Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KMQT 230747

Area Forecast Discussion
National Weather Service Marquette MI
347 AM EDT Sun Oct 23 2016

.SHORT TERM...(This evening through Sunday)
Issued at 311 PM EDT SAT OCT 22 2016

Visible satellite imagery late this afternoon is showing a ribbon of
cloud cover sliding over the eastern half of the U.P. with more
extensive cloud cover noted over Ontario and farther west over
Souther Saskatchewan. Water vapor imagery is showing a shortwave
over southern Saskatchewan, which is sliding toward the east and is
expected to move into the U.P. very late tonight into Sunday.
Otherwise, continues to be clear with surface observation showing
temperatures generally in the 50 to 55 degree range.

Tonight: A weak ridge in place this evening will slowly slide off to
the east of the area late tonight. This will keep the area mainly
dry through this time period; however, increasing moisture on the
back side of the departing ridge and ahead of an approaching
shortwave/surface low, will allow cloud cover to steadily increase
through the overnight hours, with a few showers possible far west
late tonight. Temperatures will be warmer than last night due to
increasing cloud cover across the area from the north and northwest.

Sunday: The shortwave is progged to slide from Southern Manitoba
into the Upper Great Lakes region through the day Sunday as a low
pressure system slides just to the south of the U.P. The combination
of these two features along with increased moisture will lead to
chances of rain showers throughout the day, which can be seen by
overlaying deep layer Q-conv and 1000mb-500mb RH. The system will be
fairly fast moving and moisture will not be overly abundant, so the
rain showers that occur shoud be light. Temperatures will be a bit
cooler with highs topping out in the upper 40s to around 50 for most

.LONG TERM...(Monday through Saturday)
Issued at 344 AM EDT SUN OCT 23 2016

Highly amplified pattern aloft to start the week with deep trough
over Quebec and New England while sharp ridge builds over most of
west half of the Conus. NW flow across Lk Superior Mon-Mon night
will be seasonably chilly with h85 temps around -6c. These temps
along with Lk Superior water temps 10-13c will lead to sufficient
over-water instability for lake effect showers /rain as ptype per
wbzero heights over 1000ft agl/ with delta t/s 16-19c. Soundings
show unfavorable setup for lake effect over western Lk
Superior/western cwa with inversions less than 2kft while longer
over water fetch and cooler air aloft with inversions up to 6kft
over eastern Lk Superior/eastern cwa results in better chance of
at least scattered lake effect showers.

Could see isolated lake effect showers trying to move into the
ncntrl late Mon night into Tue morning as high pressure builds
across northern Ontario and ridge slides over western cwa. Ptype a
bit more tricky than in the east as wbzero lowering to 500-1000 agl
and onshore/upslope northeast winds could result in some snow mixing
in with the rain. Dry air blo inversion should limit coverage of
lake effect into Tue morning.

Attn late Tue night into Wed will be on shortwave crossing the
central plains that undercuts the ridge in place and an associated
sfc low pressure and warm front. Sfc-h85 lows remain south of Upper
Michigan so that likely will limit widespread precip with this lead
shortwave/sfc low. NAM is strongest with the sfc low/dry air holding
the initial surge of precip well to the south over southern WI
through 12z Wed. Even if precip begins to affect cwa later on Wed, as
the previous shift alluded to the main period of concern is Wed night
into Thu as this initial system may merge with another system
approaching in nw flow aloft. Depending how quickly this phasing
occurs, sfc low may track farther north across Lk Michigan and
northern lower MI and there would be enough precip and cold air
around to result in a mix of rain/snow mainly over west and ncntrl
cwa on Wed Night and possibly over parts of the east cwa later Thu.
Only a few model runs from the GFS/ECMWF/GEM have been completely
phased aloft/far enough north with sfc low/cold enough in terms of
h85 temps and low enough in terms of 1000-850mb thickness to support
accumulating snow Wed Night into Thu. Forecast sfc temps in the mid
30s Wed night into Thu morning also suggest minimal snow accumulation
as long as the more intense forecasts with regard to stronger low-mid
level forcing do not materialize. Degree of phasing aloft with this
system will be bigger thing to watch in the coming days as that will
affect how far north the sfc low tracks and how much cold air can
occur with a deepening system. Will keep with mix of rain and snow,
similar to previous forecast.

After the initial shortwave/sfc low tracks east of the Upper Great
Lakes Thu night into Fri, will still have scattered lake effect
showers continuing. Decent agreement that h85 temps will be down to
at least -6c across Lk Superior which with sufficient h85 moisture
and indication of stronger low-level convergence with lake induced
troughing should be enough to support the scattered lake effect
rain/snow showers. If stronger shortwave drops through in this flow
pattern with this already favorable low-level environment, then
coverage and intensity of the lake effect would increase late Thu
night into Fri.

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 140 AM EDT SUN OCT 23 2016

VFR conditions will prevail at all TAF sites overnight. Low pressure
will approach the area Sunday morning bringing the possibility of
rain showers at each of the TAF sites along with MVFR ceilings.
Conditions will improve to VFR by Sun evening at IWD as drier air
moves back in behind the low.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 311 PM EDT SAT OCT 22 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
Sunday night into Monday. High pressure will build across the area
Monday afternoon through Wednesday, keeping winds light across Lake

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


MARINE...KEC is the U.S. government's official web portal to all federal, state and local government web resources and services.