Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/25/18

Area Forecast Discussion

National Weather Service Bismarck ND

 946 PM CST Wed Jan 24 2018

.UPDATE...
Issued at 946 PM CST Wed Jan 24 2018

We issued a Dense Fog Advisory for parts of north central ND into
the Turtle Mountain region in collaboration with NWS Grand Forks.
The Rolla AWOS has reported 1/4SM visibility for several hours,
and while we believed that to be localized earlier, trends in the
web camera images at Dunseith and GOES-East nighttime microphysics
RGB imagery suggest the fog is expanding into a wider area. The
last few cycles of the RAP, HRRR, and especially the ESRL HRRR
are also supportive of dense fog in that area overnight, though we
do have to admit confidence in the longevity of low visibility
even in that area is tempered by modest low-level turbulence seen
in model forecast soundings viewed in BUFKIT. Interestingly, the
rapid-refresh model suite has backed off considerably on the fog
potential in the James River valley the last few hours, so we are
less confident in the eventual possibility of an advisory in that
area than earlier. Mid- and high-level clouds streaming southeast
across the area may be slowing surface cooling a bit and that may
be one reason fog and stratus in general has been slower to form
than earlier thought, especially in the James River valley. Those
trends did support raising lows a bit in central ND overnight, but
we tempered changes slightly there too since even minor breaks in
the higher-level clouds have allowed for efficient cooling in low-
lying areas less susceptible to the increasing warm air advection
aloft. For example, Tioga quickly fell to 9 F this evening when a
break in the cloud cover passed that area.

UPDATE Issued at 556 PM CST Wed Jan 24 2018

Little change was made with this update cycle. GOES-East-based IFR
probability output from SSEC suggests stratus in north central ND
is beginning its westward propagation, and the latest iterations
of the RAP, HRRR, and NBM continue to support both that expansion
of low clouds and development of fog overnight in central ND. The
consensus of that guidance suggests the lowest visibilities and
thus highest probability of Dense Fog Advisory issuance is across
the James River Valley, but forecast soundings suggest a slightly
more turbulent near-surface layer than last night and thus the
longevity of the lowest visibilities is still too uncertain for us
to issue a headline just yet. Otherwise, the going forecast calls
for lows in the single digits F on the immediate west side of the
expected low cloud deck, from Garrison to Bismarck/Mandan, and we
have retained that given persistence trends from the past couple
nights when radiational cooling was enhanced in that region. That
said, MOS-based guidance and observed late afternoon dewpoints in
that area suggest that may be too cool, so we will be monitoring
trends the next few hours in case lows need to be increased over
that part of central ND.

UPDATE Issued at 349 PM CST Wed Jan 24 2018

Quick update to blend recent observational trends into the late
afternoon forecast, and to increase cloud cover across central ND
through the mid evening in respect to recent GOES-East imagery
which shows high-level cloud cover streaming across the area as of
21 UTC. ASOS/AWOS trends also show stratus lingering across parts
of east central ND at this hour, and we still expect expansion of
the stratus westward during the evening.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 148 PM CST Wed Jan 24 2018

Another night of weak southeast surface winds and generally clear
skies should allow fog to again form and spread westward from east
central North Dakota into portions of the south central and west
central this evening and overnight. Used the CONSHORT for guidance
for the timing and extent of the fog. At this time some uncertainty
on how dense the fog will be, but suspect there will be areas of
dense fog that may eventually require an advisory. However the
timing and extent are uncertain so will leave the advisory decision
during the evening period.

Will Thursday finally bring an end to the threat of fog?. Models
show strengthening h850/h925 warm advection flow and the a much
shallower inversion Thursday afternoon, that finally mixes out
Thursday night with the advancing surface trough and cold advection.
So do believe this will be the last night for fog.

Followed the Superblend for Thursday`s highs but did raise the high
temperatures a few degrees southwest into the mid 40s.

.LONG TERM...(Thursday night through Wednesday)
Issued at 148 PM CST Wed Jan 24 2018

A generally progressive flow remains in place for the extended so a
bit of a roller coaster temperature profile appears in store. The
building ridge across the region Thursday will maintain mild
temperatures in the 30s to middle 40s Thursday with the warmest
temperatures southwest. This will be followed by a Pacific cold
front Friday with colder air arriving behind a secondary frontal
passage Friday night. Friday looks breezy but not windy with spotty
chances of snow. The weekend looks cooler with highs in the teens
and 20s Saturday and single digits to the teens and 20s Sunday as
the colder air hours in. Wind chill temperatures could approach 20
below across the north central Saturday night.

