Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 231717

Area Forecast Discussion
National Weather Service Marquette MI
117 PM EDT Sun Oct 23 2016

.SHORT TERM...(Today and tonight)
Issued at 527 AM EDT SUN OCT 23 2016

Today: A shortwave now moving into northern Mn will slide across the
Upper Great Lakes today. Deepening moisture and deep layer q-vector
convergence associated with this feature and its associated sfc low
moving just south through northern Wi will spread rain showers into
western Upper Mi early this morning and into central and eastern
Upper Mi later this morning into the afternoon. Since this will be a
relatively fast-moving system with limited moisture, expect pcpn to
be fairly light. Temperatures will be a bit cooler than yesterday
with highs topping out in the upper 40s to lower 50s...coolest
northwest half.

Tonight: Increasing cold advection in a north-northwest flow will
lower h85 temps around -5C across eastern Lake Superior resulting in
a lake sfc-h85 delta-t of 17-18c. NAM and RAP Model forecast
soundings show inversion heights around 800 mb or above 5 kft with
lake induced CAPEs at or above 300 j/kg. This instability will be
enough to support scattered lake effect rain showers downwind of
Lake Superior so will maintain high chance pops into Alger-Luce and
northern Schoolcraft counties. Some lake effect showers will also
reach into the eastern portion of Marquette County in the evening
before shifting east overnight as winds back from a 340 (north-
northwest direction) to 320 or due northwest direction. The rest of
the CWA should be dry tonight. Min temps will range from the lower
30s over the interior west to the upper 30s/lower 40s east and along
the Great Lakes shores. Will likely be a bit breezy especially along
the Lake Superior shore from Marquette east to Whitefish Point as
northwest wind gusts may approach 30 mph at times.

.LONG TERM...(Monday night through Sunday)
Issued at 117 PM EDT SUN OCT 23 2016

Do not have good confidence in any hazardous weather events in the
long term. There is some potential for minor snow accumulations Wed
night, but that is very uncertain.

Should see some lake effect precip mainly over the E Mon night into
Tue. PoPs may need to be extended slightly west due to more
northerly winds over the central lake, but a SFC ridge and dry air
moving in from the west should inhibit that. Could see some mixed
precip over interior E with those showers, but not expecting any
significant amounts due to low temps AOA 32F.

Next system to move through the region is on Wed/Wed night. Not
surprisingly, models have changed from yesterday due to uncertainty
with the phasing of two shortwaves. Expect that uncertainty continue
and be no better over the next couple of days, lending very limited
confidence in the details of the forecast. The biggest questions
related to type over mainly the higher terrain of the central and
west. Depending of the strength/track/timing, could see precip mix
with or change to snow in these areas Wed night. However, unless the
system ends up on the stronger side, no significant accumulations
are expected due to SFC and near-SFC temps.

The previous run of models agreed well for Thu-Fri in showing temps
cold enough for lake effect, but not models disagree substantially
from Thu through Sun with all forecast elements. Will not adjust
blended initialization after Wed night given the uncertainty.

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 729 AM EDT SUN OCT 23 2016

VFR conditions will prevail at all TAF sites into this morning, but
then approaching low pressure from the Northern Plains will spread rain
into the area as conditions lower to MVFR at each of the TAF sites by
the afternoon. Expect conditions to improve back to VFR by this
evening at IWD and CMX as drier air moves in with the advance of high
pressure from the west.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 527 AM EDT SUN OCT 23 2016

Winds will remain below gales through the period. A tightening
gradient between a deep low pressure system moving through Quebec
and a high pressure ridge building into the Plains could lead to a
period of NW winds gusting to 30 knots over eastern Lake Superior
tonight into Monday. High pressure will build across the area Monday
afternoon through Wednesday, keeping winds generally light across
Lake Superior. There will be a trough passage on Thu but winds
will remain fairly light.

Upper Michigan...
Lake Superior...
Lake Michigan...


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