Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 151840

Area Forecast Discussion
National Weather Service Marquette MI
240 PM EDT Sat Jul 15 2017

.SHORT TERM...(This evening through Sunday)
Issued at 240 PM EDT SAT JUL 15 2017

Upper air pattern consists of a 500 mb ridge over the Rockies and
troughing over the Pacific NW and a trough in New England. There is
also a shortwave moving through the upper Great Lakes this
afternoon. This shortwave will dig into the lower Great Lakes
tonight and Sun. 850-500 mb q-vector convergence moves out this
evening. A weak cold front will move through the area this
afternoon and early evening and kick off some low chance to slight
chance pops. After this moves through, there could be some north
wind upslope pcpn around midnight across north central upper
Michigan with northerly flow off Lake Superior and have some slight
chance pops for this in Marquette County. Otherwise, pretty quiet
and did not make too many changes to the going forecast.

.LONG TERM...(Sunday through Friday)
Issued at 452 AM EDT SAT JUL 15 2017

Models suggest nw flow through the nrn Great Lakes this weekend
downstream from a ridge over wrn NOAM will become more zonal next
week as a strong shortwave trough advancing from srn BC to Hudson
bay by late Monday flattens the ridge. Toward the end of the
week, the pattern will amplify slightly as a trough edges eastward
from the Pacific Northwest.

Sunday, Behind the cold front from Saturday, expect a pleasant
conditions with highs from the mid 60s to lower 70s and dewpoints
down again into the comfortable upper 50s to lower 50s. Onshore
nrly gradient flow will bring the coolest air into the north.

Monday, although a strong inversion will limit the mixing depth, WAA
with developing srly flow will help push temps into the upper 70s,
except where onshore flow prevails near Lake Michigan. The gradient
should remain weak enough to allow lake breeze development from Lake
Superior over the east half of the cwa.

Tuesday, a cold front is expected to move through Upper Michigan.
The ECMWF remained slightly faster with this feature compared to
the GFS/GEFS/GEM. Temps in the lower 80s with MLCAPE values of 1k-
2k J/Kg could again support some stronger storms althoug there is
some uncertainty with the potential for thicker clouds to limit
sfc heating/instability. There may also be a threat for heavy
rain alont a slow moving west to east boundary as PWAT values
climb aoa 1.75 inch and westerly inflow of low level moisture may
favor training cells.

Wednesday-Friday, Confidence remains low with the handling of the
frontal position and associated pcpn chances. Although there is
trend toward wnw mid/upper level flow which might keep the front to
the south, it will remain close enough to maintain a threat for
additional shra/tsra especially if any stronger shortwaves emerge
from the nrn plains.

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 111 PM EDT SAT JUL 15 2017

VFR conditions will prevail at KIWD and KCMX thru the forecast
period. A cold front dropping se this afternoon may spark a few
shra/tstms. Right now, it appears central Upper MI has a better
potential of seeing sct pcpn development than western Upper MI. Have
thus included a VCTS mention during the mid/late aftn at KSAW and
VCSH at KIWD and KCMX. Passage of cold front and development of cool
upslope flow may result in low MVFR or IFR cigs tonight through
Sun morning at KSAW.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 240 PM EDT SAT JUL 15 2017

Winds will stay at or below 20 knots through the period. A cold
front will move through this afternoon and push south of the area,
winds will become north-northeasterly this evening into Sunday
around 15 to 20 knots.

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


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