Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/15/20
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
921 PM EST Tue Jan 14 2020
.SYNOPSIS...
A stationary frontal boundary will remain over North Carolina
through Wednesday, as high pressure builds across the northern
mid-Atlantic. A cold front will cross the area early Thursday
morning. High pressure and dry weather will prevail Thursday
into Friday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 910 PM EST Tuesday...
Latest sfc analysis reveals a quasi-stationary frontal boundary
draped along and just north of the NC/VA border this evening. To
the west, a weakening cold front is crossing the Great Lakes
with high pressure situated over New England and extending south
into the mid-Atlantic.
Areas of fog, along with some lingering drizzle, have developed
along and north of the frontal boundary this evening. HREF probs
and Time-Lagged HRRR each showing a good chance for areas of fog
to persist along and west of I-95 overnight, though patchy fog
is likely all zones overnight. Forecast confidence not quite
there yet to go with any fog headlines for the overnight yet.
Hi-Res guidance does show persistent low VIS overnight. However,
NAM/RAP Condensation Pressure Deficits are both on the high
side overnight. Given some modestly drier air filtering in,
this could help to limit areal coverage to some degree and/or
result in a more shallow fog. So...will go with patchy/areas of
fog inland for now, and continue to monitor local traffic cams
and obs for the next few hours.
Nudged early morning low temps down a degree or two inland
overnight closer to HRRR/RAP numbers. Overnight lows will range
from the low 40s N to the low/mid 50s over NE NC.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
As of 200 PM EST Tuesday...
High pressure will largely be in place over the local area to
start Wednesday, keeping things dry. We`ll have to wait until
late in the day before the next cold front to our west moves
close enough to provide a chance of showers across the SW in the
afternoon, and then the possibility of widely scattered showers
across the entire area from 00z-06 Thu as the cold front
enters the area. After 06z Thu, drier air should begin to
infiltrate the area from NW to SE with only lingering showers
present at the coast. Will go with 25-40% PoPs across the S/SW
after 18Z Wed, then 20-40% PoPs (highest east) Wed evening, and
then slight chc PoPs (~20%) eastern areas 06-12z Thu. There will
be some sun to start the day Wed, especially along and north of
I-64 to the eastern shore, then clearing from NW to SE by early
Thu morning. Highs Wed from the mid 50s to low 60s. Lows Wed
night in the low/mid 40s N to the low/mid 50s S.
The cold front exits the area Thurs morning, pushing all the
moisture offshore early. CAA behind it drys out things quickly
as skies become mostly sunny. Increasing pressure gradient
results in a breezy to windy day. Still mild with highs in the
50s to low 60s.
Mostly clear and more seasonable Thu night and Friday as high
pressure builds into the area. Lows mostly in the upr 20s to low
30s Thu night. Highs Friday only in the upr 30s to low 40s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 345 PM EST Tuesday...
Clouds begin to thicken and lower Friday night in association
with an upper trough lifting from the plains across the upper
midwest early in the weekend. The attendant sfc low will develop
over the Ohio Valley and lift up into New England on Saturday.
Locally, a weak warm front will lift across the local area
Friday night, with some light overrunning moisture pushing
across the region by/after midnight Friday night, bringing the
potential for a period of light mixed/wintry pcpn over portions
the area.
With respect to timing, precipitation looks to be after midnight
Friday night into Saturday morning, with antecedent dry
conditions likely not allowing accumulating precipitation before
the pre-dawn hours. Have pushed back any PoPs until after
midnight Friday night. With respect to P-Type, precipitation is
likely to start as snow across the northern half of the area
early Sat morning. Farther south, GEFS does indicate potential
for some RA/SN at the start even across South central VA/Hampton
Roads...while the new 12z/14 ECMWF...its ensemble mean and a
majority of its ensemble members are slower to moisten llvls
into the late morning/aftn Sat, likely precluding much in the
way of any P-Type issues. For the moment, have included a R/S
mention at the outset, but anticipate any issues away from the
far NW zones to be minimal at worst given the fact that temps
are likely to warm quickly Sat morning. Held on to snow mention
longer across far inland zones (ern Piedmont), with some R/S
issues potentially persisting into midday Sat, tapering off
briefly before showers re-develop Sat evening as front crosses
the area.
Post-frontal, early next week characterized by clear/dry and
more seasonable (colder) conditions. Cold, Canadian high
pressure will build across the plains over the weekend and
slowly build in our direction into the middle of next week.
Highs in the mid 40s to mid 50s Sat, in the mid 40s to lower
50s Sun. Cooler highs in the mid-upper 30s to lower 40s Mon/Tue.
Early morning lows will be in the mid 20s to mid 30s Fri night,
in the 30s to around 40 Sat night, and in the 20s inland, upper
20s to lower 30s Mon/Tue mornings next week, though some lows in
the mid to upper teens possible in typical cool spots Mon/Tue
mornings.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
As of 720 PM EST Tuesday...
IFR/LIFR CIGS across area terminals will linger through the
overnight hours and into the day on Wednesday. Hi-res guidance
does indicate a chance for brief improvement before midnight
this evening with developing stratus due to light winds/abundant
low level moisture. However, any short-lived improvement
expected to give way to deteriorating conditions once again
overnight, with periods of DZ also possible this evening at
RIC/SBY. High confidence for IFR/LIFR CIGs and VSBY overnight
for RIC/SBY...with lower confidence along the SE coast from ORF
to ECG, which will likely bounce around a bit between IFR/LIFR
CIG/VSBY overnight. Expect Fog to improve quickly after sunrise,
though CIGs could take a bit longer into the morning Wed before
improving all terminals.
OUTLOOK... There is another chc of rain later Wed aftn/evening
as another wave of low pressure tracks across the area. A cold
front crosses the area Wed night, with dry high pressure
building into the region Thurs/Fri. Low pressure approaches from
the W late Fri night into Sat and pcpn could begin as a
rain/snow mix at RIC/SBY.
&&
.MARINE...
As of 710 PM EST Tuesday...
Marine Dense Fog Advisory now in effect for all marine zones
until 7 AM EST (12 UTC). Automated weather sensors and web
cameras continue to indicate widespread visibilities of 1 NM or
less across the waters. Visbilities will linger at 1 NM or less
at times through tonight before conditions gradually improve
Wednesday morning.
Previous Discussion: Generally quiet marine conditions this
afternoon as hi pres well offshore extends wwd into the SE
coastal states. A nearly stationary front remains draped INVOF
far srn waters this afternoon and will settle S tonight. VRB
winds aob 10 kt become NNE late. Waves on the bay avgg 1-2
ft...seas 2-4 ft.
Weak sfc hi pres builds over the waters Wed morning then quickly
shifts off the coast Wed afternoon. Lo pres will track through
the lower Great Lakes late Wed then into the NE states Wed night.
Its training cold front crosses the waters early Thu to be followed
by moderate low level CAA/NNW winds and the next round of SCAs.
As is usually the case in these situations...before sfc hi pres
reaches/builds over the waters...there are at least two surges
of CAA. The second one this time (potentially a bit stronger
than the first) is expected Thu night. After review of model
guidance/wind probs...coordination w/ PHI and past two CAA
events...will raise a Gale watch for the nrn ocean waters (run
from 12Z/16-11Z/17) where highest prob for at least gusts to
35-40 kt. Elsewhere...(right now thinking) ocnl gusts to 35 kt
are a possible but would be covered in a SCA. Seas expected to
build to 5-7 ft...waves (bay) 3-5 ft. SCAs would likely be
needed for the VA rivers and sound (w/ a later forecast
package).
Winds/waves/seas decrease through Fri afternoon as sfc hi pres
does finally reach the local waters...(seas may remain elevated
on the srn ocean waters into early Sat). SCA conditions are
possible again by Sat afternoon in southerly flow ahead of the
next area of lo pres and trailing cold front.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Dense Fog Advisory until 7 AM EST Wednesday for ANZ630>638-650-
652-654-656-658.
Gale Watch from Thursday morning through late Thursday night
for ANZ650-652.
&&
$$
SYNOPSIS...JDM
NEAR TERM...JDM
SHORT TERM...JDM/MPR
LONG TERM...MAM
AVIATION...JDM/MAM
MARINE...AJB/ALB/RHR
Area Forecast Discussion
National Weather Service La Crosse WI
927 PM CST Tue Jan 14 2020
.UPDATE...
Issued at 919 PM CST Tue Jan 14 2020
A glaze of ice is still expected for areas along and south of
Interstate 90 from late tonight/early Wednesday morning into early
Wednesday afternoon. Per latest RAP guidance, still some questions
on where exactly the cutoff line between mostly freezing drizzle
and mostly snow will be (i.e. where in-cloud ice will be present
vs. where it won`t). Either way, still expect the I-90 corridor to
see some travel impacts. Therefore, with precip moving in during
commute time and being expected to impact highly traveled roads,
have opted to expand the Winter Weather Advisory to include Mower,
La Crosse, Monroe, and Juneau Counties. Have also modified the
start time for several counties to better align with expected
precipitation onset.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 230 PM CST Tue Jan 14 2020
A cold front moved through the area today, with mostly dry
conditions expected this evening and overnight. Low temperatures
tonight will range from the teens to low 20s.
Zonal flow aloft remains present for the middle of the week. A
shortwave trough will move across the area on Wednesday, bringing
with it another round of wintry precipitation to the area. Low-level
moisture increases from south to north early Wednesday morning as
a surface low and its associated warm from lift northward. This
paired with strong WAA, a good amount of lift, weak surface winds,
and no in-cloud ice aloft is the ideal recipe for freezing drizzle.
Ice accumulations ranging from a trace to a few hundreths of an inch
are expected across areas along and south of Interstate 90. This
will result in slippery conditions, with impacts to the morning
commute likely. Because of this, a Winter Weather Advisory has been
issued for northeast Iowa, southwest Wisconsin, and portions of
southeast Minnesota. Further north, cloud ice looks to be present
across areas north of Interstate 90 where the better column
saturation is in line with upper wave. Because of this, mostly snow
is expected, with accumulations around half an inch to 2 inches.
Highest amounts will be across north-central Wisconsin where the
better forcing and snow to liquid ratios will be.
Precipitation looks to exit by late Wednesday morning into
Wednesday afternoon from southwest to northeast. High
temperatures will range from the low 20s to low 30s.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 230 PM CST Tue Jan 14 2020
Strong cold air advection in the low levels Wednesday night will
allow a tongue of cold air just above the surface to briefly spill
into the region. 925mb temps will drop to around -15C at LSE, give
or take a few degrees elsewhere. Quite a pronounced low level
inversion will develop, with 850mb temps closer to around -10C at
LSE. Any clearing that creeps in from the west overnight combined
with fresh snowpack will only champion the cooling cause. Wednesday
night lows currently expected to range from the single digits below
zero for much of the area, though likely single digits above zero
across southwest/central WI where clouds will hold on longer. These
temperatures combined with brisk northwest winds will translate into
frigid wind chills through Thursday morning, approaching -20 to -25F
west of the Mississippi. Cloud trends will have to be monitored
closely, as that will have a big impact on the low temperature
forecast, but current forecast would suggest perhaps a future need
for a wind chill advisory (current forecast borderline with
criteria) for some counties west of the Mississippi. Will see a
/little/ temperature recovery during the day Thursday as the high
builds overhead and cold air advection is shoved off to the east.
Even under sunny to mostly sunny skies, though, Thursday`s highs
will range from the single digits to teens.
Main focus of the extended period remains a potential winter storm
impacting the region Friday into Saturday. Guidance is in good
overall agreement with an amplified trough dropping from the Pacific
Northwest late Thursday night into the Central Plains on Friday,
tapping into a rich supply of Gulf moisture as it does so. An
accompanying surface low will track towards the Great Lakes, but its
exact path is still far from certain. GFS continues to favor a more
northern track through WI, though the 14.12Z run brought it a little
farther south into slightly better agreement with the ECMWF. GEFS
members continue to show a considerable amount of spread in the
surface low`s track, but many seem to favor a more southern track
like the ECMWF. This will have important ramifications for how far
north the warmer air can advance into the region. If it behaves
similarly to this past weekend`s "bigger" system and we end up with
significant convection to the south, a more southern track may end
up being the favored solution. The main difference with this
upcoming system is that it will have a very large precip shield
impacting the region, so virtually everyone can be assured of some
precip. Most of this should fall as snow, perhaps with substantial
accumulation (<6") across a portion of the area. If a warm nose
materializes a la the GFS, could see some mixed precipitation across
northeast IA/southwest WI. Still too early and too much model
uncertainty to advertise specific snowfall amounts, but the system
definitely shows potential for impacts and bears watching.
Will also have to watch wind potential with this system, especially
as a respectable pressure gradient develops behind the departing
system on Saturday. Could be gusts upwards of 30 mph to cause
blowing snow and poor visibility. An expansive Canadian high
pressure system building into the region early next week looks to
offer a colder but quieter stretch of weather, perhaps with a sneaky
weak clipper system Sunday night into Monday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 536 PM CST Tue Jan 14 2020
VFR conditions expected through tonight, with light and variable
winds becoming easterly by Wednesday morning. A wintry system will
then bring snow and perhaps some freezing drizzle to the area
into early afternoon, along with low MVFR to IFR ceilings and
visibility. Latest guidance suggests RST and LSE will see
predominately snow, with the greater freezing drizzle threat
staying just south. Therefore, only have -SN mentioned for now,
but will need to keep an eye on precipitation type trends, along
with exact timing, for future issuances. Winds will quickly become
gusty and northwesterly as the precipitation exits, though MVFR
to IFR ceilings will remain in place through the remainder of the
TAF period.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 6 AM to noon CST Wednesday for
WIZ041>043-053>055-061.
MN...Winter Weather Advisory from 3 AM to noon CST Wednesday for
MNZ094.
Winter Weather Advisory from 6 AM to noon CST Wednesday for
MNZ095-096.
IA...Winter Weather Advisory from 3 AM to noon CST Wednesday for
IAZ008>010-018-019-029-030.
Winter Weather Advisory from 6 AM to noon CST Wednesday for
IAZ011.
&&
$$
UPDATE...CA
SHORT TERM...NMB
LONG TERM...Kurz
AVIATION...CA
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
754 PM CST Tue Jan 14 2020
.DISCUSSION...
Decided to extend the Marine Dense Fog Advisory to include all of
the bays and nearshore coastal waters, consistent with recent
observations, SREF visibility probabilities, and the RAP
deterministic visibilities. Ended the Advisory at 12z Wednesday to
coincide with surrounding WFOs.
&&
.PREV DISCUSSION... /Issued 619 PM CST Tue Jan 14 2020/
DISCUSSION...
Note Aviation Discussion below corresponding to the 00z TAFs.
AVIATION...
A mixture of MVFR, IFR, and LIFR ceilings, and MVFR/IFR
visibilities, are expected overnight through early Wednesday
morning. A transition to predominate MVFR conditions expected
during the mid morning hours Wednesday, and finally predominate
VFR by afternoon. Generally light south wind expected
overnight/early Wednesday, followed by increasing wind speeds
during the afternoon.
PREV DISCUSSION... /Issued 313 PM CST Tue Jan 14 2020/
SHORT TERM (Tonight through Wednesday Night)...
Warm front as of 3 PM was plodding north and finally departing our
area ahead of very mild temps in the 80s to near 90 in some locales.
Barring a rogue shower or storm this afternoon along an instability
axis spanning the Coastal Plains, the forecast remains dry through
Wednesday as forcing will be in short supply under an extension of
subtropical ridging. The main challenge through tomorrow evening
remains fog. Marine fog at present will likely expand along the
Coastal Bend this evening, but confidence erodes thereafter as
models diverge on the extent and duration of inland fog. Opted to
keep fog mention region wide overnight, but dense fog appears less
likely than last night. On Wednesday, low level flow backs more
southeasterly all the while a cold front stalls out from the Permian
Basin to North TX. Continued ridging aloft should keep us very warm
and quiet, but by Wednesday night deeper saturation focuses from the
Brush Country on west courtesy of a minor trough and stronger
isentropic ascent. Model soundings at Cotulla show drizzle and some
showers Wed night, but rainfall should be very light.
LONG TERM (Thursday through Tuesday)...
An area of mid-level high pressure centered over the Gulf of Mexico
will continue to produce warmer temperatures across the area.
Southeasterly winds will prevail on Thursday and Friday as a
shortwave trough moves across the area. The short wave trough
combined with the added moisture may result in isolated to scattered
showers and thunderstorms. The next cold front will move across the
area on Saturday which will increase our potential for rain, with
the best probabilities over the local waters. Temperatures will
remain cool after the passage of the front along with an increase
in winds. A Small Craft Advisory might be required beginning
early Sunday due to strong winds. A second surge of high pressure
will move across South Texas on Monday and should maintain cool
temperatures with strong winds over the waters.
MARINE...
Weak to moderate onshore flow will persist through Wednesday night
with fog likely. Some dense fog is possible near the bays and
nearshore waters at times. Isolated showers are possible Thursday
through Friday night. A cold front will move through Saturday
with scattered showers and thunderstorms possible along the front.
Strong northerly winds will build behind the front with Small
Craft Advisory conditions possible.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 69 80 68 77 67 / 10 10 10 30 20
Victoria 68 79 67 78 65 / 10 10 10 30 20
Laredo 68 84 69 83 69 / 0 0 10 30 10
Alice 69 84 68 81 68 / 10 10 10 30 20
Rockport 67 75 66 74 66 / 10 10 10 20 10
Cotulla 67 84 67 82 67 / 10 0 20 40 20
Kingsville 69 83 68 81 68 / 10 0 10 30 20
Navy Corpus 67 75 67 72 67 / 10 10 10 30 20
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Dense Fog Advisory until 6 AM CST Wednesday For the following
zones: Bays and Waterways from Baffin Bay to Port Aransas...
Bays and Waterways from Port Aransas to Port O`Connor...
Coastal waters from Baffin Bay to Port Aransas out 20 NM...
Coastal waters from Port Aransas to Matagorda Ship Channel
out 20 NM.
&&
$$
WC/87...SHORT TERM
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
632 PM EST Tue Jan 14 2020
.AVIATION...
MVFR stratus encompassing the southeast Michigan airspace this
evening showing signs of eroding just to the southwest, as slightly
warmer and drier air accompanies high pressure into the Ohio valley.
Recent trends and model guidance would suggest a window exists for
some degree of clearing late tonight as this process works into the
area. Greater potential for clearing/VFR will exist across the
Detroit corridor and PTK. Forecast will maintain a more pessimistic
outlook at FNT/MBS attm. Some renewed lower stratus development is
possible early Wednesday as a weak elevated warm front enters the
region in advance of an approaching low pressure system. A deeper
plume of moisture will then accompany this system, bringing a round
of light precipitation within low MVFR to IFR conditions mid
afternoon through early evening Wednesday. Conditions remain cold
enough to support snow at MBS and perhaps a brief mix at FNT.
