Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/17/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
901 PM CST Thu Feb 16 2023
.UPDATE...
Issued at 856 PM CST Thu Feb 16 2023
No major changes to the forecast this evening. Did adjust sky
grids to reflect clear skies based on latest satellite trends.
Current lows seem in the ballpark as we start creeping towards 0
and the single digits below zero across eastern areas under light
winds before the southerly winds kick in late. Still some
potential for fog showing up in models in the James valley and
just west of there, so will continue to monitor trends.
&&
.SHORT TERM...(This Evening through Friday Night)
Issued at 133 PM CST Thu Feb 16 2023
This afternoon, a few clouds and flurries are making their
way south through eastern SD. This has more to do with the clouds
being right in the DGZ rather than the forcing from the passage of a
shortwave in the trailing upper trough. Surface high pressure will
continue to dominate through tonight as it settles over the eastern
forecast area. Upper ridging will build in tonight, and that
presents a forecast challenge for temps tonight as we have waa
pushing in from the west with light winds and good radiational
cooling under the sfc high. Blended a little cooler with the HRRR
over areas with fresh snow in the east.
On Friday, the waa really takes hold with H85 temps rising to 0C
across central SD. Mixing will also increase as a dry sfc trough
swings through. By the end of the day, H85 temps rise to +2C in and
ahead of the trough, aided by southwest to westerly sfc flow. This
will push temps up into the 30s across most of the east and towards
50 degrees in snow-free areas of central SD. Downsloping will also
develop along the Coteau with gusts up to 40 mph possible in the
morning through early afternoon. Patchy to areas of blowing snow may
reduce visibility before temperatures rise above freezing.
Some cooler air will squeak back into the northeast and west central
MN on a back door cold front Friday night. Some cloud cover will
prevent temps from really tanking, but they could fall lower than
the current forecast in the teens.
.LONG TERM...(Saturday through Thursday)
Issued at 133 PM CST Thu Feb 16 2023
Summary: Mild readings still expected for the weekend, and now into
the start of next week, before arctic air is dislodged by a
clipper, before interacting with a potential mid week winter storm.
We start out with a weak broad trough overhead, no real shortwaves,
though the arctic boundary will be wobbling across the northern
plains. This boundary has a rather weak gradient at this point,
however Sunday across the eastern half of the CWA we will see a shot
at some colder air behind a backdoor front. Just some low POPs at
this point across the northern tier of the CWA Sunday afternoon with
some low level instability showers in the CAA regime.
A brief warm advection push is noted ahead of a clipper that zips
through North Dakota/Minnesota. Not a lot of moisture potential with
the system given the track has most of the moisture well to the
north, however on the backside of the system, Arctic air is forced
southwards. NBM shows a wider spread for highs Monday compared to
this time yesterday (though, NBM has added to the warmer end of the
spectrum specifically). 850mb temperatures drop from 0 to -3C Monday
18Z to -10 to -15C by Wednesday 00Z. It should be noted that even
colder air follows for the latter half of the week.
As for the system that follows mid-week, yes there is still a
digging trough out west that ejects some form of Colorado type low.
The 12Z GFS and 00Z/12Z EC are in fairly good agreement at these
timescales, with the bulk of TROWAL precipitation over South Dakota
into central Minnesota. The GEFS plumes show a wide array of QPF
outcomes however, and it should be noted the deterministic GFS falls
on the higher end of the 0.01 to 1.20 inch QPF range. As for EC
ensemble members, only a handful fail to produce much moisture.
Thus, there is fairly good evidence for potentially impactful
weather with this system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 529 PM CST Thu Feb 16 2023
Terminals KABR,KATY,KPIR,KMBG
VFR conditions are currently forecast through the TAF period. Like
last night, there are some indications of the possibility of IFR
conditions in BR/FG and low CIGs near KABR late tonight into
Saturday morning. But with confidence low once again, will only
mention SCT wording for CIGs and continue to monitor satellite
trends throughout the night. Will amend TAF forecast if changes
are needed.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...TMT
SHORT TERM...Wise
LONG TERM...Connelly
AVIATION...TMT
AREA FORECAST DISCUSSION
National Weather Service Albany NY
955 PM EST Thu Feb 16 2023
.SYNOPSIS...
A mild air mass will be over eastern New York and
western New England overnight. Scattered showers will develop ahead
of a potent cold front arriving late tonight into Friday morning
with some isolated thunderstorms possible. Rain will change to a
wintry mix, particularly over the higher elevations north of
Interstate 90 late Friday morning before ending around the early
evening. Some snow and ice accumulations may lead to hazardous
travel in those areas. Noticeably cooler, but seasonal temperatures
return behind the front by Friday night before moderating again
Sunday and Monday.