A return to milder temperatures is forecast Monday and Tuesday as
the progressive flow brings in another h500 ridge, followed by
cooler air Wednesday. Teleconnections suggest a longer cold
period is possible after Wednesday as a broad h500 trough sets up
over Hudson bay ending the progressive flow regime.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 946 PM CST Wed Jan 24 2018

The expected expansion of fog and low clouds has been slower to
occur this evening than earlier thought, but the probability of
IFR and LIFR conditions overnight and early Thursday morning is
still high roughly along and east of a line from KMOT to KJMS.
The westward extent of the fog and low clouds remains uncertain,
so forecast confidence for the KBIS TAF is modest at best, and we
merely carried a few-hour period of MVFR visibilities there.
Otherwise, VFR conditions will prevail for the 00 UTC TAF cycle
across western ND from KISN to KDIK, and will expand into central
ND by Thursday afternoon as mid-level winds strengthen and scour
out the stagnant air mass.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM CST Thursday for NDZ003>005-012-
013.

&&

$$

UPDATE...CJS
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...CJS




Area Forecast Discussion

National Weather Service State College PA

 1018 PM EST Wed Jan 24 2018

.SYNOPSIS...
Seasonably cold weather is expected through midweek with
scattered snow showers and flurries over parts of the
Alleghenies. Another mild spell will begin on Friday and last
through the majority of the weekend. Precipitation is likely on
Sunday with rain possibly ending as snow in some areas as colder
air returns to start the last week of January.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
5h trof pushing across the central and southern Alleghenies this
evening with scattered (mainly) light snow showers and flurries
across southwest quarter of central PA. Some briefly heavier
snow showers reported along and west of the Allegheny crest into
Indiana and Cambria counties at mid evening, and that`s where
we have best chances for additional accums of an inch or so.

HRRR indicates weak surface wave associated with the upper trof
pushing east of the mountains by 04z with shsn decreasing by or
shortly after then. Elsewhere, skies are mostly cloudy and will
continue so for much of the night. Mins will range from around
10F far north to the lower 20s south.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Exiting short wave trough will yield to a north-south oriented
ridge of high pressure that will bring orographic snow showers
to an end early Thursday and then provide dry weather through
late week.

After a chilly day on Thursday, expect temperatures to quickly
moderate with Friday being 10-15F degrees warmer - starting
another period of mild temperatures that will last into the
weekend as southerly flow directs milder air back into the
region.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Well, after showing some promise in yesterday`s runs, the low
pressure system advertised for Sun/Mon now looking like a lower
impact event for central PA as surface low has shifted further
to the east - moving swatch of heavier rain eastward as well.

We will still have to contend with a decent trough, and with the
surface features further east this will put us further into the
colder air. But majority of precipitation will fall as rain
before a transition over to light snow later Sunday into Monday
as precip trails off. This far out, best forecast is light
accums mainly over the central and esp NW mtns/Laurels Sun night
into Mon as trough axis slides overhead and colder air filters
back in at all levels - bringing temperatures again back to
seasonal averages to close out the month.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...

MVFR/IFR continues over western and central terminals with
occasional visibilities in the 1-3 mile range in passing snow
showers.

Conditions will improve slowly after midnight toward sunrise
Wednesday, but could remain sub VFR over the higher western
elevation terminals.

Weak high pressure will build in for Thursday bringing mainly
VFR conditions with a decreasing wind.

Outlook...

Thu-Sat AM...No sig wx expected.

Sat PM-Sun...MVFR poss in SHRA.

Mon...Widespread low cigs with rain and snow showers.

&&

.HYDROLOGY...
Harper Tavern and Hershey on the Swatara Creek have crested and
fallen below flood stage and flood warnings for both points have
now been cancelled. Elsewhere, some small streams and creeks
(Lower Mainstem Susq tributaries) are running high such as the
West Conewago Creek near Manchester following a quick 1-2 inches
of rain early Tuesday morning.

