 88 1989 88 2003 90 1961 92 1962 87 2013
VRB 87 2014 89 2003 89 2008 90 2019 87 2020
FPR 89 1989 89 2003 89 1932 90 2012 87 2020
Record Highs for the Month of February and for the Winter Season
(Dec-Jan-Feb) and dates of last occurrence:
LOC FEB HI-MAX WINTER HI-MAX
DAB 89 02/01/1985 89 02/01/1985
LEE 89 02/22/1991 89 02/22/1991
SFB 89 02/24/2012 89 12/18/2016
MCO 90 02/25/1962 90 12/07/1978
MLB 92 02/24/1962 92 02/24/1962
VRB 90 02/24/2019 90 02/24/2019
FPR 90 02/24/2012 90 02/24/2012|
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 59 84 62 85 / 0 0 0 0
MCO 61 88 64 90 / 0 0 0 0
MLB 61 84 63 85 / 0 0 0 0
VRB 60 85 63 85 / 0 0 0 0
LEE 61 87 64 89 / 0 0 0 0
SFB 59 88 63 89 / 0 0 0 0
ORL 62 88 65 90 / 0 0 0 0
FPR 62 84 65 85 / 0 0 0 0
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
SHORT TERM...Cristaldi
LONG TERM....Smith
AVIATION...Cristaldi
Area Forecast Discussion
National Weather Service Pueblo CO
648 PM MST Tue Feb 21 2023
.UPDATE...
Issued at 639 PM MST Tue Feb 21 2023
Main updates this evening were to allow the High Wind Warning
across the Sangre de Cristo mountains and Red Flag Warning across
the southeast plains expire this hour. RH values will continue to
quickly improve, while winds diminish. Some guidance hinting that
the winds will remain elevated for a few more hours this evening
over the far southern Sangres, with isolated gusts potentially in
the 50 to 70 mph range. At this time, coverage and duration are
not expected to be high enough to warrant extending the High Wind
Warning.
No other big changes planned for this evening at this time. Am
concerned for fire danger returning Wednesday afternoon over the
far southern I-25 corridor and southeast plains, south of Highway
50. With deep mixing expected tomorrow, temps in the warm sector
have the potential to rise to around 60 while dewpoints fall to
the lower teens. This will support RH values in the 15 to 20
percent range, however, winds will likely be gusting up to around
65 mph during this time. So, while confidence is not high enough
to issue a Red Flag Warning at this time, will trend the forecast
towards this possibility as well as likely message the possibility
for near critical fire weather conditions.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 334 PM MST Tue Feb 21 2023
Key Messages:
1) Strong winds over the east slopes of the Sangres will persist
into early evening before diminishing
2) Heavy snow and strong winds hit the Continental Divide
overnight
3) Strong/damaging winds south of Highway 50 on Wednesday, heavy
snow and wind continue along the Divide
4) Quick burst of rain/snow showers I-25 corridor and plains Wed
afternoon as upper trough moves across.
Currently...Downslope winds howling over the lee slopes of the
Sangres this afternoon, with numerous gusts in the 80-90 mph range
west of Westcliffe. Not quite as windy elsewhere, though still
plenty of gusts in the 40-60 mph range at many locations, and Red
Flag Warning was verifying with very low humidity over the far
southeast plains. Webcams suggest snow has yet to start along the
Continental Divide, though areas of blowing snow were noted over the
higher peaks.
Tonight...Main upper trough digs into the Great Basin as 140 kt jet
streak punches eastward through AZ. Expect snow to increase quickly
along the Continental Divide overnight, especially over the eastern
San Juans, where snowfall rates of up to 3 inches per hr will be
possible by early Wed morning. Elsewhere, snow showers will reach
the Sangres by sunrise Wed, with some light snow in most interior
valleys as well. Winds will diminish overnight, and will let High
Wind Warning end this evening, as relative lull in mid level winds
moves across the region. On the plains, cold front oozes south
toward the Arkansas River by early morning, with wrn edge of very
shallow cold air likely just west of I-25 in El Paso County, while
farther south east winds may at least briefly push westward through
Canon City early Wed.
Wednesday...Wind and snow increase over the mountains, with whiteout
conditions in the San Juans where combination of very heavy snow and
strongest winds will occur. Sangres and srn San Luis Valley will
also see snow and strong winds develop in the morning, though
snowfall rates here will be less. Winds increase further around
midday as upper level jet lifts into srn CO, and expect
strongest/potentially damaging winds over the Sangres and adjacent
lower slopes through the day. On the plains, models still struggling
with position of cold front, as HRRR/NAM solutions bring deep mixing
eastward off the high terrain and shove the cold air nearly out of
srn CO by afternoon. GFS a good deal slower with mixing, though even
it has trended farther north with the boundary, lifting it to near
the Arkansas River by 00z. We`ll see big temp and wind contrast
across the boundary wherever it ends up, with howling w-sw winds to
the south, and lighter e-ne winds and clouds to the north. Do expect
a quick burst of rain and snow showers to move off the southeast
mountains and across the I-25 corridor in the afternoon as strongest
upper lift and 700 mb front whip across, and while precip may be
fairly intense, it will be moving very quickly and likely not
persist more than an hr at most locations. Have thus trended back
precip and snow amounts along I-25, and boosted wind speeds in areas
that will likely mix in the afternoon. Temps highly dependent on
boundary placement, NBM looked like a fairly good solution, so stuck
close to it.
