Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/24/24
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1010 PM EDT Sat Mar 23 2024
.SYNOPSIS...
Low pressure will move towards Cape Cod early tonight
and then move quickly northeast towards the Canadian Maritimes by
Sunday morning. The snow and mixed precipitation will end tonight
with cold and chilly conditions. High pressure will build in from
southeast Canada to close the weekend with sunshine and below normal
temperatures, but dry conditions will continue into Tuesday with
moderating temperatures back to normal late March readings.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
All Winter Storm Warning/Winter Weather Advisories cancelled...
Flood Watch cancelled for Dutchess and Litchfield Counties...
UPDATE...As of 1010 PM EDT, steady precipitation has ended,
although some scattered flurries will continue through midnight
for areas near and east of the Hudson River, and perhaps until
daybreak for some of the highest terrain areas east of the
Hudson River.
Otherwise, brisk winds will continue overnight across the mid
Hudson Valley, Litchfield County and Berkshires, where some
gusts of up to 35 mph will remain possible.
Clouds are hanging tough, so have delayed clearing trend until
well after midnight.
Will also issue SPS highlighting potential for additional
slippery travel conditions overnight in areas where rain fell
and temperatures drop well below freezing.
UPDATE...As of 745 PM EDT, back edge of steady precipitation now
just east of the Hudson River, although some lingering lighter
snow showers/flurries continues across portions of the Capital
Region and Lake George/Saratoga region. Precipitation is
changing to heavy snow across southern VT and the Berkshires,
where some snowfall rates of 1-2 inches/hour may occur for the
next 1-2 hours.
Farther west, spotty light snow showers/flurries will linger for
a few more hours across portions of the Capital Region and Lake
George Saratoga region before ending.
Lingering rain showers may end as some flurries/light snow
showers across portions of Litchfield County.
Temperatures will drop below freezing all areas, so expect any
lingering standing water to freeze up overnight, leading to
locally slippery travel conditions. Will issue an SPS to address
this hazard overnight.
[PREVIOUS 405 PM EDT]...As of 405 pm EDT...Early Spring storm
system continues to bring heavy snow to the w-central Mohawk
Vally, southern Adirondacks, Lake George Saratoga Region,
northern reaches of the Capital Region and southern VT. Mixed
precipitation of rain, freezing, rain and sleet continues to
transition back to snow over the northern Catskills, Schoharie
Valley, western Capital Region and will swing across the
northern-central Taconics, southern VT and the Berkshires
between 4-6 pm EDT. Low pressure continues to move northeast
from coastal NJ towards eastern Long Island and southeast New
England with a war front along southeast New England.
Favorable upper level jet dynamics combined with the front and
the merging short-wave impulses helped produce the moderate
heavy precipitation. A deep fetch of low-level moisture occurred
ahead of the wave and warm front for the bands of heavy snow and
heavy pcpn. The best 850-700 hPa FGEN is over eastern NY and
this hour according the SPC RAP Mesoanalysis. This is tucked
into the mid and upper level deformation zone to the system.
Snowfall rates up to an inch/hour (maybe slightly greater) may
occur over the eastern northern-eastern Catskills, northeast
into the Capital Region and the Saratoga Region late this pm
into early tonight. These rates will be common with the band as
the hydrometeors encounter the dendritic growth zone.
The KALB ASOS had 0.44" flat ice with 0.38" in East Greenbush
and 0.40" in Niskayuna before changing back to snow. The Capital
Region could get another inch or two of snow. The Southern
Adirondacks, Mohawk Valley, Lake George Saratoga Region and
southern VT 2 to 4 inches of additional accumulation. The
northern and central Taconics may get 1 to 3 inches, as well as
the Berkshires. Further south, some a slightly coating to less
than a half an inch for the mid Hudson Valley and NW CT. The
greatest snow totals of 12-20" will be in the southern Dacks,
Lake George Saratoga Region, southern Greens and part of the
Mohawk Valley. Rainfall rates close to a third to half an inch
an hour will continue for portions of Dutchess and Litchfield
Counties where some Flood Advisories and a few River Flood
Warnings continue (see the Hydro section below).
The snow ends quickly over western New England between 9 pm and
11 pm. It will become blustery and cold with lows falling into
the teens and lower 30s with some single digits over the
southern Dacks and southern Greens. North/northwest winds 10 to
20 mph with gusts 25-40 mph are possible
Also, northern Herkimer County was canceled from the winter
storm warnings.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
Tomorrow will feature dry but cold conditions it will be breezy
with high pressure building in from southeast Ontario and
southwest Quebec. H850 temps will be running below normal. It
will be partly to mostly sunny with the sfc anticyclone ridging
in. Max temps will run below normal by 5-10 degrees and we sided
close to the GFS/MET MOS blend with highs in the upper 20s to
mid 30s over the higher terrain and upper 30s to lower 40s in
the valleys.
High pressure builds in from southern Quebec over NY and New
England with mostly clear/clear skies and light to calm winds
for radiational cooling conditions. Lows will falling into the
teens with some lower 20s in the mid Hudson Valley, NW CT and
the southern Taconics. Lows in the single digits in parts of the
Adirondacks.
The mid level flow becomes southwesterly north of a cutoff in
the western Atlantic and a storm system approaching from the
Plains. Dry weather will persist on Monday and it will still be
on the cool side for late March with highs close to seasonal
normals with mid and upper 40s in the lower elevations and mid
30s to lower 40s over the higher terrain.
Monday night into Tuesday...Clouds increase ahead of a warm
front at night, and temps should return back above normal with
the southwest low to mid level flow increasing further ahead of
the cold front and trough approaching from the west. It looks
like any showers will hold off until the night time period.
After lows in the 20s with some upper teens over the mountains
and Lake George Region. Expect highs to rebound closer to normal
with upper 40s to lower 50s in the valleys and mid 30s to mid
40s over the higher terrain.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
At the start of the extended period, a large upper level ridge will
be moving off the eastern seaboard, while a large trough starts to
approach from the Midwest for Tuesday night into Wednesday. While
it should be dry on Tuesday evening, there will be an increasing
chance for some rain showers by later Tuesday night into Wednesday,
as a storm system approaches from the west. With enough warm air in
place, any precip will just be rain showers, as temps both aloft and
at the surface will be warm enough for plain rain. Precip looks
fairly scattered and mostly light, so impacts should be little if
any. Temps will be in the 30s on Tuesday night, but will rise to
the mid 40s to mid 50s by Wednesday.
With the upper level trough overhead, will continue to mention a
slight to low chc for showers continuing for Thursday into Friday
thanks to the cyclonic flow in place. Any additional precip looks
fairly light and spotty. Even with the trough overhead, the core of
the cool air will be north of the region, so temps still look near
or even slightly above normal, with daytime temps in the upper 40s
to low 50s for valley areas. Some drier and milder weather looks to
arrive by Saturday.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Snow shifting eastward and should be ending at KGFL by 01Z/Sun,
and KALB between 01Z-02Z/Sun. Snow will linger longer at KPSF,
heaviest through 01Z/Sun then tapering off between 02Z-03Z/Sun.
IFR/LIFR Vsbys should trend to MVFR, then VFR as the snow tapers
off. However, MVFR Cigs may linger until 04Z-06Z/Sun, especially
at KPSF.
At KPOU, some spotty light showers of rain/snow are possible
through 01Z/Sun, otherwise some MVFR Cigs may occur through
02Z/Sun.
VFR conditions are then expected later tonight through Sunday.
North to northwest winds will remain elevated at 8-12 KT
overnight, with some gusts of 20-25 KT possible, except possibly
up to 30 KT this evening at KPOU. North to northwest winds will
continue through Sunday at similar speeds, though gusts should
decrease through the day.
Outlook...
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: Moderate Operational Impact. Chance of SHRA.
Wednesday: Moderate Operational Impact. Chance of SHRA.
Wednesday Night: Moderate Operational Impact. Chance of SHRA.
Thursday: Moderate Operational Impact. Chance of SHRA.
&&
.HYDROLOGY...
Flood Warnings have been issued for Brookfield on the Still
River and Stevenson Dam on the Housatonic.
A winter storm continues bring widespread moderate to heavy
precipitation to the region through today. The highest rainfall
totals are expected the Mohawk Valley, Capital Region and the
Lake George Region south and east, where 1.5 to 3.0 inches of
precipitation will occur by nightfall.
Rainfall accumulations in excess of two inches may result in
flooding of urban, low-lying, or poor-drainage areas in the mid
Hudson Valley and northwest Connecticut. Rises on area creeks
and streams are expected, and minor flooding on rivers is
possible, especially the Housatonic River, according to the
latest NERFC River Forecasts. A Flood Watch remains in effect
until 2 AM Sunday for Litchfield and Dutchess Counties. Flows
should recede overnight into Sunday with cold temperatures
moving back in the wake of the system
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...KL/Wasula
SHORT TERM...Wasula
LONG TERM...Frugis
AVIATION...KL/Rathbun
HYDROLOGY...NAS/Wasula
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
633 PM CDT Sat Mar 23 2024
...New AVIATION...
.SHORT TERM...
(Tonight through Sunday night)
Issued at 238 PM CDT Sat Mar 23 2024
* Wind Advisory in effect for Inland Cameron, Coastal Kenedy,
Coastal Willacy, and Coastal Cameron Counties from Noon-7PM CDT
Sunday...
* Small Craft Advisory in effect for the Laguna Madre and the Gulf
Waters from 10AM CDT Sunday to 1PM CDT Monday (see Marine
Section below)...
Main headline during the short term forecast period continues to
focus on the wind Sunday through Sunday Night. An intensifying
surface pressure gradient due to an approaching cold front to our
west, a powerhouse late season winter storm system over the
Rockies/Plains, and a surface high over the Gulf of Mexico will
result in strong south-southeast winds developing over Deep South
Texas and the Rio Grande Valley Sunday afternoon. With low level
jet (H850) winds sampled between 30-40 kts, several hi-res CAM
models and global deterministic models/ensembles are suggesting
south- southeast winds of 15 to 20 mph increasing to 25 to 30 mph
with gusts as high as 45 mph on Sunday. Mixing heights per NAM3km
and RAP BUFKIT soundings are expected to increase to about 850
mb, so it`s plausible to see some of these winds translate down
into the surface on Sunday. Local topographic and climate effects
could also enhance winds particularly over Inland Cameron County,
potentially activating the "Valley Wind Machine" effect.
Outside of the winds, the weather pattern will remain dry as
influences from a nearby surface high pressure system continues.
This evening into tonight, a wind shift will take place as winds
out of the northeast will shift out of the south-southeast. A mild
night is expected tonight with overnight low temperatures ranging
between 60-67F degrees (coolest temperatures over the northern
Ranchlands, warmest over the coastal areas including South Padre
Island). On Sunday, south-southeast winds will result in a thermal
gradient from east to west across the local forecast area. Areas
west of I-35 will see high temperatures in the mid 80s to lower
90s while areas east will see highs reach the lower 80s. For areas
near/along the coast, 70s are expected. Modest moisture advection
from the south will result in increased humidity levels with
dewpoints forecast to climb into the 60s.
Breezy/gusty winds will subside Sunday night into Monday ahead of
the cold front as mixing heights decrease, the strongest LLJ wind
axis shifts east, and the pressure gradient relaxes. A warm night
is expected Sunday night with overnight low temperatures in the
mid 60s to lower 70s (coolest northwest zones, warmest southeast
and coastal zones.
&&
.LONG TERM...
(Monday through next Saturday)
Issued at 238 PM CDT Sat Mar 23 2024
The long term begins on Monday with a trough centered over the
Desert Southwest and a powerful low pressure system over the
Central Plains, from which a cold front will extend south-
southwestward into Texas. Models are in agreement that the
southern end of the front will be moisture starved as it arrives
into Deep South Texas. Leading up to the front`s arrival, strong
southerly flow over the coastal waters will continue a Small Craft
Advisory into Monday morning until 1 PM [CST] Monday afternoon
due to a tightened pressure gradient of the advancing area of low
pressure and departing high pressure (see the Marine section for
additional details). As the front passes through the CWA, winds
will veer from the south to west throughout the morning and
becoming north by the afternoon.
Monday`s maximum temperatures will be above average and mostly in
the mid-to-upper 80s across most of the CWA and lower 90s just
west of the I69 Corridor as well as across the upper, middle and
lower RGV, due to the westerly flow over the Sierra Madre creating
a downsloping effect on temperatures.
Following the front, a light northerly wind Monday night will
become northwesterly as the massive low pressure system is carried
northeastward over the Great Lakes. Seasonable temperatures will
spread over the region Tuesday night and the mid-to-upper level
trough will pass over Texas on Wednesday. Onshore flow will return
by Thursday into Friday as the high pressure moves southeastward
toward the southeast U.S. Southeast winds will enhance into the
weekend as the pressure gradient tightens again between the high
pressure to the southeast and another low pressure system emerging
from the Rockies. This will be another potential period of
hazardous marine conditions (see Marine section for further
details).
&&
.AVIATION...
(00Z TAFS)
Issued at 629 PM CDT Sat Mar 23 2024
VFR conditions with increasing high cloudiness and diminishing
winds expected overnight. Low level moisture increasing by
sunrise Sunday will allow for a ceilings just above MVFR levels or
at 3000-4000 ft AGL. Light southeast winds tonight increase
substantially Sunday with gusts from the south to southeast 25-35+
knots.
&&
.MARINE...
Issued at 238 PM CDT Sat Mar 23 2024
Today through Sunday Night...The main focus during this portion
of the marine forecast will be the winds. A surface pressure
gradient is expected to intensify along the Lower Texas Coast and
adjacent waters on Sunday. Strong south-southeast winds 20-30 kts
gusting up to 40 kts are expected to develop which will result in
a rough to very rough bay and 6-10 foot seas. A Small Craft
Advisory has been issued for the Laguna Madre and the Gulf Waters
from 10AM CDT Sunday to 1PM CDT Monday.
Monday through next Saturday...A tightened pressure gradient
ahead of an advancing dry cold front on Monday will maintain the
Small Craft Advisory till 1 PM [CST] on Monday. Following, wind
will lighten to a light northerly breeze overnight Monday through
Tuesday night and become a light east- northeasterly breeze by
Wednesday. More favorable marine conditions will continue
Thursday. However, by Friday, a moderate southeasterly breeze may
become fresh on Friday and Saturday as another pressure gradient
tightens with the high pressure and a low pressure system far to
the north-northwest. Small Craft Exercise Caution and/or Small
Craft Advisories may be needed.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE 65 82 71 89 / 0 0 0 0
HARLINGEN 62 84 69 89 / 0 0 0 0
MCALLEN 64 87 69 89 / 0 0 0 0
RIO GRANDE CITY 63 90 65 88 / 0 0 0 0
SOUTH PADRE ISLAND 67 75 70 79 / 0 0 0 0
BAYVIEW/PORT ISABEL 64 81 69 86 / 0 0 0 0
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Wind Advisory from noon to 7 PM CDT Sunday for TXZ255-351-354-
355-451-454-455.
GM...Small Craft Advisory from 10 AM Sunday to 1 PM CDT Monday for
GMZ130-132-135-150-155-170-175.
&&
$$
SHORT TERM...23-Evbuoma
LONG TERM....65-Irish
AVIATION...59-GB
Area Forecast Discussion
National Weather Service Dodge City KS
557 PM CDT Sat Mar 23 2024
.KEY MESSAGES...
- Strong weather system on Sunday will bring high wind, fire
weather, and severe storms to our area.
- Snowfall is expected on the back side of the weather system on
Monday, with minor accumulations.
- Dry, warming trend Tuesday through the end of the forecast
period.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 315 PM CDT Sat Mar 23 2024
Water vapor satellite imagery and RAP upper air analysis reveal
roughly zonal flow is in place above the central plains, with a
strong trough beginning to move over the far western CONUS.
Ahead of this feature, surface analysis indicates lee
cyclogenesis is well underway with a ~1000-mb low centered over
central WY, extending southward into eastern CO. Mass response
around this cyclone is resulting in strong southerly winds
across our area, especially the western zones closer to the
surface low. As the morning cloud cover continues to erode,
boundary layer mixing will support further strengthening of the
winds through the afternoon, becoming sustained in the 25-35 mph
range with gusts to 45 mph. Afternoon highs today will range
from the mid/upper 60s west to the mid/upper 50s east.
Overnight, southerly winds will remain elevated as the surface
low is mainained by the rapidly eastward shifting upper trough.
This along with increasing cloud cover will inhibit radiational
cooling, and Sunday morning lows will only reach the mid/upper
40s.
Daytime Sunday, the strong upper level trough will continue its
progression eastward, with a lead shortwave impulse ejecting
into the central plains by 00Z Monday. As this occurs, the
surface low over eastern CO will deepen to around 980-mb,
strengthening the winds over southwest KS into the 30-40 mph
range with gusts of 50-55 mph. There is a chance we reach High
Wind Warning criteria (sustained winds of 40+ mph and/or gusts
of 58+ mph), but HREF probability of achieving warning criteria
is 10-20% at best, so there are no plans to upgrade the current
High Wind Watch just yet.
Next weather element to discuss is fire weather potential.
Latest guidance suggests a dryline will extend southward from
the surface low, initially draped along/near the KS/CO border.
As this feature mixes east during the day Sunday to near US-283
by 00Z Monday, rapidly decreasing dewpoints west of the dryline
will support minimum relative humidity dropping in the 15-20%
range. This along with the aforementioned strong winds will
foster near critical to critical fire weather conditions, and
therefore at least some of the current Fire Weather Watch will
be upgraded to a Red Flag Warning later today.
Finally, focus shifts to the potential for severe convection
Sunday afternoon. Modest moisture advection will be ongoing
Sunday morning thanks to the strong southerly winds, although
the recent cold frontal passage has diminished available
moisture from the source region (the Gulf of Mexico where
dewpoints are currently only in the mid-50s), which will act to
limit how high dewpoints will reach ahead of the sharpening
dryline. That said, very cold mid-level temperatures and steep
lapse rates will help overcome the meager moisture and support
MLCAPE in the 750-1250 J/Kg range. Kinematically, the ejecting
upper level shortwave trough will easily provide 35-45 kts of
deep-layer shear, which is more than sufficient for organized
updrafts. Current thinking is thunderstorms will initiate along
the dryline near the US-83 corridor during the 20-21Z time
frame, increasing in coverage/intensity and reaching severe
limits with time as they quickly move northeast. Primary
hazards are hail up to 2" in diameter and wind gusts up to 70
mph. A brief, isolated tornado cannot be ruled out, but poor
moisture will be a significant limiting factor.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 315 PM CDT Sat Mar 23 2024
Thunderstorms, some potentially severe, may be ongoing across
the eastern zones at the beginning of the long term period, but
these will move northeast into central KS by 02-03Z Monday.
Focus then shifts to the wrap-around precipitation as the
strong upper level trough pushes the surface low northeast.
Latest guidance suggests precipitation will begin to impinge on
our northwest zones shortly after midnight Monday morning as a
cold front pushes southward through the central plains. Cold
advection via strong northerly winds in the wake of the front
will facilitate a switch to snow as this precipitation swings
across southwest KS daytime Monday. Thankfully, the moisture
problems that affected the severe event will also limit total
snowfall, and 13Z NBM probability of exceeding 1" of snow is
only in the 40-70% range for roughly the western half of our
area. However, strong north to northwesterly winds in the 25-35
mph range with gusts of 45-50 mph combined with the light snow
will bring impacts, and winter weather headlines are being
considered. Monday evening into the overnight period,
precipitation will diminish from west to east and northwest
winds will weaken as the surface low pulls away, and a chilly
morning will be on tap Tuesday with lows in the low teens
northwest to low 20s southeast.
Daytime Tuesday through the end of the long term period, medium
range ensembles agree the deep upper level longwave trough will
move slowly eastward, and weak upper level ridging will build
in its wake over the western and central CONUS. This synoptic
pattern change will foster a dry, warming trend with afternoon
highs increasing from the 40s/low 50s Tuesday to the low/mid 70s
by Thursday/Friday.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 556 PM CDT Sat Mar 23 2024
A broad area of strong southerly momentum will persist through
the TAF. Moisture will increase overnight, leading to
development of MVFR ceilings by early Sunday morning (after
12z). A developing dryline will be the focus for discreet
thunderstorms development Sunday afternoon, as surface winds on
average gust as high as around 45 knots.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from Sunday morning through Sunday evening for
KSZ030-031-044>046-064>066-078>081-088>090.
Red Flag Warning from noon CDT /11 AM MDT/ to 8 PM CDT /7 PM
MDT/ Sunday for KSZ061-062-074>076-084>087.
&&
$$
SHORT TERM...Springer
LONG TERM...Springer
AVIATION...Russell
Area Forecast Discussion
National Weather Service Grand Forks ND
712 PM CDT Sat Mar 23 2024
.KEY MESSAGES...
- Significant weather impacts are expected Sunday through
Tuesday, from heavy snow and gusty winds. Winter storm warning
for much of eastern North Dakota and western Minnesota.
- Still some uncertainty with the northern extent of the heavy
snow. Thus, included up to Highway 2 in the Red River Valley
in the warning more for wind/blowing snow impacts than snow
amounts.
&&
.UPDATE...
Issued at 712 PM CDT Sat Mar 23 2024
Radar returns across portions of southeastern ND are manifesting
as light snow making it to the surface. Dry air continues to
inhibit snowfall further to the north. Light accumulations have
been noted on webcam observations in Valley City and the
adjacent areas. Guidance continues to struggle with the
evolution of this system as time progresses, with most CAMs not
showing much in the way of development that matches the current
radar and observational trends. Updated forecast timing to
reflect the latest trends, primarily PoPs and WX grids.
&&
.DISCUSSION...
Issued at 255 PM CDT Sat Mar 23 2024
Upper system that will bring our active weather is still coming
onto the West Coast as the Plains should see zonal flow
transition to more southwesterly tonight. Surface low pressure
will deepen to our southwest and eventually the moist conveyer
belt should start bringing the potential for large QPF values
into the Northern Plains. However, this will be fighting against
low level winds from the northeast that are very dry, with dew
points currently around the zero mark in many locations in our
CWA. Many model soundings don`t really saturate until mid to
late morning tomorrow, and a few models like the HRRR don`t
really have much reaching the ground until afternoon. There is
still also some uncertainty where the surface low will pivot
off to the northeast, with exact track of the low making a big
difference in snow totals. With dry air to overcome and track
difference there has been a recent trend in some of the ensemble
members for lower snow totals across the north. Although the
NBM has been slow to catch up to this trend and a few models
such as the NAM are still very bullish on snow trends. Highest
probabilities for over a foot look to be over southeastern ND
and west central MN, with amounts taper off rapidly to the north
and some spots in the Devils Lake Basin may not get much at all.
As the surface low wraps up and moves into Iowa by Monday, winds
that are already pretty stout due to the tight pressure gradient
will become more favorable for high speeds due to down valley
direction as well as cold air advection. Gusts up to 45 mph are
not out of the question, particularly in portions of the
Sheyenne and southern Red River Valleys. Probabilities of
visibilities down to a half mile or less are around 50 to 60
percent, even up to portions of the Highway 2 corridor on
Monday. While snow amounts in Grand Forks area are not as
certain as Fargo and the I-94 corridor, there will be wind and
periodic visibility impacts, so went ahead and put them in the
winter storm warning. Blizzard conditions are possible, but will
watch and see when and where those headlines are needed.
By Tuesday, the northern branch upper trough digging into the
Dakotas will start to push to the low off to the east and think
snow should start to taper off, although winds will remain
rather breezy. Have headlines ending Tuesday morning from west
to east but if advisory level blowing snow and snow showers
linger Tuesday into Wednesday will cross that bridge when we
come to it.
Thursday into Saturday...Northwest flow should keep things
pretty quiet for the end of next week. However, signs of a
shortwave of some sort by Saturday, although predictability is
low and there was little time to investigate this shift.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 636 PM CDT Sat Mar 23 2024
VFR conditions prevail at all sites this evening with mid to
high level clouds working into the area from the southwest. MVFR
CIGs are possible at KFAR starting around 08Z, with low to mid
level cloud cover overspreading the region from south to north
through the remainder of the morning hours. Winter impacts could
start as early as 13Z to 14Z at KFAR; however, precipitation
will initially struggle to reach the surface due to a layer of
dry air. Once this dry layer saturates, we can expect to see
light to moderate snow through much of the afternoon, which will
become progressively heavier heading into the overnight hours.
Blowing snow could sharply reduce visibility Sunday afternoon,
with significant reductions to visibility possible later Sunday
evening.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Winter Storm Warning from 10 AM Sunday to 10 AM CDT Tuesday
for NDZ024-026>030.
Winter Storm Warning from 7 AM Sunday to 7 AM CDT Tuesday for
NDZ038-039-049-052-053.
Winter Weather Advisory from 1 PM Sunday to 10 AM CDT Tuesday
for NDZ008-016-054.
MN...Winter Storm Warning from 10 AM Sunday to 10 AM CDT Tuesday
for MNZ001-002-013>016-022-023-027-028-030-031-040.
Winter Storm Warning from 7 AM Sunday to 7 AM CDT Tuesday for
MNZ003-029.
Winter Weather Advisory from 1 PM Sunday to 10 AM CDT Tuesday
for MNZ004-005-007-008.
Winter Storm Warning from 1 PM Sunday to 1 PM CDT Tuesday for
MNZ006-009-017-024-032.
&&
$$
UPDATE...Lynch
DISCUSSION...JR
AVIATION...Lynch
Area Forecast Discussion
National Weather Service Glasgow MT
843 PM MDT Sat Mar 23 2024
.DISCUSSION...
EVENING UPDATE:
Some increase to the PoPs were made to increase snow wordage to
likely as the last round of this week`s storm begins to spread
across eastern Montana. Latest RAP mesoanalysis shows an area of
700 hPa frontogenesis advecting in from southeast Alberta toward
the Hi-Line, resulting in increasing base reflectivities in our
northern zones. At the time, the band of more moderate snow
showers is moving northeast out of southern Montana and will
impact locations near Glasgow late tonight and into the overnight
hours. Latest update to the wind/wind gust grids still suggest
thresholds below Blizzard Warning for any zone in the CWA, but
will continue to monitor gusts and visibilities south of the
Yellowstone River valley and re-evaluate throughout the night.
Buckle up, it`s gon` snow!
-Enriquez
PREVIOUS DISCUSSION:
Today through Sunday Night:
High (80 to near 100 percent) confidence remains for an impactful
winter storm with the combination of blowing snow and heavy snow
at times. Moisture is advecting in from the Pacific and Gulf of
Mexico with a broad low pressure system continuing to develop
over Colorado. Model soundings show the dendritic growth zone will
be broad to support higher snow ratios, particularly on Sunday.
Falling snow will be more prevalent south and west of Fort Peck
Lake, while blowing snow will be the main factor for the most
northeastern locations like Plentywood. In fact, up to a quarter
of the latest GFS ensemble solutions keep Plentywood dry, giving
the lowest confidence for impacts there while winds still gust up
to 40 mph. Elsewhere, a general 4-8 inches is likely to be common
with some higher amounts such as from upslope enhancement favored
along the Big Sheeps or Little Rockies.
A break in snowfall for areas east of Fort Peck Lake is expected
through the early evening, but any snow on the ground will still
lead to scattered areas of blowing snow. The main event will move
in by 9PM for all of northeast MT. The Winter Storm Warning
accordingly starts at 3pm and the snow/wind/cold combination for
newborn/expecting livestock is highlighted.
Monday through Wednesday:
While the snow will taper off and winds become calmer, the fresh
snow cover and northwest flow results in a much colder than normal
forecast. There is moderate (60%) confidence that many locations
in northeast Montana drop to near or below zero Tuesday morning.
While skies become more clear at times and inversions are expected
to develop each morning, fog concerns due to daytime melting are
limited at this time.
Thursday onward:
Slightly warmer temperatures are favored along with some unsettled
conditions lead to moderate (30-50%) confidence for light
precipitation to return by Thursday night.
Zanker/Stoinskers
&&
.AVIATION...
Update Time: 2000Z
FLIGHT CONDITIONS: IFR/MVFR, with occasional LIFR in moderate to
heavy snow.
WEATHER PATTERN: An upper level trough over the region will
continue to provide snowfall and blowing snow through this
evening, with TAF sites expected to vary between MVFR and IFR
through 03Z. After 03Z, another wave of energy within the trough
will help winds increase and allow for IFR conditions to remain
through Sunday night due to falling and drifting snow.
WINDS: East at 15 to 25 knots, with gusts to 35 knots until 00Z
Monday, then East at 10 to 16 knots.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 6 AM MDT Monday for Central and
Southeast Phillips...Central and Southern Valley...Daniels...
Dawson...Eastern Roosevelt...Garfield...McCone...Northern
Phillips...Northern Valley...Petroleum...Prairie...Richland...
Sheridan...Southwest Phillips...Western Roosevelt...Wibaux.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Goodland KS
920 PM MDT Sat Mar 23 2024
.KEY MESSAGES...
- Dangerous fire weather conditions expected on Sunday.
- Severe thunderstorms capable of producing large hail and
damaging winds and even an isolated tornado, may develop
along and east of Highway 25 Sunday afternoon.
- Very strong north winds expected in the wake of an Arctic cold
frontal passage late Sunday afternoon and evening.
- Accumulating snow and blowing snow possible Sunday night into
Monday morning.
- Dangerous travel conditions likely along the I-70 corridor in
far northwest Kansas and eastern Colorado late Sunday into
Monday.
&&
.UPDATE...
Issued at 915 PM MDT Sat Mar 23 2024
After reviewing 18z data and latest 00z (NAM), there is enough
confidence to introduce a High Wind Watch to areas generally
along and west of Highway 27 (except Dundy and Cheyenne KS) from
03z-18z Monday. The 00z MET guidance has come up in its
sustained wind speeds, approaching that of the latest and prior
runs of the MAV guidance. Presently, wind gusts up to 65 are
anticipated in the Watch area.
Additionally, the latest model visibility forecasts are honing
in on lowering visibilities to around 1/2 mile or even less
within the wraparound snow thats expected to develop within the
axis of stronger winds. Will await the 00z GFS/ECMWF models
and let the incoming shift know about the likely need for a
winter weather headline of some type.
For tonight and tomorrow, stratus is again expected to impact
the area tonight, slowly lifting east and northeast during the
day tomorrow. This will impact the high temperature forecast.
Presently, high temperatures are forecast to be in the middle
50s to upper 60s. If the stratus hangs around longer than
currently expected, these readings would be optimistic.
Still expecting some rain showers to move across the area
tonight, exiting from west to east Sunday morning. We`ll then be
in a precipitation lull until early to mid afternoon when
showers and thunderstorms increase in coverage.
&&
.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 252 PM MDT Sat Mar 23 2024
Synoptic Pattern: A complex upper level trough presently
situated along the Pacific Coast will amplify as it progresses
eastward across the Intermountain West (tonight), Rockies (Sun)
and central CONUS (Mon).
Feature of Interest 1: An upper level low situated along the
Pacific Northwest coast at 19Z will dig S-SSE through CA
(tonight-Sun) into northern Mexico (Sun night).
Feature of Interest 2: Potent shortwave energy situated
offshore central CA early this afternoon will move ashore
southern CA (tonight) and rapidly track eastward across the
Desert Southwest (Sun morning).. then lift ENE into the Central
Plains (Sun aft/eve).
Overview: A developing lee cyclone in Colorado (this afternoon)
will rapidly intensify during the day on Sunday (12-21Z).. as
Feature 2 approaches from the WSW. Guidance suggests a minimum
central pressure ~978-983 mb in vicinity of the CO-KS border by
~00Z Mon. The aforementioned cyclone is progged to track E and
NE into far northeast Kansas/far southeast Nebraska by mid-day
(18Z) Monday and Iowa by 00Z Tuesday. Strong low-level northerly
flow on the western periphery of the mid-latitude cyclone will
`tap` a Canadian Arctic airmass (over Alberta/
Saskatchewan/Manitoba).. advecting it southward through the
Dakotas into the Central Plains late Sun-Sun night.
Hazard (Fire Weather): Breezy to strong (30-40 mph) SW winds,
well above normal temperatures and dry conditions (antecedent
and otherwise) on the eastern periphery of the intensifying,
eastward advancing lee cyclone will foster dangerous fire
weather conditions across much of the area on Sunday.
Hazard (Severe Storms): Convection allowing guidance such as
the 18Z HRRR and NAM NEST suggest that scattered convection will
blossom over portions of far northwest KS ~20-21Z Sunday
afternoon. Forecast soundings /thermodynamic profiles/ suggest
that convection in the Goodland CWA will largely be high-based
in nature.. and that large hail/damaging wind are the primary
hazards.
Hazard (Strong N Winds): Strong northerly winds will develop
late Sun aft/eve as the aforementioned lee cyclone progresses
east toward central KS.. and an Arctic airmass /cold front/
surges southeastward through the area. While virtually all
guidance indicates that strong wind will be present, they
continue to vary with regard to how strong. A number of factors
will influence the MSLP-H85 height gradient over the region,
including the location/intensity/motion/track of the surface low
and the magnitude of Arctic high pressure extending into the
region from the north -- evaporative cooling associated with
upstream precipitation over Nebraska/Dakotas may augment the
airmass (make it colder, increase surface pressure), for
example. At this time, expect sustained N winds ranging from
30-45 mph and gusts in the 55-65 mph range. Blowing dust may
well accompany the frontal passage.. given the abrupt nature of
the wind shift and very dry antecedent conditions. A High Wind
Warning may ultimately be necessary Sunday evening into Monday
morning.
Hazard (Snow/Blowing Snow): Precipitation is anticipated to
develop on the W and NW periphery of the mid-latitude cyclone as
it progresses ENE-NE from Kansas into Nebraska/Iowa Sunday
night into Monday. Precip magnitude/distribution will highly
depend upon the evolution of the mid-latitude cyclone, which..
in turn.. will highly depend upon the evolution of the
amplifying upper level trough progressing eastward into the
central CONUS -- and smaller scale wave interactions therein
(interactions between Feature 1 and Feature 2, in particular).
Solutions for the Tri-State area range anywhere from no
accumulating snow to 3-6" of snow. It should be reiterated that
*any* snow will further exacerbate already difficult travel
conditions assoc/w strong northerly winds.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 1242 PM MDT Sat Mar 23 2024
At the start of the long term period, the upper low center is
situated over east-central Kansas, continuing to pull off
towards the east-northeast, resulting in a north-northwesterly
flow aloft for the area. As the backside of the trough moves
through, will see a few more waves of energy possibly allowing
for development of a few showers (generally a less than 20%
chance), Monday evening and again Tuesday evening-Wednesday
morning. At least some cloud cover will persist before the
upstream upper level ridge works its way eastward mid-week. This
will promote a warming/drying trend during the latter half of
the work week, once again increasing fire weather concerns. An
upper level shortwave and a surface low in the lee of the
Rockies are then forecast to move through the area Thursday
evening-Friday. With this, less than 15% chance for some rain
across far northern portions. Towards the end of the period,
model guidance depicts an upper level trough digging south along
the west coast, which will likely become the next system to
watch for next weekend into the following week. Temperatures
during the period continue below normal through Wednesday before
warming to above normal Thursday on.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 525 PM MDT Sat Mar 23 2024
KGLD...VFR conditions are anticipated through about 11z with
winds from the south gusting up to 35kts. From 12z-15z, sub VFR
cigs and possibly some fog are anticipated to impact the
terminal with winds continuing from the south, gusting up to
30kts. After 16z, VFR conditions are anticipated to return.
Southerly winds gusting to 30kts continue through about 21z then
slowly back to the southeast then east at speeds up to 12kts. A
few thunderstorms are possible near/over the terminal after
about 22z.
KMCK...VFR conditions are anticipated through about 10z with
winds from the east-southeast, gusting up to 30kts. Rain showers
may fall over the terminal in the 03z-08z timeframe. From
11z-18z, sub VFR cigs and possibly some fog are anticipated to
impact the terminal. Winds veer slightly to the southeast,
gusting up to 30kts. After 19z, VFR conditions are forecast to
return. Winds continue from the southeast, gusting up to 30kts,
backing to the east at the end of the taf period. A few
thunderstorms are possible near/over the terminal after about
23z.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...High Wind Watch from Sunday evening through Monday morning for
KSZ013-027-041-042.
CO...High Wind Watch from Sunday evening through Monday morning for
COZ090>092.
NE...None.
&&
$$
UPDATE...99/Trigg
SHORT TERM...BV
LONG TERM...CC
AVIATION...99
This forecast discussion will be brief due to ongoing active
weather. An operational blend of models was used with minimal
alteration.
Overall not a ton of hazardous weather potential in the
extended with high pressure dominating through mid-week, before
a front enters the region and lingers through the second half of
the week. After a chilly Sunday night... temperatures are
forecast to trend upward, to around seasonal averages through
mid-week. The second half of the week will remain seasonably
warm and humid, although with lower certainty given a front in
the vicinity and the potential for onshore flow. Periods to
monitor for impactful weather will be for a little bit of
freezing rain Tue into early Wed as cold air hangs on in the
usual CAD spots of the W. Maine mtns and foothills... and again
late in the work week where some system phasing may bring a
more significant dose of rain to the region.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Short Term...LIFR restrictions will persist through around
03-06Z Sunday before improving to VFR thereafter. Precipitation type
through tonight will range from FZRASNPL at KPWM, KCON, KAUG.
Mainly SN, possibly mixed with PL at times can be expected at
KLEB and KHIE with primarily rain at KMHT, KPSM, and KRKD. There
is a moderate chance for a brief period of FZRAPLSN at KMHT
between 22Z-03Z Sunday before precipitation ends. Snow
character will be dry to near climatological means. A period of
LLWS is likely at KPSM and KRKD as a coastal front develops and
skirts the coastline, mainly between 22Z-04Z. Northerly flow of
15-25 kts and VFR conditions then will prevail on Sunday before
winds diminish Sunday night.
Long Term...VFR expected at all sites on Mon, likely Mon night
as well with mainly light NE wind AOB 20 kts... strongest for
coastal terminals and lighter across the interior. Restrictions
in lowered CIGs are expected to develop on Tue. Confidence is
low for the middle and end of the week, however numerous periods
of restrictions are expected with low CIGs, RA, and BR/FG.
&&
.MARINE...
Short Term...Low pressure will move across the waters tonight
with northerly gales expected through early Sunday, except at
Casco Bay. Seas of 6-10 ft are expected across the outer waters
with 2-5 ft in the bays. SCA conditions will then linger over
the outer waters with northerly winds through at least Sunday
night.
Long Term...Northeast flow prevails over the waters through the
first half of the upcoming week with gusts mainly between 25-30
kts over the outer waters. Winds are expected to be slightly
stronger on Tuesday, bringing 25+ kt winds into the bays... with
a chance for Gales to develop over the very outer waters. A
front crosses around midweek which will bring winds more
westerly or northerly for the balance of the week. Seas
meanwhile are expected to remain elevated between 5 and 10 feet
with a somewhat longer period of 10-12 sec until the mid- week
front crosses and seas begins to gradually diminish.
&&
.HYDROLOGY...
Flood watch remains in place across southeasternmost zones as a
period of heavy rain later this afternoon and evening may cause
urban and small stream flooding.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Storm Warning until 6 AM EDT Sunday for MEZ007>009-
012>014-018>022-024>028-033.
Winter Weather Advisory until midnight EDT tonight for MEZ023.
NH...Winter Storm Warning until 6 AM EDT Sunday for NHZ001>006.
Winter Weather Advisory until midnight EDT tonight for NHZ012-
013.
Winter Storm Warning until 5 AM EDT Sunday for NHZ007>011-015.
MARINE...Gale Warning until noon EDT Sunday for ANZ150.
Gale Warning until noon EDT Sunday for ANZ151-152-154.
Small Craft Advisory until 11 AM EDT Sunday for ANZ153.
&&
$$
Area Forecast Discussion
National Weather Service Wichita KS
630 PM CDT Sat Mar 23 2024
.KEY MESSAGES...
- Very strong south winds with peak gusts of 50-60 mph on Sunday.
- Increasing chances for showers and thunderstorms tonight
through early Monday, with a brief transition to snow possible
over parts of central Kansas on Monday.
- Some storms late tomorrow afternoon or early evening could be
strong or severe with damaging winds and quarter sized hail
the primary threats.
&&
.DISCUSSION...
Issued at 150 PM CDT Sat Mar 23 2024
A subtle shortwave trough emerging from the Central High Plains
today may bring a few sprinkles to northern Kansas this afternoon.
As we move into the overnight hours, a strong mid/upper jet over the
Southwest will translate eastward as the upper trough begins to
build over the Central Great Basin and into the Rockies. A strong
LLJ is progged to develop downstream over the Central Plains tonight
with H85 winds of 50-70 knots progged toward morning on Sunday. The
core of the H85 jet may exceed 70 knots during the day on Sunday as
a very strong pressure gradient force is progged to develop over the
area. The ECMWF EFI has values of .8 to .9 for both wind speed and
wind gust with a SOT of 1 for wind gust strongly supporting an
unusually high wind event across the area on Sunday. RAP time/height
X-sections of wind and mixing layer height at point KRSL would
support 55+ knots or 63+ mph during the late morning hours. A high
wind warning will be issued for central and parts of south central
KS with a wind advisory downstream across the Flint Hills and
southeast Kansas. A wind advisory will follow the high wind warning
for all of the area on Sunday night.
Some elevated showers and storms will also be possible late tonight,
especially after 08Z when the LLJ noses into central KS which which
should serve to moisten the H9-H8 levels sufficiently for scattered
elevated storms as large-scale forcing for ascent increases. These
storms may be capable of small hail and some strong wind gusts. Some
elevated showers and storms may be ongoing through much of the
morning hours but by late morning/early afternoon we expect a lull.
Widespread cloud cover in the warm sector will likely dampen any
diurnal rise limiting the low level buoyancy later in the afternoon.
After a brief lull, an eastward moving dryline will become a focus
for additional development during the mid to late afternoon hours.
This dryline will likely be west of our forecast area where new
updrafts are anticipated after 2-3 PM. A slow eastward progression
of the dryline is anticipated with the arrival into our forecast
area after dark. This leads to lower confidence on more robust sfc-
based convection in our forecast area given such meager low-level
moisture progged in the warm sector on Sunday evening. This gives us
low confidence in tornado activity and lower confidence in robust
sfc-based supercells in our forecast area. But given such favorable
wind fields and cyclonically curved hodographs there remains a low
threat for supercell storms and perhaps a tornado although the
primary threats are expected to be damaging winds and large hail
with steep mid-lvl lapse rates in a high shear/low CAPE
environment.
As the lead wave ejects northeast of the area early on Monday
another pv anomaly will rotate through the base of the trough
elongating it and keeping some threat of a light wintry mix in the
forecast for much of central Kansas on Monday. Pops may need to be
expanded southward for areas mainly west of I-135 where a light
wintry mix will be possible on Monday during the day. There remains
a low probability (20-30%) for light snow accumulations across
portions of central Kansas although the bigger impacts are still
expected to remain north of the forecast area. Large-scale forcing
for subsidence should bring a rapid demise to any lingering light
snow or snow flurries by early Monday evening. Much colder air is
still progged to overspread the area in the wake of this system
with multiple nights of a hard freeze anticipated. Lows in the
teens and 20s will be common across the area early Tue and again
early Wed mornings.
Thu-Sat...rising heights/increasing thickness will support
moderating temperatures and dry weather conditions across the area
late in the week with above normal highs in the 70s returning on Fri
and Sat.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 625 PM CDT Sat Mar 23 2024
Southeast winds will increase late tonight and veer to a more
southerly direction by daybreak. Low clouds will also be in the
increase as richer low level moisture streams northward into the
region with cigs in the IFR/MVFR category. South winds will
really ramp up during the late morning/afternoon hours with
higher wind gusts of 40kts-50kts possible over central/south
central Kansas. We should see some scattered elevated
showers/embedded storms develop late tonight and move northeast
across the region. Meanwhile another round of storms will
develop over western Kansas Sunday afternoon with some of these
storms producing severe weather. Some of this activity could
spread into central Kansas during the evening hours on Sunday.
&&
.FIRE WEATHER...
Issued at 150 PM CDT Sat Mar 23 2024
Very strong southerly winds of 50-60 mph are expected on Sunday.
High relative humidity and multiple rounds of showers and storms
will limit the fire weather threat.
A very high fire danger may return on Thursday for parts of central
Kansas and much of the area on Friday, as relative humidity drops to
25-35% with above normal temperatures and breezy south winds.
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 7 AM to 7 PM CDT Sunday for KSZ032-033-
047>051-067-082-091.
Wind Advisory from 7 PM Sunday to 10 AM CDT Monday for KSZ032-
033-047>051-067-082-091.
Wind Advisory from 7 AM Sunday to 10 AM CDT Monday for KSZ052-
053-068>072-083-092>096-098>100.
&&
$$
DISCUSSION...MWM
AVIATION...CDJ
FIRE WEATHER...
Area Forecast Discussion
National Weather Service North Platte NE
1052 PM CDT Sat Mar 23 2024
.KEY MESSAGES...
- Ice accumulations from from freezing rain/sleet may range up
to two tenths of an inch across north central Nebraska
tonight into Sunday morning.
- Potential for thunderstorms Sunday afternoon and early
evening, especially across southwest and south central
Nebraska where storms may produce isolated wind damage and
large hail. Heavy downpours of rain are possible.
- A strong storm system impacts the area Sunday into Monday,
though uncertainty remains in extent of potential impacts.
Initially, precipitation falls as rain and a wintry mix,
before transitioning over to snow Sunday night. Snowfall will
be heavy at times. Additionally, strong north winds 25 to 40
mph with gusts to 60 mph Sunday night into Monday will create
widespread blowing and drifting snow, with blizzard conditions
possible and widespread travel impacts expected Sunday night
through late Monday night.
&&
.UPDATE...
Issued at 1051 PM CDT Sat Mar 23 2024
Based on the latest HRRR and current temps, went ahead and added
Custer, Thomas and Hooker counties to the current winter weather
advisory. This was for the increased threat for light freezing
rain overnight. The window for this will be tight as
temperatures should rise in these counties by mid morning
Sunday. In these areas, we could see a light glaze of ice
overnight. The advisory will run for the same time period as the
existing advisory.
&&
.SHORT TERM /THROUGH MONDAY/...
Issued at 355 PM CDT Sat Mar 23 2024
Tonight, surface low pressure will deepen across southeast Wyoming
and eastern Colorado, where a stationary front will be located. To
the east of this front, models are indicating an increase in
moisture advection, with dewpoints rising into the lower 30s across
southwest Nebraska into the panhandle during the evening. Rain
showers will develop across the western Sandhills, as well as
potential for isolated thunderstorms. The forecast environment does
not look supportive of any strong storms with MUCAPEs remaining
below 100 J/KG, though 0-6km shear will remain from 40-50kts. Gusty
winds and pea size hail may occur with the stronger storms. Likely
POPS are forecast to spread northeast across the forecast area
overnight. Rainfall amounts up to two tenths of an inch are
possible, mainly east of Highway 83. Bufkit sounding favor freezing
rain or sleet across the eastern half of north central Nebraska. Ice
accumulations up to two tenths of an inch are forecast. The Winter
Weather Advisory across north central Nebraska from 06Z until 18Z
Sunday remains in effect.
On Sunday, a large upper trough across the western U.S. will
progress eastward. A closed low is forecast to develop over eastern
CO by late afternoon with deep surface low pressure near 980mb over
southeast Colorado. A warm front will extend northeast across
southwest into central Nebraska. Meanwhile, an arctic cold front
will drop southeast during the afternoon. This will result in a
strong contrast in temperatures by late afternoon from the low 30s
in the northwest Sandhills to the low to mid 50s across the
southwest. This will support the chance for rain and thunderstorms
near and south of the warm front across southwest into central
Nebraska during the late afternoon, with rain mixing with or
changing to snow across the northwest Sandhills by late afternoon.
MUCAPEs will reach 500-1000 J/KG by late afternoon. A few strong
storms are possible until mid evening, containing large hail and
damaging winds. Heavy downpours of rain are shown by the majority of
the CAMs and various deterministic models ahead of the advancing
cold front late Sunday afternoon and evening. Local rainfall amounts
of a half to over three quarters of an inch are forecast.
As the cold front advances quickly southeast Sunday night, the
closed upper low will track from southeast Colorado into central
Nebraska overnight. Some model differences remain, as the ECMWF is
faster and further east with the low track. The latest forecast uses
the NBM. Rain and evening thunderstorms will continue ahead of the
advancing cold front Sunday night. There will likely be an hour
transition from rain to freezing rain/sleet, then snow behind the
front. This will lead to a period of freezing rain or sleet where
amounts may approach one tenth of an inch before a full transition
to snow.
The larger concern will be the winter weather impacts behind the
front. With deep surface low pressure off to our southeast,
northerly winds will quickly increase Sunday night to 25 to 40 mph
with gusts up to 60 mph possible. These strong winds will persist on
Monday, then diminish Monday evening. This will result in widespread
blowing snow Sunday evening into Monday. Due to the convection
nature of this system, snowfall rates may get heavy at times Sunday
night into Monday morning, which will likely lead to white-out and
blizzard conditions.
As for the heavy snow potential, confidence has increased that heavy
snow will occur over portions of southwest into north central
Nebraska. What remains uncertain is where the location of the
heaviest snowfall band sets up. The current forecast has the heavy
snow band extending from western Lincoln county broadening
northeastward across eastern Cherry county through Keya Paha County.
Much will depend on the speed of the low pressure system, which
seems to change run to run. If the system trends to the slower
solution, similar the the GFS then potential increases for the snow
to start further west and accumulate for a longer period. On the
other hand, if the system trends faster like the ECMWF, the snow
banding may develop further east. What remains fairly certain is
that the combination of the strong winds, along with the potential
for heavy snowfall to result in widespread hazardous travel
conditions. Widespread areas of blowing snow are expected, and white-
out to blizzard conditions are possible.
A winter storm watch remains in effect for most of western and north
central Nebraska from Sunday evening through late Monday night. This
includes Keith, Perkins and Lincoln County to the south and all
counties to the north and east. Forecast snowfall amounts in the
watch area range from 3 to 5 inches across Lincoln County in the
south, to 4 to 10 inches over a large portion of west central
into north central Nebraska.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 344 PM CDT Sat Mar 23 2024
The system should exit the area late Monday night. Winds will remain
strongest from 25 to 35 mph with gusts to 45 mph Monday evening,
diminishing overnight. This will leading to areas of blowing snow.
Patchy blowing snow possible into Tuesday.
An upper level ridge will build into the region Wednesday through
Saturday. Temperatures Tuesday will remain cold into the 20s and
30s, moderating into the 40s Wednesday, 50s to 60s Thursday and
Friday and 50 to 60 Saturday. The amounts of existing snowcover will
dictate the amount of warmup through Thursday, so confidence in the
warmup is below average.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 655 PM CDT Sat Mar 23 2024
Increasing clouds are expected over the next few hours in advance of
the next weather system. Precipitation arrives across the north
(KVTN) as freezing rain through early Sunday morning before a brief
break. Precipitation will then move into the region Sunday mid-
afternoon as rain and then transition to a rain/snow mix. For points
further south (KLBF), precipitation will arrive by late Sunday
afternoon starting off as rain and even an isolated thunderstorm.
