Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/29/24
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
522 PM CST Thu Nov 28 2024
...00z Aviation Update...
.KEY MESSAGES...
- Below normal temperatures continue through the weekend and
into Monday.
- Light snow possible to likely on Saturday morning, with minor
accumulations possible, especially toward central and north
central Missouri (up to 1"-2").
&&
.DISCUSSION...
Issued at 310 PM CST Thu Nov 28 2024
Current water vapor imagery overlaid with 500 mb heights and winds
shows longwave troughing across much of the CONUS with a 50+ mid
level jet descending out of the Northern Plains and nosing into
northern Missouri, yielding enhanced northwesterly flow over the
region. At the surface, high pressure resides over Oklahoma, with
north northwesterly surface winds on the order of 10 to 15 mph with
gusts up to 20 to 25 mph. High temperatures for this afternoon
should range from as chilly as the mid 30s over NE Missouri to as
warm as the lower 40s toward Pleasanton KS/Butler MO with some
scattered clouds likely lingering. The surface high over Oklahoma
slowly migrates a bit further to the northeast by tonight, which
will help yield light winds and clear skies, allowing for strong
radiational cooling and low temperatures to drop into the upper
teens to lower 20s tonight. Similar conditions are expected for
tomorrow, although highs should be a couple degrees cooler toward
the Iowa border.
We continue to closely watch the clipper system that is
projected to quickly move west to east through the region late
Friday night into Saturday. We should get some modest moisture
advection in advance of the disturbance, dew points rising from
teens into the 20s by early Saturday morning. Now that we are
within 48 hours of the event, attention has shifted toward the
high resolution models. The 12z SPC HREF suggests snow
developing over northern Missouri early Saturday morning, moving
to the east southeast through the morning hours, with snow
exiting completely to the east by noonish. The primary time for
accumulating snow still appears to be between 6 am and noon on
Saturday. WPC has come in a few hundredths of an inch lower on
QPF, which as cut down snowfall totals a little bit. Highest
snowfall totals still appear to be toward central Missouri,
where 1" to maybe 2" will be possible (Boonville to Moberly
area). There remains the chance for a mesoscale snowband to
develop, which could produce localized areas of 2"+, but at
this time it is difficult to fully anticipate where that may be.
The 18z HRRR came in quite pessimistic for snow chances, with
only a dusting for portions of central and north central
Missouri, and no accumulations elsewhere. Meanwhile, the 19z NBM
probabilities for even a trace of snow at MCI is only 26%, with
66% chance for snow to exceed a trace in Moberly and 16% chance
for snow to exceed an inch.
Cooler than normal temperatures will persist through the weekend and
into early next week as we remain beneath strong northwesterly flow
aloft on the backside of longwave troughing. Highs for Sunday and
Monday are forecast to be in the 30s with overnight lows in the
teens. A warming trend is likely to begin Tuesday and continue into
the middle of next week, with high temps returning to the upper 40s
to mid 50s by Wednesday of next week with dry conditions
prevailing.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 519 PM CST Thu Nov 28 2024
Some scattered VFR ceilings moving through the area this
evening, and expected to remain VFR. Otherwise, light NW winds
around 5kts throughout much of the TAF period. Late in the
period, winds will shift southerly, but will remain light, so
did not provide a second line at this juncture.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.
&&
$$
DISCUSSION...Williams
AVIATION...Curtis
Area Forecast Discussion
National Weather Service Grand Junction CO
416 PM MST Thu Nov 28 2024
.KEY MESSAGES...
- Sunny and cool days expected heading into the weekend.
- Quiet conditions persist into next week as dry weather
persists and a slow warmup kicks in.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 154 PM MST Thu Nov 28 2024
Some early morning fog and low clouds have burned off this
morning giving way to mostly sunny skies as high temps remain on
the cool side of things. Little to speak of weather wise as
broad northwesterly flow sets up and remains across the region.
Used persistence for low temps overnight as the NBM didn`t drop
temps enough for the cold valleys and other cold spots, looking
at you Crested Butte. HRRR guidance picked up on the low stratus
this morning over Gunnison, Steamboat Springs and around Eagle
but is showing no sign of it for tomorrow morning. The NBM is
hinting at it so left as is for now. Might need to bump up
coverage if the NBM has the right idea. Tomorrow, more of the
same with a slight warmup expected across the region.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 154 PM MST Thu Nov 28 2024
Northwesterly flow persists through the long term period.