The flood watch for York and Lancaster Counties remains in
effect through Thursday afternoon due to lingering concerns
surrounding minor flood/ice jam potential along and near the
Susquehanna River between York Haven and Safe Harbor.

Dry weather is expected in the Lower Susquehanna Valley through
Saturday with a gradual warming trend into the weekend.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Thursday afternoon for PAZ065-066.

&&

$$
SYNOPSIS...Gartner/Steinbugl
NEAR TERM...DeVoir/Gartner/Steinbugl
SHORT TERM...RXR/Steinbugl
LONG TERM...RXR/Steinbugl
AVIATION...La Corte
HYDROLOGY...



Area Forecast Discussion

National Weather Service Des Moines IA

 610 PM CST Wed Jan 24 2018

.UPDATE...
Issued at 610 PM CST Wed Jan 24 2018

Have sent a quick update for the latest fog trends with dense fog
having already developed across portions of west central Iowa, and
thus have expanded the dense fog advisory to include those
counties and start them immediately. Kept the start time for
areas further north with the fog still likely by late evening.
Overall remainder of the forecast remains on track.

&&

.SHORT TERM.../Tonight through Thursday/
Issued at 254 PM CST Wed Jan 24 2018

.Tonight into Tomorrow...The main forecast concern was focused on
stubborn stratus deck to linger/redevelop into tomorrow and the
potential for dense fog development late tonight into Thursday
morning. Leaned toward a blend of the RAP, HRRR, and NMM for fog and
sky cover into tomorrow as they have a decent handle on the current
cloud cover trends. The stratus deck over western to southwest Iowa
has begun to erode as depicted by the aforementioned models. The
stratus looks to fill back in later this evening and likely in the
100-500 foot range.  Visibility looks to diminish by around 02-05z
tonight over western to northwest portions of the CWA and persist
into the morning Thursday. Still very saturated airmass with dewpoint
depressions less than 5F and even 0F at most location up north overnight.
Plus this airmass remains stagnant over the region until the WAA
and mixing increase Thursday afternoon. Thus, confident to issue a
Dense Fog Advisory and may need to extend it further east and
south if the latest runs of the RAP and ARW hold true.

Lowered maximum temperatures across the north Thursday to coincide
with the lingering stratus/fog through the morning hours. Plus with
the snowpack in place, especially over the northwest, temperatures
will struggle to rise much tomorrow.  The 24.12z NAM had the best
handle on the cooler trend for tomorrow. Although didn`t quite go
that cold, did lower temperatures several degrees across the north.
The south remained untouched as there is higher confidence with the
fog/stratus to dissipate sooner. This resulted in a sharp gradient
in temperatures from north to south Thursday.

.LONG TERM.../Thursday night through Wednesday/
Issued at 254 PM CST Wed Jan 24 2018

./Thursday Night through Saturday Night/...Medium to High

Little change to the expected pattern evolution is anticipated
through the early part of the period...so confidence in timing and
features remains higher than average.

Main challenge with forecast will be any lingering clouds and
temperatures.  Broad shield of stratus/fog may be lingering over the
north near the start of the period and linger into the late evening
hours Thursday. Winds will eventually increase Thursday evening as
both surface gradient and winds aloft increase. This will help to
diminish the threat for fog late evening through the remainder of
the night over the far north. With increasing warm air advection
temperatures Thursday night will steady off into the mid 30s
across the south and in the upper 20s to lower 30s in the north.
Winds aloft and nearly adiabatic profiles Friday will assist in
mixing during the day especially across the south. Soundings from
Waterloo south are showing mixed winds to nearly 35 mph or higher
in the late morning and afternoon hours. Across the northern snow
fields winds may not mix as much with the stronger winds just
ahead of the Pacific cool front by 18z through 00z. Residual snow
cover will also support an inversion during the afternoon hours.
As the main storm tracks across northern North Dakota/Minnesota
into southern Canada by 00z Saturday a Pacific cool front will
drop southeast south of the region. Ahead of the boundary H850
temperatures will be on the decrease Friday but given the warm
start to the day...temperatures will recover to the lower 40s in
the north to the mid 50s in the south by afternoon.

