Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/26/23
Area Forecast Discussion
National Weather Service Boston/Norton MA
1017 PM EDT Sat Mar 25 2023
.SYNOPSIS...
A frontal system will continue to move through Southern New
England tonight, with rain coming to an end by overnight. A
gusty but dry and seasonable day for Sunday. Unsettled but
quiet weather next week with a couple of short-wave disturbances
aloft embedded in an otherwise zonal flow supporting a chance
for showers through mid-week. Temperatures during this time will
be near to slightly above seasonable. Cold frontal passage may
support a cold/blustery day Thursday before a warming trend
settles in late week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
1010 PM update...
Back edge of steadier rainfall is moving across eastern MA and
will be moving offshore during next 1-2 hours, but areas of
drizzle continue with abundant low level moisture in place. Next
shortwave and leading edge of cooling temps aloft is moving
into SNE. RAP soundings show rather steep mid level lapse rates
developing across SNE through 06s assocd with the rapid cooling
aloft which results in some elevated instability above the
frontal inversion around 850 mb. Starting to see some convective
showers develop across NJ and may see some of these showers or
even an isolated t-storm move across the coastal waters and
areas near the south coast 04-07z which is tied to a secondary
low pres which slides east along the south coast. Otherwise,
expect areas of fog to expand across SNE, with improving
conditions 08-12z from W to E as low level westerly flow
increases.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
340 PM Update:
Sunday and Sunday Night:
WNW cyclonic gradient flow for Sunday with upper low over northern
Quebec and sfc ridge of high pressure to our southwest over the OH
Valley. Lingering shallow moisture and cool pocket of air aloft (850
mb temps -4 to -7C) could lead to some SCT-BKN stratocu dotting the
mountains. Otherwise, Sunday is a mostly sunny but blustery
day, with mixing to about 850 mb. We still think peak WNW gusts
in the mid/late morning to mid-afternoon top out between 30-40
mph, with the higher end of those gusts in the Berkshires and
hills of Worcester County. If we can mix deeper, we could get
close to Advisory level gusts but this doesn`t seem likely.
Highs range the upper 40s/low 50s in the terrain, to the mid 50s
to lower 60s across CT, RI, much of eastern and southeast MA
with cooler temps near the coasts.
Gusts should ease with continued mostly clear and dry weather for
Sunday evening. Cool advection and mostly clear skies will be offset
by WNW winds 10-20 mph limiting full radiational cooling, with highs
upper 20s-around 30 NW MA, to the mid to upper 30s elsewhere.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Highlights...
* Mild weather Monday with showers Monday night into early Tuesday
* Unsettled Tuesday and Wednesday as area of low-pressure passes
just south of southern New England
* Warm trend settles in late next week with an opportunity for
substantial precipitation next weekend
Monday through Tuesday night
Upper-level ridge ahead of a 500 hPa shortwave trough shifts east
over southern New ENgland early Monday and advects a warmer air mass
over the region. Northwest flow at 925 hPa where temps will range
from 0 to 5 Celsius should support a mild day on Monday afternoon,
especially across the coastal plain where downsloping effects should
support efficient warming of the boundary layer. Highs in the mid to
upper 50s should be common east of I495. Dry air in place early in
the day should support sunshine early, but increasing moisture ahead
of an approaching short-wave aloft will support increasing
cloudiness Monday afternoon.
By Monday night the aforementioned short-wave at 500 hPa will be
traversing across the Northeast. This combined with the presence of
a left-exit jet region at 250 hPa should support a period of showers
late Monday night into early Tuesday. Highest PoPs currently placed
over the areas south of I-90 where the highest moisture/best forcing
should reside. Period of showers will be short-lived as the upper-
level short wave and associate surface coastal low eject over The
Atlantic waters by early Tuesday morning.
Unsettled weather may persist into Tuesday/Tuesday night as modest
low-level moisture and strong jet dynamics may be enough to produce
a few isolated rain showers during the day and maybe even some snow
showers over the high terrain late Tuesday night as a another short-
wave aloft traverses over the region. Confidence is low at this time
given a complex synoptic setup, so have leaned on the NBM for
guidance which places chance PoPs over much of southern New England
Tuesday and Tuesday night. There was a period a couple of days ago
where this time period looked quite active, but model guidance has
trended toward lower chances for any substantial precip.
Wednesday and Thursday
Unsettled weather pattern should trend toward less clouds and more
sunshine by Wednesday afternoon. Temps look to be seasonable with
925 hPa temps between 0 and 5 Celsius. Another round of showers may
be possible Wednesday night as a cold front pushes through the
region, but moisture looks to be limited during this time frame.
FROPA will result in chilly temperatures near or below freezing
Thursday morning. This would be followed by a cool/blustery day on
Thursday afternoon with gusty post-frontal winds out of the
northwest.
Friday and Saturday
A broad upper-level ridge is progged to build over The Northeast
late next week. This would come with above normal temperatures and
strong moisture transport out of the south. This would set the stage
for a potential round of substantial precipitation to start next
weekend.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
00Z TAF Update:
Tonight: Moderate confidence.
Ongoing rain across eastern areas should continue until about
01-03z to then become more intermittent with mist/fog. Mixed
signals but brief heavier convective downpours, possible iso thunder
at PVD and the SE MA/Cape/ACK airports around 03-07z. Clearing
in all areas after 09z. E/SE winds around 10-15 kt with easing
gusts, with a wind shift to SW around 5-9 kt around the pre-dawn
hrs.
Sunday and Sunday Night: High confidence.
VFR. W/WNW winds 13-20 kt with gusts 25-35 kt peaking around
15-22z, then gusts diminishing around sundown to sustained
winds 8-15 kt for evening.
KBOS Terminal...High confidence in TAF/trends, moderate on
timing. Light rain continues through 01-03Z with mainly MVFR ceilings.
IFR after 03-04Z with intervals of mist/light fog with precip
becoming more intermittent. E winds continue until wind shift
to SW around/after 08-09Z. Conditions improve thereafter.
KBDL Terminal...High confidence
Outlook /Monday through Thursday/...
Monday: VFR. Breezy. Slight chance RA.
Monday Night: VFR. Slight chance RA, slight chance SN.
Tuesday: VFR. Slight chance RA.
Tuesday Night: VFR. Chance RA, chance SN.
Wednesday: VFR. Chance RA.
Wednesday Night: VFR. Breezy. Slight chance RA.
Thursday: VFR. Breezy.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
345 PM Update:
Overall moderate to high confidence.
Existing Gale Warnings and Small Craft Advisories were maintained. E
to SE wind gusts will continue to increase through remainder of the
afternoon into early tonight, then decrease quickly after midnight
as winds flip to SW. Seas will still be supportive of small craft
advisories after gale warnings end. Rain continues tonight, with
potential for thunder near and over the southern waters later
tonight/overnight.
WNW gusts increase Sunday to at least small craft levels. Possible
borderline Gale force gusts but think SCA gusts 25-30 kt should be
more common. Gradually decreasing seas/waves but should remain
at least at SCA levels into Monday AM.
Outlook /Monday through Thursday/...
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain.
Monday Night through Tuesday Night: Winds less than 25 kt.
Slight chance of rain.
Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain.
Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain.
Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until midnight EDT tonight for ANZ230-236.
Small Craft Advisory until 2 AM EDT Sunday for ANZ231>234.
Small Craft Advisory until 8 AM EDT Sunday for ANZ235-237-250-
251.
Gale Warning until 1 AM EDT Sunday for ANZ254-255.
Small Craft Advisory until 8 PM EDT Sunday for ANZ256.
