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Area forecast discussion 
National Weather Service Gaylord Michigan
925 PM EST Wednesday Nov 25 2015

issued at 925 PM EST Wednesday Nov 25 2015

Upstream cold front now extends from Western Lake Superior through northwest
Wisconsin into central Iowa southwestward into the Southern Plains late
this evening. Areas of light rain have pushed NE into the western
two-thirds of our County Warning temperatures hold nearly steady in the upper
40s to lower 50s. Areal coverage of rain will continue to gradually
increase from west to east during the balance of the night as deep
moisture surges northward along and ahead of the cold front. All
precipitation will remain liquid throughout the night per latest model
soundings...although do expect temperatures will fall into the lower 40s
overnight. As low level moisture increases...areas of fog should
begin to develop...especially within the higher terrain areas.


Near term...(this evening through tonight)
issued at 311 PM EST Wednesday Nov 25 2015

Overview...middle and lower level clouds are making their way across
Lake Michigan this afternoon in advance of an area of rain that is
developing ahead of the cold front/surface low moving out of the upper
Mississippi Valley and into the upper Great Lakes. This feature is
associated with northern branch of the 500 mb jet feature that is
moving from the Canadian prairies to the northern plains. South to
southwest flow has been warming the region, and slowly beginning to
moisten the middle and upper levels, as evidenced by increasing cloud
cover over north Michigan this afternoon. Besides satellite, there is
also evidence of this on the VAD wind profile as Hydro scatterers
have been showing up since about 18z starting around 15kft and
beginning to thicken between 13 kft and 17kft.

Tonight...the moistening will continue as the good isentropic up
Glide and the 500 mb jet streak continue to coincide to pull more
moisture into the upper Great Lake ahead of the cold front. The surface
low that is associated with this cold front, will continue to move
to the NE, from north of the boundary waters region, into Ontario,
and into James Bay. The front, itself, looks to stall overnight in west
Wisconsin/west upper overnight, before beginning to move through east
upper and north lower some time in the afternoon on Thursday. So in the
meantime, the rain that is developing is expected to continue to
move east into Michigan overnight, ahead of the front and spread
across the forecast area, by 06z. The rain is expected to continue
as the cold front moves its way to c upper by around 12z.


Short term...(thursday through saturday)
issued at 311 PM EST Wednesday Nov 25 2015

High impact weather potential...a rainy Thanksgiving...turning
somewhat wintry Thursday night/Friday.

Rex block takes shape over western North America as we move through the
period...with downstream confluent flow aloft into southeast Canada and the
NE Continental U.S.. an incoming northern stream shortwave will interact with
moist southerly flow to generate precipitation Thu-Fri. At the surface...a
cold front slowly push southeast across northern Michigan Thursday-Thursday night. This
will result in a changeover to wintry precipitation from northwest to southeast...though
not long before precipitation exits. Precipitation trends...including p-type
concerns...are the primary issue.

Thanksgiving...rain should already largely be in place to start the
morning...with the possible exception of some downsloping locales of
NE lower (with strong SW low-level flow in place). Northern Michigan
remains at the nose of a 35-45kt SW 850mb jet...resulting in steady
Theta-E advection. That advection increases a bit very late in the
day. Entire forecast area in is a favorable location for precipitation
relative to the middle-level fgen maxima...which is found over central
Minnesota and western Superior. Again...this is shifting to a somewhat more
favorable position late in the day. However...through most of the day
there is dry air present in the 700-500mb layer. Moisture present
from 700mb on down is plenty deep enough to support precipitation...but for
most of the forecast area...most of the day...said precipitation will be
light. Precipitation rates will increase late in the day...especially in
southern sections of the forecast the forcing mechanisms
mentioned above increase. Precipitation will be all rain...though cold
advection is underway in eastern Upper Michigan in the afternoon...the
surface-based melting layer is holding strong through 00z.

Maximum temperatures from the lower 40s near Whitefish Bay to the lower 50s in
some southern sections.

