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Area forecast discussion 
National Weather Service Grand Rapids Michigan
746 am EDT Wednesday Jul 29 2015

Latest update...
aviation

Synopsis...
issued at 330 am EDT Wednesday Jul 29 2015

Scattered showers and thunderstorms are expected today as a cold
front crosses the region. Gusty westerly winds behind the front will
usher in more comfortable less humid air for the remainder of the
week although highs will remain in the lower to middle 80s.

&&

Short term...(today through friday)
issued at 330 am EDT Wednesday Jul 29 2015

Isolated showers have developed overnight on the leading edge of the
higher precipitable water around two inches moving in from the
southwest ahead of the approaching cold front. Suspect coverage of
showers will remain rather limited this morning across SW lower Michigan as
more expansive area of convection impacts Iowa and Illinois.

Our best Prospect for better coverage of storms will be this
afternoon east of Highway 131 where sb convective available potential energy near 1500 j/kg are
prognosticated just ahead of the front. RUC forecast soundings exhibit steep
low level lapse rates with surface to 3 km values around 8.5c near
jxn. Based on the high precipitable water values of up to 2.25 inches we will
have to watch for the possibility of some torrential rainfall and
possibly a localized wet microburst damaging wind event.

Convection ends from west to east 18z-22z with the passage of the
front then decreasing clouds and falling surface dew points expected.
Breezy conditions likely Thursday once deeper mixing commences.
Some gusts to 30 miles per hour will be possible in the afternoon.

Have kept Friday dry for now although some small probability of precipitation may need to
be added in later forecasts as next weak surface front/trough drops south.

Long term...(friday night through tuesday)
issued at 330 am EDT Wednesday Jul 29 2015

There has not been much change over the the past few days with
regard to the expected pattern. We continue to expect little to no
rain through Sat...before an unsettled weather pattern takes shape
later this weekend and into next week.

We have continued with a dry forecast for the Friday night and Sat time
frame for now. We will see what is left of the weakening cold front
trying to move through on Friday slip southeast of the area Friday evening. We
can not rule out a shower developing near this front...however the
chance is low enough to leave out of the forecast for the time being. A
lack of moisture with the Friday front will only diminish by Sat as the
front moves out. There is not really significantly cooler air behind
this...so we continue to expect highs around 80.

The chances of rain does go up on sun...and will continue through the
end of the period on Tuesday. The area will be under the influence of
broad long wave troughing centered well north in Canada. We will see
the jet core drop a little further south with a train of short waves
helping this cause. Being closer to the jet...we will have more of
an opportunity for the short waves to directly impact the area. We
will also see the low level flow become a little more favorable to
bring sufficient moisture to the area for rain. Exact timing of the
short waves will be problematic as is usual in a pattern like this.

Temperatures do not look to be too bad in this pattern. The
unseasonably cool air will remain just north of the state...north of
the jet core. We will see average to just slightly below average
temperatures during this period for our area. This equates to highs
generally around 80 and lows around 60.

&&

Short term...(today through friday)
issued at 330 am EDT Wednesday Jul 29 2015

Isolated showers have developed overnight on the leading edge of the
higher precipitable water around two inches moving in from the
southwest ahead of the approaching cold front. Suspect coverage of
showers will remain rather limited this morning across SW lower Michigan as
more expansive area of convection impacts Iowa and Illinois.

Our best prospects for better coverage of storms will be this
afternoon east of Highway 131 where sb convective available potential energy near 1500 j/kg are
prognosticated just ahead of the front. RUC forecast soundings exhibit steep low
level lapse rates with surface to 3 km around 8.5c near jxn. Based on
the high precipitable water values of up to 2.25 inches we will have to watch of
the possibility of some torrential rainfall and possibly a localized
wet microburst damaging wind event.

Convection ends from west to east 18z-22z with the passage of the
front then decreasing clouds and falling surface dew points expected.
Breezy conditions expected Thursday once deeper mixing commences.
Some gusts to 30 miles per hour will be possible in the afternoon.

Have kept Friday dry for now although some small probability of precipitation may need to be
added in later forecasts as next weak front/trough drops south.

Long term...(friday night through tuesday)
issued at 330 am EDT Wednesday Jul 29 2015

There has not been much change over the the past few days with
regard to the expected pattern. We continue to expect little to no
rain through Sat...before an unsettled weather pattern takes shape
later this weekend and into next week.

We have continued with a dry forecast for the Friday night and Sat time
frame for now. We will see what is left of the weakening cold front
trying to move through on Friday slip southeast of the area Friday evening. We
can not rule out a shower developing near this front...however the
chance is low enough to leave out of the forecast for the time being. A
lack of moisture with the Friday front will only diminish by Sat as the
front moves out. There is not really significantly cooler air behind
this...so we continue to expect highs around 80.

The chances of rain does go up on sun...and will continue through the
end of the period on Tuesday. The area will be under the influence of
broad long wave troughing centered well north in Canada. We will see
the jet core drop a little further south with a train of short waves
helping this cause. Being closer to the jet...we will have more of
an opportunity for the short waves to directly impact the area. We
will also see the low level flow become a little more favorable to
bring sufficient moisture to the area for rain. Exact timing of the
short waves will be problematic as is usual in a pattern like this.

Temperatures do not look to be too bad in this pattern. The
unseasonably cool air will remain just north of the state...north of
the jet core. We will see average to just slightly below average
temperatures during this period for our area. This equates to highs
generally around 80 and lows around 60.

&&

Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 745 am EDT Wednesday Jul 29 2015

It should remain VFR for the most part today despite a cold front
with scattered showers moving through. However some brief periods
of MVFR conditions are possible where/when the showers are
occurring. The best chance of thunderstorms will be from about 17z to 22z
east of a GRR-azo line.

Skies will clear from west to east after 18z with winds
increasing out of the west to 12-22kts. Clear skies and west winds
of 5-10 kts are expected after 00z tonight.

&&

Marine...
issued at 330 am EDT Wednesday Jul 29 2015

Conditions may approach Small Craft Advisory criteria late tonight
and early Thursday due to strong westerly flow behind the cold
front. This will need to be monitored. This situation could also
support beach hazard statements especially considering the current
warm water temperatures and overall attractive beach conditions
supportive of a high beach population.



&&

Hydrology...
issued at 1250 PM EDT Tuesday Jul 28 2015

River levels are falling and well below bankfull. With under a
half inch of precipitation expected into next week... these
conditions should continue.

&&

GRR watches/warnings/advisories...
Michigan...none.
Lm...none.
&&

$$

Synopsis...Meade
short term...Meade
long term...njj
aviation...Meade
hydrology...63
marine...Meade

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