Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/25/23
Area Forecast Discussion
National Weather Service Wilmington NC
935 PM EST Sun Dec 24 2023
.SYNOPSIS...
Above normal temperatures will continue over the next few days.
Rain chances increase late Monday and remain elevated through
Wednesday as a front approaches the area. Drier and colder air
will move over the region late Wednesday through the end of the
week.
&&
UPDATE/...
Added a few POPs down in Gtown County based upon radar trends. HRRR
time lagged guidance seemed to have the best handle and was followed
closely.
&&
.NEAR TERM /THROUGH MONDAY/... Mid to upper ridge will continue to
slip eastward while high extending in from the northeast loses its
grip on the Carolinas tonight into Monday. A warm front extending
from deepening low pressure system over the upper Midwest will lift
up through the Southeast into the Carolinas through Monday. A weak
coastal trough and increasing onshore to SE flow may produce a
spotty shwr or two, mainly off the SC coast, but otherwise, moisture
through the column with gradually lower and thicken on Monday with
pcp approaching from the southwest through the aftn. Most models
show increasing and thickening clouds with pcp reaching the Pee Dee
and into northeast SC through late aftn/early evening. Winds will
tend to back a bit through tonight, remaining light, as sfc high has
not completely lost its grip on the area, but will increase into Mon
with some gusts by aftn.
Overnight lows will be about 10 degrees warmer than yesterday as low
level SE flow increases and mid to high clouds increase. Overall,
most places will have a mild and dry Christmas day, at least to
start with increasing clouds and temps similar to today, well into
the 60s to near 70.
A Coastal Flood Advisory has been issued for minor coastal flooding
along the lower Cape Fear River downtown Wilmington surrounding high
tide Mon morning which will be around 830 am.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
A 538 decameter cutoff low over central Kansas on Monday evening
will slowly shift to northern Missouri by sunrise Wednesday. The 12
UTC ECMWF and GFS agree with the 500 millibar pattern with
southwesterly flow aloft. The isentropic 295K field shows an upward
lift from the warm air advection, overtaking the forecast area by 00
UTC Tuesday. Most of the period will see showers, with an isolated
thunderstorm possible during the daylight hours on Tuesday. The
rainfall will taper off over Northeast South Carolina late Tuesday
night.
Lows both Christmas night and Tuesday night will be in the middle
50s with highs in the upper 60s inland and a few 70s near the
coast.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The 500 millibar upper-level cutoff low position differences are
minor between the ECMWF and GFS, but by the weekend, there is more
difference as the ECMWF opens up the cutoff low and is absorbed by
the northern stream. The GFS maintains the cutoff low off the New
England coast. At the surface, the surface low and secondary cold
front will shift off the coast by Thursday morning. Any
precipitation left in Southeast North Carolina at sunrise on
Wednesday will be quickly replaced with very dry air through the end
of the week. As the cold air advection rushes in behind the mid-week
front, high temperature near 70 on Wednesday will cool into the low
to middle 50s by the weekend. Wednesday night`s lows will be in the
middle to upper 40s and will drop to around freezing by the end of
the week.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR with only high clouds around for most of the period. Some lower
clouds may move in from the west towards the end of the TAF period
for LBT and FLO but have left out for now. The light radar returns
off the NC coast are largely not reaching the ground and will not
lead to flight restrictions on the off chance that they do.
Extended Outlook...VFR dominates through Monday morning outside
of brief morning fog. Flight restrictions are possible late
Monday through Tuesday as a storm system affects the area.
&&
.MARINE...
Through Monday...Winds will increase and veer from E-NE to E-SE
through Monday, reaching up to 10 to 15 knots on Christmas Day.
This increasing onshore flow will push seas up to 3 to 5 ft by
Mon morning with 6 fters in the outer southernmost waters off of
Georgetown by Mon aftn. Have issued a Small Craft Advisory for
zone AMZ256 beginning noon on Mon with rest of waters following
suit Mon night.
Monday night through Friday...
A coastal front will linger through Tuesday night until a
surface low pressure occludes over the waters by Wednesday
morning. Northwest flow will develop in the wake of the low,
which will continue through Friday. The coastal front and the
developing surface low over the Florida panhandle will cause an
increase in southeast winds to 15 to 20 knots Tuesday and
Tuesday night. The flow will build the seas to 5 to 6 feet off
Georgetown County Coast Christmas night. The near-shore wave
prediction model indicates the 6-foot seas will build northward
across all the waters on Tuesday morning and fall below 6 feet
Wednesday as the occluded low pulls north of the coastal waters.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...Coastal Flood Advisory from 7 AM to noon EST Monday for NCZ107.
MARINE...Small Craft Advisory from midnight Monday night to 6 AM EST
Wednesday for AMZ250-252-254.
Small Craft Advisory from noon Monday to 6 AM EST Wednesday
for AMZ256.
&&
$$
SYNOPSIS...ILM
NEAR TERM...RGZ
SHORT TERM...RH
LONG TERM...RH
AVIATION...MBB
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
945 PM EST Sun Dec 24 2023
.SYNOPSIS...
Cool high pressure remains in control through the weekend.
Unsettled weather returns early this week as low pressure and
attendant cold front approach the region from the west. Upper
trough will linger over the area though late week, with
possibility of another frontal passage.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 945 PM Sun...Mid-Atlantic high pressure remains in
control tonight although cirrus is gradually beginning to spill
over the area from the west as moisture is advected ahead of a
negatively-tilted shortwave trough digging into eastern TX.
Offshore, weak trough is taking shape with distant showers
beyond 40 miles of the Crystal Coast. Surface trough is expected
to gradually lift towards the coast overnight, and by early
morning a few showers could threaten the Outer Banks primarily
south of Hatteras.
First reports of fog already coming in across Dare and Hyde
counties this evening, and expecting reports to gradually
increase overnight as temperatures continue their fall into the
low 40s and eventually upper 30s. Primary question remains how
thick cirrus deck will be overnight and whether it will inhibit
fog formation as it overspreads from southwest to northeast.
Guidance suggests the best chance of persistent patchy fog will
be north of Highway 264 where skies will remain clearest the
longest (supported by HREF, LAMP and HRRR guidance), but some
spotty patches of fog are possible as far south as New Bern and
Richlands shortly after midnight, before eroding as thicker
cirrus moves overhead. Used a manual combination of areas AOB 42
degrees and sky cover under 50% to paint patchy fog into the
grids, which aligns closely with preferred probabilistic
guidance.
Lows tonight ranging from the upper 30s/low 40s inland to
mid/upper 40s for the beaches.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
As of 0400 PM Sun...Coastal trough moves towards SOBX bringing
slight chances of showers Monday morning into the afternoon
ahead of the frontal system impacting ENC in the long term. A
wide range of uncertainty still exists regarding the speed and
time of arrival to SOBX for the coastal trough, ranging between
5AM and 2PM. Cloud cover increases throughout the day Monday, as
the frontal system approaches, and high temperatures will be
similar to today, but Tds will be higher from the moisture
advection.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
As of 345 AM Sunday...One more dry day Monday, before a complex
frontal system brings rain to eastern NC Tuesday and Wednesday.
Drier but much cooler weather returns by the end of the week.
Monday through mid week...A strong upper trough will become
cutoff from the main northerly jet stream flow Tues through Wed.
At the surface, a complex area of low pressure will develop
over the central U.S., bringing blizzard conditions to parts of
the northern Plains, while pushing a cold front toward our area
Tuesday and Wednesday. Rain is expected Tuesday into early
Wednesday across the entire area with widespread rainfall
amounts of greater than a half inch expected. Ahead of this
front, a weak coastal low will form Tuesday night, which will
enhance our rains especially along the Crystal Coast and Outer
Banks. In these areas 1 to 2" is expected with locally higher
amounts possible.
Given widespread clouds, weak kinematics, and lack of
instability, will continue to leave out any mention of thunder
at this time over our land areas. The most unstable guidance
gives us around 150 j/kg of CAPE Tuesday night but instability
parameters appear to be overdone with a warm bias on surface
temps. If we were to hear thunder, the best chances would be
from southern Onslow and Carteret Counties offshore. For now
will confirm thunder chances to near the Gulf Stream waters
Tuesday night, where some limited instability is most likely to
be realized. Daytime highs will remain mild or well into the 60s
through Wednesday.
The picture at the end of the week has become more clear, with a
trend toward drier and much colder conditions expected. The low
mentioned above will gradually fill in with time, and the
associated pocket of cold air aloft will drift eastward, just
glancing our area. With a northwest flow descending out of the
mountains we will be sunny Thursday through Saturday with temps
generally in the 50s for highs, with 20s at night.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
SHORT TERM /through 18z Mon/...
As of 650 PM Sun...VFR conditions prevail across all eastern NC
sites this evening. Main challenge tonight is once again fog
potential as strong radiational cooling once again takes hold.
Best chances for patchy MVFR fog are along and west of Highway
17 where highest dew points were in place this afternoon and
crossover temps are most likely to be exceeded. More persistent
fog is likely from here north of Highway 264 where skies will
remain clear, while further south high cirrus will gradually
encroach. Visibilities could drop as early as 04z for all
terminals and hang on through 13z with light flow to start the
morning.
Clouds continue streaming in throughout the day Monday, with
ceilings gradually dropping as the frontal system approaches.
VFR conditions are still expected through the TAF issuance as
low clouds don`t start moving in until the long term.
LONG TERM /Monday night through Thursday/...
As of 400 AM Sunday...Sub-VFR conditions Tuesday and early
Wednesday due to rain. VFR returns Thursday into next weekend.
&&
.MARINE...
SHORT TERM /through Monday/...
As of 0400 PM Sun...Latest obs show NE winds 5-15 kt and seas
2-4 ft. High pressure overhead and coastal trough offshore will
continue to bring light to occasionally moderate winds 5-15 kt
and seas 2-4 ft through Monday. Coastal trough will switch winds
offshore of SOBX from NE`rly to E-SE`rly, becoming gusty at
times but likely below SCA criteria.
LONG TERM /Monday night through Thursday/...
As of 400 AM Sunday....SCA conditions again likely early
Tuesday through midweek due to strong pressure gradient between
departing high pressure to the north and a front approaching
from the west. 6 foot waves across most of our coastal water
Tuesday, peak 6 to 9 feet by Wednesday with winds 20 to 30 kts
out of the Southwest. Behind a cold front winds shift into the
southwest Thursday and diminish a tad, but seas will remain
elevated.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MHX
NEAR TERM...MS/RJ
SHORT TERM...CQD/RJ
LONG TERM...EH
AVIATION...EH/MS
MARINE...EH/CQD/RJ
Area Forecast Discussion
National Weather Service Marquette MI
702 PM EST Sun Dec 24 2023
.SHORT TERM...(Through tonight)
Issued at 320 PM EST SUN DEC 24 2023
Key Messages:
- Some fog, locally dense, to linger, mainly across central Upper
MI tonight.
- Patchy -dz, mainly central, gives way to rain showers spreading
into western Upper MI overnight.
- For the second day in a row, a record high min temp to be set.
Current record high min temp for today (12/24) at the NWS site in
Negaunee Township is 33F set in 1982.
Water vapor imagery and RAP analysis show a mid-level trof extending
from Manitoba thru the Great Plains. Ahead of the trof, showers
extend from TX/LA to MN. Very anomalous moisture has been spreading
n ahead of the trof. Precipitable water over MN this morning was
near 375pct of normal for this time of year and was near a record
high for the month of Dec at KINL per SPC sounding climatology.
Closer to home, unseasonably warm conditions continue under
southerly flow. Current temps are running 10 to 20F+ degrees above
normal, ranging from the lwr 40s F s e half to the upper 40s F far w
where downsloping is aiding warming and eating holes in the low
clouds to allow for some periodic sun to appear. Low clouds dominate
elsewhere once again. Similar to yesterday, fog has diminished in
coverage this aftn, and vis has improved for most. There are still a
few spots with vis 1/2sm or less, mainly around the Bay of Green
Bay.
Under an unseasonably warm air mass with abundant column moisture
and low clouds dominating, it will be yet another unseasonably warm
night for late Dec. Temps will only fall back to 38-44F, which is
still an incredible ~15-20 degrees above the normal high temps for
this time of year. Here at NWS Marquette in Negaunee Township, we
won`t fall to 33F for the rest of the calendar day, so a new record
high min temp will be set for 12/24. Under continued southerly sfc
winds tonight, fog should expand in coverage again, mainly thru the
central fcst area where these southerly winds are an upsloping wind.
With 35-45kt winds just above the sfc, dense fog coverage should be
less than recent nights. Some patchy -dz has been occurring in the
upslope areas, and that will likely continue. Cold front associated
with the mid-level trof to the w is currently pushing across MN. As
the front continues moving e tonight, the shra lifting n thru MN
will shift e as well, reaching western Upper MI after midnight.
.LONG TERM...(Monday through Sunday)
Issued at 238 PM EST SUN DEC 24 2023
Key Messages:
- Unseasonable warmth continues Christmas Day into Tuesday, with
temperatures running 20-30F above normal.
- Periods of light rain expected Christmas Day into Wednesday.
- Temperatures become not as warm for the end of the week, but
potential for any significant lake effect snowfall continues to
decrease.
Positive 500 mb height anomalies will encompass most of Canada and
the northern tier of the US on Christmas Day, with these anomalies
reaching +2 to +3 sigma over southern Canada. This is indicative of
the continued unseasonable warmth across the UP over the Christmas
holiday. A midlevel trough will split to our west, with the northern
part heading into Hudson Bay, and the southern part forming a
sprawling cutoff low over the central Plains. An area of rain will
be approaching from the west associated with a low-level front tied
to the composite trough, but this will slow its eastward progress as
it loses the support of the midlevel trough, and the southern
portion of the front will retrograde a bit in association with the
surface low to our south. So, relatively high probability of
rainfall (>70%) to start the day over the northwest half will
actually decrease through the day with many areas staying dry. Moist
southeasterly winds will keep plenty of low clouds and patchy fog
around, especially in areas prone to upslope flow from that
direction. The low level jet increases in magnitude Monday night as
the surface low drifts gradually northward, which should result in
rain filling back in through the night from south to north. Steadier
rain tapers off from south to north on Tuesday as midlevel dry air
wraps into the UP. Rain chances remain into Wednesday but are capped
at around 40% due to uncertainty with another round of possible
cyclogenesis in the vicinity of Detroit.
Temperatures Christmas Day through Tuesday will continue to run some
20-30F above normal, with highs in the mid to upper 40s and lows
Monday night likely not falling below 40 in many locations. The lows
are especially notable as they will challenge the all-time warmest
December low temp at WFO Marquette (41F on 2 Dec 1982).
Unfortunately for those hoping for a return to more normal winter
weather, the trend for the forecast during the end of the upcoming
week has been warmer and less snowy. The uncertainty is tied to how
quickly another round of ridging builds into southern Canada. Recent
ensemble consensus delayed this ridging enough to allow a trough to
dive down from Canada, resulting in a return to seasonable
temperatures and periods of lake effect snow. The trend has shifted
toward ridging building in quicker, with a lack of any such cold
airmass, at least until after the end of the week. Forecast
temperatures do trend downward, but not as significantly as prior
forecasts, and with lower probability of precipitation.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 702 PM EST SUN DEC 24 2023
Abundant low-level moisture ensures low clouds persist thru this
forecast period, particularly at SAW where LIFR cigs prevail due to
southerly upslope winds. LLWS is forecast at all terminals this
evening as a ~45 knot low level jet develops above sfc based
stability. This LLJ weakens Monday morning ending the LLWS threat.
Conditions at SAW are likely to remain blo airfield landing mins
into Monday morning, but improving trends are forecast for Monday.
Although fcst improves for Monday, there appears to be potential for
another stretch at or below airfield minimums Monday night.
At CMX, expect low MVFR cigs to prevail, but periods of VFR are
possible tonight as lower clouds briefly scatter out. Cigs lower to
IFR Mon morning as a cold front approaches with -shra developing
around 08Z.
At IWD, cigs lowered to IFR early this evening and now expect that
to prevail through the forecast period. With cold front approaching
late tonight, -shra will begin late tonight around 08Z.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 238 PM EST SUN DEC 24 2023
Southeasterly winds will continue to gust 20-30 kt through tonight,
highest over the east half, as the pressure gradient tightens ahead
of an approaching low pressure system. Overlake stability will keep
gusts mainly below gale force, but some higher observing platforms
may record a couple of brief gusts to 35kt. These winds will
diminish Monday morning, but northeasterly winds will strengthen
during the day as the pressure gradient tightens due to low pressure
over the Plains and high pressure building over Ontario. Cold air
arriving at low levels will allow some higher winds to mix to the
surface. There is greater than an 80% chance of gales over the zones
between Isle Royale and Duluth beginning Monday late afternoon, and
a 40-70% chance between the Northern Lake Superior Buoy and Isle
Royale. Gales will likely continue through Tuesday afternoon,
peaking Monday night where there is a 40-70% chance of winds
exceeding 40 kt over the western arm of the lake. Northerly winds
will remain elevated at times through the upcoming week to around 25
kt, but potential for gales is low (<20%) at this time.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning from 1 PM EST /noon CST/ Monday to 5 PM EST /4 PM
CST/ Tuesday for LSZ162.
Gale Warning from 5 PM Monday to 1 PM EST Tuesday for LSZ263.
Gale Warning from 9 PM Monday to 10 AM EST Tuesday for LSZ264.
Lake Michigan...
Dense Fog Advisory until 10 AM EST Monday for LMZ221-248-250.
&&
$$
SHORT TERM...Rolfson
LONG TERM...Thompson
AVIATION...Rolfson/EK
MARINE...Thompson
Area Forecast Discussion
National Weather Service San Francisco CA
422 PM PST Sun Dec 24 2023
...New AVIATION, MARINE...
.SYNOPSIS...
Issued at 105 PM PST Sun Dec 24 2023
Dry conditions and seasonal temperatures continue through Christmas
Day. Next rain system arrives early Wednesday with a series of low
pressure systems to impact the region into the New Year.
&&
.SHORT TERM...
(This evening through Monday)
Issued at 105 PM PST Sun Dec 24 2023
Today will feature highs in the mid 50s to lower 60s (colder in the
regions hills/peaks) with passing high clouds. By tonight, expecting
temperatures to cool into the mid/upper 30s to mid 40s near the
coast/bays. A few of the colder interior spots may dip down briefly
into the lower 30s. That said, holding off on any frost/freeze
products as high cloud cover may very well limit cooling.
On Christmas Day, expect an ever so slight warm up of about 2-5
degrees across the region. Sprinkles/light rain showers are possible
in the North Bay, with the highest probabilities for rain up to 20-
30% in the coastal ranges of Sonoma County. Otherwise, dry
conditions will prevail. A Beach Hazards Statement is out for large
breaking waves; more information is available in the Beaches section
below.
&&
.LONG TERM...
(Monday night through next Saturday)
Issued at 105 PM PST Sun Dec 24 2023
By late Tuesday, the next frontal system will be approaching the
coast with the bulk of the rainfall expected during the day
Wednesday. Precipitation amounts will range from 1-2" across the
coastal ranges of the North Bay (locally up to 2.5"), 0.5-1.25" in
the North Bay Valleys, the interior Bay seeing 0.10-0.50", and the
Central Coast seeing up to 0.10-0.25". Locally higher amounts are
likely in the coastal rages south of San Francisco. Winds will also
increase out of the south with stronger gusts in the ridges/peaks
with this passing system.
Attention then shifts to a new system expected to come in late
Thursday into Friday. Rain totals are still being refined, but early
indications indicate that significant rainfall may be more
widespread with this system, especially south of the North Bay.
Beyond that ensemble guidance continues to show a series of upper
level troughs heading into the western United States into the first
week of the new year, with an active pattern possible well into the
middle of January. As always, it`s still a good idea to make sure
gutters and storm drains are clean and to follow forecast updates
from a trusted source.
&&
.AVIATION...
(00Z TAFS)
Issued at 406 PM PST Sun Dec 24 2023
Currently VFR at all TAF sites. There is moderate confidence that
patchy dense fog will impact STS again tonight between 07Z and 19Z.
There is low confidence and great uncertainty on if SNS will advect
fog from southern Monterey County like it did last night. If the
event somehow were to happen, HRRR is currently timing it between
12Z and 17Z. The rest of the terminals are forecast to remain VFR
through the TAF period.
Vicinity of SFO...Currently VFR with light offshore flow and high
clouds. Terminal is forecast to remain VFR through the TAF period.
Winds will become offshore overnight before returning to breezy
onshore flow tomorrow afternoon.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Currently VFR with breezy onshore flow at
both TAF sites. Drainage flow will commence overnight before the
return to breezy onshore flow tomorrow afternoon. There is low
confidence and great uncertainty on if SNS will advect fog from
southern Monterey County like it did last night. Dew points in
Monterey County right now are similar to what they were 24 hours
ago; however, a couple of things that could derail the event from
happening are high clouds over the terminal and persistence being
difficult to pull off given this is a semi-rare event. The WRF is
also forecasting much lower relative humidities tonight versus what
it had forecasted for last night. If somehow this event does happen,
timing is looking to be between 12Z and 17Z based on the HRRR. We
will continue to monitor the latest models/guidance and ensure that
the 06Z TAFs reflect that.
&&
.MARINE...
(Tonight through next Friday)
Issued at 406 PM PST Sun Dec 24 2023
Winds will continue to diminish throughout tonight. A new long
period northwest swell will arrive early Christmas day creating
hazardous conditions for small craft. Strong winds return midweek
with widespread gales possible with an approaching weather
system. Another system arrives late week.
&&
.BEACHES...
Issued at 105 PM PST Sun Dec 24 2023
A Beach Hazards Statement is in effect from 1 am PST to 7 pm PST
Christmas Day. Expect hazardous wave conditions with breaking waves
10 to 12 feet and localized beach erosion. Large waves can sweep
across the beach without warning, pulling people into the sea from
rocks, jetties and beaches.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from 1 AM PST Monday through Monday
evening for CAZ006-505-509-529-530.
Coastal Flood Advisory from 7 AM to 11 AM PST Monday for CAZ006-
506-508.
PZ...Small Craft Advisory from 9 AM to 9 PM PST Monday for Mry Bay.
Small Craft Advisory from 9 PM this evening to 3 AM PST Tuesday
for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60
NM.
Small Craft Advisory from 9 AM Monday to 3 AM PST Tuesday for
Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras
Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory from 3 AM Monday to 3 AM PST Tuesday for
Pigeon Pt to Pt Pinos 10-60 NM.
&&
$$
SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Sarment
MARINE...RGass
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Area Forecast Discussion
National Weather Service Pocatello ID
154 PM MST Sun Dec 24 2023
.SHORT TERM...THIS AFTERNOON THROUGH MONDAY NIGHT...
Have no fear...the weather won`t keep Santa out of southeast Idaho
tonight! A ridge of high pressure will support quiet and dry
conditions from this afternoon right through Christmas Day, with
high temps running about 5 degrees below climatology (lower 20s to
lower 30s) and lows closer to 10 degrees below climatology (single
digits and teens and colder still in the Stanley and Copper basins).
High pressure following departing storm systems this time of year of
course means fog and low stratus concerns. As expected, fog was
quite localized this AM, although briefly dense where it did occur.
The overall airmass looks fairly similar tonight with both the NBM
and HRRR supporting a repeat of patchy development from the Snake
Plain, Arco Desert, and Mud Lake corridor eastward into some valley
locales between I-15 and the WY border. Have again been generous in
adding patchy freezing fog to the forecast for these areas from 7 PM
tonight to 11 AM Christmas Day, but this will be the only hazard
we`ll contend with and it shouldn`t be terribly widespread.
Confidence in development is high, although exact placement of those
dense pockets is not...portions of I-86 between American Falls and
Chubbuck, I-15 between Blackfoot and Roberts, the INL, and US-20
south of Island Park may again be among the candidates. Again, no
fear though...Santa has experience navigating such conditions.
Plus...you know...Rudolph. - KSmith
.LONG TERM...TUESDAY THROUGH NEXT SUNDAY...
The extended portion of the forecast remains rather uneventful
overall. A shortwave moving well north of the area on Tuesday may
allow just enough moisture to sneak into the region to support some
isolated to scattered snow showers, mainly in the higher terrain,
but QPF is very low and no major impacts are expected. Otherwise,
high pressure looks to continue to control sensible weather for
much of next week. Another weak shortwave passing north of the
area on Thu could spark a few snow showers but most areas, once
again, will likely remain dry as this feature appears equally
unimpressive to the first one. Late in the period, models aren`t
in very good agreement with the U/L pattern across the western
U.S. so for now, will keep with NBM forecast that introduces low
end PoPs region wide with temps on the warm side of normal by a
few degrees. In short, no high-impact weather systems are expected
with temps gradually warming as the week progresses. - McKaughan
&&
.AVIATION...
VFR conditions finally prevailing at all regional terminals after a
prolonged period of low clouds and fog at KPIH, KIDA and to a lesser
extent, KDIJ. Winds through the period will be light under high
pressure. Given the status quo weather pattern, wouldn`t be
surprised to see BR/FG development once again at KPIH and KIDA as we
near sunrise Monday morning. Models are definitely more aggressive
with it tonight than they were this morning so I suppose confidence
in development is a bit higher so already have mention of this in
the forecast. - McKaughan
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
500 PM MST Sun Dec 24 2023
.UPDATE...Updated 00Z Aviation Discussion.
&&
.SYNOPSIS...
A gradual warming and drying trend is expected this week in the
wake of the low pressure system that produced widespread rainfall
across the Desert Southwest. Some areas of dense fog will be
possible again Monday morning, which could make travel hazardous
in spots, particularly across southeastern California and southern
Arizona. A return to slightly above normal temperatures is
expected late in the week as high pressure predominates across the
intermountain West.
&&
.DISCUSSION...
Areas of dense fog and low clouds were prevalent across the lower
deserts this morning and continue to dissipate this afternoon.
Latest RAP streamline analysis and water vapor imagery reveal a
somewhat drier northwesterly flow. However, at the surface
conditions remain exceptionally moist in the wake of the
widespread rainfall that fell Friday. Dewpoints have changed very
little over the past 24 hours and remain in the upper 40s and
lower 50s. With the anomalous low-level moisture in place,
temperatures were slow to rise through the 50s though near normal
high temperatures in the 60s are expected this afternoon.
Areas of dense fog will again be the main weather hazard through
tomorrow. Although the low-level moisture will begin to scour out,
particularly across Mohave and San Bernardino counties as well as
the lower Colorado River Valley, conditions will again be
favorable for fog development again further south across portions
of southern Arizona and southeastern California Monday morning.
The forecast is weighted heavily towards the HREF mean, which
depicts the greatest threat across Pinal, Maricopa and Imperial
Counties. The HREF indicates there is a 20-50% chance visibilities
will fall as low as one quarter of a mile in these areas, which
could result in hazardous driving conditions.
Cooler, drier conditions will lead to some chilly morning
temperatures for the start of the new week as some of the colder,
sheltered areas may see lows dip to near freezing readings. NBM
probabilities for freezing temperatures peak upwards of 40-60% by
Tuesday/Wednesday mornings for places such as Casa Grande and
Arizona City with elevated probabilities present for Globe and San
Carlos in southern Gila County. Elsewhere across lower desert areas,
lows will generally bottom out in the lower 40s through the first
half of the week.
Ensembles remain in good agreement that an amplified upper level
ridge will build across the western CONUS by the middle part of the
week. This will translate into continued dry conditions along with a
gradual warming trend for the second half of the week. Near to
slightly below normal high temperatures in the low to mid 60s during
the first part of the week will climb into the upper 60s to around
70 degrees for the latter part of the week. Forecast uncertainty
increases by next weekend as global ensembles indicate the potential
for more troughing in the eastern Pacific. For now, dry conditions
are favored to persist through the week.
&&
.AVIATION...Updated at 2356Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The primary aviation weather concerns through the TAF period will
be the potential for another round of patchy fog Monday morning.
SCT-FEW clouds at 3,000-5,000 feet are lingering around the
Phoenix metro, but expect periods of clear skies through the
evening. Model guidance is hinting at the potential for another
round of patchy fog developing by early Monday morning, especially
across southern portions of the Phoenix metro area, affecting
primarily KPHX and KIWA with around a 20% chance of MVFR and lower
visibilities. Any fog that does develop Monday morning is expected
to be more patchy and isolated than what we saw this morning.
Clouds are expected to gradually lift and clear out throughout the
day on Monday. Winds during the period will follow diurnal
tendencies with light speeds aob 5 kts.
Southeast California/Southwest Arizona including KIPL and KBLH:
Model guidance is hinting at the potential for another round of
fog developing early Monday morning, mainly at KIPL, with a 20-40%
chance of MVFR and lower visibilities. The models are also hinting
that the densest fog and lowest visibilities may stay just east of
the KIPL terminal. Winds are expected to remain light and variable
at KIPL through the TAF period. At KBLH winds will also be light
but favor a northerly component. With the exception of any fog
development in the morning skies are expected to remain clear
through the TAF period.
&&
.FIRE WEATHER...
Drier conditions will continue to prevail through the week as
rain chances have now come to an end. Min RHs today will generally
be around 50-60% for most areas before falling to around 25-45%
Monday. Light winds are favored to continue, though some breezy
northerly winds will be possible Monday down the Lower Colorado
River Valley. Temperatures to start off the new week will remain
near to slightly below normal before warming up during the latter
half of the week.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Hirsch/Smith
AVIATION...Berislavich/Lojero
FIRE WEATHER...Smith
Area Forecast Discussion
National Weather Service Salt Lake City UT
325 PM MST Sun Dec 24 2023
.SYNOPSIS...High pressure will build over the area through
midweek. A series of weak storm systems may impact the area at
various points next week with another system potentially moving
into the area into next weekend.
&&
.SHORT TERM (Through 12Z/5AM Tuesday)...Ensemble and deterministic
solutions are in generally good agreement through the period in
their relative depictions of fairly steady-state cold, dry, deep-
layer northwest flow remaining largely in place. This will ensure
that temperatures remain ~5F-10F below normal at the start of the
period across Utah and SW Wyoming while temperatures rebound to
near normal levels across southern Utah by the end of the period.
Just enough boundary layer moisture remains in place to support
some stratocumulus plumes off of area lakes such as Utah Lake, the
Great Salt Lake and Bear Lake early this afternoon, with a few
orographically-enhanced clouds anchored to terrain features across
northern Utah as well. Model cross-sections suggest a gradual
decrease in boundary layer moisture as we head through tonight,
suggesting that the bulk of this cloud cover will diminish.
Otherwise, high clouds will be on the increase from the northwest
tonight. Expect temperatures to drop down into the upper teens to
around 20 across the Wasatch Front tonight, with single digit lows
in other higher elevation mountain valleys. These lows will rival
some of the coldest values we`ve seen so far this season. With
little to no wind, apparent temperatures are forecast to remain
just above extreme cold criteria for most areas.
With a weak shortwave expected to move through the area from
northwest to southeast Monday, and another similar wave on
Tuesday, model soundings generally suggest these waves will
prevent strong inversions from developing, as Utah and SW Wyoming
remain on the periphery of a building Great Basin ridge.
.LONG TERM (After 12Z/5AM Tuesday)...Model solution space is
well-clustered around the idea of building the above-mentioned
ridge across Utah and SW Wyoming as we head into the late Tuesday
through early Friday timeframe, and it is during this period when
inversions are forecast to strengthen. Until then, a modest wing
of mid-level warm advection coupled with a weak shortwave
cresting over the building ridge axis may bring a few snow
showers to mainly high terrain areas of northern Utah on Tuesday.
Just over half of the solution space now brings a few hundredths
of an inch of liquid equivalent precipitation to these areas on
Tuesday. However, just under half of ensemble members remain dry,
suggesting measurable precipitation is not yet a sure bet at this
point.
In the Friday-Saturday timeframe, solution space is fairly well-
clustered around the idea that deep-layer southwest flow will
begin to develop across the area as the ridge begins to move off
to the east. This may open the door to renewed precipitation
chances, as just over half of ensemble members from the GEFS, EC
and Canadian advertise measurable precipitation, especially over
high terrain areas. CW3E plots suggest very low values of IVT,
however, suggesting moisture quality will be rather paltry.
Ensemble QPF bears out this notion, with no one day forecast to
receive more than 0.10" of QPF -- even across the mountains. There
is a cluster here and there that does advertise 0.10"-0.25" by
the time we get into next weekend, representing those solutions on
the wet end of the spectrum. For the snow lovers out there, we
don`t see a much to get too terribly exited about over the next 7
days. Otherwise, models are well-centered around the idea of
building a modest warming trend into the area from late week into
next weekend as a result of the developing SW flow regime.
&&
.AVIATION...KSLC...Light winds and VFR conditions are forecast
through Christmas Day. Some low level moisture lingers which is
forecast to bring a few clouds between 4 and 6,000 ft AGL.
.REST OF UTAH AND SOUTHWEST WYOMING...Light winds and VFR
conditions are forecast across the region resulting from high
pressure. Fog is not currently to redevelop at LGU tonight or
tomorrow as most short term are forecasting decreased amounts of
moisture in the low levels. This stated, the HRRR is one short term
model that is forecasting fog redevelopment tonight and it is very
aggressive in the fog development. If the model is correct in its
prognosis, expect fog at and after midnight, resulting in IFR
conditions.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
ADeSmet/NDeSmet
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity
Area Forecast Discussion
National Weather Service Tallahassee FL
944 PM EST Sun Dec 24 2023
...New UPDATE, MARINE...
.UPDATE...
Issued at 907 PM EST Sun Dec 24 2023
Evening satellite and radar show swaths of rain showers
overspreading parts of the Tri-State area ahead of a frontal
system centered around the Northern Gulf Coast. A tightening
pressure gradient combined with a an apparent low-level jet (~40
kts at 2kft via KEOX/KEVX) will make for breezy conditions
overnight, especially along the Emerald-Forgotten coasts and
offshore where wind hazard headlines are active. The 0Z KTAE
sounding shows that the air column has moistened considerably with
Precipitable Water doubling from 12 hrs ago and southeast winds
just above the surface ranging from 25-30 kts. Meanwhile,
instability remains weak at this point, so inland thunder remains
away from the forecast.
Tonight`s rain chances were refined to account for current radar
trends and the 0Z HRRR run. The latter depicts a temporary lull
over the next 2-3 hrs before upstream convection attempts to
organize and arrives from the west around 7 or 8Z. However, a meso
surface low appears to develop over MS, then races northeastward
across the Wiregrass while a convective cluster or line "detaches"
and moves eastward with the strongest activity extending from
south of I-10 to over the Gulf. The exact placement of a maritime
warm front will dictate how much/where instability gets realized,
which aims to stay mostly offshore. That said, if we can get some
overlapping of instability with the strong low-level shear, then
an isolated strong to perhaps severe storm capable of a damaging
gust or tornado is possible near the coast.
&&
.NEAR TERM...
(Through Monday)
Issued at 244 PM EST Sun Dec 24 2023
A large upper level trough west of the area will affect us over the
next 24 hours with increasing rain and a slight chance of
thunderstorms. The local area will be in the favorable left exit
region of the subtropical jet with a decent low level jet of 40-50
knots developing across the Florida panhandle late tonight as well.
Some models such as the 06z GFS, 12z GFS, and 12z NAM indicate an
even more robust low level jet developing with MCS development just
offshore, and this will have to be monitored. The limiting factor to
a severe weather threat will be instability, with guidance showing
only meager instability making it to the coast while the shear is
most favorable. This limited instability is what is precluding SPC
from introducing any severe risk. However, if instability does
manage to make it just inland from the coast while the shear is
maximized, then a tornado or two could occur near the coast. The
most likely time for this is expected to be in the 5am-10am CT
window. In addition, windy conditions are expected at the beaches
with gales blowing onshore from late tonight through Monday morning.
A wind advisory is in effect from coastal Walton county eastward to
coastal Franklin county.
Later in the day, the low level jet is expected to weaken somewhat,
and widespread rain is likely inland. With all the cloud cover and
rain expected, high temperatures are expected to be held down in the
mid 60s to near 70.
&&
.SHORT TERM...
(Monday night through Tuesday night)
Issued at 244 PM EST Sun Dec 24 2023
The biggest concern in the short term appears to be the potential
for fog Monday night. Several models and MOS guidance are indicating
the potential and it makes sense. Winds are forecast to go calm to
nearly calm following the rain on Christmas as the pressure gradient
weakens. Couple that with dew points remaining in the lower to
middle 60s and a clearing sky, and fog should be able to form in
some capacity. The biggest questions are how widespread it becomes
and how dense it can get.