&&
$$
SYNOPSIS...Loconto/RM
NEAR TERM...KJC
SHORT TERM...Loconto
LONG TERM...RM
AVIATION...Loconto/RM
MARINE...Loconto/RM
Area Forecast Discussion
National Weather Service Cheyenne WY
534 PM MDT Sat Mar 25 2023
.SHORT TERM...(Late this afternoon through Monday night)
Issued at 330 PM MDT Sat Mar 25 2023
Another active start to the weekend with strong winds and snow causing
travel woes across much of the CWA. The culprit is a potent shortwave
trough stretched out northwest to southeast across WY, northeast CO
and west/southwest NE. Frontogenetical lift along/east of the trough
was producing a nearly stationary band of light to moderate snow over
much of the NE Panhandle this afternoon. Strong west to northwest
700-800mb flow and subsidence which produced wind gusts of 55 to 75
MPH this morning over portions of southeast WY was slowly decreasing
this afternoon. High Wind Warnings were allowed to expire at 2 PM
for Arlington, I-80 Summit, Bordeaux and Cheyenne. Ongoing snow and
blowing snow have been problematic for travelers along I-80 from the
WY/NE border eastward including Kimball and Sidney. Sidney has been
reporting 1/4 to 1/2SM visibility in snow and blowing snow. In a
recent forecast update, the Winter Weather Advisory for Cheyenne
County and Sidney was upgraded to a Winter Storm Warning.
Most high-res models including the HRRR and NAMNest are progging more
light to moderate snowfall oriented northwest to southeast along the
axis of maximized QG lift across the NE Panhandle late this afternoon
and tonight. The 18Z WPC projects up to a 1/3 inch of liquid equivalent
precipitation along and east of a line from Harrison to Sidney NE. Snow
ratios of 12 to 14:1 equate to another 3 to 5 inches of snow accumulations.
Winter Weather Advisories remain in effect until 6 AM Sunday for the
majority of the NE Panhandle. Fortunately, wind speeds will diminish
this evening and overnight tonight minimizing the blowing snow threat.
This band of snow slowly lifts northeast Sunday with occasional light
snow showers trailing to the southwest across the Panhandle and southeast
WY as somewhat drier air aloft filters into the CWA behind the exiting
trough. Partial clearing will allow slight temperature moderation Sunday
with highs in the 30s to around 40 east of the Laramie Range.
The lull in the snow shower activity Sunday will be brief as the next
upper low and shortwave trough moves into the central Rockies and High
Plains Sunday night and Monday. Energy will split north and south, with
the southern split generating light to moderate snow along the I-80
corridor in southeast WY and the southern NE Panhandle. Persistent
banding of snow could set up from Pine Bluffs to Sidney with 3 to 6
inches. Winter Weather Advisories may be issued Sunday morning. Winds
gusting to 25 MPH may produce patchy blowing snow. The snow will taper
off Monday evening. Below average temperatures will continue Monday
with highs in the 20s and 30s.
.LONG TERM...(Sunday night through Saturday)
Issued at 330 PM MDT Sat Mar 25 2023
A widespread precipitation event is taking shape for the extended
forecast, along with chances for gusty winds and below-average
temperatures. Thursday and Friday feature a large, upper-level system
with the potential to bring widespread snowfall across the CWA.
Tuesday and Wednesday will likely be the calm days before the storm
in the extended forecast as an upper- and mid-level ridge moves into
the area. A 700-mb ridge will exit ahead of the upper- and mid-level
ridge on Tuesday, bringing westerly winds to the CWA and a threat
for gusty winds across the wind prone regions. Gusts currently look
to stay below criteria levels. Little to no precipitation is expected
Tuesday and temperatures will be slightly warmer, though still below
average. Wednesday will also feature a ridge over the region, below-
average temperatures, and gusty winds.
A large, upper-level low off of the coast of California on Tuesday
is progged to move inland mid-week. This system could be potentially
impactful depending on the exact track it takes. There is significant
disagreement between the GFS and ECMWF as to the exact path this
system will take. The GFS suggests a quicker, southerly track with
a weaker upper-level low moving inland and propagating south along
the California coast Thursday. The associated 700-mb low is forecast
to move just south of the CWA on Friday, enhancing precipitation
potential across the region. The GFS suggests the low will move
out of the area Friday afternoon. Conversely, the ECMWF suggests a
slower, northerly track with a slightly stronger upper-level low
moving down the coast of California before turning inland Thursday.
The 700-mb low moves across the central portion of the CWA Friday
afternoon, suggesting less precipitation for the southern CWA and
more for the northern portions. The ECMWF suggests the low moves
out of the area by 00Z Saturday, 12 hours later than the GFS. While
the timing between the GFS and ECMWF differs, both have consistently
shown this system for the past several days. This system will need
to be monitored as it gets closer to determine the exact track the
low will take.
The remainder of the extended forecast looks relatively quiet as the
upper-level trough moves out of the area and a ridge builds in once
more. After the system moves out Thursday evening into early Friday
morning, winds increase as 700-mb height gradients tighten under the
ridge. CAG-CPR height gradients approach the upper-40s, suggesting
the possibility for stronger winds Friday and Saturday. Temperatures
increase to near-average by the end of the extended forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 527 PM MDT Sat Mar 25 2023
Wyoming TAFS...Surface pressure gradients will remain sufficiently
strong through the period to produce wind gusts of 25 to 35 knots.
An upper level trough will produce scattered to broken clouds
from 5000 to 15000 feet AGL, with occasional snow showers
producing visibilities of 2 miles and ceilings around 1800 feet
AGL at Rawlins until 02Z.
Nebraska TAFS...Surface pressure gradients will remain strong
enough to produce wind gusts up to 32 knots until 05Z. Scattered
to numerous snow showers associated with a shortwave trough aloft
will continue to produce IFR and MVFR ceilings and visibilities
this evening, with VFR and MVFR ceilings and visibilities
prevailing late tonight and Sunday morning.
&&
.FIRE WEATHER...
Issued at 330 PM MDT Sat Mar 25 2023
Snow showers and gusty west to northwest winds will continue through
tonight. Somewhat drier air filters into the districts Sunday, followed
by higher humidities and snow showers Sunday night and Monday with the
passage another low pressure system. Unseasonably cool temperatures
and daily chances for snowfall will continue next week.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...Winter Weather Advisory until 6 AM MDT Sunday for NEZ002-003-019-
021-095-096.
Winter Storm Warning until 6 AM MDT Sunday for NEZ055.
&&
$$
SHORT TERM...MAJ
LONG TERM...AM
AVIATION...RUBIN
FIRE WEATHER...MAJ
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
800 PM EDT Sat Mar 25 2023
.AVIATION...
A strong low pressure system is lifting northeast of the terminals
this evening. Predominately MVFR conditions with scattered rain/snow
showers at press time as gusty winds continue with the west to west
southwest winds. Gusts of 30-40 knots can be expected over the next
couple of hours before wind gusts gradually decrease toward midnight
and into the early morning hours. Strong subsidence in the wake of
the low, evidenced by satellite, should bring a clearing trend with
VFR conditions after 06-07Z tonight. There is potential for MVFR
ceilings to return tomorrow morning from MBS to PTK associated with
the cold air advection and enhanced lake moisture. Some uncertainty
still exists in regards to the overall timing and coverage of these
clouds, but MVFR conditions will be most likely across MBS. Winds
tomorrow remain westerly with gust potential to around 15 knots.
For DTW...Southwest winds (240-260 degrees) remain gusty at 30-40
knots through about 02-03Z with a gradual drop in winds towards
midnight and the early morning hours tonight. Precipitation chances
in the form of rain and melting snow still exists for a few more
hours this evening before subsidence brings clearing trend with
conditions lifting to VFR.
DTW THRESHOLD PROBABILITIES...
* High for cigs at or below 5 kft through evening, then low
tonight.
* Moderate for rain/snow mix early evening.
* Low to moderate for crosswind thresholds during the early
evening.
&&
.PREV DISCUSSION...
Issued at 340 PM EDT Sat Mar 25 2023
DISCUSSION...
Weakening inversion behind the occluded front has allowed for more
efficient mixing down of the 50+kt LLJ with southern locales now
gusting 40-50mph. As the low/front lifts into the Thumb evening,
winds across the central portions CWA will see a similar rapid
uptick in strength. Have expanded the wind advisory into Livingston
county as the area resides under the edge of the LLJ and should see
similar magnitude gusts to the surrounding southern/eastern
counties. Locally higher gusts, up near 50-60mph, will be possible
early this evening as convective showers pull stronger elevated
momentum towards the surface- DTW saw a 67mph gust late this
afternoon from this process. Scattered shower activity gradually
shifts northward with the low this evening with a partial to full
transition to snow late evening/early tonight as temps fall to or
below freezing. Accumulations still expected to be minor at a half
inch or less due to worsening moisture quality on the backside of
the low.
More pleasant day in store on Sunday as the gradient weakens over
southern lower MI with the departure of Saturday`s low allowing
winds to fall below 25mph. Additionally the drier airmass in the
wake of low pressure allows for more sunshine, at least for the
first part of the day, partially offsetting the cooler -1 to -3C
850mb temps supporting highs in the mid to upper 40s, perhaps
nudging into the low 50s around the Metro/Ohio border areas. Cloud
cover increases latter part of the day in advance of an approaching
low-amplitude shortwave.
This wave reaches the area by Sunday night into early Monday morning
bringing the next chances for rain/snow showers. Model trends have
been quicker with the arrival speed of the wave placing the bulk of
associated precip within the overnight period. This more favorable
nocturnal timing supports a better potential for some light
accumulations given lows will be hovering around or just below
freezing (in the north). Where this strip of accumulations sets up
still carries a fair amount of uncertainty owing to current model
spread within the 12Z runs. The Canadian (NH/RGEM) and RAP are the
northernmost solutions favoring areas along and north of the I-69
corridor picking up an inch or so of wet snow. NAM/GFS/ARW are the
southerly solutions instead favoring areas along and between the M-
59/I-69 corridors. Areas south of the M-59 corridor have the best
potential regardless of track to remain warm enough to keep p-type
all rain or rain-melting snow mix. There is a possibility for
another window of rain/wet snow over areas south of M-59 latter half
for the day Monday tied to developing low pressure over the Ohio
Valley/western Appalachians (advertised by the NAM/Canadian-
NH/ECMWF). This carries low confidence however again owing model
disagreements in whether or not the NW flank of this low actually
reaches southern SE MI or holds to our south over OH.
Cooler airmass settles over the central Great Lakes behind the
Monday wave(s) as 850mb temps fall to -5 to -6C by daytime Tuesday.
Temps dip further late Wednesday as a cold front drops out of the
upper Great Lakes bringing another chance for rain/snow showers.
This midweek cool down is short-lived however as upper level ridging
over the Plains expands into the Great Lakes Thursday shunting
thermal troughing into the Northeast. Much warmer conditions take
hold by Friday as developing low pressure over the central Plains
lifts a warm front through the SE MI. More rain chances will
accompany this front to end the work week/start next weekend.
MARINE...
An area of low pressure over southern Lake Huron currently will lift
northeast into Quebec by tonight. The bulk of the rain has passed
but there remain showers over the area with may result in a few
gusts to around 50 knots. Later this evening the cold air on the
backside of the low will bring some light snow showers or rain snow
mix until the system pulls further east and high pressure builds in
and brings drier conditions. The gale warnings continue for now and
we should be able to start expiring/canceling some as we get closer
to midnight. In addition, the strong westerly gales across Lake Erie
have started lowering water levels across western Lake Erie which
will continue into the overnight so the Low Water Advisory continues
as well. Winds relax late tonight with the high pressure building
back into the region. High pressure will hold through Sunday but may
get dislodged north by a weak system moving across the southern
Great Lakes Monday which will bring the next chance of
precipitation.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Wind Advisory until 2 AM EDT Sunday for MIZ049-054-055-062.
Wind Advisory until midnight EDT tonight for MIZ063-068>070-075-076-
082-083.
Lake Huron...Gale Warning until 4 AM EDT Sunday for LHZ361>363-421-422-441>443-
462>464.
Lake St Clair...Gale Warning until 4 AM EDT Sunday for LCZ460.
Michigan waters of Lake Erie...Gale Warning until 4 AM EDT Sunday for LEZ444.
Low Water Advisory until 5 AM EDT Sunday for LEZ444.
&&
$$
AVIATION.....AA
DISCUSSION...KDK
MARINE.......DRK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
958 PM CDT Sat Mar 25 2023
...Short Term Update...
.UPDATE...
Issued at 958 PM CDT Sat Mar 25 2023
-- Various thoughts regarding ongoing/near-future snow potential
through the overnight hours:
- Honestly, no big surprises so far tonight. Have opted to make NO
CHANGE to going Winter Weather Advisory on this shift, as kudos
to preceding day shifter for seemingly capturing the most likely
counties to experience the heaviest amounts/narrow banding in
the initial issuance.
- So far tonight, we`ve had only a handful of ground truth snow
reports. County dispatch in Holdrege did "ballpark estimate"
around 3" of slushy wet snow, and a spotter in southeast Adams
County has reported some "big flakes" under the heart of the
"bright banding" evident on radar. We`ve also heard "ground
covered" reports in Kearney/Minden (as supported by area web
cams too). Meanwhile, precip (all rain) has long since ended in
our KS zones as the mid level dry slot pushed up through that
area.
- Although it`s never a good idea to completely buy into/sell-out
to one model, we are late enough in the "forecast game" for this
event that it`s hard not to lean our thinking and official
forecast fairly strongly in the direction of short-term/higher
res models such as HRRR/RAP.
- As a result, we are expecting the VAST MAJORITY of snow in
excess of one-half inch to accumulate within the existing
Advisory area overnight, as the mid level
frontogenetic/convergence zone (evident mainly 700-500
millibars) continues to slowly traverse our CWA from west-to-
east, with subsidence on the backside of the wave gradually
allowing snow to end from west- to-east. Although models such as
HRRR continue to fluctuate slightly with the latitudinal
position of the heart of the west- southwest to east-northeast
band (likely to average no more than 20-30 miles across), the
vast majority of locations with the potential for 2-4" (and
MAYBE localized 4-6+") should concentrate roughly 15 miles
either side of a line from Holdrege-Doniphan-Aurora-York (while
also affecting Kearney, Grand Island etc.).
- While do not feel compelled to expand the Advisory at this time,
have issued a Special Weather Statement (SPS) for several
counties both just to its south (along the state line) and also
a few to the north (mainly Howard/Nance), as parts of those
counties could realize up to around 1".
- Timing-wise, snow should mostly end by 3-4 AM for counties west
of the Highway 281 corridor, while persisting until closer to 7
AM in our far eastern counties (such as York/Polk). Still think
overnight shift might consider cancelling Advisory a few hours
early in eastern counties (and several hours early in west), but
will defer to them to make this call based on latest data.
- So far, accumulations have been much more efficient on
grass/elevated surfaces than roads (owing to marginally-
supportive pavement temps), but anywhere snow comes down heavy
some slushy accumulation is still likely on roads.
- All in all, this looks like a solid "Advisory event", although
amounts will surely very widely from well under 1" in much of
the official Advisory area, to localized pockets to at least
4-6" in the very heart of the main narrow band. Fortunately,
winds should not be a major issue, with even gusts mainly at-
or-below 20 MPH, minimizing blowing/drifting (not to mention the
very wet/dense nature of the snow). There may be isolated places
that exceed official Warning criteria of 6", but there is not
enough confidence in widespread amounts this high to justify an
upgrade.
- One one FINAL note (I promise): from a purely
optimistic/beneficial perspective, much of the southern 2/3 of
our CWA has already or will eventually end up receiving at least
0.25-0.75" of MUCH-NEEDED precipitation from this event. For
much of our area, this will be BY FAR the biggest precip event
so far in what had been a very dry March (for example, prior to
this official totals so far in March were merely 0.06" in
Holdrege and 0.21" in Hastings).
&&
.DISCUSSION...(This evening through Saturday)
Issued at 343 PM CDT Sat Mar 25 2023
Key Messages:
* Challenging Forecast - Narrow Mesoscale Snowband is expected to
develop this evening and overnight hours for areas along and
near the I-80 corridor.
* This Narrow Mesoscale Snowband may be only 15 to 20 miles wide
in some locations. Snow amounts in this band could be 4-6 inches
or even higher.
* Another challenge is that due to warm road and ground surfaces -
the snow will struggle to accumulate unless on elevated surfaces
or during high snowfall rates.
* A couple more systems for the next week - snow/rain potential
Monday night and another system towards the end of the workweek.
The main key point today is the potent small disturbances moving
across the heart of the area today and tonight. This system has
already dropped 3 to 6" or more across portions of NE Colorado, SW
Nebraska and into the Nebraska Panhandle. This event will continue
to evolve with precipitation rotating northward and eventually
setting up in line with the I-80 corridor. Snow could begin in far
western sections as early as 5pm and then the transition will
continue throughout the remainder of the evening from
west/northwest to east/southeast. Temperatures may even be at
or just above freezing with snowfall, especially in some of the
heavier snowbands.
The narrow snowbands could be 15 to 20 miles in width and the snow
amounts in those bands could be quite a bit higher than
surrounding areas. The latest runs are a bit less, the bands could
see up to 4 to 6 inches or even more (some models have shown
totals over 6 inches, up to 8 to 10). These extreme amounts are
more of the worst case scenario, but overall the exact placement
of these snowbands are challenging. Honestly, we won`t know where
they are until they set up. An area just south of I-80 from Dawson
County southeast into Phelps county (towards Holdrege) is in a
band and then another band looks to be from around south of
Kearney moving northeast towards York as the disturbance
transitions eastward. Outside of these bands, snow amounts of a
trace to 1 to 2 inches are possible, but more likely on the lower
end. A Winter Weather Advisory was issued for the counties
surrounding I-80 to account for the potential for the higher
snowfall totals. More people will NOT see greater than 2" than
will see it.
Temperatures have been a challenge today over western portions of
Kansas and Nebraska where the snow has been falling, and thus have
tweaked temps down through the next 12 to 18 hours to help
account for snow potential vs. rain. Ice and a wintry mix is not
expected as precipitation is expected to transition to rain to
snow.
Precipitation should exit by sunrise, but kept the Advisory until
9am to be sure precip is gone. It may be cancelled early by the
overnight shift.
Cloud cover will persist Sunday and the day will be cool with
highs in the low 40s expected.
There is another disturbance moving across the area Monday night
into Tuesday morning that will bring another chance for
precipitation that will be on the threshold of rain/snow.
Temperatures will finally warm as we move into the middle of the
work-week as return flow increases as a lee low develops and
deepens. Thursday currently looks to be the warmest day ahead of
the next disturbance. While I did not look at it much - it could
be a concern for fire weather with warm temperatures and depending
on where the dryline sets up. Winds will be breezy. Something to
watch throughout the next few days in addition to the other precip
chances. The next disturbance to move across the area will bring
yet another chance for precipitation.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 730 PM CDT Sat Mar 25 2023
-- General overview:
The vast majority of the period will feature sub-VFR ceiling
(mainly MVFR), with at least a 4-6 hour period of sub-VFR
visibility also likely this evening-overnight as a generally west-
east oriented band of rain-changing-to-slushy/wet-snow pivots over
the area. However, the majority of the period will feature VFR
visibility and precipitation-free conditions. Winds will not be a
significant issue, with the strongest sustained speeds mainly at-
or-below 13KT and gusts mainly at-or-below 18KT.
- Ceiling/visibility/precip overview:
Light rain and MVFR ceiling is already underway at KEAR, with
similar conditions expected to arrive at KGRI by 02-03Z. The
overall biggest time frame of concern is 02-08Z KEAR/03-09Z KGRI,
as this block will feature the vast majority of steady
precipitation and possible-to-likely snow accumulation.
Officially, have MVFR ceiling prevailing at both sites, with MVFR
visibility KGRI and IFR at KEAR, but depending on how heavily snow
falls at least a brief period of IFR ceiling and/or LIFR
visibility is certainly possible. Snow will be very wet/slushy,
and honestly actual accumulation on paved surfaces/runways is
somewhat up-in-the air. Realistically though, at least a few
inches of slush is certainly possible. Once precip/snow pushes out
by 08-09Z, the remainder of the period is likely dry. As for
ceiling, confidence is fairly high that MVFR will hang on through
at least the vast majority of the of the period, although did
insert a medium-confidence return to VFR by 23Z.
- Winds:
No big issues here. The overall-strongest speeds of the period
will focus during these first 12 hours, generally sustained near-
to-below 13KT/gusts near-to-below 18KT out of a northeasterly to
northerly direction. Speeds during the latter half of the period
will be a bit lighter, mainly sustained near-to-below 10KT out of
the north.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 9 AM CDT Sunday for NEZ048-049-
060>064-072>077.
KS...NONE.
&&
$$
UPDATE...Pfannkuch
DISCUSSION...Billings Wright
AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
846 PM MDT Sat Mar 25 2023
.UPDATE...
Issued at 830 PM MDT Sat Mar 25 2023
A Winter Weather Advisory remains in effect through 09Z Sunday
for Dundy and Hitchcock counties in NE. The WWA has been cancelled
elsewhere. Expect conditions to gradually improve overnight as
precipitation tapers off from west-to-east.
Hazardous travel conditions.. in the advisory area and elsewhere..
will persist well after precipitation ends.. as snow and slush on
area roads turn to ice.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 309 PM MDT Sat Mar 25 2023
At the beginning of the short term period, the latest RAP analysis
shows the CWA having a generally westerly flow aloft with a
shortwave disturbance passing through the flow over the CWA. Current
surface observations show snow occurring in areas along and north of
I-70 with areas along the NE/KS seeing reduced visibilities below
one mile due to blowing snow. Opted to continue the Winter Weather
Advisory with areas still continuing to highest impacts from the
current system with an SPS issued for some eastern counties where
the threat looks to not last as long. North-northwesterly winds
gusting up to around 40 mph appear to support the blowing snow
threat thought they look to slow down a bit going into the evening
hours. Going into tonight, models continue to show the westerly flow
aloft with the shortwave disturbance over the CWA as an upper air
low moves into the area over the ID/OR border. An area of
frontogenesis looks to continue across far southwestern NE
supporting snowfall chances through the night. Will continue to
monitor this in case an upgrade or expansion is needed, but will
continue with the aforementioned method for this snowfall. Overnight
lows for tonight look to be between the middle teens and middle 20s.
On Sunday, forecast guidance shows the westerly flow continuing
through the entire day being in the base of a relatively broad
trough with another shortwave seen during the evening and the
aforementioned upper air low moving over WY by the night. At the
surface, the precipitation chances look to lessen in the morning
giving a possible brief break. However, a surface low looks to
develop in southwestern CO causing winter precipitation chances to
return beginning in western half of the CWA for the the late
afternoon and spread across the rest of the CWA going into the
evening and overnight hours. Precipitation looks to begin as a light
rain-snow mix, but transition to all light snow as temperatures cool
going into the overnight hours. Current snowfall amounts look to
range between a few tenths to around 2 inches in Yuma county
overnight with snowfall chances and amounts looking to ramp up going
into Monday. Blowing snow does not look to be an issue as winds look
to be lighter compared to Saturday`s. Daytime highs on Sunday range
between the upper 30s and middle 40s with overnight lows in lower
teens to middle 20s.
.LONG TERM...(Monday through Saturday)
Issued at 239 PM MDT Sat Mar 25 2023
The long term period looks like a roller coaster with cold
temperatures and snow to start the week, warmer and drier conditions
for the mid part of the week and then cooler and potentially wetter
conditions near the end of the week.
With an upper level shortwave swinging through the area Monday,
cooler temperatures and chances for snow are expected. With the
feature in the area and models suggesting low level moisture will be
available, cloud cover and snow is forecasted which will help keep
temperatures below average in the 20`s with the rest of the area
seeing 30`s and maybe some 40`s if surface winds remain from the
south. In regard to the snow, where temperatures remain below
freezing and along an area of lower level convergence associated
with a cold front will have the greatest chances for snow. This is
currently favoring locales north of I-70 and especially near the Tri-
State border. Most of the area should see a trace to around 4
inches, but there is the potential for banding along the front. If
the bands do form, snowfall totals could be significantly higher
with 10+ inches in narrow areas. Currently this would favor Eastern
Colorado and areas near the Tri-state border.
For Tuesday and Wednesday temperatures will gradually warm as upper
level ridging moves over the area. However, Tuesday will remain
below average in regard to temperatures with the higher surface
pressure moving through the area. Skies will clear though as drier
air also move through. With this, Wednesday may see near to above
average temperatures depending on upper level cloud cover and how
quickly the next trough moves in from the west. Currently leaning
towards the warmer solutions as it is unlikely that the cooler air
with the large trough in the Northern CONUS would make its way this
far south which would leave only the upper cirrus clouds to hinder
temperatures. With 850mb temperatures forecasted to reach 10 to 15
C, 50`s to 70`s degrees F are possible for the max temp.
Thursday is dependent on the timing and progression of the next
upper level trough moving in from the west. Most deterministic
guidance holds the trough and associated surface low from moving
through the area until late Thursday and early Friday. In this
scenario, Thursday would see well above average temperatures with
850mb temps reaching 20C. There would also be the potential for
stronger winds and maybe some dust if the low doesn`t develop too
far south. These then would push through slowly on Friday giving the
area lingering chances for rain and snow. However, it is worth
noting that the GEFS ensemble spread and, to a much lesser degree,
the EPS were showing the potential for the trough to progress into
the area faster. If this were the case Thursday would see near
average temperatures with chance for precipitation and Friday would
likely be cooler.
For the weekend, guidance varies on what would happen after that
trough though the general trend looks to keep either zonal flow or a
broad trough over the area which favors near to below average
temperatures and maybe some chances for precipitation.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 600 PM MDT Sat Mar 25 2023
GLD: A brief period of MVFR ceilings cannot be ruled out this
evening and overnight. Otherwise.. VFR conditions are anticipated
to prevail through the TAF period. Breezy (20-30 knot) NW winds
will weaken to 10-15 knots late this evening.. becoming light and
variable overnight. Winds will remain light and variable through
the duration of the TAF period.
MCK: Adverse aviation conditions associated with low ceilings and
occasional snow will prevail this evening through Sunday morning.
Improvement may be slow.. with VFR conditions not returning until
Sunday afternoon. W winds at 10-15 knots may shift to the NW and
increase to 20-30 knots at the beginning of the TAF period
(00-04Z time frame). Winds will become light and variable late
tonight / early Sunday morning.. remaining light and variable
through the duration of the TAF period.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...Winter Weather Advisory until 3 AM MDT /4 AM CDT/ Sunday for
NEZ079-080.
&&
$$
UPDATE...Vincent
SHORT TERM...076
LONG TERM...KAK
AVIATION...Vincent
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1005 PM EDT Sat Mar 25 2023
.SYNOPSIS...
A front will stall across the lower Piedmont tonight and remain
nearly stationary through Monday. This will provide chances for
showers and thunderstorms periodically until high pressure pushes
the front south of the area Tuesday. Mild high pressure will settle
over the region midweek, then shift to our east by the end of week.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 945 PM EDT Saturday: Southerly flow has advected some 60s
dewpts into Elbert/Abbeville/Greenwood counties, and a few showers
are developing along this moisture boundary. The last few runs of
the HRRR have been showing convection develop in this manner, but
seems overdone on the intensity of the cells. With that said, there
is plenty of shear with 80 kt of 0-6km bulk shear and supercell
composite progged to get to around 8 on the SPC mesoanalysis
page. So there is still a marginal threat of severe wind or hail,
if any of these cells can get a little taller. Have bumped up
PoPs along the southern and southeastern edges of the forecast
area for the next few hours to line up with the trends. Otherwise,
the forecast looks good.
For the rest of the evening and into the overnight hours, a weak
front will stall over the southern edge of the fcst area. The
new 00Z mesoscale model guidance is not in very good agreement on
convection coverage or timing overnight thru Sunday morning. But
they all generally agree that we will see a decent uptick in
coverage at some point between now and midday Sunday. Made some
minor tweaks to the hourly PoPs thru 12z Sunday, but left the rest
as is.
In the wake of a strong negatively tilted short wave, our flow
aloft will stay southwesterly and quick overnight and thru the
day on Sunday. This should effectively prevent the cold front
from making much of any progress past our fcst area, meaning we
should not expect much of an air mass change. The model guidance
redevelops and spreads convective precip across the fcst area from
the southwest on Sunday, but might be negatively impacted by some
feedback in the model from convection across the Deep South. The
fcst confidence for Sunday is fairly low as a result, but will
indicate a chance of showers increasing into the afternoon. More
clouds and higher precip chances means high temps were dropped
about a category, but still above normal.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 200 PM Saturday: A stalled frontal boundary will be draped
across the Southeast Sunday evening into Monday afternoon. A sfc
wave is expected to track northeast along the stalled boundary late
Sunday night into daybreak Monday. This will act to increase shower
and thunderstorm chances at the beginning of the short term fcst
period. Have categorical to likely PoPs across NE GA, the SC
Upstate, and the SW NC Piedmont. Have Likely to chance PoPs across
the NC mtns and Foothills as well as the NW NC Piedmont. Thunder
chances mainly look to be east of the NC mtns, however could not rule
out isolated thunderstorms across the SW NC mtns around daybreak
Monday. QPF Sunday evening into Monday should be the highest across
the southern zones and the ranging from roughly 0.75 to 1.5 inches.