For highlights, no changes to winter advisories/warnings for tonight
and Wed. For high wind, did add the Wet Mountains to the High Wind
Warning for Wed afternoon, as downslope wly flow develops and HRRR
suggests 60-70 kts possible
.LONG TERM...(Wednesday night through Tuesday)
Issued at 334 PM MST Tue Feb 21 2023
Key Messages:
1) Light to moderate snow is expected through much of the day
Thursday along the mountains.
2) Light pockets of snow along the mountains, mostly central and
western mountains, Friday and Saturday.
3) Another system passes over Colorado, bring increased
precipitation chances for much of southern Colorado.
4) Next week brings quieter and warmer weather to southern Colorado.
Thursday... Active weather is expected for the start of the long
term period. Synoptically, a trough is expected to be exiting the
region during the AM hours, with strong southwesterly flow
developing behind it, which both ensemble and deterministic model
guidance support, leading to greater confidence in this pattern
evolution. With synoptic support decreasing as the trough exits, any
precipitation over the plains and valleys is expected to dissipate
during the early AM hours and dry conditions to prevail the rest of
the day. With that said though, scattered to widespread pockets of
light to moderate snow are anticipated to persist along the
mountains, particularly the San Juan Mountains, through the entire
day given strong orographic forcing taking place. As for
temperatures, a cooler day is expected for much of the region. For
areas west of the I25 corridor, despite downsloping winds, cloud
cover and fresh snowfall will help to keep temperatures below
average for this time of year. Along and east of the I25 corridor is
more messy with where the cooler and warmer air will be. A cold
front is expected to be draped across the eastern plains Thursday
and there is still some uncertainty in regards to the eventual
location of this front during the day, which leads to uncertainty to
how temperatures will eventually evolve throughout the day. With
that said, current thinking is the front will take on a
northwestward to southeastward orientation across Pueblo County and
down into Baca County. Areas north of this front will be colder,
while areas south of it will have downsloping and warmer
temperatures.
Friday - Saturday... For the end of the week and start of the
weekend, a slow downtrend in active weather is expected. Largely,
flow will maintain the southwesterly component Friday, with a more
ridging pattern Saturday. This pattern will be unfavorable for
precipitation across most of southern Colorado both days, and given
that, dry conditions are expected. The exception to this will be
along the central and western mountains, where pockets of light snow
are expected, particularly Friday when orographic forcing will be
best. Looking at temperatures, a solid warming trend is expected for
much of southern Colorado. Downsloping westerly winds will bring
compressional warming each day, with Saturday being the warmest of
the two.
Sunday... The last day of the weekend brings another system to
southern Colorado. Ensemble models are in good agreement about
pushing a short wave trough across the southern Colorado region
throughout the day Sunday. This wave will increase precipitation
chances for the region, but especially along the mountains, where
orographic forcing will be taking place. Given the current time of
the wave, Sunday will still see a warmer trend, with much of the
area still expected to have downsloping westerly winds. This will
keep the southern Colorado region above average for this time of
year.
Monday - Tuesday... Finally into next week, another relatively
quieter couple of days is expected for southern Colorado. Ensemble
model guidance remains in agreement about the pattern evolution,
building a ridge over the Colorado region. Given increasing descent
with this feature, which is unfavorable for precipitation, dry
conditions are expected for southern Colorado. Despite the short
wave from Sunday, both Monday and Tuesday will remain above average
for the time of year given, you guessed it, more westerly and
downsloping winds inducing more compressional warming for much of
the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 334 PM MST Tue Feb 21 2023
At KALS, VFR overnight, then vcsh after 10-12z Wed as snow showers
begin to move off the mountains across the Valley. Snow showers will
become more widespread 17z-23z, with brief periods of IFR cigs and
vis likely under heavier precip. Could see some areas of low
visibility in blowing dust as well, especially nr portion of the
Valley in the afternoon. South winds overnight will shift to the sw
and become strong after 15z Wed, with some gusts approaching 50 kts
after 20z.
At KCOS, VFR tonight, then MVFR cigs with a chance of snow showers
after 15z Wed as a cold front drops through the area. Expect a
period of gusty sw winds until 02z, then lighter e-ne winds
overnight and Wed morning. Winds will likely become s-sw after 22z
on Wed as snow showers move through and front lifts back north
through the terminal.
At KPUB, VFR the next 24 hrs. Gusty west winds expected this
afternoon and evening, then a lighter w-sw wind overnight. E-NE
winds then forecast after 11z Wed morning behind a cold front, with
lowering VFR cigs. Low chance of rain/snow showers Wed after 18z,
then strong sw winds develop after 21z, with gusts to 40 kts
possible as front lifts back north.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 AM MST Thursday for COZ058-059-
061>063-072>075.
Winter Storm Warning until 5 AM MST Thursday for COZ060-066.
Blizzard Warning until 5 AM MST Thursday for COZ067-068.
High Wind Warning from noon to 7 PM MST Wednesday for COZ069>075-
078>080-087-088-094-099.
Winter Weather Advisory from 8 AM to 8 PM MST Wednesday for
COZ070-071.
Winter Weather Advisory from 11 AM to 8 PM MST Wednesday for
COZ084.
&&
$$
UPDATE...RODRIGUEZ
SHORT TERM...PETERSEN
LONG TERM...SIMCOE
AVIATION...PETERSEN