Temperatures will start out 5-10 degrees below normal, but as
ridging builds in, temperatures will gradually warm to near or
slightly above normal. Clear skies and calm winds will promote
radiational cooling and some downright frigid overnight
temperatures, along with occasional valley fog through the weekend.
Dry weather dominates, although a few weak waves clipping the
northern mountains will bring a low (<15%) but non-zero chance of
light snow showers over the high peaks, with little, if any,
accumulations.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 416 PM MST Thu Nov 28 2024
VFR and light winds will remain in place over the next 24 hours.
No confidence in low cloud/fog forecast with very dry air in
place but will continue to monitor satellite trends and adjust
as necessary.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...TGR
LONG TERM...BGB
AVIATION...TGJT
Area Forecast Discussion
National Weather Service Goodland KS
849 PM MST Thu Nov 28 2024
.KEY MESSAGES...
- Patchy fog cannot be ruled out over a limited portion of
northwest KS Friday morning (mainly Wichita, Logan and Gove
counties between ~3-9 AM CST), however, recent runs of the
HRRR suggest that dense fog, if any, may be relegated to
southwest KS.
- Dry weather continues through next Thursday.
- Near to below normal temperatures depending on location
through Sunday then above normal temperatures Monday through
Thursday.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 140 PM MST Thu Nov 28 2024
Tonight...a cold 1030mb surface high settles over the area this
evening before slowly moving east after midnight. Light winds
are forecast through midnight. After midnight, southwesterly
winds of 10 to 15 mph develop generally west of Highway 27.
RAP/HRRR models have a narrow corridor of fog developing after
midnight from around Atwood south through Brewster into
Tribune/Leoti areas. NBM/NAM models show no visibility
restrictions. Will let the incoming shift get another look at
more updated guidance for possible addition to the forecast. Low
temperatures are forecast to be in the teens.
Friday-Friday night...we remain under northwest flow aloft.
There will be some high clouds moving through the northwest flow
aloft pattern, otherwise moisture remains absent for
precipitation. We`ll be watching for a possibility of freezing
fog after midnight generally east of a line from Benkelman to
Oakley where NAM boundary layer humidity nears saturation and
towards the HRRR/RAP13 visibility reduction forecasts. SREF
model also has this area highlighted for reductions in
visibility. A blend of NAM/GFS/UKMET 850mb temperatures show
about a 6F rise compared to Thursday and using those along with
the better performing high temperature guidance the past several
days supports readings in the 40F to 50F range, warmest along
the CO/KS border. Low temperatures are forecast to be in the
upper teens to lower 20s.
Saturday-Saturday night...there could be some morning low
cloudiness east of the CO/KS border, otherwise it looks like
we`ll have some increasing high clouds during the afternoon with
mid and high clouds overnight. Presently, it looks to remain
dry. NAM/GFS 850mb temperatures cool 1F to 5F compared to Friday
and blending that with the better performing temperature
guidance from the past several days supports high temperatures
in the lower to upper 40s, coolest over snow covered areas in
eastern Colorado and east of a line from McCook to Hill City.
Low temperatures are forecast to be in the middle teens to lower
20s.
Sunday-Sunday night...the forecast will remain dry. There is a
bit more disagreement amongst the available guidance regarding
the high temperature forecast, mainly due to whether or not the
cooler airmass that moves into the area Saturday moves out of
the area or remains in the area. Given this uncertainty, there
is much confidence in the temperature forecast so will stay with
the NBM guidance highs in the lower 40s to lower 50s which is
within a few degrees of the blended better performing guidance.
Low temperatures are forecast to be in the middle teens to lower
20s.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
Issued at 140 PM MST Thu Nov 28 2024
Monday...we`ll continue with a dry forecast as moisture is
lacking for any precipitation. There is excellent agreement in
850mb temperatures from the GFS/GEM models (+5C to +8C) while
the ECMWF has 0C to 5C. GEFS 2m temperatures seem to be in the
middle of the three models. The current forecast is calling for
highs to be in the lower 40s to lower 50s which seems to trend
toward the GEFS model. Low temperatures are forecast to be in
the middle teens to middle 20s.
Tuesday through Thursday...continued dry. NBM guidance has
highs in the 50s, flirting with 60s each day. Could see warmer
temperatures than forecast Tuesday and Wednesday based on
GFS/ECMWF/GEM 850mb temperatures while Thursday could see cooler
temperatures than currently forecast based on these models
850mb temperatures. Low temperatures generally in the 20s to
near 30.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 845 PM MST Thu Nov 28 2024
GLD: VFR conditions are anticipated to prevail through the TAF
period. While patchy fog cannot be ruled-out over portions of
western Kansas a few hours on either side of sunrise (10-16Z
Friday).. current and recent runs of the HRRR suggest that sub-
VFR fog, if any, will be relegated to southwest Kansas (well
south of the GLD terminal). Light/variable winds will shift to
the SW and increase to 10-15 knots a few hours after sunrise
(~16-17Z) and persist through the afternoon. Winds will weaken
and become variable at or around sunset Friday evening (~00Z
Sat).. near the end of the TAF period.
MCK: VFR conditions are anticipated to prevail through the TAF
period. Light/variable winds will shift to the SW and increase
to 10-16 knots a few hours after sunrise (~16-17Z) and persist
through mid-afternoon. Winds will weaken during the late
afternoon.. becoming variable an hour or two prior to sunset
Friday evening (~22Z).
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
SHORT TERM...99
LONG TERM...99
AVIATION...Vincent
Area Forecast Discussion
National Weather Service Gray ME
815 PM EST Thu Nov 28 2024
.SYNOPSIS...
An area of low pressure will track along the southern New
England coastline and over the Gulf of Maine tonight with snow
across the north and interior while the coast and southeaster NH
sees mostly rain. Seasonably cool temperatures are expected
into the weekend and into early next week. A few scattered
upslope snow showers will be situated over the northern
mountains during this period.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
810 PM Update...Have updated the forecast to drop some winter
weather advisories from southwestern NH as well as the winter
storm warning for Sullivan County. The forcing for ascent has
moved out into Maine, and temperatures are largely above
freezing.
Otherwise, snow banding continues across central ME into the
foothills with an inch per hour rates remaining possible for the
next few hours before moving out. Power outages continue to
increase across central ME and and portions of central and
northern NH. It is likely that the upward trend will continue,
especially in ME, through at least midnight.
6 PM Update...Updated forecast is out for the rest of the
evening hours with little change. Have blended in the last
couple of runs of the HRRR into temperature a PoP grids, and it
seems to be matching observations rather well. The rain/snow
like has made it as far south as PWM as of this hour. The
immediate Midcoast of ME as well as southeastern NH remains rain
or a rain/snow mix at this time. However, for southern and
coastal zones, the back edge of meaningful accumulating
precipitation is already moving out. The heaviest snow will
continue to be across northern NH and central ME northward into
the foothills for the next few hours then taper off there toward
midnight. Won`t change any advisories or warnings at this time,
but foresee possibly canceling some southern zones early.
Northerly winds will continue to be quite gusty on the coastal
plain tonight as the low pressure system deepens as it moves
away.
Previously...
As of 20Z, low pressure has continued to migrate east of Long
Island Sound as it undergoes cyclogenesis per latest surface
observations and high resolution models. Bright banding
continues on latest radar imagery just west of the office with
very high returns. Local webcams just west of the office
continues to show large snowflakes the size of quarters in the
high precipitation return area.
Snow will continue across northern and central portions of the
forecast area for the remainder of this afternoon and into the
evening hours. Southern areas which have received rain for much
of the day will switch to a period of snow as colder air feeds
in around the periphery of the system. This remains noted well
per latest WPC snowband probabilities. Warnings and advisories
will remain in place.
In any case, as low pressure intensifies and tracks along and
near the coastal front just offshore the Maine coast between
00Z and 03Z, expect a period of strong winds along the
shoreline. Have upped the forecast for peak wind gusts based on
surface observations and trends upstream along with the high
resolution guidance. Would not be surprised if winds approached
advisory criteria for a short period at locations such as
Rockland.
Made some adjustments to the snowfall totals including increase
amounts over Cheshire County where bullish reports of snow have
been reported by trained spotters.
Overnight lows will eventually drop into the 20s overnight in
most areas with lower 30s along the coast. Some areas may ice up
with the rainfall from today despite the initially warm ground
temperatures.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Any leftover precipitation on Friday retreats to the mountains
as upslope winds allow for scattered snow showers across the
higher terrain. The most sunshine will be downwind of the
mountains where temperatures will reach the lower to mid 40s.
Expect northern areas to top out only in the 30s.
Partly cloudy conditions can be expected Friday night with just
a few snow showers continuing in the mountains. Temperatures
will fall mostly into the 20 to 25 degree range.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Key Message: Cooler than normal with little in the way of
significant precip thru the middle of next week.
Overview: Longwave trofing dominates the forecast period.
Generally cooler than normals with offshore flow. That will
bring plenty of upslope snow showers but little chance for big
precip events until the latter half of the week.
Impacts: Aside from the first real cold shot of the season...no
significant weather in anticipated thru midweek.
Forecast Details: Upper low over southern Canada is forecast to
open up and then swing thru the region Sun into Mon as the
larger trof axis tries to reorient east. This will likely
support increased upslope snow shower activity and a reinforcing
shot of colder air to keep readings below normal.
This remains the pattern thru midweek more or less...with
occasional S/WV trofs enhancing upslope flow and keeping the
colder temps locked in. Besides the low level moisture wrung out
over the mtns...it will be a dry...offshore wind...and so there
does not appear to much threat of high QPF events in the period.
A stronger cold front is forecast to cross the region late next
week and could establish a baroclinic zone more favorable for
East Coast cyclogenesis beyond that.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
Short Term...LIFR and IFR conditions in low ceilings with rain
along the coast and snow inland this evening. Conditions
gradually improve on Friday as any leftover precipitation
retreats to the mountains with upslope conditions with VFR
conditions south of the region.
Long Term...Primarily VFR conditions forecast thru the period.
Breezy west winds will prevail most days...with occasional
surface gusts up to 20 kt. Some upslope cloud cover is likely
around HIE...and local MVFR CIGs are possible any day that the
upper forcing is more favorable to nearby SHSN.
&&
.MARINE...
Short Term...Winds will peak this evening with gale force
conditions expected over the waters out of the northeast as low
pressure tracks along a coastal front. Winds then back to the
west to northwest overnight and into Friday before gradually
diminishing.
Long Term...Offshore flow will dominate the period. Periods of
SCA conditions are more likely than not...but will be based on
the timing of individual disturbances in the weather pattern.
The forecast is mainly near SCA gusts outside of the bays to
marginal SCA gusts at times thru the end of the forecast.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Storm Warning until 4 AM EST Friday for MEZ007>009-
012>014-033.
Winter Weather Advisory until 4 AM EST Friday for MEZ018>022.
NH...Winter Storm Warning until 4 AM EST Friday for NHZ002>006.
Winter Weather Advisory until 4 AM EST Friday for NHZ001.
MARINE...Gale Warning until 4 AM EST Friday for ANZ150>154.
&&
$$
SYNOPSIS...
NEAR TERM...Ekster
SHORT TERM...Cannon
LONG TERM...Legro
AVIATION...
MARINE...
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
521 PM CST Thu Nov 28 2024
.KEY MESSAGES...
- Snow is expected (90% chance) on Saturday. Most will see accumulations
of up to 1" with 2"+ possible where the heaviest snow falls.
- Abnormally cold weather will persist through early next week.
&&
.SHORT TERM... (Through Late Friday Night)
Issued at 152 PM CST Thu Nov 28 2024
A streak of abnormally cold low temperatures will begin tonight as
cold air continues to filter into the region behind yesterday`s
system. Lows are expected to bottom out in the 15 to 25 degree
range. These temperatures are 5 to 10 degrees below average and more
akin to deep winter than late fall. A possible mitigating factor to
tonight`s lows is cloud cover. Current satellite shows a large,
unbroken shield of low-level stratus upstream of the CWA. RAP low-
level moisture guidance suggests that this cloud cover will clip the
CWA, moving through west-central and south-central Illinois
overnight. If this occurs, the forecast low temperatures for tonight
may be too low in these areas. A cold start to the day and continued
cold air advection will ensure that Friday will be chilly in terms
of ambient air temperature. Highs in areas north of I-70 are
expected to remain at or below 35 degrees, with much of the area
south of I-70 landing in the 35 to 40 degree range, if not slightly
warmer. However, wind chills areawide will fall 5 to 10 degrees
below the forecast highs, with the most intense wind chills being in
northeast Missouri and west-central/south-central Illinois where
winds will be more elevated.