Otherwise, the rest of the forecast is fairly ho-hum with a weak
area of high pressure building into the southeast leading to drier
conditions for Tuesday. Overnight lows generally near 60 are
anticipated Monday night with daytime highs climbing into the upper
60s to lower 70s. It`s worth noting that if fog is able to hold on a
little longer than currently expected that temperatures could trend
a little cooler Tuesday afternoon. Slightly cooler air begins to
work in Tuesday night with lows dipping into the upper 40s to middle
50s, which is still above normal for late December.
&&
.LONG TERM...
(Wednesday through Saturday)
Issued at 244 PM EST Sun Dec 24 2023
Cooler conditions are expected later this week and into the final
days of 2023. Daytime highs drop from the middle to upper 60s
Wednesday afternoon to the 50s the rest of the period. Overnight
lows follow a similar path with upper 30s across the Wiregrass to
near 50 in the southeastern Florida Big Bend Wednesday night to the
30s for everyone Thursday night and beyond. No rain is in the
forecast at this time.
All of this is thanks to a huge cut-off H5 low that will finally
begin moseying east during the period. As it does so, it will send a
reinforcing cold front later Wednesday night into Thursday, sending
temperatures below normal for the final days of the year.
Temperatures at 850mb are generally forecast to remain between -5C
to 0C, which supports daytime highs generally in the 50s. If there`s
a bit more cloud cover than currently anticipated, some locations
may not even break out of the 40s!
&&
.AVIATION...
(00Z TAFS)
Issued at 622 PM EST Sun Dec 24 2023
Conditions will continue to deteriorate from west to east,
becoming MVFR/IFR as the night progresses. Winds will strengthen
and become gusty, gaining a southerly component as time
progresses. Showers will begin to taper from west to east late in
the period as winds relax.
&&
.MARINE...
Issued at 907 PM EST Sun Dec 24 2023
The Orange Beach buoy (42012) is reporting a sustained 27-kt east
wind with a gust of 35 kts and 10-ft waves. These gale conditions
should spread eastward towards the western waters later tonight.
Recent hi-res guidance shows convectively induced gusts in excess
of gale force spreading as far east as waters out to Ochlocknee
River Christmas morning. Observations will have to be monitored
closely to see if the current Small Craft Advisory east of
Apalachicola need to be upgraded or extended to cover the
nearshore legs of the Nature Coast. For the evening update, a
blend of the 0Z HRRR and latest NBM were used on the winds to
better capture current trends.
From the CWF Synopsis...A tightening pressure gradient ahead of
an incoming storm system will make for continued deteriorating
conditions tonight as southeast winds increase to high end
advisory levels with frequent gale force gusts likely over waters
west of Apalachicola. Widespread showers are moving from the west
and forecast to organize into a convective line or cluster capable
of strong gusts or waterspouts into Christmas Day through
Apalachee Bay where a Small Craft Advisory is in effect up to the
Ochlocknee River. Isolated thunderstorms could be strong in the
offshore waters. Winds and seas quickly subside Christmas night
into Tuesday as the pressure gradient weakens. More favorable
marine conditions are anticipated the rest of the week with
cautionary levels possible Thursday behind a reinforcing cold
front.
&&
.FIRE WEATHER...
Issued at 244 PM EST Sun Dec 24 2023
East to southeast winds will remain in place through Christmas day
along with an increase in rain and perhaps an isolated thunderstorm.
The cold front will move through on Tuesday with winds becoming
northwesterly. There are no fire weather concerns through Tuesday.
&&
.HYDROLOGY...
Issued at 244 PM EST Sun Dec 24 2023
Generally less than 1 inch of rain is now anticipated through
Christmas night. That said, there is an outside chance of a couple
of inches of rain near the coast, but that appears to be the
reasonable worst case scenario. If the heavier rain rates
materialize, then there could be some nuisance flooding. The Weather
Prediction Center (WPC) has a Marginal Risk (level 1 of 4) for
Excessive Rainfall for Christmas Day.
As far as the rivers are concerned, the Aucilla, Econfina, and
Fenholloway Rivers continue to slowly fall through minor flood
stage. The rainfall over the next couple of days isn`t forecast to
cause any additional impacts on the rivers.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 62 67 62 71 / 80 100 30 20
Panama City 62 69 60 68 / 100 90 20 20
Dothan 60 67 59 67 / 100 100 20 20
Albany 61 66 60 70 / 90 100 40 20
Valdosta 61 69 62 71 / 60 100 50 20
Cross City 61 69 62 72 / 50 90 50 20
Apalachicola 64 67 60 66 / 100 100 20 20
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Monday evening for FLZ108-112-114-
115.
High Surf Advisory from 1 AM EST /midnight CST/ to 7 PM EST /6
PM CST/ Monday for FLZ108-112-114-115.
Wind Advisory from 1 AM EST /midnight CST/ to 9 AM EST /8 AM
CST/ Monday for FLZ108-112-114-115.
GA...None.
AL...None.
GM...Small Craft Advisory until 9 PM CST this evening for GMZ750-752-
770-772.
Small Craft Advisory from 6 AM to 6 PM CST Monday for GMZ750-752-
770-772.
Gale Warning until 6 AM CST Monday for GMZ750-752-770-772.
Small Craft Advisory until 7 PM EST Monday for GMZ755-775.
&&
$$
UPDATE...IG3
NEAR TERM...DVD
SHORT TERM...Reese
LONG TERM....Reese
AVIATION...Humphreys
MARINE...Reese/IG3
FIRE WEATHER...DVD
HYDROLOGY...Reese