Weather

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Area forecast discussion 
National Weather Service Grand Rapids Michigan 
1147 PM EDT Wednesday Aug 27 2008 


Latest update...aviation... 


Synopsis...(318 PM EDT Wednesday Aug 27 2008) 
a departing high pressure system in combination with an approaching 
weak cold front will bring a short warming trend to the area 
Thursday with highs mostly in the 80s. Then... as the cold front 
marches through the areas early Friday morning... an area of showers 
and isolated thunderstorms will accompany the front. Once the front 
comes through dry weather will return by Friday afternoon and last 
through the Labor Day weekend. A slow warming trend will being on 
Saturday and last through the middle of next week. 


&& 


Short term...(318 PM EDT Wednesday Aug 27 2008) 
(tonight through Friday night) 
the departing high pressure system in combination with the flow 
around the remains of "fay" will bring some low clouds back 
northwest toward the Lansing...Jackson and Battle Creek area after 
midnight. The shear associated with the approaching cold front will 
help to keep the clouds out of the areas near and west of Route 131. 
That same shear will keep the clouds over WI at 18z out of the area 
too so western sections will see mostly clear skies tonight. A 
little fog is possible since higher dew point air will come in from 
the east thanks to the remains of "fay". That more moist air could 
produce some advection fog late tonight. 


Once the fog and low clouds mix out I except a fair amount of 
sunshine Thursday. The clouds will have a hard time coming in 
Thursday since southwest Michigan will be between the approaching 
northern stream system the upper level system from the remains of 
"fay". The shear between the two system will limit the clouds and 
allow temperatures to warm into the lower to middle 80s most areas. 


Once the front crosses the area Thursday night into Friday 
morning... the nearly solid line of convection over WI at 00z will 
run into and area of upper level convergence on the left front quadrant 
of the upper jet core. There is a decent coupled jet feature with 
this system but that will track over Upper Michigan. Thus with only 
weak low level warm advection and some surface wind convergence only 
limited showers are expected. The best chance of measurable rain is 
north and west of the intersection of Route 10 and US-131. That is 
most likely between midnight and 5 am. 


Friday the front will be through by 6 am and skies will clear across 
the County Warning Area. Being south of the polar jet and being on the anticyclonic 
side of the jet with surface high pressure building mostly clear 
skies should dominate the weather by Friday afternoon. 


Gernally clear skies and light winds will allow for lows in the 
lower to middle 50s Friday night as the surface high moves across the 
area. 


&& 


Long term...(153 PM EDT Wednesday Aug 27 2008) 
(saturday through thursday) 
models continue to indicate upper ridge currently over the eastern 
Pacific will build in over the area this weekend and will amplify a 
bit as upper trough over the western US coast digs a bit. