Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 191449
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1049 AM EDT FRI AUG 19 2016

.UPDATE...
Issued at 1040 AM EDT Fri Aug 19 2016

Decaying convective complex working across Lake Michigan late this
morning, and this trend should continue as it leaves the better
forcing and pushes into Northern Michigan. Still expect to see
scattered showers/storms into western half of the area
(especially I-75 westward) through midday before this activity
dissipates. Tougher question becomes how much additional
shower/storm activity will develop this afternoon. Sunshine over
parts of Eastern Upper and Northeast Lower this morning, and this
is the area where instability will be maximized (1200-1500 j/kg).
Will focus on this area for afternoon development of additional
showers/storms. Severe storms do not appear likely given the
anemic wind fields, but PWAT values of 1.75 inches point toward
locally heavy rainfall potential. High temperatures generally in
the lower to mid 80s, although slightly cooler around
precipitation areas.

&&

.SHORT TERM...(Today and tonight) Issued at 351 AM EDT
Fri Aug 19 2016

...Unsettled weather for the next few days then turning cooler...

High impact weather potential: Periodic thunderstorms and heavy
rainfall through Saturday. Marginal risk for severe storms
Saturday.

Overview: Deepening/closed mid level trough and surface low analyzed
over the Hudson Bay region with a slow moving cold front
stretched down through the upper midwest to secondary low
pressure in western Iowa. Abundant low level moisture/instability
across the plains and midwest is fueling several rounds of
showers/storms from Nebraska into Minnesota, and down through
southern Wisconsin into the lower lakes. Weaker instability axis
extends into upper Michigan where a thin line of fairly benign
showers/storms has been working eastward through the night, driven
by smaller pocket of QG-forcing moving through that area. Quieter
weather down through lower Michigan for the moment.

Today: Tough forecast from a precip/pop/timing standpoint. Right
off the bat will of course have to address narrow line of
showers/storms that will move through eastern upper Michigan and
the tip of the mitt counties this morning. High resolution
guidance suggests this line will weaken over the next several
hours. Will see, but plan to have a period of categorical/likely
pops across that far northern part of the CWA this morning. Given
slow moving line, some locally heavy rainfall is possible.

Meanwhile, surface cold front will lean into eastern upper Michigan
down through Wisconsin as we go through the day, edging deeper
moisture/instability axis into the region. Better instability
forecast to remain down through the midwest/lower lakes region
while better convergence/focus for more widespread showers/storms
remains closer to the front across upper Michigan and down through
Wisconsin. However, with daytime heating, we should be able to
muster upward of 1500 J/KG MLCAPE by this afternoon with the best
low level convergence once again across NE lower. So I think the
best chances for showers/storms through the day will be across
eastern upper (closer to the front) and NE lower Michigan. Severe
weather potential is low although with PWAT values in excess of
1.5 inches and slow moving convection, locally heavy rainfall
remains a good bet.

Tonight: Strong short wave energy digging into Montana this morning
expected to drop into the northern plains by Saturday morning,
beginning the process of developing a strong surface low over Iowa
that will further deepen and swing up through the western Great
Lakes this weekend (dare I say hints of a fall like system). Up
this way, surface front stalls across upper Michigan in response
to deepening wave in the midwest. Not much forcing for us through
most of the night and in fact we develop a bit of subtle upper
level ridging in response to the deepening trough upstream. So
plan on diminishing pops through the evening hours and overnight
as we await arrival of strong wave on Saturday, but will keep at
least slight chance/chance pops going given our warm and soupy
airmass.

.LONG TERM...(Saturday through Thursday)
Issued at 351 AM EDT Fri Aug 19 2016

(8/20)Saturday...The rain is well underway as the sfc low moves up
into the Upper Great Lakes region. The GFS and ECMWF have pretty
close tracks with the rain covering the forecast area. The one thing
to note in difference from last night`s forecast is that the track
is a little more north and west. This allows the warm sector to get
into N Lower, just before the cold front moves through late in the
day. A 500 mb jet streak with winds of 45 to 50 knots will move
through while the cold front passes through. So will expect that not
only do we have good instability (MLCAPE ~1000J/kg) but decent
environmental shear (0-6km 43kts). After 00z, the sfc low is out of
the forecast area and the cold front is through as well with the
cold air beginning to push into the region.

(8/21)Sunday...We run into some issues with the rain on Sunday as
mid level dry air begins to push into the region as the 500 mb
trough rotates out of the Upper Great Lakes and into Lower Great
Lakes and New England. Water temperatures over N Lake Michigan are
around 22C with the 850 mb temperatures falling to +6C. With the
lower level (850 mb) moisture still around 70%, there is a chance
for some lake effect rain. have some slight chance pops over the
region from the instability that is set up. However, we lose the
instability overnight as the as the sfc ridge begins to build into
the region and the 500 mb heights rise.

Extended (Monday through Thursday)...As the 500 mb trough moves
out the flow looks to flatten out a bit. A sfc trough/warm front
begins to form up in the Upper Great Lakes. The GFS shows rain,
while the ECMWF is pushing the rain north. The pattern begins to
amplify a bit as the 500 mb ridge builds up again on Tuesday. This
ridge will keep the Upper Great Lakes will stay dry through
Wednesday. the models then diverge a bit with the GFS speeding up
the rain and pushing it through by Thursday, while the ECMWf is
mush slower with the rain not getting out of the region until
Friday morning.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 651 AM EDT Fri Aug 19 2016

A period of IFR cigs will impact MBL and TVC this morning.
Conditions will trend back to VFR for all terminal sites later
this morning and through the afternoon hours. But scattered
showers and storms will be possible this afternoon into the early
evening hours, with the best chances occurring at APN.

Tonight, reduced vsbys with mist/fog expected once again later in
the evening and overnight. Shower and thunderstorm chances will
remain low through the night with better chances coming on
Saturday.


&&

.MARINE...
Issued at 351 AM EDT Fri Aug 19 2016

Lighter winds/waves will persist on the lakes through today and
tonight. But a deepening (nearly fall like) storm system is
expected to swing up through the western Great Lakes later
Saturday through Sunday. SW winds will ramp up ahead of the low
later Saturday/Saturday night and Sunday morning, shifting to the
NW later Sunday and Sunday night. Gale force wind gusts will be a
concern later Saturday through Sunday.


&&

.APX Watches/Warnings/Advisories...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...Keysor
SHORT TERM...Adam
LONG TERM...JSL
AVIATION...Adam
MARINE...Adam



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