Snow will eventually become the dominant precipitation type after
sunset (00Z Monday) and temperatures drop below freezing.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 1 PM CDT /noon MDT/ Sunday for
NEZ004>010-024>029-038-094.
Winter Storm Watch from Sunday afternoon through Monday
evening for NEZ004-094.
Winter Storm Watch from Sunday evening through late Monday
night for NEZ005>010-023>029-035>038-057>059.
&&
$$
UPDATE...Buttler
SHORT TERM...Roberg
LONG TERM...Roberg
AVIATION...Kulik
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
632 PM CDT Sat Mar 23 2024
.KEY MESSAGES...
* A potential for flurries and light snow showers overnight.
* Periods of breezy winds and rain are expected from Sunday
night into Tuesday.
* A brief cooldown of temperatures into the upper 40s to lower
50s Tuesday and Wednesday will be followed by warming
temperatures from the middle to end of next week.
&&
.DISCUSSION...
Issued at 130 PM CDT Sat Mar 23 2024
Through Sunday night:
Fair weather cumulus continue to build downstream of the lake and
float over the southeastern half or so of the CWA while the rest of
the area is nice and sunny. The late March sun is slowly chipping
away at yesterday`s snowpack up in our far north, but most of
Winnebago, Boone, and McHenry counties remain blanketed for now.
Meanwhile, the lake continues to churn up scattered light snow
showers aloft over parts of northwest Indiana. Model soundings still
show a conditionally unstable layer up to around 850-800 mb with
lapse rates through the layer near 9 K/km. Looking at area obs and
webcams though, it doesn`t look like this snow is able to punch
through the dry air off the surface and hasn`t been since late
morning.
Tonight, a large storm will begin to take shape over the
Intermountain West and turn our low level flow southerly. Low level
warm advection will ramp up and we`ll get our first sample from this
storm in the fashion of some flurries and light snow showers.
Chances for true snow showers look better in our northwest within
the stronger warm advection. Flurries look more likely farther east
and into the Chicago metro. The RAP and HRRR have been consistently
more aggressive with bringing snow showers all the way to the lake.
However, they are also far more aggressive with the low level
moisture and they heavily dampen the magnitude of a low level
hydrolapse where other models are suggesting it will be pretty
stout. Kept snow showers mostly west of the metro tonight with
flurries elsewhere. Dustings to very minor accumulations will be
possible under any snow showers.
A southerly low level jet on the lee of the developing storm will
continue to graze our western and northern CWA during the day
tomorrow and bring scattered snow chances to these parts during the
morning. As the low levels continue to warm, this will transition
into a chance for a wintry mix and then to rain for the afternoon.
More bonafide rain showers look to expand across our west late
tomorrow night as the storm makes headway across the Plains. The low
level jet will also bring highs in the 40s to near 50 tomorrow and
southeasterly winds gusting as high as 25 to 30 mph. Further details
on this storm can be found in the long term discussion below.
Doom
Monday through Saturday:
Monday into Tuesday, a seasonably strong low pressure system will
move from the Plains to the Upper Mississippi River Valley leading
to periods of inclement weather across the northern United States.
In our local area, the main impacts from the system will be periods
of breezy winds and waves of showers and a few thunderstorms.
On Monday, the tightening low-level pressure gradient will support
increasingly breezy southwest winds. Even modest mixing into stout
low-level flow will afford efficient downward transport of 35 to 45
mph southwesterly wind gusts, especially east of I-39 and south of I-
80 where cloud cover is currently favored to be thinnest. Showers
and thunderstorms may develop as early as Monday morning west of I-
39 within a region of persistent WAA (especially if any mesoscale
gravity waves propagate into the region). As a southeastward-
drifting cold front starts moving through our area, showers and a
few thunderstorms will expand in coverage and parade through our
area into early Tuesday morning. The slow motion of the front and
replenishing source of low-level moisture via southwesterly winds
ahead of the front should support a somewhat wide swath of soaking
rainfall across much of our area. Ensemble mean QPF ranges from 0.75
to 1.25", within which embedded streaks of higher amounts may
materialize where thunderstorms develop. Contingency forecasts using
the 95th percentile rainfall from the GEFS applied to areal river
forecast points suggest a few river stages may approach or exceed
bankfull early next week where eventual rainfall amounts are highest
(particularly in northeastern Illinois).
On Tuesday, increasing mixing heights into the strong low-level wind
field via CAA will support gusty northwesterly winds. Eyeballing
BUFKIT thermal and wind profiles suggests gusts may again return to
the 35 to 45 mph range, particularly during the afternoon. Depending
on the eventual structure and speed of the low, we`ll have to keep
an eye on the threat for a few thunderstorms to redevelop along the
cold front in northwestern Indiana during the afternoon hours.
In the wake of the storm system, Wednesday will be relatively cool
with highs in the upper 40s. Ensemble guidance strongly supports a
quick rebound in temperatures into the lower 60s (at least away from
Lake Michigan) by the end of next week as a ridge builds into the
central United States. The next signal for precipitation appears to
favor next weekend as a low-amplitude trough rides through the crest
of the developing ridge into the Great Lakes.
Borchardt
&&
.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 632 PM CDT Sat Mar 23 2024
Key Aviation Impacts for the current TAF period:
- Chance for light snow around KRFD after midnight. Some
flurries are possible around Chicago terminals, but impacts
are not expected
- Southeast wind gusts 20 to 25 knots are expected on Sunday.
As surface winds diminish, there is a chance for the risk of
LLWS at terminals after 00Z
Winds are gradually diminishing and consistently out of the
east. Skies are VFR and expected to remain so through the TAF
period; however, cloud cover above 5000 feet will increase
through the night from the next system moving toward Illinois.
MVFR level cigs are not expected, but maintained a SCT group
between 3000-4000 feet for the risk of mid level clouds moving
in as the front passes. Models are suggesting dry enough
conditions to keep -SN out of Chicago terminals, although some
non-impactful flurries remain possible but mention was left out
of the TAF. The best chance for snow to make it to the surface
is around KRFD, so the PROB30 was converted to a TEMPO for the
expected timeframe for snow and reduced cigs/vis.
On Sunday morning, winds out of the southeast will increase
providing a period of stronger gusts between 20 to 25 knots from
the late morning and through the afternoon. As the sun sets
Sunday night, a low level jet will slowly increase as surface
gusts diminish. There is still some uncertainty on exact timing
and magnitude of when the jet strengthens, but confidence was
enough to introduce the risk for LLWS into the TAFs for the
Chicago terminals.
DK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 10 PM CDT this evening for the IL
and IN nearshore waters.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Melbourne FL
1020 PM EDT Sat Mar 23 2024
...New UPDATE, MARINE, AVIATION...
.UPDATE...
Issued at 1015 PM EDT Sat Mar 23 2024
Mostly dry conditions prevailed over the southern half of the area
this evening, while showers and stronger lightning storms
impacted locations across the north, especially along the Volusia
and Brevard coast. Lightning activity has since pushed offshore,
leaving behind some light to moderate showers that are drifting
southward.
A cold front is forecast to gradually push through overnight, and
winds will veer north-northwesterly behind the frontal passage,
becoming gustier toward daybreak Sunday. RAP analysis is already
indicating a tightening of MSLP isobars from the eastern Gulf to
the FL peninsula, so it will be just a matter of time before winds
start to pick up. PoPs were updated to reflect radar and hi-res
guidance trends, along with hourly temperatures that cooled
quicker this evening across the north. Lows overnight are still
expected to fall into the upper 50s and low 60s areawide.
&&
.MARINE...
Issued at 1015 PM EDT Sat Mar 23 2024
Tonight...Boating conditions are forecast to deteriorate quickly
tonight as a cold front moves across the local waters. A Small
Craft Advisory begins at 11 PM and will continue into Sunday.
North-northwest winds increase 20-25 kt with occasional gusts
approaching gale force (north of Cape Canaveral) toward daybreak.
Seas build in response, reaching 7-9 ft offshore, generally north
of Sebastian Inlet. Nearshore seas will reach 5-7 ft by sunrise
Sunday, mainly from the Cape northward. Lightning storms will
gradually end over the far offshore waters overnight, but isolated
to scattered rain showers will continue into Sunday.
&&
.AVIATION...
(00Z TAFS)
Issued at 1015 PM EDT Sat Mar 23 2024
VFR continue tonight. Light SHRA are moving south, along with a
cold front. NW winds gradually increase after 03z-06z, gusting as
high as 20 to 25 kt thru 15z Sun. Gusty winds may approach 30 kt
during the day Sun., especially at the coast. Sct-bkn low-mid
level clouds are expected Sun. with VFR conds prevailing. Light
showers may brush coastal terminals but confidence remains too low
for inclusion in the TAF.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 60 70 58 75 / 50 0 0 0
MCO 61 73 59 78 / 10 0 0 0
MLB 62 73 62 76 / 10 20 0 0
VRB 60 75 62 78 / 10 20 0 0
LEE 59 73 55 79 / 20 0 0 0
SFB 60 72 57 78 / 30 0 0 0
ORL 61 73 58 78 / 10 0 0 0
FPR 59 75 62 77 / 10 10 0 0
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory until 11 PM EDT Monday for AMZ550-552-555-
570-572-575.
&&
$$
UPDATE.......Schaper
LONG TERM....Fehling
AVIATION.....Schaper
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
805 PM CDT Sat Mar 23 2024
.KEY MESSAGES...
- Heavy snow and major travel impacts look likely area-wide
Sunday afternoon through Monday morning. Snowfall rates of
1-2"/hour are possible Sunday afternoon and evening,
especially across southern Minnesota and western Wisconsin.
- Warm air is expected to advance faster and farther north into
the area. This has resulted in some reductions to the snowfall
forecast along and south of a line from Eau Claire, to the
Twin Cities, and Granite Falls.
- Snow continues through Monday night for western and north-
central Minnesota. Light snow lingers over the entire area
through Tuesday. Gusty northwest winds late Monday night
through Tuesday will likely lead to travel impacts from
drifting snow across western Minnesota.
- Gradual melt expected next week as highs slowly warm back
toward 50 by the end of the week.
&&
.DISCUSSION...
Issued at 235 PM CDT Sat Mar 23 2024
We`ve seen increasing clouds in western MN, with some light
radar returns as well. This is with some WAA/fgen around h7.
This band of forcing/moisture will continue to slowly move ENE
through the night, reaching along and northeast of the I-94
corridor by Sunday morning. This precip will be struggling to
reach the ground with a very dry sub-cloud layer in place and
this is simply a precursor to the main show to come. That main
show is associated with the jet streak you can see on water
vapor imagery moving across AZ/NM, with an attendant surface low
developing over eastern CO.
That CO low will be tracking northeast across the Plains on
Sunday, going across the southeast corner of MN Monday night,
reaching central Lake Superior Tuesday afternoon. There will be
a strong push of moisture and warm air from the south with this
low and the biggest uncertainty continues to reside around how
quickly the rain/snow line will move north across southern MN
Sunday night and where it will stall out across west central
and central MN during the day on Monday. The trend with the
forecast today was to be a bit more aggressive with bringing the
transition to rain into the region Sunday night, with the
rain/snow line getting a bit farther north and west on Monday
than the previous forecast. The greatest uncertainty in the
snowfall forecast sits from Eau Claire, to the Twin Cities, and
Granite Falls. The big question is how much QPF do we dump into
the snow bin before we transition to rain. The difference
between the 12z NAM and HRRR highlights this issue well. The
HRRR dropped 1.2" of QPF into the snow bin for MSP before
transitioning to rain around 8z Tuesday. The NAM makes the
switch to rain about 6 hours earlier and only has 0.5" of QPF
falling as snow. This would have some rather significant impacts
on the total snow seen in the Twin Cities. An early transition
like the NAM would struggle to see us get 5" of snow, while a
later transition could see totals make a run for 10+". On Monday,
we`ll see a trowal wrap into the region, which will push the
heavier precip amounts out into western MN, while a dry slot
aloft helps cut down on precip rates on Monday for eastern MN
and western WI. As the low shifts off to the northeast Monday
night, we`ll see the precip and cold air (so transition back to
snow) push east out of western MN and across central MN.
For headlines, we have replaced any watches with
warnings/advisories. We continue to run a warning out in west
central into central MN through Monday night. The main
uncertainty with the Warning was how far south to take in MN
given the rain/snow line that will be actively moving north
across southern MN Sunday night. With the potential for 2" per
hour rates right out ahead of the rain/snow line, we erred a bit
on the side of caution with the southern extent of the warning,
bringing it down to Goodhue over to Brown county. For our
southern 2 tiers of counties (Mankato/I-90 corridor), we went
with an Advisory. The other tough task was to try and hone in on
timing for the warning, trying to tie it to the transition from
snow back to rain. We have three rows of end times for the
warning at 9z Monday for south of the Twin Cities, an end time
of 12z Monday for the Twin Cities and Eau Claire, with a 15z
expiration for north of the Twin Cities and Eau Claire.