Quiet conditions will be interrupted on Saturday as the next system
approaches. A shortwave will traverse the Plains and enter the Mid-
Mississippi Valley from the northwest on Saturday morning. A ribbon
of moisture will advect into the region with the shortwave. As the
system arrives, most of the atmospheric column from the low to upper
levels will saturate. With the column being entirely below freezing,
the only precipitation type expected is snow. Model soundings show
strong lift within the dendritic growth zone during the beginning of
the event. This setup, along with an isothermal layer below the DGZ,
suggest SLRs greater than 10:1 with aggregation aiding in the higher
values. The previously forecast SLRs of 12:1 to 14:1 still seem
appropriate which will yield drier and fluffier than average snow.
Ensemble QPF still favors 24 hour totals of 0.10 to 0.15 inches,
with only a 20% chance of values greater than 0.20 inches at
Columbia and St. Louis. Given the SLRs, this translates to 1 to 2
inches of snow in the primary shot of snow, with lesser amounts on
the frays. Mesoscale banding is also expected to occur somewhere
within the CWA on Saturday, though exact placement is uncertain.
Where banding does occur, 2 to 4 inch totals are likely.
It`s all but a certainty that most locations will see some snow on
Saturday. However, uncertainty remains regarding where the heaviest
snow will fall and how this will affect accumulations overall. The
system is expected to enter central Missouri near sunrise and move
east through the day. Central Missouri receiving snow during the
cold morning hours will aid in accumulation. SLRs will be higher,
and the ground will be cooler leading to less compaction and a
higher likelihood to stick instead of melt on surfaces. Locations
further east will see snow later in the day. This will give daytime
heating the chance to warm the ground, leading to more melting and
compaction. Model soundings also show weaker lift further east,
suggesting less efficient snow and thus lower SLRs. If all of this
came true exactly as discussed, it would mean that if COU and STL
got exactly the same amount of snow, snow totals would be higher
further west where the snow would be more airy and less likely to
melt. Of course, this does not take mesoscale banding into
consideration, which could easily overcome warm ground temperatures
where ever it sets up.
Both ensemble and deterministic models still vary in where the band
will be, but its footprint exists generally along the I-70 corridor
if not just north of it. Details concerning features like this will
be resolved closer to the event. The takeaway is that it will likely
exist. If it does station itself over I-70, potential impacts to
travel will increase. Regardless, travelers should be aware of slick
spots on roadways due to winter weather this weekend.
Jaja
&&
.LONG TERM... (Saturday through Next Thursday)
Issued at 152 PM CST Thu Nov 28 2024
Sunday and Monday will provide a cold introduction to the month of
December as cold air settled over the area remains in place. Low
temperatures will start the days off in the teens to low-20s, and
highs are only expected to climb into the 30s for most places. The
high pressure keeping us cold will also keep the wind at bay during
this period, keeping harsh wind chills away at least.
We begin to warm up on Tuesday and through the mid-week as that
surface high slides east. Although the NBM shows confidence in a
warmer trend, the magnitude and speed of the warmth is uncertain.
This is reflected in larger spreads in the interquartile range
beginning on Monday. This can be attributed to variability in
guidance concerning a shortwave diving into the region early in the
week. The timing, strength, and location of the trough will dictate
how much cloud cover and cold air we see from its passage and when.
Optimistically, portions of the area may see highs in the low 50s by
this time next week.
Jaja
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 516 PM CST Thu Nov 28 2024
The MVFR ceilings are improving to low-end VFR from northwest to
southeast at the start of the forecast period. Currently the St.
Louis metro terminals, including KSTL, are the only terminals
still at MVFR flight conditions. These ceilings are expected to
lift within the first two hours of the TAF period, and could do so as
early the passage of the clear patch of air currently pushing
through the metro.
Stratus is expected to hang on across the area into the overnight
hours, though remain low-end VFR. A surface high will continue
pushing into the region and will eventually erode and scatter the
stratus, leaving a nearly clear sky for tomorrow and the remainder
of the TAF period. Winds will remain northwesterly and elevated
near to above 10 kts with some gusts around 20 kts possible
during the afternoon tomorrow.
Delia
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX