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Office: MQT

FXUS63 KMQT 131120
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
620 AM EST Wed Dec 13 2017

.SHORT TERM...(Today and tonight)
Issued at 439 AM EST WED DEC 13 2017

...Slippery Morning and Evening Commutes Expected Across Portions of
Upper Michigan Today...

A clipper system is currently tracking across the Upper Mississippi
Valley as multiple shortwaves evident on water vapor imagery
continue to dig southeast towards the region. 850mb winds have back
to the south-southeast this morning, which allowed lingering lake
effect snow east of Marquette to push offshore this morning. Across
the west, light snow was observed; however, a more robust band of
snow has developed across central Minnesota and northwest
Wisconsin, which will be the main forecast concern for the day.

Today: The main concern is the strong fgen band expected to track
along the Wisconsin/Michigan border through the day today as the
main clipper system tracks across southern Wisconsin this afternoon.
This band is expected to track west to east across western and
central Upper Michigan this morning and will impact the morning
commute. As strong isentropic lift develops along this band of
frontogenesis, expect fairly deep lift to develop and allow for snow
to fall moderate, to even heavy, at times. Forecast soundings show
this deep lift with a fairly deep residence time for hydrometeors
through the DGZ. Therefore, expect this system snow to be rather
efficient. However, with the thermal profile anchored more towards
the -10C isotherm, SLRs should be lower than 20:1, and will make for
a wetter, more sloppy snow. The track of the surface and 850mb low
coupled with 850mb temperatures around -15C, we're also looking at a
good setup for lake enhanced snow across the south central. This
will lead to localized amounts a bit higher on the west side of the
Bay of Green Bay. The system snow will come to an end across the
west this afternoon, but may linger into the evening hours across
the south central. Across the Keweenaw and eventually north central
Upper Michigan as the 850mb flow comes around to the east and then
northeast later this morning and afternoon, respectively, and
remains between -15 and -18C expect lake enhanced snow to impact
those locations. Across the north central, this lake enhanced snow
will transition over to lake effect by this evening. Did expand the
winter weather advisories and issued an SPS to account for the
impacts expected during the morning and evening commutes.

Tonight: As the clipper system continues to track southeast across
the lower Great Lakes cold air advection will ramp up across the
Upper Great Lakes and allow for lake effect snow to return, if not
already ongoing from this afternoon. As a few weak shortwaves dig
across the region overnight, this will back the 850mb flow and push
the resulting lake effect snow from northeast to northwest snow
belts. With 850mb temperatures progged to remain around -18C over
night, expect lift through the DGZ to be strong enough to support
additional snowfall accumulations, possibly upwards of 3 inches in
some spots.

.LONG TERM...(Thursday through Tuesday)
Issued at 408 AM EST WED DEC 13 2017

Intermittent lake effect snow is expected through much of the
extended forecast with continued colder temperatures. The greatest
impact will likely be early in the extended late Thursday into
Friday evening as moderate to heavy lake effect snow is possible.

Thursday through Friday night: The deep troughing over the eastern
CONUS is expected to linger through this time period allowing below
normal temperatures to remain in place. 850mb temperatures are
progged to be between -16C and -22C, warmest Thursday into Thursday
evening. The colder temperatures will slide in aloft Friday and
Friday night as a reinforcing shot of colder air sinks southward
into the U.P. with another strong shortwave aloft. Initially winds
will be westerly across the U.P. Thursday and Thursday evening;
however, a surface low is expected to develop and intensify over
eastern Lake Superior as this wave digs into the area. This will
effectively shift the winds to the north to northwest across much of
the area, especially over the eastern half of the U.P. This would
allow for favorable conditions for a period of moderate to heavy
lake effect snow for north to northwest wind favored snowbelts
Friday into Friday evening. Inversion heights are progged to jump to
around 10kft and 15kft as the wave slides overhead. Again, this
would point to a period of heavy lake effect snow late Thursday
night into Friday evening as deep layer moisture and forcing exist
through much of the sounding. Current thinking is that several
inches of lake effect snow may fall from portions of the north-
central U.P. and especially through the eastern U.P. along Lake
Superior. Models are fairly similar in pegging those areas for the
heavier snow; however, a slight change in wind direction will shift
the favored snow bands. Stay tuned for updates for this time period,
but it does appear that headline worthy snowfall totals are possible
Friday into Friday evening across the eastern half of the U.P.
downwind of Lake Superior.

Saturday into Sunday: A weak low pressure system is expected to
slide to the south of the U.P. as yet another upper-level
disturbance slides across the Upper Great Lakes.  This will provide
just enough moisture and lift to provide very light lake effect snow
or possibly flurries across the U.P. 850mb temperatures moderate
significantly with much of the area seeing 850mb temps in the -6C to
-8C range.  This will minimize any lake enhancement for this time
period. Surface temperatures will warm as well with most locations
seeing highs in the mid to upper 20s by Sunday.

Rest of the extended: Broad troughing is reinforced over the eastern
CONUS generally allowing for northwest flow aloft as a broad ridge
continues over the western CONUS. This will lead to intermittent
lake effect snow chances through much of this period with the
favored bands depending largely on the low to mid level flow. Models
differ on timing of the better shortwave enhancements during this
time period, which is typical for the end of the extended forecast;
therefore, will stick with a consensus of the models with the
intermittent lake effect snow chances, mainly downwind of Lake
Superior.
&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 620 AM EST WED DEC 13 2017

A band of moderate snow is expected to track across Upper Michigan,
impacting primarily KIWD and possibly as far north as KSAW this
morning. Reduced visibilities down into the LIFR category will be
possible in the stronger parts of this band along with IFR ceilings.
Winds will become easterly and the northeasterly throughout the day
today, allowing upslope flow and additional snow showers across KSAW
and KCMX through the end of the day. Tonight, lake effect snow
showers will return to all terminals at times with MVFR ceilings and
reduced visibilities.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 408 AM EST WED DEC 13 2017

Winds will remain at or below 25 knots through Thursday night as the
pressure gradient relaxes across Lake Superior. Winds will increase
to 20 to 30 knots late Thursday night through Friday evening as the
next low pressure system develops and strengthens over eastern Lake
Superior. Winds will then remain in the 15 to 25 knots range through
the beginning of the work week.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory from 11 AM this morning to 1 AM EST
     Thursday for MIZ005.

  Winter Weather Advisory until 7 PM EST /6 PM CST/ this evening
     for MIZ010>013.

Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...Ritzman
LONG TERM...KEC
AVIATION...Ritzman
MARINE...KEC



Office: DTX FXUS63 KDTX 131452 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 952 AM EST Wed Dec 13 2017 .UPDATE... Lead isentropic ascent producing patches of moderate snow this morning. Snow will be continuous, but mostly light, for the next several hours as the column slowly saturates. Minimal accumulations of an inch east of US-23 by 18z with 1 to locally 2" to the west. Clipper is still on track to unfold as forecast. A morning update will be issued to fine tune the position and magnitude of the heavy snow band. The biggest change to the official forecast will be to lighten snow on the front and end of the event and ramp up snowfall during the peak. 1 inch per hour rates are a certainty with a brief period of 2"/hr rates possible. The event peak is still forecast to begin around 20z. There remains some uncertainty along the southern periphery of the heavy snow band. As it stands, it is highly likely that snow will come to an end in part or all of Lenawee and Monroe County in the 18-21z period before the warm conveyor ramps and allows suthern areas to fill back in. Any minor deviation in storm track from forecast expectations will cause this afternoon snow void to shift north or south. && .PREV DISCUSSION... Issued at 556 AM EST Wed Dec 13 2017 AVIATION... A strong clipper system is forecasted to dig into the central Great Lakes region today, bringing widespread accumulating snowfall. Lower VFR deck will trend to MVFR as light snow moves into region 15z-16z. Peak of the event is expected between 20-01Z over southeastern Michigan with periods heavy snow possible. VLIFR to LIFR conditions will be possible in heavy snow during the evening. East to north winds are forecasted during the event with speeds in the 10 to 15 knot range. Snow will end by 05z-06z with a trend back to VFR overnight into Thursday. For DTW...MVFR light snow developing after 15Z today with IFR light snow after 16Z. Peak of the event is expected between 21-02Z with VLIFR/LIFR in heavy snow possible. //DTW THRESHOLD PROBABILITIES... * High confidence in cigs at/below 5000 ft agl for the Taf period. * Moderate to High confidence in heavy snow with visibilities less than 1/2sm and cigs at or less 200 ft agl 21-02Z PREV DISCUSSION... Issued at 337 AM EST Wed Dec 13 2017 DISCUSSION... Heavy Snow to Impact The Evening Commute. Strong clipper system entering the Western Great Lakes this morning, with the 990-992 MB Low tracking through far southern Lake Michigan this afternoon, as the two strong upper level waves/500 MB height fall centers are already in lockstep and beginning to merge, with the consolidated max height fall center tracking close to the southern Michigan border early this evening. Excellent low level jet (55+ knots at 850 MB) over the Ohio Valley nosing into southern Lower Michigan during the day, leading to intense lift/isentropic ascent/FGEN lined up over the heart of the CWA 18-23z, the worst possible time for the evening commute. Overall moisture content still not very impressive, as specific humidities rise to around 2.25 G/KG, but across a fairly deep layer. Still, pristine thermal profiles with the best lift in the DGZ should be conducive for good snow to liquid ratios 15:1 far south to 18:1 north (on average through most of the event). Expecting about a 3-4 hr window of snowfall rates at or above 1 inch, and if the 00z NAM negative EPV in the 850-700 MB layer verified, then could see rates approach 2 inches, however most other models are bit more stable. Real good model consensus depicting max QPF slightly better than 4 tenths of an inch. The 00z Euro, which seems to be lined up with fairly well right now, trended a bit farther north. Thus, some big concerns with the mid level dry slot impinging north this afternoon across the southern Michigan border, shutting off precipitation for a period, possibly as far north as the I-94 corridor. None-the-less, local probabilistic guidance (heavily influenced by SREF) also indicating high likelihood of 7 inches across Wayne county, and with possibility of a little moisture flux boost/low level convergence off Lake Erie after 21Z as sfc-925 MB winds come around to the south and then southeast, and went ahead and upgraded Wayne and Washtenaw counties. Otherwise, farther north, feel pretty good with a swath of 5 to 8 inches (isolated higher totals possible), and upgraded the majority of the counties to a winter storm warning (15z-5z). Went with an advisory for Bay county and Thumb region as residual dry airmass holds on longer, but winds shifting to the north this evening should allow for some Lake Huron enhancement continuing past midnight, allowing those counties to be in the 3 to 7 inch range. Went with advisory for Lenawee and Monroe for 3 to 6 inches with the dry slot concerns and being so close to the surface low, along with the diminished snow to liquid ratios. Clearing out late tonight with winds diminishing, and should be able to dip into the 5 to 15 degree range with the fresh snow cover, which will likely hold maxes into the 15 to 20 degree range for Thursday as 850 MB temps reside in the negative mid teens. Digging trough axis swinging through Thursday night into Friday looks to provide additional light snow, especially with the help from Lake Michigan with the westerly flow. Possible messy wintry mix or even rain scenario for the end of the weekend as low pressure is forecasted to track through the Western Great Lakes (per 00z euro), with a good shot of temperatures climbing into the mid to upper 30s. MARINE... Winds and waves will subside steadily early this morning and have allowed Gale Warning to expire. A storm system will then bring moderate snow from across southern Lake Huron southward today. As this low pressure passes to the south, winds will increase from the northeast tonight and then back to northwest on Thursday. While gale conditions are not anticipated, the strong onshore flow will lead to building waves and the need for Small Craft Advisories over the near shore waters tonight into Thursday before winds back to northwest and takes the higher waves east away from the Michigan shore. Cold air will help produce bands of lake effect snow on Lake Huron Thursday. Another system will help back the flow to the southwest for Friday while bringing more snow activity to the lakes. At this time, winds are not expected to reach gales again at least through the upcoming weekend. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Winter Storm Warning until midnight EST tonight for MIZ047-053- 060>062-068>070-075-076. Winter Weather Advisory until 5 AM EST Thursday for MIZ049-054-055- 063. Winter Weather Advisory until midnight EST tonight for MIZ048-082- 083. Lake Huron...Small Craft Advisory from 7 PM this evening to 5 AM EST Thursday for LHZ422. Small Craft Advisory until 10 AM EST Thursday for LHZ421-441>443. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ UPDATE.......JVC AVIATION.....DG DISCUSSION...SF MARINE.......DG You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Office: APX FXUS63 KAPX 131453 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 953 AM EST Wed Dec 13 2017 .UPDATE... Issued at 953 AM EST Wed Dec 13 2017 Forecast working out pretty much as planned by overnight crew. Large warm air advection wing of light to moderate snow tied to upstream "clipper" low overspreading northern lower Michigan this morning. Heaviest snows remain further upstream within intensifying thermal regime and attendant fgen response. Core of these strongest dynamics expected to clip along and south of the M-55 corridor, with the focus shifting further south with time this afternoon and early evening. Sharp northern gradient to the accumulating snow expected (likely not much further north than M-68) given low level dry air feed and developing downward branch of tightening fgen response. Inherited snowfall gradient looks to be working out rather well, with advisory amounts (3 to 5 inches) still expected in current headline area. Will continue to monitor radar and observation trends for a possible need to include a tier of counties further north into the advisory. && .NEAR TERM...(Today through Tonight) Issued at 358 AM EST Wed Dec 13 2017 ...Round of snow across central and southern lower Michigan... High Impact Weather Potential...clipper system brings accumulating snow across central and southern lower Michigan...will be close call for this CWA. Pattern Synopsis/Forecast...Early morning water vapor imagery reveals a sharp negatively tilted trough axis running from Hudson Bay through the mid Atlantic coast with strong short wave energy and surface low pressure running up through New England. Sharp thermal gradient and resulting modestly strong upper jet streak resides across the far western Great Lakes into the Ohio Valley with a core of -20C H8 air skirting through northern Michigan and >0C H8 air nosing into Wisconsin. Further upstream...our next short wave and attendant surface low is diving quickly into the upper Midwest along that thermal gradient. Already some light warm advection/FGEN forced light precip stretching from the western U.P. down into Lake Michigan and just starting to edge into western portions of lower Michigan. Primary Forecast Concerns...Snow accumulations and headline potential today along the far southern portion of this CWA. Short wave and attendant surface low will race quickly southeastward today...with the surface low track essentially along a line through Chicago by midday and on across far southern lower Michigan/northern Ohio this evening...before kicking eastward off the Atlantic coast by Thursday morning. Strong warm advection forcing along the northeastern side of this system slides through lower Michigan through the course of the day with the heart of strongest FGEN/deformation dynamics and highest QPF cutting across west central lower Michigan and down through SE lower Michigan. Broad upper vertical motion signal collocated through the DGZ should yield some higher snow->liquid ratios and a nice swath of 4 to 7 inch snowfall through central lower Michigan. Still some forecast uncertainty on the exact position and northern extent of strongest forcing and heaviest snow...with various guidance cycles wavering just bit on this point. Consensus still keeps the heart of the heaviest snow just south of the CWA (Ludington through metro Detroit)...with snow accumulations around 4 inches skirting the the M-55 corridor over through Gladwin county. Close call...but have decided to err on the side of caution and nudge up snow accumulations just a bit from inherited forecast...as well as push higher pops a little further northward. Will also hoist winter weather advisory for Manistee through Missaukee counties...and Gladwin county with with 3-4 inch accumulations across those areas. System quickly kicks east of the region tonight with winds backing southeast to north by Thursday morning. Will probably see some lake effect/lake enhancement along the Lake Huron shoreline/NE lower Michigan later this afternoon through tonight (have added some higher snowfall totals to Arenac and Iosco counties to account for that)...and lake effect snow showers re-emerging along the Lake Michigan and Lake Superior shoreline areas overnight into Thursday. && .SHORT TERM...