After this system, we`ll see a chilly day on Wednesday as a
surface ridge moves in. That and all the fresh snow will help
hold highs in the 20s/low 30s for Wednesday, but as the high
moves east, we`ll see warmer air move in, with highs in the
40s/50s expected to end the week. For precip, models continue to
show a good deal of run-to-run shifts with the potential for
precip and the end of the week into next weekend, but right now,
there`s be a trend to pushing any precip chances out into next
week. At this point it should be warm enough that if it does
precip, the main type should be rain.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 734 PM CDT Sat Mar 23 2024
-SN is already being reported at TAF sites in western MN so the
event is officially underway. Though intermittent at this point
with where the snowfall will be reported, more widespread
snowfall will develop through this evening into the early
morning hours for all sites, with both ceilings and
visibilities dropping to MVFR range tonight followed by IFR
conditions likely during the day Sunday. During the day Sunday
will have the heaviest rates and worst flight conditions,
including down to 1/2sm, also in conjunction with strong SE
winds. Sustained speeds will increase to 15-20kts with gusts
25-30kts (potentially even higher at times). So, the theme here
is that a highly impactful system is now underway and will make
for highly degraded flight conditions across all TAF sites.
KMSP...Have made few changes from inherited TAF, running with
-SN commencing at about 05z. The ob is reporting VIRGA and the
KMPX radar is showing snow in the upper levels around MSP but
not yet at the surface, so this indicates that there is some
lower level dry air that needs to be overcome before snow is
realized at the surface. It likely will not take long so it is
possible some snow showers may come in an hour or so earlier
than 05z. The more sustained snowfall is expected to start
overnight into Sunday morning, with the heaviest rates coming
late morning through the afternoon hours. Rates of near 1 in/hr
are possible Sunday afternoon of heavy wet snow. The heavy snow
will continue through Sunday evening then a rain/snow mix looks
to develop Sunday night. Even at that point, conditions will
likely remain in IFR category.
/OUTLOOK FOR KMSP/
MON...IFR Likely. Chance LIFR/+SN early. RA/SN mix likely
afternoon- evening. Wind ENE 15G25-30kts.
TUE...IFR/MVFR likely. Chance RA/SN mix thru afternoon. Wind NW
15G25-30kts.
WED...VFR, w/ MVFR possible. Chance -SHSN. Wind W 15G25kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Winter Storm Warning from 10 AM Sunday to 7 AM CDT Tuesday for
Benton-Chippewa-Douglas-Kanabec-Kandiyohi-Lac Qui Parle-
Mille Lacs-Morrison-Pope-Stearns-Stevens-Swift-Todd-
Yellow Medicine.
Winter Storm Warning from 10 AM Sunday to 7 AM CDT Monday for
Chisago-Isanti-Sherburne.
Winter Storm Warning from 10 AM Sunday to 4 AM CDT Monday for
Anoka-Carver-Dakota-Hennepin-Meeker-Ramsey-Scott-
Washington-Wright.
Winter Storm Warning from 10 AM to 10 PM CDT Sunday for Brown-
Goodhue-Le Sueur-McLeod-Nicollet-Redwood-Renville-Rice-
Sibley.
Winter Weather Advisory from 10 AM to 7 PM CDT Sunday for Blue
Earth-Faribault-Freeborn-Martin-Steele-Waseca-Watonwan.
WI...Winter Storm Warning from 10 AM Sunday to 7 AM CDT Monday for
Barron-Chippewa-Dunn-Polk-Rusk-St. Croix.
Winter Storm Warning from 10 AM to 10 PM CDT Sunday for Eau
Claire-Pepin-Pierce.
&&
$$
DISCUSSION...MPG
AVIATION...JPC
Area Forecast Discussion
National Weather Service Marquette MI
819 PM EDT Sat Mar 23 2024
.KEY MESSAGES...
- A brief period of quiet and dry weather continues through tonight.
- Late season winter storm lifting out of Colorado through the
early part of the coming week will bring accumulating snow
late Sunday into Monday morning.
- Heaviest snow accumulations will be Sunday night, resulting in
hazardous travel into early Monday before a transition to rain
during the day Monday.
- High end east to southeasterly gales are expected across Lake
Superior Monday into Monday night.
- Westerly lake effect snow, mainly for the Copper Country
Wednesday into Thursday.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 217 PM EDT Sat Mar 23 2024
Water vapor imagery and RAP analysis show mid-level troughing over
central and eastern Canada, anchored by a deep mid-level low
centered on the Hudson Bay shore of Ontario. At the surface,
sprawling surface high pressure centered over Manitoba is building
into the Great Lakes.
In spite of very dry midlevel air, lake-induced stratocumulus is
apparent on satellite courtesy of chilly NW flow over Superior
(850mb temperatures hovering around -18 to -20C). The Day Cloud Type
RGB shows higher cloud tops across the eastern UP, with a longer
fetch off of Superior. There, weak, cellular, lake-induced snow
showers are apparent on radar with some drops in visibility noted in
ASOS sites as well. Elsewhere, lower-topped, patchy strato-cu across
much of the western and central UP, becoming somewhat more organized
over Marquette county along the lake breeze. Precipitation has yet
to develop there, but will not rule out some light snow showers as
cloud tops do appear to be climbing. Totals across northern
Marquette county and across the eastern UP should only peak at
around a quarter to half an inch, with just isolated flurries and
snow showers elsewhere. Otherwise, temperatures are climbing through
hte 20s this afternoon, and should peak in the upper 20s and lower
30s across most of the area.
Any lingering flurries should end by sunset. The surface high
continues drifting eastward overnight, resulting in a wind shift
over mainly to the SE. With 850mb temps across northern Lake MI
around -12C, some flurries may develop into portions of central
Upper MI late tonight. Otherwise, expect midlevel cloud cover to
increase from the south courtesy of warm air advection ahead of the
much-advertised deepening low pressure system over the Plains.
Precipitation should hold off until after 12Z Sunday. Increasing
clouds and a shift over to southerly flow likely means that
overnight lows will occur fairly early in the night; expect most of
the area to fall into the teens, with some cooler pockets possibly
bottoming out in the single digits by 06Z. After that, temperatures
hold steady and perhaps even increase towards morning.
&&
.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 357 PM EDT Sat Mar 23 2024
The long-term forecast is mostly dominated by the presence of a low
pressure lifting through the Plains into Canada. As this low
continues its northward journey, the warm front moves through late
Sunday through Monday. This warm front initially brings snowfall
across the area Sunday night before transitioning to all rain Monday
(there could be a wintry mix of sleet/freezing rain over the
interior west mid-Monday). The rain continues into Tuesday before
the cold front of the parent low transitions what`s left of the
precipitation back over to snow late Tuesday. Afterwards, we could
see some lake-effect snow over the west snow belts, particularly the
Keweenaw, Wednesday into Thursday. Some more normal to above normal
temperatures and additional synoptic precipitation could return late
this upcoming week.
A surface high pressure ridge around 1030mb moving into Quebec
Sunday in conjunction with the deepening low off the Colorado
Rockies looks to increase southerly flow across the area, eventually
becoming southeasterly late in the afternoon. While antecedent dry
air near the surface should keep any snowfall aloft from hitting the
ground, it`s not likely but still possible (20 to 30% chance) that
we see some light snow develop over the higher elevations over the
western U.P. and the south/southeasterly flow upslope areas Sunday
morning into early Sunday afternoon. However, as the warm front of
the parent low (in Colorado at this time) begins to lift towards
Upper Michigan late Sunday, expect to see snow chances increase from
our southwest to northeast throughout the afternoon to evening
hours.
We expect most of the winter weather/snowfall impacts to be felt
across the area Sunday night when the brunt of the warm front makes
its way across Upper Michigan. Some impressive frontogenesis and
isentropic lift will allow moderate to heavy snowfall rates to
develop over Upper Michigan throughout the overnight hours; the HREF
hourly mean snowfall rates generally range from half to 1 inch per
hour rates, with the stronger snowfall rates being seen over the
western U.P. While the atmospheric thermal profile would initially
suggest high SLRs, with model soundings showing turbulence
developing within the warm front (causing snow crystal fracturing)
and warming temperatures within the profile, I`ve slightly lowered
SLRs even further down to generally 12:1 in the evening hours to
10:1 late during the night. CAMs show a dry slot working its way
into Upper Michigan late Sunday night from the southeast to
northwest within the warm front. This dry slotting will work to keep
snow totals lower over the eastern U.P. However, with snowfall
lasting longer over the western U.P. Sunday night into Monday
morning, the snow totals are project to be higher. Therefore, I`m
thinking we could around 2 to 5 inches of snow over the east and
around 5 to 7 inches over the west before we get into the daylight
hours Monday morning; there could locally be more over the Keweenaw
as some southeasterly lake-enhancement could come into play. The
slick roads and accumulating snowfall could make travel hazardous
over the western U.P. by Monday morning.
Monday`s forecast is a bit tricky as the parent low lifts through
northwestern Iowa. What model and ensemble guidance is agreeing on
is that we should see an anomalously high amount of precipitation
across most of our area Monday into Tuesday (see the ECMWF EFI for
instance). And the guidance suggests that eventually we will see a
transition from snowfall to rain across the area Monday. However,
what`s in question is when this will occur. The most recent model
guidance suggests that a wintry mix of sleet and freezing rain is
possible over the interior west mid Monday morning into Monday
afternoon before the full transition over to rain. With the most
recent guidance hitting this solution, I`ve tailored my forecast
grids to reflect this. Now, whether this solution stays or is
adjusted with future forecast packages remains to be seen...
Guidance keeps light to moderate rainfall across the area Monday
evening through Tuesday as the parent low lifts through the Upper
Mississippi Valley into western Lake Superior. A subtle shortwave
rotating around the low keeps the system rainfall going across our
area until Tuesday evening; once the parent low lifts into northern
Ontario Tuesday night, the cold front of the low is expected to move
through. Thus, expect any remaining light precip across our area to
transition back to snow Tuesday night into Wednesday from west to
east. Overall, guidance has around 1 to 2 inches of liquid falling
across our area from late Sunday through Tuesday. Hopefully, this
additional precipitation will reduce fire weather concerns as we
move towards summertime.
Behind the low, I`m thinking that we will see lake-effect snow
showers develop over the west snow belts as delta Ts get into the
upper teens. An additional shortwave looks to reinvigorate the lake-
effect snowfall Thursday before ridging moving in looks to kill it
Friday. We could see more precipitation as we move into next
weekend; however, it will depend on where a shortwave low moving
through the Plains tracks.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 818 PM EDT Sat Mar 23 2024
VFR conditions will hold steady into early afternoon tomorrow.
However, they will quickly deteriorate at that point when the next
Plains system moves closer to the Upper Peninsula. Widespread MVFR
conditions will become predominant at all TAF sites with
visibilities dipping into the IFR range as snow overspreads the TAF
sites. Meanwhile, winds will generally be southeasterly in the 5 to
10 kt range.
&&
.MARINE...
Issued at 357 PM EDT Sat Mar 23 2024
Light winds of 20 knots or less continue this afternoon into Sunday
morning before an approaching low pressure system progressively
increases winds from the east and southeast Sunday afternoon into
Monday; gales of 35 to 45 knots look to occur along the
International Border and over the western U.P. Monday into Monday
evening, with the highest winds being seen over the far western lake
near Minnesota. As the warm front of the low begins moving over the
lake Sunday night through Monday, we could see mixing decrease over
the lake and end the gales. However, if the warm air advection is
weak enough near the surface, we could see gales continue into
Tuesday, with the highest gales being seen near Whitefish Point.
Once the cold front moves through Tuesday night and Wednesday, we
could see westerly gales return across Lake Superior along and
behind it.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Storm Watch from Sunday afternoon through Monday
afternoon for MIZ001>003-009.
Lake Superior...
Small Craft Advisory from 8 PM Sunday to 8 AM EDT Monday for
LSZ251.
Gale Watch from Monday morning through Tuesday morning for
LSZ162-243>245-251-263-264-266-267.
Small Craft Advisory from 2 AM EDT /1 AM CDT/ Monday to 2 AM
EDT /1 AM CDT/ Tuesday for LSZ240.
Small Craft Advisory from 2 AM EDT /1 AM CDT/ to 8 PM EDT /7
PM CDT/ Monday for LSZ241-242.
Small Craft Advisory from 2 AM to 8 AM EDT Monday for LSZ243.
Small Craft Advisory from 5 PM Sunday to 8 AM EDT Monday for
LSZ244-245.
Small Craft Advisory from 5 PM Sunday to 2 AM EDT Tuesday for
LSZ246>248.
Small Craft Advisory from 11 PM Sunday to 2 AM EDT Tuesday for
LSZ249-250.
Lake Michigan...
Small Craft Advisory from 8 PM Sunday to 8 AM EDT Monday for
LMZ221-248-250.
&&
$$
SHORT TERM...LC
LONG TERM...TAP
AVIATION...TDUD
MARINE...TAP
Area Forecast Discussion
National Weather Service Pendleton OR
845 PM PDT Sat Mar 23 2024
.UPDATE...