&&
.NEAR TERM /THROUGH FRIDAY/...
Winter Weather Advisory in effect for Northern Herkimer,
Hamilton, Northern Warren, and Northern Washington Counties
from 1 AM to 7 PM EST Friday...
.UPDATE as of 953 PM EST...The KENX radar has become quiet with
just some isolated showers or sprinkles over the forecast area.
A weak sfc trough will push north in the southwest flow aloft,
as the main frontal boundary will be lifting northward from the
lower Hudson Valley, PA, and southern New England overnight.
Some weak isentropic lift will increase overnight for some
showers to start to increase again between 06Z-10Z north and
west of the Capital Region. As the low pressure system
approaches from the west with its cold front between
09Z-12Z/FRI, as the threat for isolated thunderstorms increases
with modest MUCAPEs of 100-300 J/kg and negative Showalter
indices of zero to -3C. We increased the slight chance of
thunderstorms to just north and west of the Capital Region. It
may need to be expanded later further east. A strongly forced
line of gusty showers and embedded thunderstorms may move
through in the late morning/early pm based on some of the CAM
runs (3-km HRRR and NAMnest). Temps will be steady or slightly
rise overnight with lows in the 30s to mid 40s. Some spotty
light mixed pcpn looks like it will hold off close to daybreak
in the advisory area.
.PREV DISCUSSION [0632 PM EST]...
Isolated to scattered light rain showers associated with a
short-wave in southwest flow aloft and the warm advection with a
frontal boundary lifting northward across PA, NJ and southern
New England towards upstate NY continue to move off to the north
and east of the forecast area. Some isolated/widely scattered
showers will linger early this evening, but overall mainly
cloudy and milder conditions will persist with lows in the mid
30s to mid 40s but temps will then steady or rise with
increasing south to southwest winds, as warmer air streams in
ahead of the approaching wave and cold front. We updated the
PoPs based on the latest radar trends and the 3-km HRRR and
Namnest. We also added a slight chance of thunderstorms in the
early morning hours over the western Adirondacks/western Mohawk
Valley/northern Catskills with negative Showalter values of 0 to
-3C ahead of the cold front in the warm sector between
09Z-12Z/FRI. This may need to be expanded more with later
updates.
The previously cutoff low aloft has opened into a shortwave
trough to its northeast, resulting in a very positively tilted
upper trough tracking eastward across central portions of CONUS.
A surface low has developed beneath this upper support near the
confluence of the Ohio and Mississippi Rivers, and is expected
to track northeastward toward northwest portions of the forecast
area. While the region remains within the broad warm sector of
this cyclone, warm advection is far less robust today compared
to yesterday, which combined with persistent cloud cover, has
resulted in unseasonably warm temperatures that have nonetheless
fallen well short of daily records. Scattered warm sector
precipitation is now beginning to move into the Catskills and
Mid-Hudson Valley, and will continue to spread shower chances
north into the bulk of the forecast area into tonight. This
setup will allow temperatures to remain fairly steady through
the overnight hours with little diurnal variation which is
expected to break record high minimum temperatures across the
region tonight. Low temperatures will vary from the upper 20s in
the southwest Adirondacks to the low 50s in the far southern
Mid-Hudson Valley.
Precipitation coverage will increase from west to east overnight
as the cold front approaches the region from the west. With
temperatures well above normal values, precipitation will be all
rain throughout the region ahead of the front. However, behind
the frontal passage, gusty west-northwest winds and robust cold
advection will set in and cause temperatures to rapidly decline.
Precipitation will change over to wintry mix or snow before
ending Friday afternoon to evening. The southern Adirondacks and
Lake George Region will be favored for the highest snow
accumulations of up to two inches and ice accumulations of up to
a quarter inch, yielding potentially hazardous travel. Elsewhere,
a dusting or up to an inch of snow and sleet are possible with
little ice accumulation. High temperatures will be well above
normal values ahead of the frontal passage, ranging from the 30s
in northern zones to upper 50s to near 60F in the Mid- Hudson
Valley, but will occur fairly early in the day ahead of the
rapid cool down into the teens and 20s across the region by the
early evening.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
Broad surface high pressure beneath relatively zonal flow aloft
will build into the region from the southwest Friday night into
the weekend. Lows Friday will fall to near seasonal normals, but
will feel much colder than the recent mild temperatures, varying
from the single digits in the southern Adirondacks to low 20s in
the Mid-Hudson Valley. Tranquil weather will remain in place
through Saturday as temperatures rebound to somewhat above
normal values. Highs on Saturday will be in the mid 20s to low
30s in high terrain and mid 30s to low 40s at lower elevations,
while Friday night lows will largely be in the 20s across the
region.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Impactful weather, possibly involving snow or a wintry mix, could
occur late Wednesday into Thursday, with best chances for
a period of snow/mixed precipitation for areas mainly north of I-90.
Otherwise, chances for precipitation remain limited, mainly for late
Monday into Tuesday with a possible fast moving northern stream
disturbance passing by with perhaps some rain/snow showers.
Above normal temperatures are favored through at least Tuesday, with
highs mainly in the 30s/40s and lows in the 20s/30s Sunday morning,
and teens/20s Monday and Tuesday morning. Temperatures may trend
closer to normal levels Tuesday night into Thursday, although
lingering uncertainties in storm track could keep milder
temperatures farther north. Highs mainly in the 30s/40s although 20s
possible for northern areas, with lows generally in the teens and
20s.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00Z Sat...VFR conditions continue under stratus in an area
of weak forcing ahead of an approaching low pressure system. Area of
showers moved through earlier along a warm front aloft. For the next
several hours, little to no precipitation is expected, although a
couple of showers or patches of drizzle cannot be ruled out.
Ceilings will gradually lower as additional moisture is brought in
ahead of the approaching low. There is some uncertainty with how
fast MVFR cigs develop. This forecast used mainly 05-08Z, but some
guidance indicates that it could be earlier. IFR cigs are expected
to develop toward Friday morning (11-14Z timeframe) as precipitation
becomes steadier. A couple of heavier downpours are possible along a
strong approaching cold front in the 15-18Z timeframe which could
reduce visibilities to IFR levels, and a rumble of thunder and gusty
winds cannot be ruled out. A sharp wind shift will accompany the
front, with cigs rising back to VFR late Friday afternoon into the
evening in its wake, with showers diminishing as well.
Winds will be light and variable much of the night, increasing out
of the south at 5 to 10 kt late tonight into early Friday morning. A
period of low level wind shear is likely beginning around 12Z Friday
and lasting a few hours until the frontal passage. Along the front,
winds will turn sharply to the west-northwest (except northerly at
KGFL) with gusts to 25 kt for the remainder of the period.
Outlook...
Friday Night: Low Operational Impact. Breezy. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Washingtons Birthday: Moderate Operational Impact. Breezy. Chance of SHRA.
Monday Night: Low Operational Impact. Breezy. NO SIG WX.
Tuesday: Low Operational Impact. Breezy. NO SIG WX.
&&
.CLIMATE...
Record High Minimum Temperatures for Thursday, February 16th:
Albany 38/1984
Poughkeepsie 41/1954
Glens Falls 35/2006
Record High Maximum Temperatures for Thursday, February 16th:
Albany 61/2006
Poughkeepsie 72/1954
Glens Falls 61/1981
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory from 1 AM to 7 PM EST Friday for
NYZ032-033-042-043.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Picard/Wasula
NEAR TERM...Picard/Wasula
SHORT TERM...Picard
LONG TERM...KL
AVIATION...Thompson
CLIMATE...ALY staff
Area Forecast Discussion
National Weather Service Burlington VT
933 PM EST Thu Feb 16 2023
.SYNOPSIS...
Low pressure tracking from the Ohio Valley just south of the
forecast area will bring a wintry mix of rain, sleet, snow, and
freezing rain to the region tonight through Friday afternoon. Travel
will likely be difficult overnight and for the morning commute with
snow and ice covered roadways. Dry weather and seasonable
temperatures are expected for the weekend, followed by near to above
normal temperatures and a few chances for rain and snow next week.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 930 PM EST Thursday...Based on additional lightning
occurring near Toronto and new 00z NAM 3KM/12KM and HRRR have
including a slight chc of thunder along and mainly south of a
Potsdam to Saranac Lake to Burlington to MPV line for late
tonight into Friday mid morning.
Little change needed with mid evening update. Did continue to
tweak hrly temps based on obs, which indicate a slightly slower
arrival of 32F and colder air into northern NY and VT overnight.
Cooler air continues to bleed into our region on
north/northeast winds of 5 to 10 knots. In addition, delayed
arrival of higher pops by 1 to 3 hours, as timing in latest
guidance is a bit slower, but similar idea of heaviest/most
intense mixed precip arriving btwn 4 AM and 11 AM on Friday.
Given thermal profiles with cold shallow/dense air undercutting
warmer air aloft, best potential for an icy mix wl be northern
NY into the central/northern CPV and parts of northern VT on
Friday morning. Once again its not the amount of precip, but
timing of the heaviest 1 to 3 hour band of freezing rain/sleet
that wl have the greatest impact on the morning commute, along
with rapidly falling temperatures and the potential for a flash
freeze. Given the sharp temp drop expected, any lingering water
wl quickly freezing by mid to late morning acrs most of the fa,
while mixed precip changes to a period of snow before ending by
mid aftn. A challenging and very hazardous morning commute is
anticipated acrs parts of the area, including the
central/northern CPV, given the timing of the heaviest mixed
precip. Still would not be surprised of a few rumbles of
thunder, as we are already seeing pockets of lightning north of
Lake Ontario and another north of Lake Erie. Indicates the
elevated instability, along with the strong dynamics associated
with potent s/w energy crntly over the Ohio Valley.
Previous discussion below:
Little overall change has been made from the previous forecast
with the highlight for the next 24 hours being a mixed precip
event where moderate rain, snow, and ice is expected across the
region. A few refinements have been made to accumulations based
on the latest model guidance, but no changes in the advisory
area at this time.
The large-scale synoptic pattern features a robust low pressure
system currently moving into the Ohio Valley this afternoon, with
anomalous moisture noted as PWATs are progged to be above the 90th
percentile for mid-February, approaching 1" across our southern CWA
Friday morning, to around 0.75" along the Canadian border. The low
track is everything with this system, as a few days ago it looked as
if it would pass northwest of the region, and now is forecast to
basically track over Albany. This puts the BTV CWA in the crosshairs
of a complex low/mid-level thermal profile with north-northeasterly
winds in the St. Lawrence and Champlain Valleys driving sub-freezing
air below a warming mid-level airmass coming up from the south.
Given this, it`s expected that we`ll see just about every
precipitation type across our region tonight into Friday.
The onset of precipitation continues to trend later based on todays
NWP guidance, and now doesn`t look to move into northwestern NY
until after 8 PM, then slowly spreads into the Adirondacks and far
northern Champlain Valley around midnight. Much of central and
southern Vermont likely won`t see precipitation begin until the pre-
dawn hours on Friday, and southeastern Vermont not until around
sunrise. As for the ptype, trends in guidance have been toward
cooler solutions across the north, favoring snow and sleet at the
onset, and generally a sleet and freezing rain mix thereafter
through early Friday before colder mid-level air arrives from west
to east after sunrise and transitions all precip to snow by Friday
midday before ending in the afternoon. For central and southern
areas, south of the warm front, rain looks to be the dominant ptype
until the frontal passage, and while sections of Rutland, Orange and
Windsor counties will remain in the advisory for now, impacts look
to be be almost nil there.
Based on the expected ptypes discussed above, a reduction in ice
accretion has been made from the previous forecast, with a general
0.1-0.2" across much of northern New York, the Champlain Valley and
northern Vermont. Meanwhile, we`ve increased snow amounts across the
Canadian border and specifically along the Route 11 corridor, where
snow and sleet will likely accumulate to 3-5". Elsewhere a general
dusting south to 3" north is expected, and mainly post frontal
passage mid-morning Friday to early afternoon.
One additional note will be gusty northeasterly winds in the St.
Lawrence Valley from midnight to sunrise Friday where gusts may
exceed 30 mph at times, adding to the hazardous road conditions with
blowing precipitation. Winds will gust towards 25 mph post frontal
passage in the Champlain Valley as well on Friday.
Finally, snow showers will decrease in areal coverage heading into
Friday evening with a seasonably cold night on tap as temperatures
drop to slightly below normal values in the single digits and teens.
Modest north-northwesterly winds should preclude the development of
black ice, but it`s certainly something that can`t be ruled out.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 326 PM EST Thursday...Saturday will feature seasonable and fair
weather. For reference, typical highs are in the upper 20s to mid
30s for mid February. Saturday night will not be quite as cool as
Friday night as milder air moves in aloft, with 925mb temperatures
rising from -12C to -3C. A weak disturbance passing to our north may
bring a few flurries or scattered snow showers to our northern zones
overnight Saturday, but no weather impacts are expected.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 326 PM EST Thursday...The long term forecast generally features
benign weather. The warm up really goes up a notch on Sunday with
925mb temperatures climbing to +5C with temperatures rising into the
upper 30s to low 40s. A weak shortwave passing to our north could
bring some showers overnight Saturday into early Sunday, but no
weather impacts are expected and there will be plenty of clouds
along with mild weather on Sunday.
Monday will be even milder with mid 40s possible and breezy
southerly winds. A more significant cold front will cross the region
later Monday into early Tuesday, bringing temperatures back to
seasonal normal if not slightly below. The frontal passage will be
accompanied by mixed rain and snow showers, but given that the
colder air seems to be lagging behind the front, minimal weather
impacts are expected. Looks like we stay at or slightly below normal
through mid week with generally quiet weather. This is consistent
with CPC`s temperature outlook trending below to near normal for our
region in the 8 to 14 day time range. There might be a storm system
towards the latter part of the work week but given that we are still
7 days out, largely went with a blend of guidance.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00Z Saturday...VFR conditions will be rapidly shifting
to MVFR and IFR between 04Z and 06Z as low pressure tracks over
the region and brings a myriad of precipitation types.
Spotty precipitation is moving through the airspace over the
next couple of hours, which will lead to some lowering ceilings
but little impact. Steadier precipitation will develop first at
MSS towards 04Z, and gradually expand south and eastward
between 06Z and 10Z through the rest of the region. Ptype will
be mainly a FZRAPL mix until 12Z Friday when it will change to
SN and SNPL for the remainder of the period, although MPV and
RUT may stay on the warm side with southerly winds and
predominately rain. Vsby will be variable in precip, but mainly
MVFR trending IFR especially with heavier frozen precipitation
in the 10Z to 16Z period. Areas of LLWS are likely as well
through midday Friday, mainly across central/southern terminals.
Outlook...
Friday Night: Mainly VFR, with areas MVFR possible. Slight chance
SHSN.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. Slight chance SHSN.
Sunday: VFR. Slight chance SHRA, Slight chance SHSN.
Sunday Night: VFR. NO SIG WX.
Washingtons Birthday: Mainly MVFR, with local IFR possible.
Chance SHRA.
Monday Night: Mainly MVFR, with local IFR possible. Slight chance
SHRA, Slight chance SHSN.
Tuesday: VFR. NO SIG WX.
&&
.HYDROLOGY...
As of 326 PM EST Thursday...Although widespread flooding is not
anticipated at this time, area waterways will need to be
monitored over the next 24-48 hours as runoff from snow melt and
precipitation continues, potentially allowing for river ice
movement.
Much above normal temperatures will continue through today,
resulting in additional snow melt. Widespread precipitation
will move across the region overnight and persist through
Friday. However, much of this precipitation will fall as a
wintry mix across northern areas, while central/southern VT will
see rain through early Friday morning before changing over to
the wintry mix. Hence, while snowmelt will continue through
today across the region, northern areas should see runoff from
snowmelt and precipitation lessen overnight and Friday as
colder temperatures settle over the region. The northern streams
have the most ice cover and even a few isolated ice jams in
place, but overall threat for any ice movement or additional
jams will be limited to just the next 12-24 hours. Meanwhile,
central/southern sections have lesser ice cover and there should
be a more prolonged period of runoff from snowmelt and rain
before the cooler temperatures. Therefore some ice movement will
be possible on these waterways, though ice coverage and
strength should be limited enough to prohibit any widespread
concerns. That being said, with snowmelt and runoff expected,
especially in south central Vermont, some rivers may approach
bankfull; note that the current forecast from the NERFC shows
the Otter Creek at Center Rutland gage exceeding action stage
later Friday, which seems within the realm of possibility.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Winter Weather Advisory from 1 AM to 7 PM EST Friday for
VTZ001>009-016>018.
Winter Weather Advisory from 7 AM to 7 PM EST Friday for
VTZ010-011-019>021.
NY...Winter Weather Advisory until 1 PM EST Friday for NYZ026>031-
034-035-087.
&&
$$
SYNOPSIS...Lahiff
NEAR TERM...Lahiff/Taber
SHORT TERM...Chai
LONG TERM...Chai
AVIATION...Kutikoff/Lahiff
HYDROLOGY...WFO BTV
Area Forecast Discussion
National Weather Service Charleston SC
921 PM EST Thu Feb 16 2023
.SYNOPSIS...
A cold front will sweep across the area Friday. High pressure
will then return this weekend and persist into the middle of
next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Late this evening: The setup for tonight will feature the
forecast area sitting in the warm sector ahead of an approaching
cold front. The HRRR and HREF are in good agreement that nearly
all of the overnight period will be dry, with the line of
showers just ahead of the front arriving in the far western
zones right around or just after sunrise. The gradient will
maintain a warm southerly flow through the night and overnight
lows shouldn`t drop out of the 60s. One forecast issue to keep
an eye on will be the potential for fog to develop just off the
coast across the marine areas and perhaps advect inland along
the immediate coast. We have maintained patchy fog late tonight
as a result.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Friday: A cold front will swiftly move through the region and
move offshore by late afternoon/early evening. From model
guidance, showers will be possible ahead and along the front but
at this time, coverage does not seem widespread. Therefore,
lowered POPs slightly as some areas could receive little to no
rainfall. Interestingly enough, our high temperatures (upper
60s/mid 70s) for the day will likely be in the morning. Once the
cold front moves through, temps will drop. This will make for a
tricky temperature forecast. Otherwise, gusty winds are
expected across land areas. While there are some indications of
gusts greater than 25 knots across Lake Moultrie/Marion, have
opted to not issue a Lake Wind Advisory. Although, there could
be a need for one with later forecast updates. Low temperatures
will be in the mid 30s to low 40s.