Elsewhere, simply a cold rain/drizzle as surface temperature remain
above freezing.
For DTW...Low stratus holds firm late this evening, but clearing
just upstream will work into the airspace overnight. Confidence in
maintaining this clearing into Wednesday morning remains low. Light
precipitation late Wednesday expected to fall as rain.
DTW THRESHOLD PROBABILITIES...
* High for cigs aob 5kft this evening. Low after midnight. Medium
again late morning Wednesday onward.
* High for ptype as rain Wednesday afternoon/evening.
&&
.PREV DISCUSSION...
Issued at 401 PM EST Tue Jan 14 2020
DISCUSSION...
Another day of balmy, moist boundary layer conditions across
Southeast Michigan with nothing more than some very minor visibility
restrictions in haze. Temperatures today were able to climb a solid
7 to 10 degrees above normal. Little to no sensible weather is
expected tonight as the column remains strongly statically stable.
The only point of conversation centers on whether or not clouds will
erode tonight. Larger scale features show strong support for active
subsidence as differential anticyclonic vorticity advection, deep
cold air advection, and favorable jet positioning for descent moves
overhead. Forecast soundings show this with a fairly significant
lowering base of the subsidence inversion. The end result is
substantially thinning of the saturation and cloud bearing layer in
the model and suspect that it will become increasingly difficult for
opaque stratus. There are at least some hints of thinning back
across northern Illinois. Temperatures are on the cooler end of the
spectrum that relies on some breaks.
The next Pacific shortwave in the high frequency pattern is now
passing over the Intermountain West. Fast, zonal flow will guide it
to the doorstep here locally already late Wednesday afternoon and
Wednesday evening. A very big difference exists in the dynamical
support for the Wednesday wave versus the others: which includes
phased split stream flow with coupled upper level jet dynamics. The
stronger Potential Vorticity reservoir that resides to the north of
the jet will heavily influence the wave with time, but not before it
is well to the east of Southeast Michigan. This increases confidence
in a relatively warmish solution for Wednesday. With all of the
precipitation algorithms that exist, one needs to drill down into
forecast soundings now more than ever. Forecast soundings are
certainly interesting with the NAM a cold outlier. The ECMWF
forecast sounding for Wednesday afternoon is overwhelmingly warm
early with the RAP there as well. The 14.12Z run of the ECMWF becomes
cold enough for snow across the far north. Soundings also show depth
of saturation lacking which brings considerable ice nucleation
question. Will roll with likely PoPs with a potential for drizzle or
sprinkles most areas 20-03Z. There is potential for a slushy snow
accumulation of up to 1 inch for the far northern cwa, primarily the
northern Thumb and possibly in the Tri Cities.
Uncertainty pertaining to the Winter System Saturday...
Great continuity has existed amongst the medium range model guidance
in advancing a deep Pacific trough across North America late
Thursday through Sunday. Consensus of the solutions suggests that a
surface low will track right through portions of the cwa. There has
been some question regarding the timing of the parent PV anomaly.
Stonybrook Ensemble Sensitivity Analysis of 00Z GEFS suggested that
an overwhelming amount of the uncertainty amongst the members could
still be explained by east to west variance of the main PV anomaly.
This is on top of the d(prog)/dt trend that has existed recently
with the slowing of the GFS operation runs. Interesting to note that
even the EOF2 explained signal shows some uncertainty with the
magnitude of the MSLP over Lake Superior which is likely due to
timing of the very strong inverted surface trough and is another
indication of significant timing uncertainty. The overall pattern
setup and synoptic scale features suggest a very high amount of warm
air advection occurring in advance of the low due to both a +65 knot
low level jet in warm sector and also because of slab/layer lift
from hard cyclonic rotation. Expecting a lot of warm advection. A few
thoughts...1. Be mindful of Ptype algorithms as forecast soundings
suggest precipitation rates will again be very important for ground
truth. 2. Given the large wavelength of governing features and a
d(prog)/dt tendency in 12Z ECMWF for some broadening/less wrap up of
absolute vorticity expect warm air advection to be flashing rapidly
to the east. 3. Signs suggest that high rate accumulating snowfall
could fall in a period of 6 hours or less before turning over to a
mix or all rain. Exact timing, duration, and snowfall intensity
remains unknown at this time.
MARINE...
A weak low pressure system over central Ontario will continue east
into Quebec tonight. A trough/cold front swinging around the low
through lower Michigan this afternoon resulted in gusty southwest
winds generally under 20 knots though as the air will be warming.
Another stronger low will then track across the southern Great Lakes
Wednesday into Wednesday night. Increased northwest flow will usher
in a colder airmass which will lead to unstable conditions over the
waters for Thursday. Gust may reach 30 to 35 knots across the lake
Huron basin late Wednesday night. Local forecast guidance has been
trending down with the chance to reach gales so will hold off on a
Gale Watch at this time. Wave heights will build along the
shoreline of the Thumb likely necessitating Small Craft Advisories
Thursday. The cold air will increase mixing depths over the water
which may result in snow squalls as well. Large area of high
pressure then arrives Thursday night into Friday, assuring lighter
winds (under 20 knots) but still cold and potentially light snow
showers lingering into Friday morning.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....MR
DISCUSSION...CB
MARINE.......DRK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Quad Cities IA IL
950 PM CST Tue Jan 14 2020
.UPDATE...
Issued at 944 PM CST Tue Jan 14 2020
Temperatures have cooled in several areas below Min T forecast,
and the low level cooling has outpaced model solutions with
latest surface freezing line roughly along a Centerville, Iowa
to Macomb, Illinois line. As a result have coordinated with
ILX and DMX to add another tier or so of counties (roughly
along a Fairfield to Monmouth line) to the winter weather advisory.
Temperatures are rather cold north as evidence by teens in a few
spots along the Hwy 20/30 corridors currently, and while they
will be on the rise overnight with the arrival of the clouds some
of the new guidance is suggesting these areas may struggle to
reach the freezing mark for a high on Wednesday. Thus much of the
event in these areas likely spent in the 20s, and possibly lower
to mid 20s optimum for ice accretion. Thus, despite this being a
light precipitation event I would expect quite the travel impacts
for Wednesday morning... with the Hwy 20/30 corridors to north of
I-80 most concern. To the south concerns still with icy travel but
would anticipate a gradual warming at or above freezing in the
morning, which would eventually abate freezing drizzle. However,
even if surface temps climb above freezing would still need to
watch the bridges and overpasses.
&&
.SYNOPSIS...
Issued at 249 PM CST Tue Jan 14 2020
Clouds have been slow to exit the area this afternoon as cold
advection brought cooler temps into the area this afternoon.
Current satellite has clear skies south of Interstate 80, where
temperatures have climbed into the mid 30s to mid 40s. Elsewhere,
cold air associated with an arctic high was bringing the first
real taste of winter close to our area. Tonight another wave is
forecast to move through the flow and lead to drizzle and possibly
light freezing rain.
&&
.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 249 PM CST Tue Jan 14 2020
Key Messages:
1. Freezing drizzle to affect the AM commute, but temperatures are
expected to be rise above freezing during the day leading to
short term impacts.
2. Cold front will start to drop temps during the day from the
northwest to the southeast.
A quick moving wave, along with a split jet and H85 WAA will set
the stage for precip Wednesday morning. Of main forecast concern
are the surface temps. The surface warm front will be pushing
north into the area, allowing for temps to warm up overnight
across the south pre-daybreak. Where the above freezing temps are
at precip onset will drive any impacts from FZDZ or FZRA. The
southern end of the advisory therefore has a high bust potential
and later shifts will need to monitor where this freezing line is.
The 18z HRRR and NBM experimental, both have the freezing line
half a county north of where our forecast has it at 12z. This will
need to be watched closely. Right now it looks as the best chance
for fzdz or fzra during AM commutes will be the IC/CID, ALO, and
DBQ areas. Where temps are below freezing, there is no doubt that
freezing rain or drizzle will be the main ptype. Any untreated
surface will be slick tomorrow until temps warm above freezing.
After the precip ends, cold air will move into the area. In fact
temperatures in the teens are possible along the highway 20
corridor in IA before 00z Thursday.
.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 249 PM CST Tue Jan 14 2020
A significant storm system will be impacting the Midwest late this
week and into the weekend.
Wednesday night and Thursday
Assessment...high confidence
Quiet, dry and cold conditions will be seen with temperatures well
below normal. Wind chills are expected to be below zero Wednesday
night. Attention then turns to the approaching storm system.
Thursday night through Saturday
Assessment...high confidence on a storm system. Low confidence
regarding potential impacts.
Key Messages:
1) Unlike the last system, arctic air will be in place across the
area so precipitation will start out in the form of snow.
2) There continues to be large disagreements between the global
models regarding storm track and timing. Both of these will affect
precipitation amounts and precipitation types. Given the differences
in storm track and timing, confidence on precipitation type and
amounts remains low.
3) All global models agree that there will be a large surge of
moisture producing precipitation ahead of the low.
The GFS is the farthest north on storm track with the CMC global the
furthest south with the ECMWF in between. The GFS and CMC have
switched track solutions compared to 48 hours ago.
Quiet and dry conditions will be seen Thursday evening. The question
is will precipitation enter the far south and southwest areas prior
to sunrise Friday.
The ECMWF has been consistent in keeping Thursday night dry along
with areas east of the Mississippi Friday morning, followed by
widespread precipitation Friday afternoon through Saturday morning.
