Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 200857

Area Forecast Discussion
National Weather Service Marquette MI
357 AM EST Mon Feb 20 2017

.SHORT TERM...(This evening through Monday)
Issued at 303 PM EST SUN FEB 19 2017

Though not near as warm as what occurred on Sat, seeing yet
another warm Feb day. Readings so far have topped out in the mid
50s over interior west cwa (warm spot at 3 pm was 59 degrees at
Watersmeet) but with lighter onshore winds, temps over rest of cwa
have stayed in the upper 30s to lower 40s near the Great Lakes
and in the the mid to upper 40s elsewhere. Thicker mid clouds
affected area this morning and intervals of mid to high clouds are
poised to swing across this evening and overnight. Clouds are
streaming ahead of deepening trough and organizing sfc moving from
the northern Rockies to the northern Plains by Mon morning. For
tonight, kept lowest min temps tonight over interior central and
east closer to departing lighter winds/high pressure ridge. Light
south winds and moisture off Lk Michigan could lead to fog though
mid clouds should limit the potential for widespread or dense fog.
Different story over western cwa where south winds sharply
increase after midnight due to increasing southerly gradient btwn
the departing high and approaching low pressure system in the
plains. Still south winds should keep mins around 40F at IWD.

On Monday, clouds thicken from west to east and rain arrives late in
the day. Otherwise will be breezy and temps will still be above
normal. Warmest readings well into the 50s will be over west due to
warmer start and as S-SE winds downslope. Flow off the Great Lakes
elsewhere will result in highs in the 40s, though it could be as
warm as low 50s near WI border and as cool as upper 30s over far
east cwa. May see another day with record highs too as based on
current forecast, IWD (51 in 1961), CMX (47 in 1961), IMT (50 in
1961) and NWS MQT (44 in 2003) could all be close to seeing records

Shortwave trough slides to Manitoba to Upper Great Lakes 18z-24z.
Main sfc low deepens blo 1000mb over central Manitoba by Mon
evening. Deep layer q-vector convergence spreads rain fm west to
east in the aftn. Large scale forcing is moderate strength but main
driver for rain will be strong 925-850mb moisture transport due to
SSW 50kt H85 wind and pwat over 1.25 inches aimed into scntrl cwa
21z-24z on Mon. Lowest SI/s are west of cwa closer to mid-level
drying which may steepen lapse rates. Given strength of moisture
advection with the strong h85 wind max cannot rule out rumble of
thunder. Main result from any instability will be enhancing rain
rates. Heaviest rain is expected just beyond short term so there is
more with the heavy rain and hydro issue potential in the long term

.LONG TERM...(Tuesday through Sunday)
Issued at 357 AM EST MON FEB 20 2017

Will see some rain exiting E Tue morning, then some potential for
some isolated to scattered rain showers over the N (possibly just
over Lake Superior) Tue afternoon/evening as a weak shortwave moves
through. Highs Tue will be in the mid 40s to mid 50s.

Models continue to trend stronger with a shortwave moving through
the area Wed into Wed night. This favors a SFC low developing and
moving through, probably more over the western CWA given the trend
toward a stronger solution. If the western solution does work out,
not much precip will fall across the CWA, mostly across the far W
and the Keweenaw, and most of that should be rain or a mix or rain
and snow. Will have to watch this time frame as there remains plenty
of uncertainty.

Attention then turns to Fri into Sat as models continue to bring a
strong low pressure system SE of the CWA. While models are generally
coming into a better consensus on track/strength/timing, confidence
in details remains quite low given the complexities and time range
of this system. Models disagreement will probably increase with the
next few runs as is normal in this scenario. The system won`t even
move E of the CO Rockies until Thu night. Given the current track of
the GFS, ECMWF and GEMnh, all or most of the CWA will see snow, with
the most snow over the north-central U.P. where upslope and lake
enhancement will increase synoptic amounts. Would not be surprised
to see that change though. Blowing snow would also be an issue,
especially near Lake Superior. Stay tuned.

The weekend will see temps well cold enough for LES in the NW-WNW
snow belts.

Flood potential continues to seem low given more limited snow pack
in most areas. NCRFC ensembles do not suggest even close to bankfull
stage at the AHPS sites across the CWA.

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1216 AM EST MON FEB 20 2017

Expect VFR conditions into early aftn at KIWD/KCMX/KSAW under an
overall dry air mass. Conditions should deteriorate with the
arrival of a low pressure trough and rain showers late aftn into
evening. Conditions should drop to MVFR from west to east during
the afternoon. Cigs should drop into the IFR range this evening
with some LIFR conditions possible.

A tightening pres gradient and resulting increasing winds above a
low level inversion will lead to LLWS at KIWD overnight and even
though it will be during the day, persistent strong low-level
inversion will expand the LLWS potential to KCMX and KSAW later today.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 303 PM EST SUN FEB 19 2017

Winds stay 25kt or less into Mon morning (strongest over far west
near Duluth) then as low pressure deepens northwest of Lk Superior
into Mon evening, SE winds increase to 30 kts Mon aftn with gales 35-
40 kts late Mon aftn into Mon evening over much of eastern and north
central Lk Superior. Gale warning has been issued. Winds should then
stay mostly 25kt or less Tue thru Thu. Stronger winds, perhaps
gales, are expected Fri into Sat as a low pres system tracks ne thru
the Great Lakes region.

Upper Michigan...
Lake Superior...
  Gale Warning from 4 PM this afternoon to 1 AM EST Tuesday for

Lake Michigan...


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