(Thursday through Friday) Issued at 358 AM EST Wed Dec 13 2017 ...Light lake effect possible Thursday followed by moderate snow Thursday night through Friday... High Impact Weather Potential...Moderate snowfall amounts possible Thursday night through Friday, especially within the W to N flow snowbelts. Pattern Synopsis/Forecast...Deep longwave trough that's been entrenched over the eastern CONUS for the last week or so will finally begin to weaken and lift out of the region during the period. This will happen as the highly amplified ridge over the West Coast begins to break down under the influx of another incoming trough over the Pacific Northwest. Locally here in the Upper Great Lakes, 850mb temperatures will be warming just a little bit on Thursday, but will still be cold enough to support some light NW flow lake effect. Thursday night into Friday, a potent closed upper low will dive south from northern Manitoba into the Upper Great Lakes, with a surface low quickly developing in response over the region. Primary Forecast Concerns...Snow amounts through the period, particularly Thursday night through Friday. Winds Thursday will gradually back from NW to W during the day, fairly light over land. Temperatures will be sufficiently cold at 850mb, but moisture will likely be a limiting factor for potential lake effect activity. Looks like an increasing amount of dry air just above the surface through the day and a nearly saturated layer initially extending from roughly 925-850mb but becoming shallower through the day. Inversion heights top out at around 800mb. So, moderate confidence in the likelihood of some lake effect bands, but don't anticipate they'll get out of hand with available moisture looking rather limited. Backing wind direction should also help keep snow amounts in check. As of now, only looking like around an inch or less across portions of northwest Lower and western Chippewa Co. Thursday night through Friday looks more concerning in terms of snowfall potential. Moisture will begin to increase Thursday night out ahead of the next system with forecast soundings showing a deepening saturated layer with time. Forcing will be somewhat limited at first, but deepening lake aggregate troughing should provide a favorable setup for intensifying snow bands overnight. Additional synoptic support will arrive on Friday as an upper trough drops in, and late in the day the closed upper low itself. Inversion heights will be around 700mb or higher, so a favorable setup for lake enhancement, especially within the W to N snowbelts. 850mb temperatures actually look to be relatively "warm" compared to recent days, hovering around -13 to -15C, but that will still be sufficient given the still warm open waters. Also a respectable DGZ depth, coinciding with low level omega. All this to say, the setup is looking more and more favorable for some decent snowfall Thursday night through Friday for western Chippewa County and northwest Lower, where snowfall may exceed 4 inches. Will have to monitor for potential headlines for affected counties. Also worthy of mention is that temperatures will gradually moderate through the period with highs solidly back in the 20s by Friday. .LONG TERM...(Friday night through Tuesday) Issued at 358 AM EST Wed Dec 13 2017 High impact weather potential...Continued occasional chances for snow and lake effect snow. Lake effect snowfall will continue into Friday night, diminishing towards daybreak Saturday. A band of isentropic ascent will push in from the southwest on Saturday out ahead of an incoming clipper system, which will provide snow chances over the weekend. This will be followed by potential for some more lake effect on Monday and Tuesday. Temperatures will continue to moderate through the weekend into early next week as upper flow pattern becomes more zonal. GEFS member spread in surface temperatures has decreased quite a bit over the last few runs, suggesting increasing confidence in the potential for milder temperatures. Highs in the lower 30s look plausible, perhaps even mid 30s near the coasts. That would introduce the chance for some rain in spots as opposed to this seemingly perpetual recent snowfall. && .AVIATION...(For the 12Z TAFS through 12Z Thursday morning) Issued at 630 AM EST Wed Dec 13 2017 Low pressure system will roll southeastward through the western Great Lakes region bringing a swath of heavier snowfall to central and southern lower Michigan. Overall MVFR conditions across northern lower Michigan today. But heavier snow will spread into the MBL and TVC terminal sites this morning bringing a several hour period of IFR conditions to those sites. System exits tonight. A mix of VFR to MVFR cloud cover will remain with some light lake snow showers lingering along the Lake Michigan and Lake Huron coastlines. && .MARINE... Issued at 358 AM EST Wed Dec 13 2017 Weaker winds out there this morning...and will transition into increasing southeast/east winds today as low pressure passes down through the lower Great Lakes region. Winds further back northerly by Thursday morning. Some gustier winds/higher waves redevelop along the Lake Michigan and Lake Huron nearshore areas and may require an new round of small craft advisories later this afternoon and through tonight. && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY until 7 PM EST this evening for MIZ031>033-041. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...MB NEAR TERM...BA SHORT TERM...MK LONG TERM...MK AVIATION...BA MARINE...BA
