Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 280324

Area Forecast Discussion
National Weather Service Grand Rapids MI
1124 PM EDT Thu Oct 27 2016


Issued at 314 PM EDT Thu Oct 27 2016

High pressure will continue to build in and bring fair weather
tonight through Friday. A low pressure system will bring scattered
light rain showers Saturday into Saturday night. Another ridge of
high pressure will bring fair weather again for Sunday into early
next week. Temperatures will average above to much above normal
Friday through the weekend into early next week.


Issued at 1124 PM EDT Thu Oct 27 2016

Clearing has been pressing south last couple hours, with most
locations east of HWY 131 and north of I-96 now CLR. The recent
clearing leads to concerns for fog/stratus development so have
added some patchy fog to the forecast overnight.


.SHORT TERM...(This evening through Saturday night)
Issued at 314 PM EDT Thu Oct 27 2016

Primary short term fcst concerns involve determining probabilities
for showers and convection Saturday through Saturday night.

High pressure will continue to build in tonight and bring fair and
seasonably cool wx. Some breaks in the cloud cover will develop
overnight. It will be partly sunny and seasonably mild Friday as
southerly winds help to boost high temperatures into the upper
50`s to lower 60`s.

An isolated light rain shower or sprinkle may develop during the
early morning hours Saturday over our northern fcst area as the
next low pressure system approaches from the northwest.

This system will bring scattered light rain showers to most of
our fcst area Saturday and Saturday night as moisture ramps up
significantly and precipitable water values reach around 1.25 to
1.5 inches.

I have also introduced a chance for thunderstorms to the forecast
for Saturday through Saturday night mainly near to south of I-96.
12z short range guidance consensus shows weak to moderate elevated
instability will develop just to the north of the sfc boundary
across this area and the llj will also provide some forcing for
convective initiation to occur.

.LONG TERM...(Sunday through Thursday)
Issued at 314 PM EDT Thu Oct 27 2016

To start the long term...mid level heights will rise steadily Sunday
into Monday as a ridge builds in from the west.  A considerable warm
up is expected as a result as the warm air advection deepens and
strengthens.  In fact the wind may lead to impacts on Monday as good
mixing combines with a 40 knot low level jet. Little in the way of
moisture will be around for precipitation and any lift remains weak.
So we will continue the theme of dry with moderating temperatures.

A mid level shortwave tracks northeast out of the central Rockies
later Monday before tracking through the western Great Lakes on
Tuesday. This system will send a weakening cold front through the
region Tuesday.  This frontal passage looks dry given the lack of
moisture. Models are in decent agreement on this scenario.

The front then lifts slowly north Tuesday night into Wednesday. This
time the front will have relatively much more moisture with it. PWAT
values climb up to around 1.5 inches...along with the arrival of
another low level jet.  Even some elevated instability is shown. As
a increased chance for rain exists Tuesday night into
Wednesday. How far north the front goes is uncertain...with
considerable differences in the models.  The GFS suppresses the
front south by Thursday and would support drying conditions.  The
new High Res Euro develops a wave on the front and keeps it over the
region...which would allow for wet weather into Thursday.  Will
feature a risk for showers into Thursday.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 812 PM EDT Thu Oct 27 2016

Cigs of 2500-3500 ft are expected to linger tonight then depart on
Friday from south to north. Light winds tonight will become south
overnight and increase on Thursday to 10 to 20 kts with higher
gusts along the lakeshore.


Issued at 314 PM EDT Thu Oct 27 2016

Have decided to hoist a small craft advisory from midday Friday
through midday Saturday. Wind speeds will reach 20 to 30 kts out of
the south to sw in this time frame and wave heights will build to 4
to 8 feet late tomorrow through tomorrow night. Wind speeds and wave
heights will subside Saturday afternoon.


Issued at 1043 AM EDT Thu Oct 27 2016

Rainfalls from a half inch to over an inch occurred in the past
24 hours. Rivers and streams will stay below bankfull. River
advisories for Sycamore Creek at Holt and Maple River at Maple
Rapids have been cancelled as the rain has not translated into
large river rises. Flooding is not expected.


LM...Small Craft Advisory from noon Friday to noon EDT Saturday for



SHORT TERM...Laurens
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