Precipitation then ends from west to east Saturday afternoon.
The GFS has been slowing down the arrival of precipitation until
after 3 AM Friday with precipitation overspreading the entire area
during the day Friday. Widespread precipitation Friday night with
precipitation ending from west to east during the day Saturday.
The CMC global is similar to the GFS in bringing precipitation in
after 3 AM Friday but then is much faster in overspreading the area
with precipitation Friday morning. Widespread precipitation Friday
night with precipitation ending from west to east Saturday.
Since the arctic air is already in place (Boehmke rule) all areas
will eventually see some accumulating snow on Friday. Late Friday
afternoon and Friday night the potential for mixed precipitation,
including freezing rain, is possible. How far north it occurs is in
question. Some areas in the far south have the potential of seeing
precipitation change over to all rain.
Late Friday night and into Saturday the precipitation will
transition back over to all snow as colder air gets pulled south
after the low passes east of the area.
Saturday night through Tuesday
Assessment...high confidence
Arctic high pressure will build into the Midwest Saturday night
through Tuesday bringing temperatures well below normal along with
dry conditions. Wind chills Saturday night and Sunday night will be
below zero and may approach or exceed 20 below zero Saturday night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
ISSUED AT 608 PM CST Tue Jan 14 2020
A transient period of lower MVFR cigs is possible at CID, DBQ,
and MLI this evening with some lingering low level moisture
trapped within weak flow. Otherwise, predominantly VFR conditions
through 06z. After 06z, as a fast moving storm system will spread
mostly light freezing rain or freezing drizzle across the
terminals lingering through Wednesday morning. Some light ice
accumulations appear likely. Conditions will likely drop to lower
MVFR and IFR in the precipitation, which depending on surface
temperatures could be mainly rain at BRL. Do envision with some
warming on Wednesday that icing conditions should abate from south
to north perhaps as early as 09z-14z at BRL and MLI, and closer
to 16z-18z at CID and DBQ. In the wake of the system Wednesday
afternoon NW winds will become gusty up to 25 kts, which will
bring in drier air and likely lead to improvement to VFR and
eventual clearing into Wednesday evening.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Weather Advisory from 4 AM to noon CST Wednesday for
Buchanan-Clinton-Delaware-Dubuque-Jackson-Jones.
Winter Weather Advisory from 2 AM to noon CST Wednesday for
Benton-Cedar-Des Moines-Henry IA-Iowa-Jefferson-Johnson-
Keokuk-Linn-Louisa-Muscatine-Scott-Washington.
IL...Winter Weather Advisory from 4 AM to noon CST Wednesday for
Carroll-Jo Daviess-Stephenson-Whiteside.
Winter Weather Advisory from 2 AM to noon CST Wednesday for
Bureau-Henderson-Henry IL-Mercer-Putnam-Rock Island-Warren.
MO...NONE.
&&
$$
UPDATE...McClure
SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...08
AVIATION...McClure
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
617 PM CST Tue Jan 14 2020
.UPDATE...
Issued at 452 PM CST Tue Jan 14 2020
Concern for impactful freezing drizzle has increased and is
supported by the latest 18Z NAM and recent HRRR model runs. Model
soundings indicate a several hour period this evening with a
saturated low layer from right off the surface to around 800 mb.
This layer is below freezing, but not cold enough for ice
crystals and is of sufficient depth to produce freezing drizzle.
Therefore, we expect the stratus deck to quickly expand north
across the area this evening, thicken, and produce some freezing
drizzle in eastern areas. Consequently, a winter weather advisory
has been issued for our Nebraska counties along and northeast of
a Hamilton, Clay, Nuckolls County line. We may have to adjust the
size of this advisory later once we see how things progress.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 319 PM CST Tue Jan 14 2020
Stratus lingers in the far southeast corner of the area this
afternoon, and more stratus is moving north toward the area. The
east wind has not allowed for much warming this afternoon.
There are a couple of concerns for the evening and overnight time
frame. First, the stratus and likely some fog along with it, will
continue to spread across the cool surface. The latest HRRR has the
fog spreading into the area early this evening and spreading across
the entire area before midnight. Some models try to give a little
precipitation with this, but not all of them. Have added a little
drizzle/freezing drizzle for this evening. It should be light and
not last very long. The fog will linger into the overnight hours,
but a cold front is expected to move into the area during the night.
Late tonight the winds should turn to the west and the fog should
move out of the area from west to east. Most of the fog should be
gone by morning.
Skies will clear out behind the cold front. A cool surface high is
expected to affect the area and even with sunny skies, the
temperatures will be a little slow to warm up. The southwest will be
quite a bit warmer than the northeast, which is closer to the
center of the surface high.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 319 PM CST Tue Jan 14 2020
Wednesday night into Thursday are expected to be dry and cool. By
Thursday afternoon there will be a little warm advection bringing
moisture back to the area. Most models are starting to show some
light precipitation late in the afternoon with the warm advection.
This is expected to start to the south and move into the area.
During the evening, the leading wave will move in and precipitation
will spread across the area. The upper low is not expected to move
out of the area until Friday night. The problem with this the
precipitation type. Surface temperatures are going to be on the
cooler side for much of the period, but temperatures aloft are a
little warmer and so expect there to be some freezing rain in the
mix of wintry weather. Then during the day Friday, temperatures are
expected to warm up and precipitation will change to rain for much
of the area. This system will need to be watched to see what
happens.
The rest of the period will have zonal flow and there will be a few
weak systems that move through. Temperatures will be mainly on the
cool side, but will vary a little day to day.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 543 PM CST Tue Jan 14 2020
There are numerous aviation concerns especially this evening into
early Wednesday morning. A low stratus deck is quickly moving
north across the region this evening with falling ceilings
expected through the evening hours. In addition, a light freezing
drizzle will also be possible for a few hours this evening,
primarily in the Grand Island area and points east from there. Any
freezing drizzle at our TAF sites should end by around midnight or
1 AM, but fog could also be a problem across the area this evening
through just after dawn. Confidence in visibility forecast is low
as visibility in fog can be rather variable, but plan on at least
the possibility of impactful visibility reductions. There will be
some low level wind shear tonight, but not enough to meet our
threshold for inclusion in the TAF.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 1 AM CST Wednesday for NEZ049-063-
064-076-077-086-087.
KS...NONE.
&&
$$
UPDATE...Wesely
SHORT TERM...JCB
LONG TERM...JCB
AVIATION...Wesely
Area Forecast Discussion
National Weather Service Grand Rapids MI
1101 PM EST Tue Jan 14 2020
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 302 PM EST Tue Jan 14 2020
- Risk for wintry mix Wed Aftn/Eve
- Lakeshore flooding possible Wed Night/Thu and the weekend
- Impactful storm possible Fri Night into Sat Night
&&
.UPDATE...
Issued at 1103 PM EST Tue Jan 14 2020
I increased the fog overnight as I still believe the skies will
clear from southwest to northeast after midnight as a thermal
ridge builds into the area in the 925 to 850 layer. On the RAP
model the 900 mb temp warms from -4c to +6c in 6 hours. Clearly
there is strong subsidence in this layer. This warming is already
clearing the clouds over southwest Lake Michigan. Some patchy
dense fog has been noted over northern Indiana over the past hours
(SBN had dense fog for a time). So with the warming, and clearing
of the lower clouds with light winds I believe we will see some
fog.
Another though on the precipitation type on Wednesday afternoon,
as it turns out when the precipitation moves in temperatures and
thickness values will be falling. I suspect we will see a quick
change to snow near and north of I-96 once the precipitation
beings.
&&
.DISCUSSION...(This evening through next Tuesday)
Issued at 302 PM EST Tue Jan 14 2020
- Risk for wintry mix Wed Aftn/Eve
A wave of low pressure tracks in from the west during this
time. Overall the system remains weak and the DGZ looks largely
unsaturated. The deepest moisture will position across northern
parts of the CWA especially up around Route 10. This is the area
that should see the most QPF from this event. Surface temperatures
will largely determine what if any impacts occur. Guidance is
showing temperatures climbing to above freezing values along and
south of Interstate 96 by the time the light precipitation moves
in. Further north though...it looks like a window for perhaps some
freezing drizzle/rain could develop. The system is very weak
currently with no precipitation and the moisture that is lifting
up from the Southern Plains is limited...thus confidence on the
risk for impacts is not real high. Furthermore...satellite imagery
shows lots of breaks in the clouds upstream in the Central Plains
so we may see some sun on Wednesday possibly allowing for higher
surface temperatures.
- Lakeshore flooding possible Wed Night/Thu and the weekend
Onshore winds that will approach gale force Wednesday night into
Thursday morning will support high waves. Cold air advection will
also enhance the wave formation. With a risk for 8
footers...lakeshore high water impacts will exist.
Lakeshore high water impacts will likely become a problem once again
over the weekend as an onshore component of wind will exist along
with a potential for higher winds. The wind at 925 mb is shown to
be in the 30 to 40 knot range Saturday night. Mixing should reach
into those values.
- Impactful storm possible Fri Night into Sat Night
Overall a warmer trend has been seen in the models over the past
couple of runs. This angles the risk for an all snow event
further north through the CWA. Thus Route 10 once again looks to
be the area that will see the highest snow amounts from this
potential storm. Also...this system will likely have a dry slot
that is shown to move in early on Saturday...which could also
impact the precipitation types. So for now snow arrives Friday
night...then as the warmer air advection strengthens the snow will
mix with and change to a period of freezing rain/sleet before
switching to plain rain during the day. Accumulations of snow look
likely along with coatings of ice...but the risk for widespread
moderate or higher impacts is lower than what we saw yesterday.
That rain could end up being steady which could generate another
round of runoff. This risk will need to be monitored closely.
Lake effect/enhanced snow will likely return to the area Saturday
night into Sunday so accumulations and limited impacts on the
backside of the storm are possible. Overall through it is looking
like the rapid departure of this storm will allow for the
atmosphere to dry out quickly.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 638 PM EST Tue Jan 14 2020
I will admit I am not 100% about clearing the low clouds out this
evening, given this is Michigan in mid January but I do believe
there is enough warming in the layer where our low clouds are to
clear those clouds. The I-94 TAF sites should see the clearing by
03z and for the I-96 and in the 06z time frame. Satellite loops
show the clearing spreading ENE this evening and surface
observations show this clearing trend too. At 1803z, BEH went to
SCT023. If in fact I am correct about the clearing, this would
lead to dense freezing fog after midnight. since wind are
expected to go near calm at the surface and there is melting snow
around to add moisture to the air. The dense fog would be less
likely at GRR and MKG and most likely for AZO, BTL, and JXN.
Whether or not the fog does develop a storm with a seasonably
strong cold front is headed for this area Wednesday. There is
enough warming in front of the system so as to bring rain to
area by mid afternoon and that would also bing in low ceilings.
More than likely the rain will change to snow after 00z.
&&
.MARINE...
Issued at 302 PM EST Tue Jan 14 2020
Winds and waves will increase considerably Wednesday afternoon
into the evening as the wave of low pressure tracks through.
Based on the mixing heights and winds at those levels...gales look
possible.
Over the weekend...on the backside of the departing
storm...the pressure gradient tightens up and a surge of cold air
moves in. This should spell high waves and a risk for gales once
again.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 4 AM EST Wednesday for LMZ844>849.
Gale Watch from Wednesday evening through Thursday morning for
LMZ844>848.
&&
$$
UPDATE...WDM
SYNOPSIS...MJS
DISCUSSION...MJS
AVIATION...WDM
MARINE...MJS
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
930 PM EST Tue Jan 14 2020
.SYNOPSIS...
Surface high pressure will briefly build into the region
tonight before a cold front brings a few isolated rain showers
back into the area Wednesday afternoon. Cooler air will return
to the region by Thursday. Additional chances for precipitation
will again return by this weekend as another strong system
moves through the region. A return to colder temperatures will
evolve late this weekend into early next week.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
The main item of interest tonight -- as high pressure traverses
the area and winds become calm/light and variable -- will be
the prospect of fog development. There remains quite a
consistent and strong signal for such development --
particularly in western/northern portions of the local area.
This remains well supported by various ensemble datasets (namely
the HREF), as well as via traditional sounding analysis
techniques. In fact, a sharpening inversion starting at about
1kft AGL will help trap near-ground moisture, with a relatively
saturated layer in the bottom 600-800ft or so. This is supported
by both the NAM and the RAP while the drier GFS shows a less
favorable setup. However, am inclined to go with a foggier
solution -- especially in consideration of what evolved earlier
this morning and what occurred last night a bit more upstream.
As of late evening, FG/BR has developed as expected. It remains
patchy and variable so far, so will continue to highlight patchy
lowered visibilities in a SPS. With all of this in mind, do
feel that a dense fog advisory may eventually be warranted
across at least a portion of the local FA later tonight. Will
wait to see exactly where the pooling of low level moisture is
most significant before proceeding with a headline, but many
spots will likely wake up with at least some areas of fog, with
some dense fog possible as well.
Lows tonight will range from the lower 30s in the north to the
lower 40s in the south, with widespread stratus/fog by daybreak
Wednesday morning for most of the local area.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
The morning fog/stratus will be a bit slow to lift/scatter out
Wednesday morning, especially with the influx of deeper-layer
low level moisture with onset of deeper WAA in the low levels
ahead of the next system. Did maintain a chance of light rain
showers Wednesday afternoon as some weak low level forcing
pivots through the region. The optimal time period for isolated
to scattered light rain showers will be early afternoon in the
west to late afternoon in the east as the weak surface low
progresses ENE through the Ohio Valley. Did cut PoPs somewhat as
forcing will remain relatively weak and moisture depth remains
somewhat marginal, suggesting coverage is likely to be only
isolated to scattered at best.
The highs tomorrow present a bit of a tricky challenge as there
will be several competing factors both for and against warmer
temperatures. For one, skies will be pretty much overcast
through the full extent of peak diurnal heating (with some fog
rather slow to burn off through the morning hours), despite the
return of weak southerly flow during this time frame in the low
levels. Additionally, the prospect of some isolated to
scattered light pcpn with CAA taking hold late in the afternoon
into the evening add some more complexities to fcst temp traces
as well. Either way, anticipate that highs will range from the
mid/upper 40s in the north to a degree or two either side of the
60 degree mark in the south.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
A return to drier and colder weather can be expected Thursday into
Thursday night as surface high pressure builds southeast into the
Great Lakes and the Ohio Valley. Highs will range from the lower 30s
northwest to near 40 southeast. Lows will fall into the upper teens
to the lower 20s.
Friday will be a transition day before the next weather system
affects the region this weekend. Clouds will be on the increase from
the west as the high moves off to our east. It will be chilly but
seasonal on Friday with highs ranging from the lower 30s north to
the upper 30s south.
Embedded mid level energy will once again pivot from the central
Plains to the Great Lakes this weekend. Warm, moist ascent
associated with a warm front will spread pcpn from west to east
across the area Friday night, continuing into Saturday. Pcpn may end
up being a mix of snow, sleet, freezing rain and rain, depending on
location and how fast stiff southerly flow push temperatures above
freezing. There are some timing issues among the models, with the
more delayed/onset of pcpn portends less mix and more rain due to
more time to warm. Thus, will keep a rain/snow mix in the forecast
until this timing can be better resolved. All locations should
eventually change over to rain on Saturday as southerly winds
increase ahead of deepening low pressure across the western Great
Lakes. In fact, winds could gust to around 40 mph per model
soundings/momentum transfer and have placed this threat in the HWO.
Highs on Saturday will warm back into the 40s and 50s. By Saturday
night, as the low moves east, colder air will rush back into the
region. Pcpn will come to an end behind a cold front but clouds will
linger. Again, winds may gust to around 40 mph. Lows will fall to
near 20 west to the upper 20s east. By Sunday, clouds will remain
but it will be much colder with highs struggling to warm into the
mid 20s north to the lower 30s south.
Models are depicting a mid level trough to rotate southeast across
the Great Lakes and New England by early next week. This should keep
clouds across the region with lake effect snow showers relegated to
downwind locations of the Great Lakes. It will remain cold. Highs
Monday and Tuesday will range from the upper 20s to the lower 30s
with lows between 15 and 20.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Aviation will be affected by FG developing under a strong low
level inversion. VLIFR visibilities are expected. Ceilings down
to 300 ft will accompany the FG. As winds increase toward
daybreak and into the afternoon, we may see some improvement in
visibilities. However, ceilings may remain IFR, with slow
improvement to MVFR possible. CVG is forecast to have west winds
gusting to 20 knots late in their 30 hour forecast.
OUTLOOK...MVFR to IFR ceilings possible Wednesday night. MVFR
ceilings and visibilities possible Friday night into Saturday.
Gusty winds likely on Saturday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...KC
NEAR TERM...KC/Coniglio
SHORT TERM...KC
LONG TERM...Hickman
AVIATION...Coniglio
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
936 PM CST Tue Jan 14 2020
.UPDATE...
936 PM CST
Have elected to issue a dense fog advisory for areas southeast of
a Streator to Gary line this evening. Otherwise, no changes to
winter weather advisory headline for late tonight/Wednesday
morning.
Weak surface high pressure ridge extends northwest to southeast
across the forecast area this evening. Light/variable or calm
winds within the ridge axis have combined with mainly clear skies
and small temp-dew point depressions to result in quickly
developing fog and low stratus across southeastern parts of the
cwa. High res guidance, including the HRRR and RAP, hit low
visibility pretty hard overnight into Wednesday morning, and
current observational trends (surface obs and GOES imagery)
support expansion of fog over the next several hours. Based on
these trends, have opted to issue a dense fog advisory generally
southeast of a Streator to Gary line, running through 15Z/9 am
Wednesday. Same guidance does indicate a northward expansion
through the I-80 corridor across northern IL, while GLAMP suggests
perhaps more of a low stratus farther north. Either way, will need
to monitor fog trend into the overnight hours for possible need
for expanding the dense fog advisory farther north.
As for the freezing drizzle potential into Wednesday morning, no
changes were made at this time. GOES vapor imagery depicts a low
amplitude mid-level short wave propagating out of the central
Rockies this evening, with a weak surface low evident over central
Kansas. Warm advection/isentropic ascent across the Missouri
Valley was also visually evident in an expansive area of low
clouds developing northeast into southwestern IA. Satellite
extrapolation of this area of low clouds brings them into parts of
northern IL before sunrise, in agreement with the timing in the
current forecast. Forecast soundings over north central IL by
morning indicate a deepening low-level saturated layer up to about
7000 ft, with a strongly veering wind profile and low level omega
suggesting persistent forcing for ascent and drizzle production.
Surface temps especially north of the I-88 corridor in the mid and
upper 20s will likely rise slightly during the early morning, but
it appears that a period of freezing drizzle is likely. Temps
hovering around 32 currently farther south/southeast including in
the heart of the Chicago urban area. Thus the greatest chance and
longer duration potential for freezing drizzle will likely remain
north and west of Chicago proper. Slowly rising temps should allow
readings to moderate above freezing from southeast to northwest
during the morning hours of Wednesday. Current forecast and
winter weather advisory match these trends nicely, and therefore
no changes appear necessary at this time.
Ratzer
&&
.SHORT TERM...
315 PM CST
Through Wednesday night...
Highlights:
The main concern is a likely period of freezing drizzle and
travel impacts for the morning commute I-80 and north and outside
of Chicago. Have issued a Winter Weather Advisory for portions of
northern and north central Illinois. Where confidence is a bit
lower and duration shorter of overlap with temps of near or just
below 32F, will be issuing a SPS to mention possibility of patchy
slick conditions.
Castro
Through Tonight:
We are starting to see the clearing advertised by model guidance
coming to fruition from southwest to northeast this afternoon.
Temperatures have warmed into the upper 30s to the mid 40s today.
That is important as surface/road temperatures will respond
accordingly. With the clearing skies there is a cold front in
western IL this will advance into at least portions of the area
this evening. RAP/NAM forecast dewpoints dip into the mid 20s at
least for a time this evening mainly across north central Illinois
and areas north/west of Chicago.
With high pressure moving in and these lower dewpoints, it seems
reasonable that mid to upper 20s temperatures will spread into the
area. This is important to provide a lower starting point and
also cool road temps below freezing after them starting above
freezing going into tonight. There is fair agreement that
precipitation chances will increase overnight into Wednesday
morning as our next shortwave/trough will approach from the west
and corresponding isentropic lift will ensue.
KMD
Wednesday through Wednesday Night:
The model guidance has come into better agreement on the track of
the weak surface low from the KS-MO border at 12z northeastward
across the central or southern CWA by the early afternoon. This
progression will lead to easterly winds I-80 and north turning to
east-southeast winds through the morning and east-southeast winds
becoming southerly south of I-80. Surface temperatures are
absolutely critical to exactly how Wednesday morning plays out
with precipitation type. Confidence has increased enough in an
overlap of temperatures at or a bit under freezing and drizzle to
perhaps occasional light rain occurring for the issuance of the
Winter Weather Advisory.
As low clouds blossom and moisture depth quickly increases from
the predawn hours west to the remainder of the area during the
morning, in response to ascent from the mid-level short-wave,
there will be increasing warm advection and isentropic ascent.
Forecast soundings indicate decent lift through a deep saturated
layer that does not include ice nucleation aloft, with saturation
level only up to -4 Celsius. Therefore, favored precipitation
type is drizzle and freezing drizzle, though collision coalescence
could yield periods of light rain/freezing rain as opposed to
pure drizzle. Ice accretion of a light glaze to perhaps up to a
couple hundredths of an inch will be possible. Spotty freezing
drizzle could enter into portions of northwest and north central
Illinois prior to 6AM and then spread east-northeastward Wednesday
morning.
Low level flow turning more southerly with time will mitigate how
far south the subfreezing temperatures will get, with
temperatures then gradually warming from south to north into the
early afternoon. Confidence is medium-high in at least a 2-3 hour
window in the advisory counties of temps 32F or less, with longest
duration I-90 and north and west of the lake. Road temperature
response tonight will also be important to monitor as to the
magnitude of road impacts. Would anticipate untreated, elevated,
or less heavily traveled roads to have the highest chance of
developing slick spots. With the possibility of a couple hour
window of patchy freezing drizzle in parts of Will, Grundy, Lake
IN, and Porter Counties, will issue a SPS for these counties.
The other thing we`ll need to monitor for, with the weak gradient
as the surface low passes nearby and low dew point spreads, is for
the very low stratus to potentially build down to fog. With lower
confidence in this part of the forecast, have gone with patchy
fog mention through early to mid afternoon, but can`t rule out
locally dense fog. The socked in low overcast and farther south
low track should generally yield cooler high temps tomorrow,
coolest north. Cold front passage should occur from west to east
from the mid afternoon through the early evening. Prior to lower
clouds eroding, drizzle and perhaps spotty showers will be
possible through sunset.
Strong low level cold advection leading nearly 1045 mb high
pressure ridging from the northern Plains will send temps into the
lower teens to around 20 by early Thursday, with wind chills in
the positive and negative single digits thanks to brisk west-
northwest winds. Winds will gust to up to 35 mph over the lake,
building waves over the southeastern portion of the lake. There`s
a good chance a Lakeshore Flood Advisory will need to be issued
for Porter County IN shoreline.
Castro
&&
.LONG TERM...
315 PM CST
Thursday through Monday...
The main focus in the long term period is a messy winter system
Friday into Saturday that will likely bring at least some snow and
ice accumulation to much of the area. It`s still too early for
specifics, but confidence is increasing in accumulating wintry
precip and the likelihood of travel impacts Friday PM, Friday
night, and possibly into Saturday for portions of the area.
Impressively strong nearly 1045 mb surface high will be a key
player in the wintry precip forecast. On Thursday, the high center
will shift across the upper MS Valley by early evening. Winds will
steadily diminish through the day, with the first below normal
high temperatures of the week favored under plenty of sun. The
high pressure will center over the central lakes by early Friday,
with strong surface ridging encompassing the region. Given very
dry air modified Arctic/Canadian mass (low dew points) under the
surface high, temperatures will quickly fall Thursday evening into
the teens for most areas, and upper single digits possible in
favored cold spots of interior northern Illinois. Increasing mid
and high level cloud cover overnight in advance of Friday`s system
will then probably cause temps to steady or slowly rise toward
daybreak.
A wedge of very dry air at the low levels up to just under 700 mb
is expected to slow precipitation onset Friday at least some, with
top down saturation gradually occurring in response to large scale
ascent from approaching mid-level short-wave and isentropic
ascent. Virga should gradually give way to snow primarily during
the afternoon and evaporative cooling will initially make thermal
profiles cold enough for snow. The big question is exactly how
long evaporative cooling will hold off increasing warm advection
as due southerly flow at 850-925 mb ramps up to 40+ kt. The models
rarely if ever over-forecast warm advection aloft, but often
under-forecast it.
At the same time, surface low being well west of the area into
Friday evening will keep the surface warm front locked well south,
along with surface wet bulb processes keeping temperatures
generally sub freezing. Conceptually, Friday PM-night set-up
should favor precipitation type transitioning from snow to perhaps
a brief period of sleet then freezing rain then rain as evaporative
cooling eventually loses out to warm advection, barring a sizable
change in this setup. P-type change from frozen to possibly plain
rain Friday night will be driven by exact surface low track,
which is still uncertain at this juncture. How quickly thermal
profiles stay cold enough for snow after precip onset will dictate
snow accumulations, with duration being shortest south and
longest WI state-line counties, where several inches of snow is
possible. Until surface low draws closer later Friday evening,
enough of an easterly component to surface wind could hold back
surface warming and the concern for ice accumulations and travel
impacts.
Temperature trend will be non-diurnal into Saturday morning, with
a decent chance of the entire CWA being above freezing, especially
if surface low tracks farther north. As the deepening low shifts
off to the east, precipitation could then transition back to snow
Saturday afternoon, though by then precip may very well have shut
off. All in all, confidence is increasing in impacts from Friday`s
system, but is still low in the specifics. That said, would
anticipate at least portions of the area needing a winter weather
headline overlapping with the Friday evening commute and busier
roads Friday night at the start of the weekend.
In the wake of the system, a solid shot of below normal
temperatures is anticipated through the start of next work week,
with location and depth of snow cover modulating how cold it may
get. The lake effect machine may finally turn on after a long
hiatus, though activity may be primarily east of Porter County
until winds turn more north-northwesterly on Monday.
Castro
&&
.AVIATION...
For the 00Z TAFs...
Aviation concerns:
- Patchy MVFR ceilings this evening.
- Visibility tonight with fog potential.
- IFR/LIFR cigs with drizzle Wednesday morning.
- Period of freezing drizzle early Wednesday.
MVFR clouds had largely eroded across the terminals this
afternoon, though GOES IR satellite indicates some patch
redevelopment currently along an RPJ-DKB-ORD corridor, in the
1100-1500 foot range. Will need to watch trends with these MVFR
cigs, as another concern is the potential for fog to develop as
winds become light if skies clear. Weak surface high pressure
ridge across the area through the evening will allow winds to
become light and variable for a time, then trend light easterly
after midnight.
Another in a series of quick-moving mid-level disturbances will
then approach the area from the west during the predawn hours of
early Wednesday. This is expected to bring another period of
drizzle/freezing drizzle into Wednesday, along with lowering
ceilings visibility. Surface temps will be very close to the
freezing mark as precipitation develops, before temperatures begin
to gradually climb. RFD would appear to have the greatest threat
of FZDZ with colder surface temps there, with chances for freezing
precip decreasing farther southeast toward MDW and GYY. ORD will
be on the edge temp-wise, with some potential for a brief window
of freezing precip. While temps will rise above freezing, drizzle
will likely persist into the early to mid afternoon hours before
a cold front pushes through. East winds will gradually back
southeast and then south ahead of the front, shifting west with
the passage of the front and becoming gusty to 20+ kts behind the
front in the late afternoon/evening. IFR/LIFR cigs would likely
linger with the drizzle/fog prior to cold fropa, with improvement
occurring post-frontally later in the day.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Winter Weather Advisory...ILZ003-ILZ008-ILZ010-ILZ011-ILZ019...4
AM Wednesday to noon Wednesday.