Saturday and Sunday: In the wake of the cold front, high
pressure will build into the region. Cold air advection on
Saturday will support high temperatures in the 50s with lows in
the mid 30s to mid 40s. On Sunday, highs will be about 10-15
degrees warmer. Otherwise, there is no rain in the forecast for
the weekend and plenty of sunshine is expected.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
High pressure will generally prevail through Thursday and dry
weather is expected. Although, a weak front could linger in the
vicinity and there could be a few showers throughout the week.
High temperatures will warm each day and eventually be in the
80s by Thursday. Low temperatures will begin in the 40s and be
in the 60s by Wednesday night.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
The 00z TAF period begins with VFR conditions at KCHS, KJZI, and
KSAV. The first issue will be the potential for LLWS to develop
around or just after midnight and then persist through about mid
morning. Winds will then become gusty at least mid morning and
then continue through the rest of the period. A band of showers
is expected to move through the terminals, roughly in the 16-20z
time period. No thunder is expected at this time and the TAF`s
only advertise showers. We could see brief periods of MVFR
conditions with the showers and that is included in a TEMPO
group at each site.
Extended Aviation Outlook: VFR should return to the terminals
Friday evening and persist into Tuesday.
&&
.MARINE...
Southwest winds across the marine zones will gradually
strengthen tonight as a cold front approaches from the west.
Gusts across the nearshore Charleston County waters and the
outer GA waters should see frequent gusts around 25 kts by the
pre-dawn hours Friday morning. Seas will build to 3-5 ft by late
tonight.
One challenge tonight will be the potential for sea fog, along
with the location and timing of any sea fog pushing onshore.
Afternoon visible satellite and marine web cameras indicate that
the marine areas are free of sea fog. Surface dewpoints will
gradually rise into the low to mid 60s. Given nearshore water
temperatures in the upper 50s and winds turn parallel to the
coast, sea fog should develop over portions of the waters. The
gusty SW winds is expected to move the fog around, pushing
onshore from time to time. The forecast will feature a mention
of patchy fog over the waters and adjacent coast.
Friday through Tuesday: On Friday, a cold front will move
through the region followed by high pressure on Saturday. A
tight pressure gradient will lead to less than ideal marine
conditions. Small Craft Advisories will remain in effect into
Saturday for gusty winds and elevated seas. There are still some
indications that there could be isolated Gale Force gusts, but
have opted to not issue a Gale Watch at this time. After
Saturday, will improve to 10 to 15 knots and seas less than 5
feet.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory from 7 AM Friday to 7 AM EST Saturday for
AMZ330.
Small Craft Advisory from 1 AM Friday to 1 PM EST Saturday for
AMZ350.
Small Craft Advisory from 7 AM Friday to 1 PM EST Saturday for
AMZ352-354.
Small Craft Advisory from 1 AM Friday to 7 PM EST Saturday for
AMZ374.
&&
$$
NEAR TERM...BSH
SHORT TERM...RAD
LONG TERM...RAD
AVIATION...BSH/RAD
MARINE...NED/RAD
Area Forecast Discussion
National Weather Service Quad Cities IA IL
846 PM CST Thu Feb 16 2023
.UPDATE...
Issued at 841 PM CST Thu Feb 16 2023
The highly dendritic last gasp of the deformation zone passage is
now east of our counties in Illinois. We`re on target for expiring
the winter headlines, and have begun to scale back on messaging.
Drifting is ongoing, but visibilities are mostly over 5 miles, if
not 10, so blowing snow is not a major factor lingering after it
stops snowing.
Snowfall in that band was observed in the 1-3 inch range, and for
the Quad Cities, this has brought at least the Iowa side into the
expected event range, with locations in northern Scott county into
Cedar seeing 4-6 inches. Just to the west, Johnson county, which
remarkably stayed in the good band through the event, has seen 9
to 11.5 inches! It`s interesting to see how the wide range in the
NBM probabilities both seemed to verify though not with perfect
placement skill.
ERVIN
&&
.SYNOPSIS...