./Saturday Night through Wednesday/...Confidence Medium

By Saturday night a secondary Arctic boundary will swiftly pass
southeast of Iowa. This will likely usher stronger northwest winds
along with colder air and cloud cover for most of Sunday. Chances
for light snow/flurries will exist immediately behind the front
overnight into early Sunday morning at this time weak subsidence is
apparent in the time height cross sections across the north. There
appears to be a consistent signal for clouds through the day. Models
are also suggesting that the cold air advection will be short lived
becoming weaker cold to neutral by late in the day and then winds
begin shifting to southwest Monday night. Surface high pressure will
briefly affect the region Monday though passing weak waves aloft
bringing some clouds across the region. Highs Sunday and Monday will
be cooler with highs back in the 20s north to the mid 30s south.
With warm air advection in full swing Tuesday temperatures will
recover to the 40s/50s with slightly cooler readings by Wednesday
with another weak Pacific front tracking east of the region.

&&

.AVIATION.../For the 00Z TAFS through 00Z Thursday evening/
Issued at 610 PM CST Wed Jan 24 2018

Low stratus to remain through much of the period with IFR to LIFR
CIGS across the northern TAF sites. Some VFR conditions across the
south, with possibility that fog/low stratus could move back in.
Better chances at KDSM than at KOTM. Otherwise winds to remain
light out of the south to southeast through much of the period.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM CST Thursday for IAZ004>006-015-
016-023>025-033>035-046.

Dense Fog Advisory until 9 AM CST Thursday for IAZ044-045-057-
070.

&&

$$

UPDATE...Beerends
SHORT TERM...Podrazik
LONG TERM...REV
AVIATION...Beerends




Area Forecast Discussion

National Weather Service Detroit/Pontiac MI

 543 PM EST Wed Jan 24 2018


.AVIATION...

Stratus trends over the next 24 hours will remain the main aviation
challenge. Some brief breaks in the low cloud deck and a slight
downslope component under light northerly flow led to a subtle rise
in ceilings across metro Detroit to just above 3k ft. Earlier breaks
have since filled in. Regional observations and latest RAP and HRRR
guidance suggests a persistence forecast through the night with
respect to ceilings. Weakening low level flow with sfc high pressure
building overhead may however lend itself to some additional breaks
in the overcast, confidence of which is rather low attm. A warm
frontal feature will then lift north across Se Mi Thurs morning into
early afternoon. Lowering inversion heights ahead of this front are
likely to result in a subtle drop in ceilings. Warmer and drier low
level air will then lift into the region behind this front,
suggesting the stratus will clear out Thurs afternoon.

For DTW...Persistence will suggest holding cigs around 3500 ft
through much of the night. The approach of the warm front after 08Z
may however lead to drop in the cigs back into the MVFR range.

/DTW THRESHOLD PROBABILITIES...

* Moderate in ceilings below 5000 ft tonight and Thursday morning.

&&

.PREV DISCUSSION...
Issued at 308 PM EST Wed Jan 24 2018

DISCUSSION...

NEAR TERM / REST OF TODAY THROUGH TONIGHT

As of 305 PM EST...Cyclonic flow and weak cold air advection
continue across the region this afternoon, as a shortwave impulse
continues to pass by to the south across northern Indiana and Ohio.
With the cyclonic flow in place, lake moisture plume continues to
drift downstream across southeast Michigan resulting in persistent
cloudy conditions with dreary stratus. Enough dry air in the low-
levels has resulted in a mainly dry day though, but occasional
saturation near the -10 C layer and boundary layer forcing has been
enough to squeeze out a few flurries from time to time. With the
shortwave impulse passing by, enough lift could drift northward into
far southern Michigan riding the PV surge to potentially squeeze out
some more persistent light snow showers towards this evening, but no
accumulation is expected.

For tonight, upper-level heights will begin to rise as surface high
pressure ridges into the region. A slackening of the pressure
gradient will allow winds to become light and variable overnight,
but a pesky residual boundary layer moisture trapped underneath the
subsidence inversion will keep stratus around through much of the
night. The best shot at seeing some clearing will be across far
southern areas towards the Ohio border. A few lingering flurries
will be possible into late this evening before the increasing
anticyclonic flow aloft ends these chances. Towards daybreak, a
release of Lake Michigan moisture, albeit weak and subtle, will
drift into portions of the Saginaw Valley. Forecast model soundings
show ice nucleation in the -8 to -10 C layer, which may be just warm
enough with a lack of ice present above this layer to promote a
couple hour window of freezing drizzle. Confidence not high enough
to mention in the HWO at this time, but something to keep an eye on
overnight. With cloud cover lingering, bumped up low temperatures a
couple degrees tonight, ranging from the mid and upper teens north
of M-59 to lower 20s south.