Thursday night/Friday...cold front exits northern lower Michigan to the southeast Thursday
night...with ridging building south to Lake Superior by late Friday.
Our most expansive/heaviest precipitation will be Thursday night. 700mb fgen
strengthens just NE of Superior...and we see around 50kt of moist SW
850mb flow. Precipitation will end from north to S Friday as drier air advects
in from the northwest.

Two layers of warm air need to be eroded to turn things over to elevated at the 800mb...the other at the surface. Model
forecasts suggest the former will erode just a smidgen faster than the
latter...though it is close. We could perhaps see a period of sleet
as we transition from rain to snow...but freezing rain appears
unlikely. This changeover will only make slow southward progress.
That changeover begins in eastern Upper Michigan Thursday evening...but doesn/T
make it as far as pln until overnight...and probably late overnight
at that. (Models have been trending slower with the cold frontal passage.)
Changeover gets to tvc/apn Friday morning...and southeast sections in the
afternoon. But all of this is only barely ahead of precipitation ending

Will kick snowfall amounts in eastern Upper Michigan up 2-3
inches. Tip of the mitt something like an inch...less than that

Min temperatures range from middle/upper 20s in eastern well into
the 40s in the far southeast. Readings will go nowhere on Friday thanks to
steady cold advection on a brisk north breeze.

Friday night/Saturday...high pressure slowly settles in from the
northwest...providing some quieter weather for this portion of the Holiday
weekend. Plenty of dry air in place...and 850mb temperatures only as cold as
-4c or so...resulting in minimal lake response. Chilly min temperatures Friday
night...middle teens to middle 20s. Maximum temperatures Saturday in the middle to
perhaps upper 30s.


Long term...(saturday night through wednesday)
issued at 311 PM EST Wednesday Nov 25 2015

High pressure will keep things clear and quiet for the start of the
extended. The next real active time looks to be next Tuesday. An
initial disturbance early in the week that had been prognosticated as far
north as central Michigan is continually progging further south as
high pressure remains in place over the Great Lakes...pushing the
storm track south. Confidence remains low for exact timing and
placement of the storm system currently prognosticated to arrive in the
Tuesday timeframe. Solutions range from a vertically stacked
occluding low passing through The Straits and bringing a
deepening low passing through Southeast Michigan and bringing snow...also tapping
into more Gulf moisture with a more southern path for the 500 mb low.
These are similar tracks to what we have recently seen...and seem
well within reason. Will need to watch the evolution and handling of
the 500 mb cutoff in the coming days to hammer out the finer details of
timing...track...and p-type issues.


Aviation...(for the 00z tafs through 00z Thursday evening)
issued at 615 PM EST Wednesday Nov 25 2015

Conditions will rapidly deteriorate to MVFR and then IFR tonight
into Thursday as widespread rain spreads into all of northern lower
Michigan ahead of a cold front currently stretching from The
Arrowhead through Iowa into the Southern Plains. Northern lower Michigan will
remain on the warm side of this front through 00z all
precipitation will remain liquid through this time. Low level wind shear will continue to
impact all taf sites through Thursday evening as southerly winds
just off the deck remain strong ahead of the cold front.


issued at 311 PM EST Wednesday Nov 25 2015

Tonight through Friday...gale warnings on Lake Michigan will stay up
through 06z as the Middle Lake Michigan buoy has continued to show up
with a few gale gusts through the morning and early afternoon.
However, as the cold front approaches the region will expect that
with the slack gradient around the surface storm will see the winds
diminish through the morning, and into the afternoon until frontal
passage. Once the front passes then the winds should pick back up to
Small Craft Advisory criteria. The gradient should begin to slacken
on Friday as high pressure builds back into the upper Great Lakes.


Apx watches/warnings/advisories...
LH...Small Craft Advisory until 7 am EST Thursday for lhz345>349.

Lm...Small Craft Advisory until 7 am EST Thursday for lmz323-341-342-

Ls...Small Craft Advisory until 7 am EST Thursday for lsz321-322.



near term...jsl
short term...jz
long term...Mayhew

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