The northern zones will see lower QPF values ranging from around
0.25 to 0.75 inches. Should see showers and thunderstorms exit the
CWA sometime Monday afternoon, but with models still not in great
agreement on when activity will exit the region, maintained a slight
chance PoP through the afternoon hours. The southeastern periphery
of a Sfc ridge tries to build into the western Carolinas late Monday
into Tuesday night, however global models show upper-level
shortwaves tracking overhead the CWA during this timeframe. This
would act to keep rain chances around, so have slight chance PoPs
Monday night and chance PoPs Tuesday into Tuesday night. The overall
thunder potential looks too low to mention at this time. Cloud cover
Sunday night and Monday night will lead to lows around 10-15 degrees
above climo. With WNW/W`ly 850 mb flow and gradually decreasing
cloud cover on Monday, expect highs to be around 10 degrees above
climo. Highs Tuesday afternoon and lows Tuesday night will be much
cooler and near climo as the FROPA pushes SE of the CWA and as the
SE periphery of the sfc ridge noses into the region.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 230 PM Saturday: The aforementioned sfc high finally builds
into the western Carolinas and northeast Georgia Wednesday into
Thursday morning leading to drier conditions. Should see low RH
values on both Wednesday afternoon and Thursday afternoon ranging
from the mid to lower 30s across much of the CWA. However, with
light winds expected during peak daytime heating, the overall fire
wx potential looks low. The SW periphery of the sfc ridge remains
over the Southeast Thursday night into early Friday while a sfc low
tracks out of the Central Plains into the Midwest. The sfc low then
tracks NE into the Great Lakes region Friday night into early
Saturday. This will act to drag a cold front across the TN Valley
and towards the western Carolinas on Saturday. Have dry weather
Wednesday through late Thursday, with PoPs increasing from west to
east ahead of the FROPA late Thursday night into Friday night.
Capped PoPs to chance for now as this is towards the end of the fcst
period and as models are still not in great agreement on the timing
of the FROPA. Went with high end chance PoPs on Saturday as models
seem to agree that the bulk of the rain should track across the CWA
during the first half of the weekend. Both the potential for thunder
and severe wx looks to be low for now. Highs will be on a gradual
warming trend through the long term fcst period. Highs Wednesday
afternoon and lows Wednesday night will be a few degrees below climo
thanks to the sfc high building overhead. Highs will be a few
degrees above climo Thursday becoming several degrees above climo
Friday into Saturday. Lows will be a several degrees above climo
Thursday night becoming well above climo Friday night.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Wind gusts should taper off quickly to
start the 00z TAFs, as the boundary layer decouples and the
winds diminish considerably. Moisture returns late tonight with
mid/high clouds increasing. An upper wave will bring a round of
showers possibly across the Upstate and CLT in the 12-18z time
frame. Will handle with VCSH and/or PROB30 for SHRA. Cannot rule
out some thunder embedded with this activity, but confidence is
too low to mention in the TAFs attm. Then a lull in convection is
expected in the aftn and early evening, but moist SWLY flow will
try to bring in or sustain some MVFR cigs across the Upstate and
possibly CLT. Wind direction gets tricky with the old cold front
stalling across the region overnight. The fcst indicates a NE wind
at KCLT Sunday morning, but that could very easily end up more SE
to S by midday. Another round of SHRA and possibly TSRA may start
to impact CLT before the end of the 00z TAF period, so will add
a PROB30 for late Sunday evening.
Outlook: Moisture returns Sunday evening into early next week. This
may result in another period of associated restrictions at area
terminals. Dry high pressure returns the middle of next week.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...ARK/Wimberley
NEAR TERM...ARK/PM
SHORT TERM...AR
LONG TERM...AR
AVIATION...ARK
Area Forecast Discussion
National Weather Service New Orleans LA
1044 PM CDT Sat Mar 25 2023
...New UPDATE...
.UPDATE...
Issued at 942 PM CDT Sat Mar 25 2023
Overall no major changes made to the forecast outside of updating
some hourly PoPs and weather. Main concern is the subtle
disturbance coming across the TX Big Bend region. The first subtle
piece of this is already running over Austin, TX and could begin
to approach western portions of the CWA before 7z while the bulk
of the energy may be closer to 8z. This may be what the HRRR is
picking up on as it tries to fire off convection overnight and
this could develop just west of the area and move into locations
near and northwest of BTR. This may be a little bullish but given
the rather amped up airmass in place this could be more than
sufficient to get storm to break through that warm nose around
h78-h8 and then just rapidly develop. These would likely not be
sfc based so not as concerned with damaging winds or tornadoes,
but large hail could be an absolute concern. There will be a lot
of CAPE in the hail growth region to work with and maybe a little
upper lvl diffluence in place as well. Mid lvl lapse rates are
just as impressive around 7-7.5 c/km while 0-6km bulk shear of
around 55-60kt will be quite capable of leading to organized
convection. So the big take is if we can actually get convection
to develop and break through h8 there is a good chance we could be
dealing with a few severe storms during the early through late
morning hours along the LA/MS border. /CAB/
&&
.SHORT TERM...
(This evening through Monday)
Issued at 232 PM CDT Sat Mar 25 2023
A somewhat diffuse cold frontal boundary resides across the northern
half of the forecast area. Much of the thermal/moist gradient
resides to our north, however, eyes will focus on one particular
detail, which could have some implications on the forecast this
evening and overnight. This would be backing and increasing
surface flow leading to the cold front sharpening. This is
important as the environment is conducive for convection. MLCAPE
of 1500-2000 j/kg with H5 temps around -14C...steep lapse rates,
especially in the hail growth region is enough to catch some
attention. The EML is still present, which will limit coverage.
The thought it with the sharpening frontal boundary the low level
ascent may be just enough to overcome the inhibition allowing for
convective initiation to take place later this evening. Low level
hodographs signal the potential for splitting supercells with
large hail and wind being possible. That said, a right mover
especially in closer proximity to the surface boundary may have a
tornadic potential. Again, coverage this evening will be limited
mainly to SW MS.
Starting early Sunday both CAMs and Globals show clusters of storms
developing along the front, which by that time should still reside
along our northern forecast zones. As the front lifts northward as a
warm front, isentropic upglide will take place, with much of the
elevated convection/shower activity on the opposite side of the
front further north into MS. However, there will be a severe weather
potential right along the front. Severe hail and damaging winds are
the primary concerns, however, any storms that root into the
boundary layer and interact with the front or perhaps developing LLJ
later in the day may contain a tornadic potential as well.
Going into Sunday night and into Monday a weak upper level impulse
may drive the front southward again meandering over the area. If
multiple rounds of convection develop we may start to see a
localized hydro risk, especially where the heaviest rainfall is
anticipated over the Florida Parishes and SW MS. With instability
still lingering along and head of the front, we`ll also need to
watch for an isolated strong to perhaps severe storm through the end
of the period. Although with the shelf waters a bit on the cooler
side, instability may be more limited closer to the tidal lakes
and coast.
Finally, fog potential will be there overnight tonight and into
Sunday. Both stat and ensemble guidance are signaling this
potential. Moisture pooling ahead of the front along with southerly
return flow over the aforementioned cooler SSTs will help with
advecting marine fog inland especially over the MS Gulf Coast.
(Frye)
&&
.LONG TERM...
(Monday Night through Saturday)
Issued at 232 PM CDT Sat Mar 25 2023
Going into the early portions of the next workweek, the surface
front will remain rather close. Subtle/weak vorts within the
active WSW flow aloft will keep rounds/clusters of convection
developing over the area. Not expecting continuous rainfall, but
periods of showers and thunderstorms will remain possible from
Monday and into Tuesday. Will need to monitor for convective
clusters and locations that may receive multiple rounds of heavy
rainfall for a localized flooding threat.
By midweek an amplifying mid and upper level trough will finally
help push the front through the region and should allow us to
finally dry out. Temperatures will remain on the milder/warm side
as a progressive upper flow begins to transition to an upper level
ridge by late week. This ridge should persist through the end of
the forecast period as the H5 high centers over the southern Gulf
of Mexico. This will place our region in southwesterly flow.
GLobals have a frontal boundary and parent trough moving toward
our region on Saturday...with strong southerly return flow well in
advance of this feature, continued "middle of the road" POPs late
in the period, especially across the northern tier. (Frye)
&&
.AVIATION...