Winter Weather Advisory...ILZ004-ILZ005-ILZ006-ILZ012-ILZ013-
ILZ014-ILZ020...6 AM Wednesday to noon Wednesday.
Dense Fog Advisory...ILZ023-ILZ032-ILZ033-ILZ039 until 9 AM
Wednesday.
IN...Dense Fog Advisory...INZ001-INZ002-INZ010-INZ011-INZ019 until 9
AM Wednesday.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Marquette MI
723 PM EST Tue Jan 14 2020
.SHORT TERM...(This evening through Wednesday)
Issued at 303 PM EST TUE JAN 14 2020
WV imagery and RAP analysis indicate a broad mid/upper level trough
over the western CONUS and a ridge over the southeast U.S. resulting
in a wsw flow through the western Great Lakes. One shortwave trough
which provided a dusting of snow and some fzdz to Upper Mi earlier
this morning has now lifted north of Lake Superior this afternoon.
Another wsw flow shortwave is due in from the Central Plains on Wed
with a few inches of light snow likely on Wed and some n-nw flow LES
behind the system Wed night into Thu.
Tonight, Increased ridging/subsidence from the west should ensure
generally quiet conditions through much of the night before the next
shortwave from the Plains brings in some possible light snow into
the far west late. Otherwise, lows will drop into the teens to lower
20s.
Wednesday, a shortwave trough is progged to lift across the Northern
Plains from the Pacific coast and bring widespread snow across the
UP through the day. At the mid levels, the shortwave and weak height
falls coincide with decent 700 mb fgen and a fairly brief period of
isentropic ascent late morning into early afternoon, especially
along and just north of the WI border. Model averaged qpf from
system generally ranges from .1 to .2 inches and with SLRs ranging
from 12-15/1 would expect generally 1-2" of snow with maybe a few
isolated spots receiving closer to 3". Anyway, it looks like a sub-
advisory event. Behind the shortwave, 850mb temps fall to -12 to -
13C by Thursday at 00Z, allowing for northerly flow LES to kick in,
especially toward evening. Expect highs mostly in the 25 to 30F
range.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 418 PM EST TUE JAN 14 2020
For about a week now, a strong positive height anomaly has been over
the Pacific with the center of the max anomaly s of the Aleutians.
This has forced a mean trof over western N America, supporting an
active storm track downstream across the central and eastern Lower
48. In the coming days, the positive height anomaly will briefly
amplify northward. It will then shift across northern AK/far nw
Canada, allowing the western N America trof to retrograde beneath it
out to the Gulf of AK this weekend. Ridging e of this Gulf of AK
trof will connect with the aforementioned positive height anomaly,
forcing sharper nw flow downstream into the Great Lakes for a time
early next week. GFS/CMC/ECMWF ensembles then spread positive
height anomalies eastward across Canada and the Upper Lakes for
the remainder of next week, though low amplitude troffing is
indicated with axis generally centered from Hudson Bay thru the
Great Lakes. As a result of these large scale changes, the active
storm track across the Lower 48 will come to an end as the western
trof retrogrades. There will be 2 more systems affecting the
Great Lakes before the pattern changes, one on Wed and a final one
on Sat. The one on Wed will produce a general light snow with
widespread accumulations of 1-2, maybe 3 inches, followed by
generally light nw flow LES Wed night into Thu. Of the entire
series of systems that has affected the Great Lakes over the last
week and including the next 2, the final system on Sat will be the
more substantial one for Upper MI, but it doesn`t look
particularly significant for Upper MI standards. NW flow LES will
follow on Sun and will linger Mon as it winds down. Next week will
then be a drier week with the pattern unfavorable for anything
noteworthy. As for temps, readings will fluctuate up to around 10
degrees either side of mid Jan normals over the next few days with
approach and passage of the 2 systems. Temps will then fall back
to prevailing blo normal for a few days early next week in the
wake of the Sat system and also under the transition to sharper nw
flow for a time. Temps should then rise back to around normal for
the remainder of next week as positive height anomalies spread e
across Canada.
Beginning Wed night/Thu, some -sn will linger into the early evening
in association with the shortwave moving across the Great Lakes
region. Otherwise, attention turns to developing nw flow LES in its
wake. 850mb temps are fcst to fall from around -12C in the evening
to around -17C by Thu morning. Although deep moisture is present,
NAM/GFS fcst soundings indicate an isothermal layer or even an
inversion based around 4kft for much of the time, preventing more
vigorous/deeper convection. That said, the DGZ will be falling into
the convective layer to fluff up accumulations. At this point,
probably looking at accumulations of 1-4 inches in the nw wind snow
belts Wed night. However, some locally higher amounts could occur
over the high terrain of the w for a couple of reasons. Under colder
air, the DGZ will become better positioned in the convective layer
over the w during the night, and there are some indications (NAM in
particular) of an enhanced convergence zone developing as backing
low-level winds to the wnw begin to spread out across western Lake
Superior, converging with the thermal troffing aided nw winds
attempting to linger over the lake. As winds continue to back Thu
morning, this enhanced convergence zone will shift to areas e of
Marquette, leading to locally heavier LES there Thu morning. During
Thu, 1-3 additional inches of very fluffy/high SLR snow will be
possible over the w as DGZ occupies nearly the entire convective
layer underneath a low 3kft inversion. To the e, expect an
additional 2-4 inches of fluffy snow, highest in Alger County where
convergence zone may tend to hang up.
Light LES will gradually shift offshore Thu night as high pres ridge
passes. There should be a window for temps to tank under the passing
high, provided lake stratocu clears out. For now, favored the lower
side of guidance with mins down around -10F at traditional cold
spots. However, could easily see temps fall toward -20F if any
locations see skies clear out early and then remain mostly clear for
a good part of the night.
Attention then turns to the final shortwave trof shifting out the
western U.S. This trof will reach the Plains Fri night and the
western Great Lakes on Sat as it takes on negative tilt. Associated
sfc low will track from the Plains across southern Lower MI. While
the track is well to the s, which normally results in the main snow
area passing by to the s of Upper MI, this situation will be
different as additional energy farther n in the trof supports an
inverted trof extending well to the n. End result will be an
expansive s-n isentropic ascent corridor ahead of the trof which
will support a large area of snow extending well to the n of the sfc
low. This kind of scenario precludes focused ascent, so instead of a
narrower band of very heavy snowfall n of the low, the snow will end
up being spread out over a very large area with accumulations not as
high as they could be. In this case, for Upper MI standards,
accumulations will likely fall more into the mdt category. On the
290K sfc, generally corresponding to the 700-750mb layer, mixing
ratios of 3g/kg are avbl, suggesting to potential of around 6 inches
of snow for the roughly 12hrs of indicated ascent. Brisk se winds
will prevail during the snow event, so where these se winds
downslope, accumulations will be less. Air mass may be just cold
enough for some lake enhancement off Lake MI, but that is far from
certain at this time range. For now, probably looking at general 4
to 7 inch snowfall Fri night/Sat. Will be locally higher if Lake MI
enhancement comes into play.
With the passage of the inverted trof Sat aftn/evening, the synoptic
snow will mostly end, and as winds shift from se to nnw and caa gets
underway, LES will develop. GFS fcst soundings indicate a low
inversion setting up at 3-5kft which would be significant inhibitor
for heavier LES. Colder air pushes the DGZ toward the lower part of
the convective layer, but it should still lead to decently high
SLRs. The ECMWF with its fcst higher inversion and sharper low-level
cyclonic flow would offer a much better scenario for mdt to possibly
hvy LES heading thru Sat night into Sun morning. Blustery nw winds
during this time will also lead to issues with blsn/drsn in the lake
effect snow belts.
LES will gradually diminish during Sun, but probably won`t end until
sometime Mon into Mon night. Dry weather will then follow on Tue.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 715 PM EST TUE JAN 14 2020
Although there could be some snow showers hanging around tonight,
as currently occurring at KIWD, the more widespread snow holds
off until tomorrow morning, with snow starting to appear in the
pre-dawn hours at KIWD first before moving into the other two
terminal areas around or just after dawn. Conditions will likely
not be that great for a good portion of the day, with snow, albeit
on the light side, persisting and accompanied by reduced
ceilings. Westerly winds tonight will become variable in the
morning before becoming more northerly by around midday.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 303 PM EST TUE JAN 14 2020
West winds along the Keweenaw Peninsula could approach gale gusts
this afternoon/evening, but sustained winds should remain in the 20-
30 knot range. After winds subside later tonight into Wed, n-nw
winds could pick up again late Wed night into Thu behind another
system with a few gale gusts possible. As a stronger storm system
moves through the area Saturday, southeast winds may increase to
near gales ahead of it (Fri night-Sat) with near north to northwest
gale force winds behind it (late Sat-Sun).