SHORT TERM / THURSDAY THROUGH FRIDAY NIGHT

Outside of possible freezing drizzle in the Saginaw Valley early
Thursday morning, dry conditions are expected as upper-level ridging
continues to build across the region. Lingering low-level moisture
will make it tough to fully erode stratus, especially north, but
developing south/southwesterly flow near the surface and warm air
advection may be enough to allow for breaks of sunshine with more of
a stratocu versus a stratus deck. High temperatures in the warm air
advection regime will reach well into the 30s across southeast
Michigan.

Cloud cover begins to rapidly diminish Thursday evening into
Thursday night as upper-level ridging and core of drier atmospheric
column air peak over the region. Expect mostly clear skies Thursday
night with lows only falling into the mid/upper 20s with persistent
warm air advection amidst a southerly flow. Continued dry with
abundant sunshine Friday as low-level southwesterly flow ramps up
ahead of approaching southern stream energy. It will be breezy on
Friday, with gusts of 20-30 mph possible. These winds will help
temperatures soar during the day into the upper 40s, with many areas
likely eclipsing 50 with the strong warm air advection and abundant
insolation in place.

Friday night, aforementioned southern stream energy continues to
approach the region as it ejects out of the Plains, but gradually
shears out with time as northern stream energy remains disconnected
associated with low pressure tracking north of Lake Superior. Still
some timing differences with the southern stream energy though, as
the GFS as expected is faster than the ECMWF.

LONG TERM / SATURDAY THROUGH TUESDAY

Heading into Saturday, the interplay between the southern stream
energy and approach of a trailing cold frontal boundary will be
critical to potential rain chances for at least a portion of the
area as temperatures remain mild into the 40s. Model guidance
continues to favor a solution that keeps the bulk of the frontal
slope forcing east of immediate southeast Michigan, but enough
forcing looks to be present to keep a mention of a chance of rain
showers, mainly south of I-96. Integrated vapor transport looks
meager with the system in general, with PWAT values only rising to
0.75 inch. Given this moisture profile, and the overall distance of
the front from its parent surface low, these rain showers will be
light in nature.

Slightly cooler air works into the region behind the frontal passage
as temperatures return to near normal. Trailing northern stream
trough diving through Sunday will promote a chance of snow showers
across the region with high pressure in its wake leading to a return
of drier weather for the start of the next work week.

MARINE...

A ridge of high pressure will start to build in across the Great
Lakes throughout Thursday and will act to keep winds calm overnight
(Wednesday night into Thursday), with light S/SE flow expected by
Thursday afternoon. Low pressure is then expected to track eastward
along the southern Canadian Provinces which will help to strengthen
the pressure gradient across the Great Lakes throughout Friday,
bringing stronger winds to the region. This will act to ramp up warm
air advection across the cooler lakes, increasing stability and
keeping wind speeds capped between 20 - 30 knots Friday afternoon
into the evening. Southwest flow is expected to persist throughout
Saturday before a cold front veers winds to the west and eventually
northwest throughout Sunday morning.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....SC
DISCUSSION...IRL
MARINE.......AM


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.



Area Forecast Discussion

National Weather Service Grand Rapids MI

 943 PM EST Wed Jan 24 2018

LATEST UPDATE...
Update

.SYNOPSIS...
Issued at 305 PM EST Wed Jan 24 2018

Relatively tame conditions are expected through the weekend.
Chances for precipitation will be limited to a couple of frontal
passages with above normal temperatures Friday and Saturday. A
cold front will approach Lower Michigan late Saturday into Sunday
with near normal temperatures returning Sunday into next week.

&&

.UPDATE...
Issued at 943 PM EST Wed Jan 24 2018

It will be an interesting overnight period. Not out of the
question we may still need headlines for the morning commute.

A short wave was crossing the CWA this evening. It will bring a
thermal trough with it where H8 temps drop to around -13C by
around 06Z. It also perks up the inversion heights to 5-6K. If
this verifies we should see a quick burst of snow come off the
lake, between now and 08Z. Already seeing some radar returns and a
few flurries here at GRR. After 08Z we lose the moisture in the
DGZ and a brief period of freezing drizzle should occur from about
08Z and 11Z. This could slicken up the roads by the morning
commute. Most of this activity should occur along and west of U.S.
131, with little to no pcpn to the east.

Not enough confidence in this scenario at this point since we are
dealing with fairly shallow moisture, so will continue to monitor.
But it does appear all the pcpn winds down by 12Z as we see warmer
air arrive aloft, ending any lake contribution, and the moisture
becomes even shallower toward daybreak.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 305 PM EST Wed Jan 24 2018

Tonight into early Thursday will be the main challenge with
respect to chances for light snow/freezing drizzle.

A shortwave will pass over the Northern Great Lakes Region through
tomorrow morning, as surface high pressure builds into the eastern
CONUS. The boundary currently stretching from Northern Illinois
into Central Ohio will return north as a warm front late tonight.
Much of the atmosphere is dry, while a shallow layer of moisture
resides at/below 850 mb. The top of this moisture layer approaches
the bottom of a thin dgz at the onset, which eventually erodes
through the morning. High res solutions, such as the NAMNest and
HRRR favor a thin ribbon of snow, but given sounding data and
overviews, it makes sense that areas of freezing drizzle could
result through mid-morning.

Expect what falls to remain light, lifting SW to NE just after
midnight for SW Michigan to late morning through Central Lower.
Higher probabilities will be along and west of U.S. 131, but
cannot be ruled out as far east as Lansing. Also note that recent
rainfall has washed area roadways clear of any treatment products,
allowing any freezing drizzle to easily adhere to the surface.
Given low confidence and probabilities for precip, no headlines
are warranted at this time. It may make the morning commute slick
is some spots, which is likely to be handled with SPS products as
necessary.

Fair weather controls much of the remainder of the period with
sunshine possible by Thursday afternoon. Even milder air moves in
with above normal temperatures and ample sunshine Friday. A weak
cold front pushes through late Friday with low chances for precip.

.LONG TERM...(Saturday through Wednesday)
Issued at 305 PM EST Wed Jan 24 2018

Energy embedded within a longwave trough stretching from off the
West Coast up through Alaska will move through the Midwest and Great
Lakes Saturday through Monday. There is good consensus within the
medium range models tracking the main low center from North Dakota
to Quebec by Saturday morning, drawing warm air and moisture up into
the Great Lakes. Precipitation ahead of a surface trough extending
through Michigan will continue south of I-96 through midday
Saturday, before moving east. Thermal profiles in the models
continue to support rain. Temperatures on Saturday will remain mild,
with highs in the 40s.

A strong cold front will drop through Lower Michigan Saturday night
and Sunday, with potential for lake effect snow increasing as
temperature differences between the lake surface and H850 increase
to near 20C. North-northwest flow will limit inland extent of snow
(mixing with rain Sunday afternoon), with accumulations Sunday and
Monday mainly staying within counties adjacent to the lakeshore.
Models are struggling to resolve the evolution of individual waves
currently embedded within the trough off the west coast, but there
is potential for a passing shortwave to spread snow further inland
Sunday night and Monday. Temperatures will cool near to below normal
early next week, with highs on Monday back in the 20s. Building high
pressure and southerly flow should bring dry weather Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 643 PM EST Wed Jan 24 2018

A mix of VFR and MVFR conditions where over the region early this
evening. There should be a trend to more VFR, but we probably
won`t lose all the MVFR.

Then toward midnight a weak system should bring lowering ceilings
again and the possibility of freezing drizzle and perhaps light
snow. The setup seems best toward the lakeshore, then the pcpn
should diminish inland. Therefore some freezing drizzle will be in
the MKG TAF the longest, with lesser impact expected for GRR and
AZO. The rest of the TAFs may escape from any freezing drizzle.

Ceilings are expected to rebound as the weak system departs.
Mostly VFR is expected from roughly daybreak and this will
continue through the day with many areas seeing the low clouds
clearing.


