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Area forecast discussion 
National Weather Service Grand Rapids Michigan
327 PM EDT Tuesday Oct 13 2015

Latest update...
synopsis/short term/long term/Hydro/marine

issued at 327 PM EDT Tuesday Oct 13 2015

Clouds will decrease Wednesday as high pressure builds into the
area. A strong cold front will bring more rain showers Thursday and
Friday followed by highs only in the 40s on Saturday. This will be
followed by a rapid warmup into the 60s by Tuesday.


Short term...(this evening through Thursday night)
issued at 327 PM EDT Tuesday Oct 13 2015

No significant changes to the forecast.

Will keep cloudy skies overnight with gradually decreasing chances
for light rain. Best window for precipitation will be before 10 PM
as water vapor imagery shows an area of lift and associated weak
radar returns moving east across Wisconsin towards the region.
Precipitation amounts will be light.

The next forecast concern is rain chances beginning Thursday.
Models are in good agreement with a sharp upper trough approaching
the region. The main question will be moisture availability as
this feature will be preceded by surface high pressure over much
of the eastern United States. Believe at least chance probability of precipitation are
justified given that deep cyclonic flow will be in place and the
upper jet will be south of the forecast area.

Long term...(friday through tuesday)
issued at 327 PM EDT Tuesday Oct 13 2015

Deep upper troughing is forecast from Friday into Saturday night
with a quick switching to ridging Sunday into Monday. More of a
zonal flow is in place for Tuesday. What this means is a much below
normal temperature regime to begin the long term...warming back
towards normal early next week.

A reinforcing shot of colder air will sweep in behind a cold front
on Friday bringing with it the coldest air of the fall. 850mb
temperatures from Friday morning right through Sunday morning will
be below zero. The thermal trough rotates through Saturday morning
with -7c temperatures in place over central lower Michigan. More than enough lake
instability will be generated with lake temperatures around +15c. Delta T/S
will eclipse 20c which should create a fair amount of lake clouds
and showers. Can see some snow mixing it at times late Friday night
and Saturday morning across central lower...but held off on it for
now as there are some moisture depth looks shallow.

We will be cold Friday night with Saturday night potentially being
even cold with the potential for more clearing. Both nights will be
possible frost/freeze headline nights depending on the amount of
cloud cover.

Brought some rain showers back into the forecast for next
Monday/Tuesday as a frontal boundary is forecast to lean in from the


Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 107 PM EDT Tuesday Oct 13 2015

Widespread MVFR ceilings are in place at 17z...with scattered
light lake enhanced rain showers as well. Have opted to go more
pessimistic than guidance as we move through the afternoon and
into tonight regarding ceilings. Guidance is trying to lift
ceilings to VFR or scatter the clouds out completely overnight.

Current thinking is that the MVFR ceilings are going to hold in
through the evening and likely the majority if not all of tonight.
The lakes are warm enough to generate lake clouds and showers
given the cold air in place aloft. Feel this will continue through
the taf period.

Have MVFR ceilings through 10z tonight at which time the clouds
should lift to VFR. Kept a VFR ceiling around 3500ft in place even
into midday on Wednesday. Showers should be on the light
kept visibilities VFR for the most part.


issued at 327 PM EDT Tuesday Oct 13 2015

Latest wavewatch 3 and wind guidance suggests that no changes are
planned for the current headlines...although it is possible the
Small Craft Advisory could be cancelled early with the early
morning update. Will be looking at the incoming ww3 run shortly
and will make last minute tweaks if necessary.


issued at 327 PM EDT Tuesday Oct 13 2015

Rivers are running normal at this time. Some more widespread rain is
possible Thursday and Thursday night. However amounts should stay
under half an inch...having little to no effect on the main Stem


GRR watches/warnings/advisories...
Lm...Small Craft Advisory until 11 am EDT Wednesday for lmz844>849.



short term...tjt
long term...Duke

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