Latest radar imagery showed shower and isolated thunderstorm
activity from earlier was winding down. Model guidance suggests
additional showers may develop overnight, especially over
northeastern Oregon. Current forecast generally looks on track.
For the evening update, made adjustments to POPS based on latest
radar and model trends and also made some adjustments to overnight
lows where needed.
&&
.PREV DISCUSSION... /issued 457 PM PDT Sat Mar 23 2024/
AVIATION...00Z TAFS...KPDT and KALW are currently VFR but may
decrease to MVFR at 11z as more rain showers enter their vinicity,
bringing down CIGs. KRDM and KBDN are also expected for breezy
conditions at around 22Z, which will have winds above 10kts. Other
than that, the remaining sites will be at VFR with winds below
10kts. However, CIGs could continue to decrease as more isolated
rain showers occur during this period thus lowering confidence due
to timing and coverage of the forecast area (30%). Feaster/97
SHORT TERM...Tonight through Monday...The band of precipitation
and breezy winds associated with a cold front passage earlier
today has lifted north and east of the forecast area this
afternoon. Behind it`s exit, radar and satellite imagery show a
scattered field of showers across the eastern mountains, a mid to
high level cloud shield over central OR, and mostly clear
conditions filling in across the Lower Columbia Basin at this
time. The upper low offshore and increasing instability from
daytime heating will support the development of scattered showers
and a few isolated thunderstorms across much of northeast OR and
portions of the southern WA Cascades and far southeast WA this
afternoon(confidence 55-65%). HREF members are showing surface
CAPE only increasing to between 250-350 J/kg with 0-6km shear of
30-50kts over northern Blues and areas east of there.
Additionally, deterministic guidance and the RAP indicate low and
mid level lapse rates increasing to 8 C/km, which will provide
some aid in initial uplift. While most of the developing showers
will produce rain, mountain areas generally above 4.5kft to 5kft
can expect to see snow. Shower activity will wind down into
tonight while the upper low opens into a trough as it dives into
CA, however a few shortwave impulses ejecting into eastern OR will
keep showers going over the eastern mountains with an a slight
chance of clap thunder as well.
Tomorrow, a weak shortwave is expected to dive across the PacNW in
northerly flow aloft, providing a chance of rain and mountain snow
showers through the afternoon, with the heaviest showers expected
to develop over the northern Blues. Snow amounts will generally
remain under 3 inches (confidence 60-70%), though an isolated
heavy snow shower or two could bring locally 4 to 6 inches in the
higher terrain (confidence 20%). The shortwave passage will also
result in a pressure gradient tightening in the afternoon and
evening across the Cascades, resulting in breezy west winds
through the Eastern Columbia Gorge and northwest winds through the
Kittitas valley. Strong winds are not expected, but wind gusts
between 30-40mph will be possible in the breeziest areas. Late
Sunday into Monday, a transient upper ridge will slide into the
PacNW, though flow aloft will mostly remain from the west to
northwest. While conditions are expected to dry out in the lower
elevations, the northwest flow aloft will allow for light snow
flurries to continue across the Cascade crest and the eastern
mountains.
Monday, the last vestiges of a cold front boundary and shortwave
aloft will slide down the BC coast into the PacNW. This will help
to increase chances of rain showers and mountain snow showers
throughout the day. However, any rain/snow accumulations will be
quite limited as much of the moisture associated with this system
will precipitate out west of the Cascades.
Temperatures will continue a gradual cooling trend into early
next week. While afternoon temperatures will be in the mid 50s to
lower 60s across the northern half of the forecast area, areas of
central OR and mountain valleys will struggle to warm out of the
mid to upper 40s tomorrow and Monday. Morning lows will be in the
30s, with 20s to low 30s in mountain valleys. Lawhorn/82
LONG TERM...Tuesday through Saturday...Ensembles are coming into
better agreement on the synoptic pattern through the next weekend.
Overall trend continues to be cool and wet, however some previous
discrepancies have been resolved, and the only major uncertainties
lie at the tail end of the period, stemming from how models resolve
the evolution of yet another broad low impacting the PacNW.
Tuesday`s weather looks fairly benign as transitory ridging builds
in behind light NW flow aloft. This NW flow may trigger some light
mountain showers (confidence 30-40%) with snow levels in the 3000-
4000 ft range, but given how weak the flow aloft is, not
anticipating anything particularly wet. Ensembles then seem to
suggest that the forecast area will lie on the apex of the
transitory ridge as a broad low moves in swiftly from behind.
Wednesday and Thursday look to be the wettest days of the period as
a result, as the low ushers in SW flow via its SE quadrant.
Confidence is moderate to high (50-60%) in an area-wide precip event
around this timeframe, based primarily on ensemble consensus this
far out. Snow levels start out warm around 4000-5500 feet before
dropping down to around 3000-4000 feet as the low pulls in colder
air into the forecast area. Confidence in QPF is low this far out
(<30%), but wouldn`t be surprised if the lower elevations see
another wetting rain with this system.
Ensembles suggest that this low will linger about the western CONUS
heading into next weekend, digging down towards California starting
around Friday. This would result in colder temperatures as the flow
aloft becomes more northerly, but would limit precip chances
primarily to the mountains, albeit with light amounts. Guidance then
diverges with regards to this low as it cuts off, disagreeing on how
fast it progresses downstream, as well as what lies behind it. Most
ensemble members seem to suggest ridging behind the low, however a
minority of members keep the low stagnant over the desert SW,
leaving us under the influence of cold northerly flow aloft beyond
the period. Evans/74
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 41 51 36 52 / 60 70 30 40
ALW 42 52 38 55 / 30 80 40 50
PSC 43 59 39 59 / 30 40 10 20
YKM 37 59 33 57 / 10 20 10 10
HRI 41 57 39 57 / 50 50 30 30
ELN 36 55 32 54 / 20 20 10 10
RDM 31 50 32 49 / 40 20 10 20
LGD 36 46 32 48 / 60 70 40 40
GCD 34 49 33 48 / 50 60 40 50
DLS 42 58 41 56 / 30 20 10 30
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&
$$
SHORT TERM...77
LONG TERM....74
AVIATION...97
Area Forecast Discussion
National Weather Service Pocatello ID
235 PM MDT Sat Mar 23 2024
.SHORT TERM...Tonight through Sunday night. Satellite imagery
shows shortwave axis shifting into Western Idaho early this
afternoon. Diffluent flow aloft, advancing cold front, and weak
instability across the northeast corner have already allowed for a
couple isolated thunderstorms to form near Rexburg and further
southwest near Atomic City. Gusty winds around 45 mph and small
hail the most likely threats as frontal boundary shifts northeast
into early evening. Elsewhere, expect showers to continue. Snow
levels ranging from around 7500 ft to 5500 ft east to west this
afternoon, falling to 5500 ft in the east and 4000 ft in the west
by midnight, sufficient to be at valley floors in many locations.
Area of secondary precipitation sliding south behind the frontal
boundary generally depicted as a low to medium confidence
convergence zone event, but GFS hanging on to a wider batch of
precipitation across the region. QPF forecast a terrain-influenced
blend between NBM mean and NBM 90 percentile look, which focuses
light snow along the I-15 corridor around/just after sunrise.
Upper trough axis shifts east into Wyoming through the day Sunday,
but secondary shortwave currently over central BC Canada enough to
help fire another round of snow showers across the region Sunday
through Sunday night. Snow totals remain below thresholds of
concern for Advisory, especially given 36-48 hour time frame, but
convective influence could certainly over-achieve in a few
locations through tonight. DMH
.LONG TERM...MONDAY THROUGH NEXT SATURDAY...
Little change in the long-term, which will be characterized by a
train of multiple shortwave troughs and low pressure systems working
in off the Pacific resulting in daily chances of rain and snow along
with cooler overall temps. Overnight low temps will generally
support snow to valley floors assuming precip is ongoing (although
accumulations should remain quite limited outside of some mntn
valleys), while snow levels rise as high as 4,500 to 5,500 feet some
afternoons, allowing rain to mix in especially in the Snake Plain
corridor and some of the adjacent srn highland valleys. Highs will
generally be in the upper 30s and 40s for most population centers,
occasionally touching 50 especially at lower elevations west of
Pocatello. Deterministic models and 500mb height cluster analysis
continue to show some increasing hope in a break in precip on Wed,
before perhaps our wettest system of the week arrives Wed night and
Thu. The Sawtooths, Smokys, White Clouds, Boulders, Pioneers, Lost
River Range, Centennials, Big Holes, and northern Wasatch Mountains
stand to see moderate snow accumulations (>50 percent of 6" of snow
or more Wed night through Fri).
With the recent spate of warmer weather, we`ve begun to see feeder
creeks and streams begin to swell and tick upward on streamflow. As
we advance through this next week of wet weather we`ll continue to
monitor these smaller creeks and streams closely as some may
approach bankful status. Larger rivers should continue to behave as
the mid and high-elevation snowpack remains largely untapped, and
the cooler temps will also help slow melting. 01/TAX
&&
.AVIATION...
Minor tweaks made to start/end time of -SHRA and VCTS at the
terminals this afternoon/eve based on fresh HRRR and HREF data, with
activity generally ending by 01-02z/7-8pm everywhere except KDIJ.
Regional winds have been verifying a bit stronger than expected this
afternoon, resulting in a recent round of amendments to nudge speeds
slightly higher (blending NBM/MOS forecast data toward recent obs),
generally 13-20kts gusting 20-30kts out of the W-SW at the Snake
Plain terminals. We`re also seeing cigs drop solidly into MVFR
territory directly under organized showers and storms, but
confidence remains low on occurrence and timing of direct hits to any
particular airport. Will continue to monitor radar, obs, and trends
closely. Winds and showers wind down this eve with just VCSH and mid-
level VFR clouds expected for the overnight and Sun AM. At KDIJ,
snow shower activity may continue for much of this period. A couple
high-res models (especially the HRRR) are also trying to generate
some convergence-induced snow Sun AM affecting KIDA and KPIH (09-
17z/3-11am window), but agreement across the model suite is poor
including on whether or not this activity will develop at all,
lending to low confidence. We`ve continued VCSH but have not
introduced impacts at this time. Expect another round of rain and
snow showers Sun afternoon across the region, along with moderate
and gusty westerly winds at KBYI. 01
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service San Angelo TX
654 PM CDT Sat Mar 23 2024
...New AVIATION...
.SHORT TERM...
(This evening through Sunday)
Issued at 1252 PM CDT Sat Mar 23 2024
...Strong gusty winds expected across West Central Texas
Sunday...
Winds will begin to shift from the southeast to southwest today
and increase in speed as the pressure gradient tightens up across
the area through Sunday night. Winds today will range from 10 to
20 mph with some gusts up to 30 mph, and will increase overnight
into Sunday morning from 15 to 30 mph with gusts as high as 45 mph
across parts of West Central Texas. A Wind Advisory has been
issued for all of West Central Texas for these strong gusty winds
from 1 AM Sunday through 7 PM Sunday.
&&
.LONG TERM...
(Sunday night through next Saturday)
Issued at 122 PM CDT Sat Mar 23 2024
A dryline is forecast to advance into our western counties by late
afternoon or early evening. By mid to late evening, the dryline is
forecast to retreat to slightly with a Pacific front advancing east
and overtaking the dryline between 10 PM and midnight. As this
happens, showers and thunderstorms are forecast to develop along
the front, with a line or broken line of storms advancing east
across the forecast area. The main question is how far east the
dryline will make it, which will determine where storm initiation
occurs. The 12Z NAM Nest keeps the dryline along our western
forecast area border, while 12Z HRRR is a bit farther east. The
current forecast has the highest PoPs east of an Abilene to San
Angelo line, with much lower chances across our western counties.
If the dryline is just bit farther west, then higher rain chances
can be expected across a larger portion of the area. A few strong
to severe thunderstorms will be possible during this time frame,
with large hail and damaging winds being the main concerns. Most
of this activity should exit the region to the east by sunrise.
Slightly cooler temperatures and windy conditions are then expected
on Monday behind the aforementioned Pacific cold front. Highs will
be in the upper 60s to lower 70s, with west winds increasing to 15
to 25 mph, with higher gusts. A cold front is then forecast to track
through the region Monday night into Tuesday morning, ushering in
much cooler temperatures. Morning lows on Tuesday will be in the mid
to upper 30s across the northern half of the area, to the low to
mid 40s across the southern half of the area. Freezing
temperatures are not anticipated at this time, but some areas,
especially across the Big Country could drop into the mid 30s.
Winds should stay up enough to prevent the formation of frost, but
this will need to be monitored over the next few days. Highs
Tuesday will be below normal, in the 60s for most locations, with
the coolest readings across the Big Country.
A slow warm up is then forecast through the end of week. Highs on
Thursday will be well into the 70s, with highs on Friday
approaching 80. A weak upper level trough will track across the
region on Wednesday, bringing a slight chance of showers and
thunderstorms to the region. Rainfall amounts are forecast to
remain light.
&&
.AVIATION...