(00Z TAFS)
Issued at 715 PM CDT Sat Mar 25 2023
VFR conditions will persist through the evening but after 06z low
clouds will start to build quickly. BTR likely to be the first
impacted but this will expand north and east across the area. Cigs
will initially hover in the IFR to MVFR range from 800-1200 ft but
slowly work into IFR over most of the area. Vsbys could be an
issue at a few sites but the main concern would be GPT. Elsewhere
probably more of a concern for low cigs. Around 13/14z there is a
chance that convection could begin to develop near the BTR and MCB
area but it looks like these storms may move north quickly. /CAB/
&&
.MARINE...
Issued at 232 PM CDT Sat Mar 25 2023
A frontal boundary will remain just north of the Gulf waters, which
will keep light to moderate southerly winds ongoing. The front will
continue to lift northward late tonight, which may allow winds to
increase a bit. With the cooler SSTs over the nearshore waters,
some marine fog will be possible as a rich low level air mass
continues to move over the cooler shelf waters. A marine dense fog
advisory will be issued overnight. Otherwise, winds will increase
again by midweek as a cold front moves through the region once
again. (Frye)
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 60 78 64 79 / 20 80 60 40
BTR 66 83 70 84 / 30 70 40 40
ASD 66 84 67 81 / 30 60 40 50
MSY 68 83 69 79 / 30 50 30 50
GPT 66 78 67 76 / 30 70 40 50
PQL 65 81 67 80 / 30 60 40 40
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Dense Fog Advisory from 1 AM to 9 AM CDT Sunday for GMZ530-532-
534-536-538-550-552-555-557.
MS...None.
GM...Dense Fog Advisory from 1 AM to 9 AM CDT Sunday for GMZ532-534-
536-538-550-552-555-557.
&&
$$
Area Forecast Discussion
National Weather Service Pocatello ID
906 PM MDT Sat Mar 25 2023
.UPDATE...Quick update tonight to note parts of the Winter
Weather Advisory being allowed to expire as expected for the Bear
River Range and parts of the Eastern Highlands, including Driggs,
Victor, Tetonia, and Ashton. Snow is not completely done in these
areas as we will still see light accumulations through the night
and Sunday, but not quite to advisory level. Also of note is a
slight south and west shift of the snow band mentioned earlier
today in the latest hi-res model runs. In this scenario, snow
totals would decrease through the Snake Plain. However, confidence
is not high enough in this scenario at this time to make any
major changes to the forecast. Moore
&&
.PREV DISCUSSION... /issued 210 PM MDT Sat Mar 25 2023/
SHORT TERM...Tonight through Sunday Night.
Broad low pressure across the area through the forecast period will
bring continued round of snow through tonight and Sunday. Everyone
will continue to see some showery snow activity on and off through
the evening and again on Sunday. The showery activity drops off as
the sun sets, and we will see the focus of more organized moisture
shift from the Eastern Highlands to the northern parts of our CWA,
particularly the Central mountains and up near the Island Park area.
Snow will then drop southward tonight through Sunday to bring more
snow to the Snake Plain, Magic Valley, and southeastern corner of
Idaho. There`s a 30-60% chance of at least 2 inches of snow from
American Falls up to Rexburg by Monday morning. That drops to about
a 10-30% chance in the Magic Valley. Overall, valley snow totals
look to be in the 1-3 inch range for the rest of this weekend as the
NBM shows only a 5-15% chance of at least 4 inches of snow for the
Magic Valley and Snake Plain by Monday morning. As you head north,
the chance of at least 4 inches of snow increases to 50-70% up near
Island Park with a 30-50% chance of 6 inches and a 15-30% chance of
at least 8 inches of snow. The uncertainty in valley snow totals
comes from where a band of moderate snow will set up on Sunday. When
looking at the hi-res models, the NAM shows the band setting up from
around Arco west towards Idaho Falls and then northeast up through
Rexburg, St. Anthony, and Ashton areas. The HRRR begins to set up
the band from near Richfield back towards Idaho Falls, but then
keeps the band together and intensifies it a bit as it drops
southward through the rest of the Snake Plain, Magic Valley, and
eventually the Southeastern Highlands. This band will impact which
areas are closer to 1 inch or 3 inches of snow by Monday morning.
Up in the Central Mountains and Wood River Valley, there is a 50-70%
chance of at least 2 inches of snow from Ketchum up to Stanley and
over in the Mackay area and that drops to a 20-40% chance of at
least 4 inches of snow. Passes in the area, Galena Summit and Willow
Creek Summit, have a 30-50% chance of at least 4 inches of snow. In
general, for the mountains across our CWA, there is a 20-40% chance
of at least 8 inches of snow with the highest amounts in the Lost
River Range, Centennial Mountains, Big Hole Mountains, Albion
Mountains, and South Hills where there is a 15-35% chance of at
least 12 inches of snow. Again, all of these are probabilities
for totals running now to Monday morning.
Wind won`t be too much of an issue for the rest of the weekend as
wind gusts continue to decrease this evening. Most will see gusts in
the range of 15-25 mph with the higher gusts through the Snake Plain
on Sunday. On Sunday afternoon, the winds will pick up a bit more in
the Magic Valley and from the I-84/86 split southward with gusts 25-
35 mph. Moore
LONG TERM...Monday through Saturday. As a low develops off the
coast and drops south, high pressure builds across Idaho. That won`t
be enough to stave off the potential of snow across the mountains.
There might a stray shower or two across the Snake Plain but the
chance of well under 10%. That low drops farther south Tuesday, with
high pressure trying to hang on over the state. The GFS, NAM and
ECMWF all bring the center of the low offshore of the northern
California coast...but how far offshore may play into the potential
for precipitation. The NAM and ECMWF are drier with a stronger
ridge, vs the GFS. The former match closer to about 65% of the
clusters, while the others have the low on the coast or even into
northern California...which would bring more precipitation in on
Tuesday with a weaker/eastward-shifted ridge. Our Blend of Models
forecast is on the wet side for the central mountains, eastern
highlands and South Hills/Albion Mountains. We suspect if the
westward trend in some of the clusters and models continues, we may
end up with a much drier day. Either way, highs will be in the mid
30s to mid 40s below 6500ft, except where a weak inversion may hold
across the Arco Desert. Midweek looks pretty wet, with rain or mix
at low/middle elevations, with snow much higher up. Snow amounts
will be greatly limited at lower elevations, with several inches
possible in the mountains. We will focus today though on the
potential for rain or melted snow amounts for that 48 hour period.
The general consensus with the probability forecasts is a 50+%
chance of between 0.10-0.50" below 7000ft across the board, this
would include mostly(if not all) rain for lower elevations and a
rain/snow mix at midslopes. For 0.50" and above for rain/melted snow
amounts, that drops to 40% or less (even in the mountains) except
for the Bear River Range, and eastern highlands...where chances are
50-75%. Finally looking at 1" or higher, those probabilities drop to
15% or less in the higher elevations, with a 15-25% chance in the
eastern highlands, and 40-50% chance of the Bear River Range. Once
this storms clears us, we end up in westerly flow...but still with
some potential of showers especially heading into next weekend. Keyes
AVIATION...More widespread should end this afternoon as we lose the
sun and instability. A more concentrated area of snow will persist
across the central mountains and eastern highlands, potentially
impacting SUN and DIJ. That area of snow shifts southeast overnight
and Sunday, with highest impact potentially being for IDA and DIJ
with PIH right on the edge. Elsewhere, expect showers to redevelop
during the afternoon. The stronger westerly winds will end after
sunset today, and pick back up tomorrow impacting BYI and PIH. In
terms of where snow impacts a particular airport, we will see
conditions dropping rapidly to IFR/LIFR. Otherwise VFR/MVFR
weather is expected. Keyes
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 10 PM MDT Sunday for IDZ066-067-
069-071-074.
&&
$$
Area Forecast Discussion
National Weather Service Raleigh NC
815 PM EDT Sat Mar 25 2023
.SYNOPSIS...
A quasi-stationary front, one separating seasonably cool
temperatures to its north from unseasonably warm ones to its
south, will retreat north across the middle Atlantic through
this afternoon and evening. The front will then settle south and
waver over NC later tonight through Monday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 815 PM Saturday...
Winds continue to reduce across the region but some ASOS and AWOS
sites are still reporting gusts up to 25 mph as of 8pm. The cold
front draped across the OH and TN valleys continue to make its way
eastward and will move across Central NC overnight and stall just
off the Carolina Coast Sunday morning. Expect overnight showers to
move across the region with a thunderstorm or two possible in areas
including the Triangle and south. Overnight, temperatures will be in
the mid 50s north to low 60s south.
Previous Discussion as of 345 PM... A closed mid/upper low and
associated surface low currently centered over southern MI will move
NE into southern Ontario and Quebec tonight. The line of showers
with isolated thunder associated with a remnant QLCS is currently
pushing east and exiting the Coastal Plain. A band of associated
clouds has finally cleared the NW Piedmont and will exit the Coastal
Plain in the next few hours, and this widespread cloud cover has
kept temperatures this afternoon lower than expected. High
temperatures are now only expected to reach the mid-to-upper-70s
across all of central NC. This cloud cover has also prevented as
much mixing of dry air from occurring. Thus dew points in the upper-
50s to lower-60s are still currently observed across many parts of
central NC, with the warm front now well north into central VA.
Strong wind gusts have also struggled to mix down to the surface,
but we are finally starting to see some gusts in the 20-25 kt range,
particularly in the north and west, and this will continue for the
rest of the afternoon once clearing takes place.
Meanwhile, a strong dryline is currently analyzed across far NW NC
and SW VA, with dew points as low as the upper-20s behind it. This
boundary is still expected to push into the NW Piedmont this
evening, then move to the SE into the rest of the Piedmont overnight
before stalling. Winds behind it will shift to the NW and lessen as
surface high pressure builds in from the NW. The 12z CAMS and latest
HRRR runs show this dryline could provide a focus for additional
shower and even storm development, given MLCAPE of 500-1500 J/kg and
dew points in the lower-60s will continue to be possible out ahead
of it. However, coverage is not expected to be widespread given the
large-scale upper forcing with the trough will be exiting to the NE
by that time. So only have slight chance POPs over the north and
west where instability will be minimal, increasing to low chance in
the south and east. Latest RAP soundings show deep-layer shear will
be impressive (on the order of 60-80 kts), and even low-level shear
could still be as much as 20-25 kts by this time. However, as
previously mentioned, there will be a lack of upper forcing, and the
column looks dry above about 850 mb, which will limit how high any
convection can get. The 18z HRRR echo tops are only 20-30 kft, and
the latest modeled updraft helicity swaths are minimal. Thus not too
concerned about a severe threat overnight. Low temperatures will
range from lower-to-mid-50s NW to lower-60s SE.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
As of 215 PM Saturday...
The stalled front to our south Sunday has been trending further
north with the 12Z model updates. This will increase chances for
showers and isolated to scattered thunderstorms further north than
previously anticipated, and additionally provide increased cloud
cover and keep temperatures lower in the afternoon. The greatest
instability should remain across the southern half of central NC,
where isolated to scattered thunderstorms are possible. With strong
shear in place, some of the storms across the southern half of the
region could be strong to severe. Portions of the Sandhills,
southern Piedmont and southern Coastal Plain are in a Marginal Risk
of severe storms, with the southern tip of Sampson county in a
Slight Risk. Damaging wind gusts and large hail are the main
threats, however an isolated tornado is also possible as the 12Z
HREF shows some long swaths of updraft helicity near the NC/SC
border. The heaviest rain is expected closer to the NC/SC border,
where one-quarter to one-half of an inch is possible, with lower
values closer to the NC/VA border. Showers will expand from
southwest to northeast throughout the day, with an decrease in
coverage in the evening. Highs will be more in the mid-70s.
A shortwave aloft will swing across the region Sunday night, helping
to expand coverage of showers across all areas, and increase
instability for the possibility of thunderstorms. These storms are
not expected to be strong at this time, but will be something to
monitor. Lows will be in the mid 50s to low 60s.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 230 PM Saturday...
The stalled front will lift north across the area Monday, followed
by a cold front swinging southeast across the region Monday night.
Showers and thunderstorms are possible again Monday as these systems
move across the region, however with decreasing instability, strong
storms are not expected at this time. Surface high pressure then
builds east from the Rockies early in the week to across the Mid-
Atlantic by Thursday. Although high pressure will build in, a
shortwave traversing east across the TN Valley and Mid-Atlantic will
generate the possibility of additional showers on Tuesday. Ridging
will help keep the weather quiet mid-week, then another cold front
and shortwave aloft will increase chances for showers Friday into
Saturday.
Although temperatures will begin 10 degrees above normal to start
the long term, colder and drier air will filter in Tuesday behind
Monday`s front. Highs in the 60s mid-week will be a few degrees
below normal, and lows in the upper 30s are even possible by
Thursday morning. Temperatures begin to rebound by late week as
southerly flow redevelops generates warm air advection.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 725 PM Saturday...
TAF period: Except for FAY, VFR conditions are expected through the
24 hour TAF period. This evening just has some passing high clouds,
with only a slight chance of showers at INT/GSO/RDU. After midnight,
a more concentrated area of clouds is expected to develop across the
south. FAY should establish a VFR ceiling, and there is a slightly
better chance of a shower before dawn, with MVFR/IFR ceilings
possible. More widespread cloud cover will move from south to north
with a front, establishing a ceiling at RDU/RWI by the afternoon.
While the chance of rain should be minimal at INT/GSO Sunday
afternoon, have added VCSH to RDU/RWI/FAY, with FAY having the best
chance for rain. FAY is also likely to have a MVFR ceiling for much
of the afternoon, with the possibility of the ceiling dropping to
IFR heights.
Although a brief southwest gust will be possible at the very
beginning of the TAF period, a light southwest wind is expected
through the evening, which will veer to the north around sunrise,
then veer back around to the south Sunday afternoon.
Outlook: The front currently south of the forecast area will move
north Sunday night into Monday, bringing widespread rain and
VFR/MVFR ceilings. A chance of rain will continue on Monday, with
conditions drying out Monday night. A chance of rain and
restrictions will return for Tuesday and Tuesday night before dry
VFR conditions return for Wednesday and Thursday.
&&
.FIRE WEATHER...
As of 200 PM Saturday...
The development and passage of an Appalachian-lee dryline
will cause mixing to become unusually deep to up to ~8-9 thousand
ft AGL east of the Appalachians and across the NC Foothills and wrn
Piedmont this afternoon-evening. The dryline and following deep
mixing will cause surface dewpoints to "mix out" into the 30s-40s F -
-with associated RH as low as 30-40 percent-- with enhanced surface
wind gusts to between 30-40 mph, locally higher. Increased Fire
Danger will result.
Outdoor burning is consequently discouraged today. Please refer
to your local burn permitting authority on whether you can burn. If
you do burn, use extreme caution and ensure fire suppression
equipment is readily available.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...MWS
NEAR TERM...CA/Danco
SHORT TERM...JJT
LONG TERM...JJT
AVIATION...Green
FIRE WEATHER...Danco/MWS