Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 282028
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
328 PM EST Mon Nov 28 2016

.NEAR TERM...(Tonight)
Issued at 319 PM EST Mon Nov 28 2016

High impact weather potential: Moderate to heavy rain tonight. Maybe
a rumble of thunder late tonight, no severe. Strong gusty winds
possible into coastal areas surrounding Lake Huron tonight, and
along NW lower coastal areas Tuesday.

Pattern synopsis and forecast:

High amplitude pattern out there this afternoon, with deep troughing
engulfing a large portion of the central conus, and an associated
deep sfc low occluding near the Dakotas/MN border. Showers are
swirling around the low, as snow on the colder backside in the
western Dakotas. A much large swath of showers was seen already
punching up through IL/WI/IN, with moderate to heavy rainfall
further south of there. These showers were associated with strong
forcing, highlighted by LLJ/WAA, DPVA and impressive upper level
divergence on the nose of a 120+kt jet. 6hr QPF amounts in the
strongest of forcing over the past 6hrs (lower Mississippi valley)
have been in the 1.00-1.50" range. PWATS there were as high as
1.80". Finally, a band of showers and thunderstorms has developed in
Iowa up into MN, along the cold front extending south of the sfc
low, and in a region of sub 500j/kg BLCAPE underneath steep mid
level lapse rates near 7c/km.

Forecast issues: Dense fog possibilities tonight? How strong can
winds be along the coastal areas of nrn Michigan? Will we hear
thunder? How much rain will we get and are there any impacts on area
rivers and streams?

The sfc low continues to occlude through tonight, while a potent
shortwave associated with the strong forcing across the lower
Mississippi, lifts into the Great Lakes. This wave wraps north of us
late tonight into Tuesday morning while the occluded front blows
through nrn Michigan. Initial weaker vorticity will push up into nrn
Michigan late this afternoon and evening, bringing the onset of
showers. The strong LLJ/WAA/DPVA/upper divergence will arrive later
this evening and into the overnight hours, with a secondary low
developing into nrn Michigan. This will bring the moderate to
possibly heavy rainfall. While we will not see the PWATS the lower
Mississippi has, we will have as high as 0.80"-1.00" which is 250%
of normal. Most of the area shouldn`t have too much trouble
squeezing out 0.75" to maybe as much as 1.00", with the higher
amounts still looking like for eastern upper. Looking at the
contingency QPF forecasts, show that even the maximum possible
rainfall would not result in any possible river flooding. The
occluded front marks the rough end to the rainfall, with a wind
shift from easterly to SW into Tuesday morning, and also the leading
edge of the steep lapse rate gradient. Although we will have little
to no CAPE, and the lapse rates will not be as steep as out west of
us now, cannot rule out the potential rumbles of thunder. As the
occluded front lifts north through Tuesday, there are strong signals
in fcst soundings of very aggressive low level drying and quick
clearing of the skies. This leads to a nicely mixed BL Tuesday then
leads to gusty and warmer conditions.

The strong easterly flow before this transition, for tonight, will
likely not result in many stronger gusts due to stability in the
near sfc layer. However, the frictionless flow coming off the lakes
for coastal areas surrounding Lake Huron, may see 40 mph winds at
times tonight. A similar situation along the coastal areas
surrounding Lake Michigan, but gusts there maybe just a bit lower to
around 35 mph.

Mild lows tonight in the low to mid 40s, as temperatures will hold
steady or slowly rise. Highs tomorrow will rise into the lower to
middle 50s for most all areas. Warmest near Saginaw Bay and in
downsloping areas of NE lower Michigan.

&&

.SHORT TERM...(Tuesday and Wednesday)
Issued at 319 PM EST Mon Nov 28 2016

...Clouds and showers through midweek with a slow cooling trend...

High Impact Weather Potential: Minimal

Pattern Synopsis/Forecast: Deep long wave trough has been carved out
across western/central North America...with several short waves
rotating through the mean trough position.  Closed low has developed
over the Dakotas/Minnesota...with a second short wave trough moving
through the base of the mean trough across New Mexico/Texas...and a
third digging into the mean trough from the Pacific northwest.  As
the upper low spins over the upper Midwest...short wave trough over
Texas will get pulled northeast and across the Great Lakes Tuesday.
The upper low will eventually nudge east and into Michigan in the
Thursday time frame...getting pulled east as the last short wave in
the series moves through the base of the mean trough and lifts into
the northeast U.S.

Secondary surface wave/triple point low (a reflection of Texas
short wave trough/jet streak) will lift north across Michigan/
Wisconsin overnight/Tuesday morning...but not much cold air
initially until Wednesday when somewhat cooler air advects into
Michigan along with a broad area of low pressure associated with
remnants of upper low moving into the upper Great Lakes. Stronger
cold advection arrives Thursday on an increasing west/northwest
wind.

Primary Forecast Concerns: Not much in the way of high impact
weather through Thursday...slow passage of the upper level low with
little pieces of energy and lingering deep layer moisture wrapping
around the system will give varying chances of light precipitation
Wednesday and Thursday.  Some hints of some instability across Lower
Michigan Wednesday but there is a bit of uncertainty in the details
especially with a weakening system in the vicinity.  Shallow lake
component won`t hurt the cause as low level temperatures slowly cool
into Thursday.  This could also lead to some snow across the higher
terrain of northern Lower Thursday morning.  Expect a slow drop in
temperatures through midweek.

&&

.LONG TERM...(Wednesday night through Monday)
Issued at 319 PM EST Mon Nov 28 2016

With northwest flow in the low levels and colder 850mb temperatures
spilling in from Canada, lake effect rain/snow showers will be
possible at times across eastern Upper and northwest Lower from
Thursday night through Saturday night. Snow shower chances will be
highest during the nighttime hours and especially favored in the
higher terrain of northern Lower. Warmer thermal profiles in coastal
areas of northern Lake Michigan will tend to favor all rain there or
perhaps a rain/snow mix at times.

The GFS and ECMWF begin to diverge significantly Saturday night into
Sunday as the ECMWF has a mid level trough quickly ejecting from the
Desert SW into the Great Lakes by Monday, while the GFS and CMC keep
a closed low over the Southwest. Have leaned more towards the GFS
solution, as the ECMWF looks too quick. The GFS brings a shortwave
trough across the northern Great Lakes on Sunday, which will provide
a better chance for more widespread precipitation. Temperatures will
trend towards more seasonable readings beginning Friday and
continuing into early next week with highs generally in the mid 30s
and lows in the upper 20s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 145 PM EST Mon Nov 28 2016

CIGS are crashing from SW to NE with increasing low level moisture
ahead of a warm front attached to deep low pressure over the
Dakotas/MN border. CIGS will continue coming down into very low
end MVFR and IFR through the day and especially tonight along with
VSBY. Moderate to heavy rainfall also develops tonight as the warm
front approaches, and ends from south to north late tonight
through Tuesday morning. As the rainfall ends, shortly thereafter,
strong drying appears as though it will scour out all low clouds,
so a return to VFR.

Easterly winds will ramp back up again tonight with the
development of LLWS, as conditions will be fairly stable with
prevailing conditions with no gusts. The warm front blows through
(when the rain ends) with winds shifting out of the SW, and we
get more mixed into Tuesday with gusts becoming the prevailing
condition.


&&

.MARINE...
Issued at 319 PM EST Mon Nov 28 2016

Deep low pressure will slowly track eastward across the Great Lakes
over the next few days. A tight pressure gradient will bring gales
to most nearshores through Tuesday, tonight in strong easterly flow
for Whitefish Bay and Lake Huron, and then behind a warm front in SW
flow for Lake Michigan Tuesday. Winds will gradually weaken and
become more variable Tuesday night into Wednesday as the weaker
gradient arrives with the sfc low. There will be an uptick in
westerly winds Wednesday night into Thursday, as cold advection sets
in, with potential advisory level gusts.

Expect moderate to heavy rainfall tonight with strong drying late
tonight into Tuesday. Maybe a few showers Wednesday with some light
lake effect rain showers Wednesday night into the weekend.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 7 PM EST this evening for LHZ346>349.
     GALE WARNING from 7 PM this evening to 7 AM EST Tuesday for
     LHZ346>349.
     SMALL CRAFT ADVISORY until 4 PM EST Tuesday for LHZ345.
LM...SMALL CRAFT ADVISORY until 4 PM EST Tuesday for LMZ323-341.
     SMALL CRAFT ADVISORY until 7 AM EST Tuesday for LMZ342-344>346.
     GALE WARNING from 7 AM to 4 PM EST Tuesday for LMZ342-344>346.
LS...SMALL CRAFT ADVISORY until 7 PM EST this evening for LSZ322.
     GALE WARNING from 7 PM this evening to 7 AM EST Tuesday for
     LSZ322.
     GALE WARNING until 7 AM EST Tuesday for LSZ321.
&&

$$

NEAR TERM...SMD
SHORT TERM...JPB
LONG TERM...MEK
AVIATION...SMD
MARINE...SMD



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