(00Z TAFS)
Issued at 501 PM CDT Sat Mar 23 2024
850 mb low level jet will be developing towards midnight, along
with low level wind shear across most of the terminals. MVFR
stratus (along with IFR stratus in southern terminals) will be
developing towards sunrise. south wind spread will be increasing
mid morning as the low level inversion breaks and a strong
pressure gradient develops. Winds gusts over 30 KTS likely Sunday,
from mid morning into the afternoon. Stratus will dissipate early
to mid afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 56 76 49 70 / 0 20 30 0
San Angelo 55 79 46 71 / 0 10 30 0
Junction 53 75 51 74 / 0 0 60 0
Brownwood 54 72 51 71 / 0 10 70 0
Sweetwater 56 77 49 68 / 0 10 10 10
Ozona 52 76 46 68 / 0 10 30 0
Brady 54 72 51 70 / 0 0 70 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 1 AM to 7 PM CDT Sunday for Brown-Callahan-
Coke-Coleman-Concho-Crockett-Fisher-Haskell-Irion-Jones-Kimble-
Mason-McCulloch-Menard-Nolan-Runnels-San Saba-Schleicher-
Shackelford-Sterling-Sutton-Taylor-Throckmorton-Tom Green.
&&
$$
SHORT TERM...TP
LONG TERM....Daniels
AVIATION...04
Area Forecast Discussion
National Weather Service Great Falls MT
827 PM MDT Sat Mar 23 2024
.SYNOPSIS...
A vigorous winter weather system will impact much of the forecast
area for remainder of the weekend. Bands of moderate to heavy
snow will move into Central and North-central Montana by this
evening while southwestern areas see a brief period rain, snow,
and even a few thunderstorms before transitioning to areas of
light to moderate snow tonight. Precipitation winds down by Sunday
afternoon, but much colder than average temperatures will linger
into early next week.
&&
.Update...
Evening update has been published, with little changes needed as
the on-going forecast is performing well. Did consider upgrading
the Winter Weather Advisory to a Winter Storm Warning for the
Gates of the Mountains zone due to the combination of gusty north
winds and snow accumulations approaching 6 inches in the Sieben
area; however, held off as the winds will be localized to just
this area vs the entirety of the zone. Otherwise, moderate to
heavy snow is lifting north northeast this evening as expected,
with visibilities falling to as low as 1/4 mile in the heaviest
snow across Central Montana including the city of Helena
(recently). Additionally, while the risk is beginning to diminish
this evening, a few flashes of lightning and rumbles of thunder
will remain possible along and south of the US Hwy 12 corridor
through the midnight hour. Regardless of whether a Winter Storm
Warning or Winter Weather Advisory is in place for a given
location, travelers should expected very slippery conditions
through Sunday morning due to the wet snow initially melting and
then freezing on road surfaces. Allow extra time to reach your
destination and reduce speeds, regardless of how much snow has
accumulated. - Moldan
&&
.AVIATION...
511 PM MDT Sat Mar 23 2024 (24/00Z TAF Period)
Showers and even a few embedded thunderstorms continue to lift
northeast from Idaho and Western Montana towards Southwest through
North Central Montana late this afternoon. These showers will
transition into a more uniform band of moderate to at times
precipitation through the early evening hours, with precipitation
expanding in areal coverage beyond 06z Sunday and persisting through
18z Sunday as the main upper level disturbance moves over the
Northern Rockies. Precipitation may initially begin as a rain/snow
mix across Southwest Montana early this evening, but quickly
transition to all snow within a couple hours of onset. Further north
across Central and North Central Montana the precipitation will be
solely in the form of snow. LIFR/IFR/MVFR conditions are largely
expected through the 2400/2500 TAF period, with the window of lowest
CIGS/VIS leading to LIFR conditions generally occurring from between
00-18z Sunday. Mountains will be obscured over the next 24 hours. -
Moldan
Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.
&&
.PREV DISCUSSION...
/ISSUED 511 PM MDT Sat Mar 23 2024/
Warm air continues to overrun a cooler surface airmass over
Central/North-central Montana for continued low clouds, patchy
fog, and cold temperatures; however, southwestern areas did manage
to warm into the 40s and 50s this afternoon after a cool and
cloudy start. Rain/snow showers associated with a leading
shortwave and H700 cold front can be seen approaching the region
already and this activity will pick up as it moves northeastward
toward Southwest Montana. The primary concern for this evening
will be quick bursts of moderate to heavy snow and or graupel.
Current RAP analysis shows little in the way of surface CAPE, but
mid- level lapse rates are running in excess of 7C/km. Given this,
gusty winds to around 40 mph or so and a few thunderstorms can
also be expected.
Farther north, snow will pick up this evening and tonight as an
H700 vort max develops and slides southeastward through the
plains. Models guidance have gone down on snowfall amounts,
despite remaining fairly consistent on QPF. The numbers with this
forecast package have not changed a whole lot from previous
shifts, but have increased ever so slightly for the central/north-
central northerly upslope areas along the highway 200 corridor.
Given this and the fact that the H700 vort max looks to enhance
snowfall in this area, I decided to upgrade the lower elevations
of Cascade/Judith Basin Counties to a Winter Storm Warning. The
area in between Great Falls and Helena will need to be monitored
as well, but confidence was too low to add those zones a this
time. The most impactful conditions with this system will occur
later this evening through early Sunday, though the winter
products extend well into Sunday to handle lingering snow and
impacts.
Moisture profiles begin thin and overall synoptic forcing
declines on Sunday as the H700 vort max moves off into
Southeastern Montana; however, a low level moist northerly flow
will maintain periods of light to moderate snow and or snow shower
activity for much of the day while the ongoing cold air advection
brings what will likely be the coldest day of the week. Most
locations will struggle to surpass the 20s and 30s, which would be
about 20 to 25 degrees below climatology. Snow winds down further
Sunday night, but lingering low level moisture will maintain at
least variable cloudiness and even some light snow over eastern
areas for much of the night. Patchy fog shouldn`t be a widespread
problem given the cloud cover, but will occur over areas that
happen to experience partial clearing, especially heading towards
Monday morning. Temperatures will mostly bottom out in the single
digits and the teens.
Ensembles favor a chilly northwesterly flow to remain over the
Northern Rockies through Tuesday while the main trough slowly
moves eastward through the plains. This will maintain below
average temperatures and lingering, mostly mountain, light snow
showers. The best chance for lower elevation snow will come with
upper level warm air advection on Tuesday, though the chances for
one inch or more of snow are running less than 20%.
Transient ridging will then bring near to above average
temperatures before another deep Pacific trough rolls through the
western CONUS for the second half of the week. While the primary
low looks to split off into the southwest/Great Basin area, there
are sufficient smaller scale features for at least cooler and
unsettled conditions for North-central and Southwest Montana. Many
ensembles offer accumulating snow late Thursday through Saturday,
some significant, but overall poor agreement and run to run
inconsistencies leave us in a wait and see position. - RCG
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 15 23 10 30 / 100 90 40 10
CTB 12 21 6 26 / 100 100 10 0
HLN 19 27 15 39 / 100 80 30 10
BZN 18 30 8 36 / 100 80 30 10
WYS 22 31 2 35 / 100 80 20 30
DLN 24 32 17 38 / 90 70 30 10
HVR 12 22 7 26 / 100 90 30 10
LWT 10 19 5 27 / 100 100 60 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM MDT Sunday for Beaverhead and
Western Madison below 6000ft-Big Belt, Bridger and Castle
Mountains-Canyon Ferry Area-East Glacier Park Region-Eastern
Glacier, Western Toole, and Central Pondera-Eastern Pondera and
Eastern Teton-Eastern Toole and Liberty-Elkhorn and Boulder
Mountains-Gallatin Valley-Gallatin and Madison County Mountains
and Centennial Mountains-Gates of the Mountains-Helena Valley-
Hill County-Little Belt and Highwood Mountains-Madison River
Valley-Meagher County Valleys-Missouri Headwaters-Northern High
Plains-Northwest Beaverhead County-Ruby Mountains and Southern
Beaverhead Mountains-Southern High Plains-Southern Rocky
Mountain Front-Upper Blackfoot and MacDonald Pass-Western and
Central Chouteau County.
Winter Storm Warning until midnight MDT Sunday night for Bears
Paw Mountains and Southern Blaine-Fergus County below 4500ft-
Northern Blaine County-Snowy and Judith Mountains.
Winter Storm Warning until 6 PM MDT Sunday for Cascade County
below 5000ft-Judith Basin County and Judith Gap.
&&
$$
http://www.weather.gov/greatfalls
Area Forecast Discussion
National Weather Service Las Vegas NV
838 PM PDT Sat Mar 23 2024
.SYNOPSIS...Strong southwest winds will gradually diminish
overnight, but linger through Sunday in San Bernardino County.
Expect scattered showers and possibly a rumble of thunder through
Sunday, with light rain amounts in the valleys and light snow
accumulations in the mountains. Sunday will be the coolest day for
most of the region, with temperatures warming back to late March
averages by the middle of the upcoming week. As March comes to a
close next weekend, a deep area of low pressure will usher in more
unsettled weather.
&&
.UPDATE...Recent radar loops showed numerous showers with isolated
brief thunderstorms over much of Mohave County early this evening.
The latest HRRR/HREF indicated these will move out of the county
before midnight. Winds speeds have decreased slightly across the
region after sunset and will continue to diminish overnight across
all but San Bernardino County as the axis of the upper level trough
transitions across our area by Sunday morning resulting in winds
becoming northwest generally 15-25 mph over Inyo County and most of
southern Nevada and far northwest Arizona. Scattered instability
showers under the cold pool of the upper low will develop during the
afternoon as indicated by the latest HRRR and HREF. The forecast was
updated through Sunday afternoon to blend CAM PoPs with the latest
NBM to increase coverage of showers a little more across the valleys
and deserts of southern Nevada and northwest Arizona. -Adair
&&
.PREV DISCUSSION...
152 PM PDT Sat Mar 23 2024
.SHORT TERM...through Sunday night. Wind event was well underway as
of midday, with gusts over 40 mph occurring at quite a few stations,
mostly in Nye and Clark counties. Winds should slowly decrease from
north to south tonight, and strong winds tomorrow should be limited
to the Barstow and Morongo Basin regions. Area radars showed
scattered light returns. One area over far southwest Clark County
was slowly increasing, where visible satellite loop suggested that a
northeastward-propagating trapped lee wave had intersected a
standing wave. Surface dewpoint depressions were still around 30F in
this area, so any rain reaching the ground should be light. Farther
north, lightning detection sensors had noted a handful of flashes
and strikes within about a 50 mile radius of Tonopah. Overnight,
heights will continue to fall as the trough draws closer, allowing
lifted indices to hover around zero, supporting scattered showers
and perhaps even a thunderstorm or two. There will be conflicting
factors on Sunday as the trough axis passes by, but cold temps aloft
keep lifted indices neutral to slightly negative and cyclonically
curved flow remains overhead. Thunder chances would most likely be
limited to Mohave County and adjacent areas of Lincoln and Clark
counties, with shower chances primarily on the higher terrain
elsewhere. High temperatures came down several degrees today from
yesterday, and should come down another five to ten degrees Sunday.
.LONG TERM...Monday through Saturday.
Active pattern expected through the long term period as a series of
weather systems move through the region, bringing cooler than normal
conditions along with periods of gusty winds and mainly mountain
rain and snow showers. As the weekends trough shifts east on
Monday, a northwesterly flow aloft will take hold Monday and Tuesday
with dry conditions for most of the lower elevations, though some
low chances for showers will persist across the southern Great Basin
and Northwest Arizona with some residual moisture and instability
present. In the post frontal environment temperatures will remain
cooler than normal both days as well.
By Wednesday, low amplitude shortwave ridge will begin to shift into
the Southwestern states allowing for a brief increase in regional
heights and allowing surface temperatures to climb close to seasonal
normals, though it will likely remain just a touch on the cool side.
Meanwhile, a deepening trough will take shape off the Pacific
Northwest Coast that will bring increasingly gusty winds to the area
for the later half of the week along with cooling temperatures.
Ensemble guidance is struggling with the details of this second
trough, with some members keeping the trough more progressive while
others develop a stronger and deeper trough that digs into the
Southwestern US over the weekend. Regardless of the exact evolution,
confidence is fairly high in a continuation of cool and unsettled
weather for the second half of the week, which may last into the
weekend. Depending on how far south the trough digs into the region,
some shower activity will be a possibility as well. Stay tuned.
&&
.AVIATION...For Harry Reid...Winds will diminish some overnight,
but there is now only a 30% chance of speeds falling below 10kts.
Northwest winds of less than 20kts should develop by late morning
tomorrow and continue through the remainder of the day.
For the rest of southern Nevada, northwest Arizona and southeast
California...Winds will gradually decrease to less than 20kts
overnight and Sunday for most areas except the western Mojave
Desert, including KDAG, where gusty west winds to 35kts will
continue into Sunday afternoon. CIGs should generally remain above
10kft AGL at most terminals, although lower bases are possible near
showers, resulting in mountain obscuration along the Sierra and
higher elevations in southern Nevada.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM...Morgan
LONG TERM...Outler
AVIATION...Planz
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