Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Grand Rapids Michigan
720 am EDT Tuesday Jul 26 2016

Latest update...

issued at 329 am EDT Tue Jul 26 2016

Warm and sunny weather is expected for southwest Michigan today
thanks to a large high pressure system that will cross the area
during the daytime hours. A Canadian cold front will move south
through lower Michigan Wednesday bringing the chance for
thunderstorms. A wave on the same cold front may bring additional
showers and thunderstorms into the area for Thursday and Friday.


Short term...(today through thursday)
issued at 329 am EDT Tue Jul 26 2016

There is little question today will be sunny and warm with light
winds thanks to a large high pressure system crossing the area.
The real question is how much convection will we see with the
Canadian cold front dropping south through the area Wednesday and
will there be a strong enough wave on the front Thursday to bring
the rain back north into michigan?

My short story is there is more than enough elevated instability
for thunderstorms Wednesday, but the upper dynamics are not all
that great. The moisture transport in the 1000/850 layer is not
all that great either. Still it is a front and there is surface
convergence so thunderstorms are possible for sure.

As for the wave on the front being far enough north to bring
precipitation to southwest Michigan, seems the best bet is for it
so stay south of the area but it will be a close call.

Long term...(thursday night through monday)
issued at 329 am EDT Tue Jul 26 2016

Chances for measurable rain don't look great during the period. The
highest chance, 30-40 percent, extends from Thursday night into
Saturday. But that's mainly because the ECMWF brings a low across
northern Indiana and Ohio. This position is much farther south than
the 12z version which showed a low moving across the northern cwa.
The GFS meanwhile continues to show no low and thus retains a dry
forecast. It seems like the ECMWF is having some issues while the
GFS remains consistent. As such we're leaning more toward a drier
forecast than the wetter ECMWF would provide. For now we'll lean
toward the GFS by showing lower pops. After Saturday both the ECMWF
and GFS show high pressure over Michigan so dry wx is expected.
Highs in the lower 80s Friday and Saturday will climb to the mid 80s
by Sunday and Monday.


Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 720 am EDT Tue Jul 26 2016

Expect nearly clear skies and light surface winds today through
tonight. Rap model sounding suggest a few cumulus mid morning into
early afternoon around 5000 ft agl but they should mix out by late


issued at 329 am EDT Tue Jul 26 2016

Not much to worry about in the short term.


issued at 1254 PM EDT Mon Jul 25 2016

No river flooding is expected through the week. Area wide rain of
around an inch with locally up to 3 inches (mainly near lake
michigan) fell this weekend. A small chance of rain is in the
forecast Wednesday through Friday. River levels have risen and are
at or above normal for this time of year. Even with the
precipitation, no rivers should approach flood level.


GRR watches/warnings/advisories...


short term...wdm
long term...99

National Weather Service Glossary of Abbreviations