Office: GRR FXUS63 KGRR 131554 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 1054 AM EST Wed Dec 13 2017 LATEST UPDATE... Update .SYNOPSIS... Issued at 330 AM EST Wed Dec 13 2017 A fast moving clipper system will pivot through the Southern Great Lakes today moving from Southeast Minnesota this morning to portions of Northern Ohio this evening. A swath of accumulating snow is expected across the southwest quarter of Lower Michigan today and this evening. The lowest accumulations will be in the far southwest towards South Haven and Kalamazoo where 2 to 4 inches may fall by midnight. Further north a swath of 5 to 8 inches is expected along and north of Interstate 96. The heaviest snow will likely fall along a line from Pentwater southeast towards Alma and St. Johns. A period of quieter weather is expected from late tonight through Thursday. Another period of snow is expected from late Thursday night into Friday with an enhancement off the lake. && .UPDATE... Issued at 1054 AM EST Wed Dec 13 2017 Current winter weather headlines will remain unchanged at this time however there are some concerns. First concern is southwest of GRR around South Haven and Kalamazoo where back edge of the isentropic lift precip has already passed through and there's not much going on. Also this area is not impacted much by the upper low later, so we may be able to cancel a few counties in the southwest cwfa early. Orientation of the warning still looks fine based on latest RAP guidance which has closed circulations at both H7 and H8 sliding through the area late this afternoon and early evening. Also the fcst soundings show a fairly deep isothermal layer and very good omega for a few hours. So while somewhat of a lull may occur this afternoon between the current isentropic event and the upper low event, the best dynamics do peak at the evening commute and heavy snow is a strong possibility at that time. Believe a heavy FGEN band of snow will be present early this evening in the warning area with the upper low, but am not completely confident on it's exact placement and areal coverage. On Monday evening the models were correct in the character of a narrow heavy snow band along the I-94 corridor but struggled with the placement even in the short term so this will need to be watched. && .SHORT TERM...(Today through Friday) Issued at 330 AM EST Wed Dec 13 2017 Made changes to the going headlines based on latest model guidance and coordination with APX, DTX and IWX. Latest model trends show the swath of heavier snow to be in a corridor along and potentially north of Interstate 96. Therefore, dropped the warning that was in place from Ottawa south down the lakeshore. The feeling is the heaviest swath will likely be on a line from Oceana County towards Gratiot and Clinton Counties. Expecting a quick hitting 5 to 8 inches today, where snow rates may reach an inch an hour this afternoon. The evening commute will be the most impacted by falling snow, slippery travel and limited visibilities. The models show the 850mb low traversing far Southwest Lower Michigan where the precipitation will be hit and miss at times down towards South Haven. Strong isentropic lift is noted on the north side of the low in the warning area. A well defined cross hairs signature can be seen as well in some of the BUFKIT overviews with significant lift in the DGZ. The snow will wind down this evening and come to an end by midnight. A lull in the activity is expected from late tonight through Thursday. The lull will be short lived though as another lake enhanced event is taking shape for late Thursday night and Friday. Several inches of accumulation will be possible across Western Lower Michigan. .LONG TERM...(Friday night through Tuesday) Issued at 330 AM EST Wed Dec 13 2017 A pattern shift still appears in order by the weekend and lasting into the middle of next week. Temps won't be as cold, and pcpn won't be as frequent or steady. Friday night will continue to see lake effect snows as inversion heights remain high with a WNW flow. However H8 temps climb into Saturday and the lake effect will dwindle. The warming aloft will result as a warm front forms near the MI/IN border, and the upper flow becomes more zonal. A cold front and mid level short wave will move in by Sunday afternoon and evening. This will bring a period of snow across the CWA, possibly mixed with rain along and south of I-96. But overall the pcpn appears light. Behind the front Monday and Tuesday only appears slightly cooler, but still not cold enough for lake effect. The models show additional weak short waves coming through Monday/Tuesday with varying timing. This is enough to keep low POPs in. Tuesday's wave appears a bit stronger so will have slightly higher POPs then. && .AVIATION...(For the 12Z TAFS through 12Z Thursday morning) Issued at 655 AM EST Wed Dec 13 2017 Aviation conditions are expected to deteriorate this morning as an initial band of snow moves into the area from the west. More widespread snow and a further deterioration is expected this afternoon and evening. Conditions will reach the MVFR category in all areas this morning and drop into the IFR category this afternoon. This afternoon and evening ceilings will likely be below 2000ft with visibilities that will vary between 1/2 mile potentially and 2 miles. A rapid improvement is expected tonight as the low responsible for the adverse weather moves away. VFR conditions should develop overnight. && .MARINE... Issued at 330 AM EST Wed Dec 13 2017 Winds and waves will pose a hazard to small craft into this evening. Low pressure will move southeast across southern Lake Michigan today. The result will be stronger south winds this morning, turning north tonight. The wave field will likely fill into our nearshore marine zones, but the highest waves will be over the open waters. A weaker wind field will be in place on Thursday. && .HYDROLOGY... Issued at 1028 AM EST Tue Dec 12 2017 Rivers are running near normal levels. No flooding or significant rises in river levels are expected. Snow is forecast periodically through the week. Temperatures have been around to below freezing for a week and similar temperatures are expected to persist through the end of this week. This should allow some ice to begin forming on area rivers, especially on the Muskegon River in Central Lower Michigan. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 11 PM EST this evening for MIZ039- 040-056-064-065-071>074. Winter Storm Warning until 11 PM EST this evening for MIZ037-038- 043>046-050>052-057>059-066-067. LM...Small Craft Advisory until 10 PM EST this evening for LMZ844>849. && $$ UPDATE...Meade SYNOPSIS...Duke SHORT TERM...Duke LONG TERM...JK AVIATION...Duke HYDROLOGY...63 MARINE...Duke