Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Grand Rapids Michigan
747 PM EDT Friday Jul 3 2015

Latest update...

issued at 306 PM EDT Friday Jul 3 2015

The area will see very quiet and Summer-like temperatures for the
Fourth of July Holiday weekend. The only chance of rain through the
weekend will be a slight chance across the interior portions of
central lower Michigan during the afternoon on Independence day.

A better chance of rain across the area will arrive late Monday and
into early Tuesday as a cold front moves through the area. Showers
and thunderstorms will become more likely at that time.


Short term...(this evening through Sunday night)
issued at 306 PM EDT Friday Jul 3 2015

Forecast challenges remain fairly minimal through the short term for
the area once again. The only thing of note remains the low chance
of a shower or storm for Sat.

The only thing around the area this afternoon are some high clouds
floating through across the south...and a good deal of smoke in the
upper levels of the atmosphere from the fires across central Canada.
High pressure is keeping the atmosphere very dry at this time with a
subsidence inversion capping any diurnal clouds trying to form.

We have maintained the low chance of a shower and storm for interior
sections of central lower Michigan for the day on Saturday. Models
remain consistent with bring a weakening cold front into the area on
Sat. Not much moisture return ahead of the front aside from some
pooling of low level moisture pooling right along the front. Convective available potential energy
of a few hundred j/kg at best along with a couple of inversions
aloft will limit the potential. The best chance of storms will be
further north across northern lower and eastern upper closer to the upper

Quiet weather looks to remain then for Sat night through Sun night
with only increasing temperatures during that period. High pressure
will reestablish itself over the area in the wake of the short
wave/front moving through the region on Sat. A bit more of a long
wave ridge will build toward the region at that time. Temperatures should
be well into the 80s on sun with h850 temperatures in the middle teens c.

Long term...(monday through friday)
issued at 306 PM EDT Friday Jul 3 2015

We expect a relatively narrow band of showers and thunderstorms to
pass through the area late Monday night/early Tuesday morning ahead
of a cold front and sharp upper trough. Confidence in timing has
grown due to better agreement between the European model (ecmwf) and GFS.

The severe threat is limited with this occurring near the diurnal
minimum for instability. Dynamics overall do not look favorable
either. While an impressive low level jet /50+ knots at 850 mb/
develops ahead of the front...our area remains south of the speed
maximum and well south of the entrance region of the associated
upper jet. There is almost no low level shear component expected
normal to the a fairly uniform band of showers and
thunderstorms should be the result. The upper trough itself is
characterized by confluent flow downstream of the axis suggesting
general weakening.

We are more concerned about nuisance flooding as impressive
precipitable water and strong moisture transport will boost
precipitation efficiency. However...a widespread flooding threat is
not expected since precipitation should move rather quickly through
the area.

No other weather of significance is expected after this.
Temperatures should remain slightly below normal with a chance for
showers and thunderstorms returning to the southern forecast area
towards the end of the work week.


Aviation...(for the 00z tafs through 00z Saturday evening)
issued at 747 PM EDT Friday Jul 3 2015

VFR conditions will continue through Saturday afternoon. There
could be some isolated showers with small areas of MVFR conditions
in the afternoon...but these were left out of the forecast because
chances are very small. Winds will be light to calm tonight then
go west to southwest on Saturday afternoon.


issued at 306 PM EDT Friday Jul 3 2015

We do not anticipate any marine headlines being needed at this time
through Sunday night. High pressure will generally be in control for
most of the period allowing for a weak gradient to remain in place.
Winds should remain below 15 knots through the Holiday weekend.
Winds will begin to increase Sunday night...with Small Craft
Advisory winds possible late Monday ahead of a cold front.


issued at 1136 am EDT Friday Jul 3 2015

Significant improvement continues on area rivers. The lone
advisory at Holt on the Sycamore Creek is expected to recede below
its banks within the next 24 hours or so.

There is minimal threat for rainfall over the next few days.
Isolated showers/thunderstorms are possible through portions of
central lower Michigan Saturday afternoon with very brief and
localized downpours possible. Otherwise...dry weather will
continue through the next three days and through the majority of
Monday. A cold front will bring in the next round of rain late
Monday evening. Expected amounts are rather typical of Summer
convection with pockets of heavier rainfall possible.


GRR watches/warnings/advisories...


short term...njj
long term...tjt

National Weather Service Glossary of Abbreviations