Issued at 205 PM CST Thu Feb 16 2023
Ongoing winter storm continues across the region, with some
impressive snowfall totals between 5 and 8 inches reported in the
Cedar Rapids and Iowa City metros. This has caused several
accidents on area roads today. A warm nose aloft as evident on max
wetbulb analysis on the SPC meso page and the 18z ILX sounding
has allowed rain, freezing rain, and sleet to fall this AM
southeast of a line from Keosauqua, through the Quad Cities, to
Sterling/Rock Falls. This greatly reduced snow amounts prior to
18z. Our 18z DVN sounding has a below freezing profile, with some
steep mid level lapse rates, and a 40-50% RH in the DGZ.
Increasing pressure gradient through the day has resulted in
strong north winds gusting over 30 mph at times.
Latest water vapor loops show upper level low rotating along the
IA/MO border, with a slight northeast track evident. Heavy snow
with snowfall rates between 1.5"-2"/hr was observed upstream in
central IA under the 25-30 dbZ radar echoes and 1/4 mile vsbys.
This will push east through the CWA this afternoon and evening.
&&
.SHORT TERM...(This evening through Friday)
Issued at 205 PM CST Thu Feb 16 2023
Forecast focus remains on the winter storm and any adjustments to
headlines and snowfall totals.
Latest radar mosaics and surface observations at 1pm show
widespread snow tracking east into eastern IA. An additional 1 to
3 inches will be possible along and north of a Fairfield to
Galesburg line. While we may not see 1.5"-2"/hr snowfall rates as
seen in central IA since the upper low continues to show signs of
weakening, the latest 12z HREF progs of 0.5"-1"/hr will bring
reductions in visibility and snow covered roads this evening.
Latest RAP omega and fgen progs also support a little weakening of
the incoming snow late this afternoon.
In addition, strong north winds gusting over 35 mph will continue
to bring significant drifting on east west roads, especially in
open and rural areas. For these reasons, decided to keep the
timing on the headlines as is with an expiration at 03z tonight.
Some of the headlines, particularly the far southern portions of
the advisory may be able to cancelled early once the bulk of the
snow moves out.
Tonight...snowfall will quickly exit the CWA prior to midnight
with diminishing clouds. Winds will also subside some, but should
remain in the 5-10 mph range to prevent temperatures from
completely bottoming out. Lowered mins a few degrees near the 25th
percentile of the NBM, which results in the single digits over
the new snowpack and lower teens elsewhere.
Friday...surface ridge axis will slide east overhead bringing a
sunny yet cold day. After a very cold start, highs will struggle
to get out of the 20s, especially over the new snowpack.
.LONG TERM...(Friday night through Thursday)
Issued at 205 PM CST Thu Feb 16 2023
Through much of the the weekend, a warm advection regime will
dominate, pushing highs above the freezing mark. Sunday, there is
some indications of a weak cool front with just a wind shift but
no real impact on temps as we mix into warmer air with zonal flow
aloft.
Next week, a very energetic pattern looks to setup over the CONUS.
Initially we`ll see NW flow with potential for a clipper system
or two early week. Thereafter, we`ll see a deeper western CONUS
trough around the middle of next week that will lead to the
potential for at least one stronger system shifting across the
Plains toward the Great Lakes. Will have to keep an eye on this as
the moisture input into the system has the potential to be
anomalously high, thereby supporting widespread moderate to heavy
precipitation possibly. Precipitation type and temperatures will be
dependent on the track of the system, and which side of the low
level thermal gradient we`ll reside on.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 529 PM CST Thu Feb 16 2023
The last heavy snow band is falling from Freeport Illinois down
through the Quad Cities and Burlington as of 5 PM, and will be in
that position through about 01z, before it moves east of the area.
This will force many change groups in the TAF forecasts between
00z and 03Z, as condition improve from LIFR/IFR to VFR. Winds will
be strong early in the period from the north to northwest, then,
as VFR conditions spread in by 03Z, winds will decrease to 14 to
20 kts. and by morning, light west to northwest winds are
expected.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Weather Advisory until 9 PM CST this evening for Buchanan-
Delaware-Des Moines-Lee-Van Buren.
Winter Storm Warning until 9 PM CST this evening for Benton-
Cedar-Clinton-Dubuque-Henry IA-Iowa-Jackson-Jefferson-
Johnson-Jones-Keokuk-Linn-Louisa-Muscatine-Scott-Washington.
IL...Winter Weather Advisory until 9 PM CST this evening for Bureau-
Hancock-Henderson-Henry IL-McDonough-Mercer-Putnam-Warren.
Winter Storm Warning until 9 PM CST this evening for Carroll-Jo
Daviess-Rock Island-Stephenson-Whiteside.
MO...Winter Weather Advisory until 9 PM CST this evening for Clark-
Scotland.