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...Rolfson
AVIATION...lg
MARINE...Voss
Area Forecast Discussion
National Weather Service Riverton WY
507 PM MST Tue Jan 14 2020
.SHORT TERM...(This evening through Wednesday night)
Issued at 105 PM MST Tue Jan 14 2020
Continued moist westerly flow has brought strong wind and snow to
portions of western and central Wyoming this morning, with the
snow generally diminishing during the afternoon and evening hours,
except from southwest into southern WY. Light snow is expected to
continue with the slightly unstable flow over the western
mountains, with snowbands also bringing some heavier snow across
southwest WY and even east of the divide from central into south-
central WY. Today`s runs of the HRRR continue to show areas of
snow showers in Fremont and Natrona counties this afternoon, with
a stronger broad band moving across Sweetwater County late this
afternoon. Plan is to keep advisories going through 5pm this
afternoon and allow them to expire. Strong winds with the snow
have created hazardous road conditions over much of the area,
particularly southwest WY. Need to mention however that
widespread light snow is still expected over western WY,
particularly around the Tetons and southern portions of YNP, from
about 9pm to 3am, as a last surge moves through the area. Some
areas of western WY mountains could see 3 inches again overnight,
with an inch or less in the lower elevations. This strong flow
pattern with the surface low about overhead is keeping colder
Arctic area to the north in Montana and right along the WY/MT
line. This boundary will likely waffle during the next 24 hours
and allow some of this colder air with north wind to push
southward into the Big Horn Basin and Johnson County. Wednesday
should then see drier zonal flow over the area with a few showers
over the western mountains. Winds should also decrease Wednesday
as the surface pressure gradient weakens, though a moderate mid-
level height gradient will continue to keep breezy conditions in
the typical areas. Temperatures Wednesday will still be on the
cool side, though the cold Arctic air slides eastward into the
northern Plains.
Wednesday night into Thursday morning will see the mid-level flow
become more southwesterly as a deep trough off the west coast
begins to form and modify the flow pattern downstream. NAM and GFS
forecasts are showing the 700mb temperatures increasing bye about
10C, which will likely strengthen basin inversions Thursday
morning. An exception could be Jackson northward where moisture in
the southwest flow will keep the skies mostly cloudy and possibly
allow some light showers over YNP early Thursday morning.
.LONG TERM...(Thursday through Tuesday)
Issued at 1240 PM MST Tue Jan 14 2020
As the ridge slides eastward a new trough will move onto the
west coast and towards the area. This trough will bring more snow
across western WY that will begin as isolated PoPs in the
northwest and increase across western and southern WY by Friday
morning. Snow could spread east of the Divide during the day on
Friday. Saturday to Sunday another ridge moves in and sets up
over the area. The Cowboy state will finally be dry for an
extended length of time. Only isolated snow may make its way into
the northwestern corner. This drier period will last through
Tuesday. Otherwise, temperatures will slowly warm up on Thursday
and Friday before cooling off again during the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 504 PM MST Tue Jan 14 2020
West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals
MVFR/IFR conditions with snow are expected across the south
impacting KRKS through about 03Z, before becoming VFR.
The far west including KJAC with MVFR conditions in snow and blowing
snow should improve possibly by 02Z as ceilings lift and the
restrictions to visibility from combination of light snow and
blowing snow improve. However this will be short lived as a band
of snow is expected to impact KJAC between 05Z and 10Z tonight
with IFR conditions likely.
After 12Z Wednesday, VFR conditions are expected across the
entire area for the rest of the TAF period with any light snow
mainly confined to the far western mountains.
East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals
Cannot rule out a few snow showers through about 03Z across the
area, but not enough coverage or confidence to include them at any
terminal. The IFR ceilings will impact Johnson County more than
likely through Wednesday morning, but these ceilings should
remain north of KCPR. The KCOD terminal looks to have some
westerly low-level wind shear through about 18Z Wednesday.
Otherwise, VFR conditions with variable mid and high-level
cloudiness.
Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.
&&
.FIRE WEATHER...
Issued AT 120 PM MST Tue Jan 14 2020
Strong moist westerly flow continues to bring snow and high wind
to much of western and central Wyoming today. The heavier snow is
starting to diminish this afternoon, though some heavy snow bands
are expected from southwest into southern WY this afternoon into
the early evening hours. These snow bands will likely come with
30-40 mph west winds as well. Light snow is expected to continue
over the western mountains through Wednesday morning, with some
moderate snow around the Teton area from 9pm to 3am. An Arctic air
boundary is sitting along the WY/MT border this afternoon, and
that boundary should push some cold north wind southward into the
Big Horn Basin and Johnson County overnight, though the boundary
will move back northward by Wednesday morning. Snow will taper off
after 6am Wednesday morning and winds will generally decrease
though stay breezy over the typical areas. Temperatures will stay
relatively cool though, with a warm turn on Thursday as the flow
becomes more southwesterly. Next storm system moves through late
Thursday night into Friday night.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...McDonald
LONG TERM...Bourque
AVIATION...Murrell
FIRE WEATHER...McDonald
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
705 PM EST Tue Jan 14 2020
.UPDATE...
Latest RAP model shows deep layer ridging from west to east residing
across the area into Wed. This will provide a warm and moist air
mass with light winds...resulting in low clouds and patchy to
areas of fog. Similar to conditions that occurred Tue morning.
&&
.AVIATION...
15/00Z. VFR gives way to OCNL MVFR AFT 06Z in BR with TEMPO
IFR VSBY/CIGS BTWN 09-13Z. VFR SCT clouds return 14Z. Winds become
LGT and VRBL overnight then shift from SE to SW during Wed AOB
08KT.
&&
.MARINE...
High pressure across the waters will keep winds in the 5 to 10
knots for the next couple of day with a sea breeze component in
the afternoons near the coast. High pressure behind a front near
the end of the week will increase winds and seas...with speeds of
20 knots or less. While some guidance would suggest patchy sea
fog suspect the water is still too warm and will omit from the
forecast.
&&
.Preliminary Point Temps/PoPs...
TPA 67 80 63 79 / 10 0 0 0
FMY 64 83 62 83 / 10 0 0 0
GIF 65 83 62 82 / 30 10 0 0
SRQ 64 80 63 80 / 10 0 0 0
BKV 59 82 60 81 / 10 10 0 0
SPG 67 78 64 77 / 10 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...09/Rude
UPPER AIR...29/Delerme
DECISION SUPPORT...69/Close
Area Forecast Discussion
National Weather Service Topeka KS
532 PM CST Tue Jan 14 2020
.UPDATE...
Issued at 532 PM CST Tue Jan 14 2020
Concerns this evening revolve around the development of fog and
whether temps will fall below freezing while light drizzle is
possible.
Latest forecast soundings show some mixing at the top of
the boundary layer. Although there isn`t progged to be a lot of
dry air where this mixing is occurring. Nevertheless confidence in
widespread dense fog is a little lower this evening. So plan to
monitor trends and see how the boundary layer evolves. Think there
will be periods where visibilities will be a mile or less, just
not sold they will be at a quarter of a mile for an extended
period of time.
As for temps, RAP and NAM forecast soundings keep surface temps at
CNK and MYZ in the mid and upper 30s. And with the stratus
already moving in, I don`t expect temps to fall off very quickly.
The area of concern might be right at the state line where temps
just north of the state line are already at freezing. So I don`t
plan to issue a winter weather advisory for freezing drizzle at
this time. If temps cool off across the northern tier of
counties, I may have to put out a short duration advisory.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 333 PM CST Tue Jan 14 2020
Skies cleared today near and north of Interstate 70, while a stratus
deck of clouds hung out over the southern CWA. The stratus was
building back to north this afternoon and is expected to stick
around through tonight. Fog is likely to redevelop again tonight
and early tomorrow morning since the ground remains fairly moist
following recent snow and ice melt. In the meantime, an area of
low pressure will move out of Colorado and into southern Kansas
tonight. Lift will increase ahead of the low and CAMS are showing
light QPF developing mainly north of I-70 this evening. Thus, I
have included a chance for drizzle for a few hours as that system
approaches. Locations near the Nebraska border are more likely to
see freezing drizzle which could lead to some slick spots on
roadways late this evening and tonight. That system will then
continue eastward across the state, shifting our winds to the
northwest by early tomorrow morning. CAA will occur in its wake as
a 1045mb surface ridge starts building southward out of Canada.
Northwest winds will increase and become breezy tomorrow in
response to rapid pressure rises. The increasing winds should
help disperse fog after sunrise. Daytime warming will be limited
to just a few degrees during the afternoon as the cooler airmass
settles over the area tomorrow. The combination of cooler temps
and breezy winds will create wind chills in the 20s and 30s
through the day.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 333 PM CST Tue Jan 14 2020
There is one significant system that looks to impact northeast
Kansas during the long-term portion of the forecast period.
A cool airmass will remain in place over the region on Thursday as
the surface ridge shifts eastward toward the Great Lakes. Aloft, a
large trough will move onshore over the west coast with deep
moisture advection increases ahead of it over the south-central
CONUS. As the wave approaches, low level lift and WAA will increase
and a widespread batch of precipitation is expected to overspread
the area Thursday night. An early analysis of the temperature
profile suggests a mixed bag of precip types Thursday night and
early Friday morning, including snow, sleet and freezing rain.
Temperatures are expected to warm to above freezing during the day,
which should allow for a transition to rain. However, slick
conditions with some minor snow or ice accumulations look possible
early Friday before that transition commences. The Euro is more
robust with QPF than the GFS, but the general model consensus is
for a half an inch to an inch of total liquid equivalent
precipitation. If these trends continue, an advisory will be
warranted.
Conditions then look drier but cooler through the weekend. Northwest
flow aloft could keep things chilly into early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday)
Issued at 532 PM CST Tue Jan 14 2020
With a weak warm front along the KS river valley and decent warm
air advection over the boundary, IFR and LIFR conditions look
probable. A cold front is progged to move through the terminals
between 11Z and 14Z. Increased mixing and dry air advection behind
the front should cause conditions to quickly improve during the
late morning hours.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Wolters
SHORT TERM...Teefey
LONG TERM...Teefey
AVIATION...Wolters