&&

.HYDROLOGY...
Issued at 1241 PM EST Wed Jan 24 2018

Low lying areas near river banks, are and will for a short time,
have some minor flooding. Substantial precipitation is not expected
until at least this weekend, so the water will have time to move
through the river system. Smaller and rapid response rivers are near
crest or have crested, while main stem rivers will crest over the
next few days. Most of the ice is off of area rivers, so ice jam
concerns are very low.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

UPDATE...JK
SYNOPSIS...JAM
SHORT TERM...JAM
LONG TERM...HLO
AVIATION...JK
HYDROLOGY...63




Area Forecast Discussion

National Weather Service Marquette MI

 633 PM EST Wed Jan 24 2018

.SHORT TERM...(This evening through Thursday)
Issued at 413 PM EST WED JAN 24 2018

WV imagery and RAP analysis indicated mid/upper level ridging over
UT through the nrn Rockies and a downstream trough over the Great
Lakes into the OH valley. A weak clipper shortwave trough moving
toward the MN arrowhead supported some light snow or flurries nw
of Lake Superior. Otherwise, patchy sunshine prevailed over Upper
Michigan as weak sfc ridging moves off to the east.

Tonight, the combination of the shrtwv and weak trough may bring
some light snow showers through wrn Lake Superior into the Keweenaw.
However, little or no accumulation is expected.

Thursday, WAA will increase as the mid level ridge move eastward and
low pressure develops into the plains. With a dry airmass upstream,
no pcpn is expected as most of the WAA will result in layer warming
rather than net isentropic lift. Some isold -shsn may be possible
over the Keweenaw. However, any deeper moistening or significant pcpn
is expected to remain north of the cwa.

.LONG TERM...(Thursday night through Wednesday)
Issued at 413 PM EST WED JAN 24 2018

Models suggest that a progressive pattern will prevail into the
middle of next week. Mid/upper level ridging will advance through
the cntrl CONUS to the Great Lakes from Wed into Fri as a trough
moves through the wrn CONUS. Temps will climb well above normal from
Thursday into Friday and then drop closer to normal for Sunday and
Monday. Expect warming again from Mon into Wed as another trough
moves through the plains reaching the wrn Great Lakes Wednesday.

Thursday night-Saturday, a vigorous shrtwv and associated low is
expected to lift into nw Ontario by Friday night which will draw
unseasonably warm air into the region. With gusty southerly winds
and 900 mb temps to near 6C, expect highs into the lower 40s, with
some mid 40s possibly for downslope flow locations. A frontal
passage Friday night will bring drier air into the region with weak
850 mb CAA. However, wsw winds should still provide enough mixing to
keep temps at or above freezing. There may be some light rain
showers changing to snow late Saturday into Saturday evening as a
shortwave moves through. Some lake enhancement into the west will
also be possible as 850 mb temps drop to around -12C.

Saturday night through Tuesday, a period of nw to n flow LES will be
possible as 850 mb temps drop into the -15C to -18C range. The
snow may be enhanced Saturday night and sfc trough passage as
models have trended toward a strong shrtwv. Any LES should taper
off toward Monday as sfc and mid level ridging build into the
region. Strengthening WAA will again support potential for light
snow Tuesday. There may be enough moisture inflow to support some
light accumulations.

Wed, expect a brief warmup into the 30s. However, models have
trended faster with the frontal passage minimizing the potential
for higher temps. Snow or rain changing to snow may be possible with
if supported by a stronger mid level shrtwv, per ECMWF.
&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 633 PM EST WED JAN 24 2018

Mainly MVFR conditons expected at KIWD and KCMX into early Thursday
morning before steadily improving by mid morning. KSAW will be
mainly VFR this evening before low level moisture increases tonight.
This will lead to MVFR conditions later this evening into the
overnight hours at KSAW, before steadily improving Thursday morning.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 413 PM EST WED JAN 24 2018

Winds will remain below 20 knots through Thursday before increasing
to southeast winds 20 to 30 knots and south gales to 35 knots
thursday night and Friday, respectively. West gales to 35 knots are
then possible Friday night and into Saturday, before winds relax to
15 to 25 knots through Monday. Winds look to increase to 20 to 30
knots again Tuesday and Wednesday.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLB
LONG TERM...JLB
AVIATION...KEC
MARINE...BB