&&
$$
UPDATE...Ervin
SYNOPSIS...Gross
SHORT TERM...Gross
LONG TERM...McClure
AVIATION...Ervin
Area Forecast Discussion
National Weather Service Pocatello ID
204 PM MST Thu Feb 16 2023
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT.
A ridge of high pressure is set up over most of Idaho today and into
at least the first half of Friday. Mainly clear skies this evening
and early tonight will allow temperatures to drop quickly once again
and it will be quite cold for Friday morning. A few more clouds will
work their way into the area overnight and some low stratus and
patchy fog is expected to develop. It doesn`t look like enough cloud
coverage to insulate us from some dangerously cold wind chills once
again, but it does add some uncertainty to the forecast lows/wind
chills. That said, lows tonight into Friday morning will drop below
zero for most, though stay in the single digits above zero for the
"warmer" Magic Valley area and parts of the Southern Hills. In the
coldest areas, temperatures will drop to near 15 degrees below
zero with wind chills down to 15 to 30 degrees below zero in much
of the same areas as last night. Even with the uncertainty of
some increased cloud cover, have decided to go with another Wind
Chill Warning, though some included areas could be more marginal
than last night. We gradually warm through the day on Friday and
highs will be back in the 20s for many, but pushing into the low
to mid 30s in parts of the Magic Valley. A trough moving into from
the northwest will flatten the ridge in the second half of
Friday. This shifts us back to northwesterly flow aloft by Friday
night and sets the stage for potential weekend snow...
AMM
.LONG TERM...SATURDAY THROUGH NEXT THURSDAY.
A VERY active and potentially impactful wx pattern remains
expected in the long-term portion of the forecast. We`re
conceptually dividing the action into two pieces: First, a
progressive shortwave trough embedded in NW flow bringing snow Sat
eve through Sun afternoon (accumulations ranging from a light
coating at lower elevations to perhaps 4+ inches east of I-15),
possibly a break/lull in between systems Sun eve into Mon AM,
followed by (second) a large, sprawling, slow-moving, deep low
pressure center dropping in from the north (rotating down the back
side of a Canadian parent low) bringing long-duration snows Sun
night through at least Wed. BOTH systems have trended a bit wetter
in today`s guidance envelope. At this range there remains a
significant amount of uncertainty on how this second, stronger,
longer-duration systems evolves, with 500mb height cluster
analysis focusing a lot of that uncertainty on strength/amplitude
and how quickly this low tries to push SW toward the Pacific coast
(as shown in the 12z deterministic model runs), and the GFS is
significantly wetter than the ECMWF for most of the event, but a
few things on our minds so far: 1) Warmer temps Mon may make a run
at 40-50 degF from Pocatello west across Shoshone, Burley, and
Malta which would favor rain for the first day of this system and
cut down on snow accumulations there, BUT the most significant
precip looks to favor Tue/Wed when temps are cooler and more
supportive of snow everywhere, 2) Blowing/drifting snow could be a
widespread issue Mon-Wed with WSW winds gusting 30+ MPH, and 3)
The overall flavor of this system looks to target the
mntns/highlands near and east of I-15 for the most significant
accumulations, and gosh...the potential certainly exists to be
measuring snow in feet in some areas by Wed eve, especially from
mntn passes up into the backcountry. At least several inches of
snow will also be possible across lower elevations including our
Snake Plain population centers. SO, we encourage everyone to stay
tuned as the forecast evolves over the next few days, and bear in
mind that widespread travel impacts will be possible in the Mon-
Wed timeframe, perhaps especially Tue-Wed. We`ll dig into more
specifics on timing, accumulations, and winds as the event
approaches. 01
&&
.AVIATION...A building ridge of high pressure is expected to bring dry, mostly
sunny/clear, VFR conditions to all SE Idaho terminals for the next
48 hours or so, with light winds less than 10kts. Confidence in this
synoptic picture is high, with of course the only fly in the
ointment being can we pull off any fog and/or low stratus
development during the mornings. For Fri AM, signals in the guidance
are mixed, with the HRRR the most aggressive with development out
across portions of the Arco Desert region perhaps getting close to
KIDA. Consensus is best in this area being most favorable across all
models that generate any development, and the overall airmass
shouldn`t be radically different than what we saw this AM, so for
now have only hinted at things for KIDA with VCFG and SCT009 after
04z/9pm this eve through late AM Fri. Subsequent shifts will
continue to evaluate this potential. Otherwise, FEW to SCT high
clouds should cross the region overnight tonight into Fri AM. 01
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Wind Chill Warning from 11 PM this evening to 10 AM MST Friday
for IDZ052>054-058-061>064-066-067.
&&
$$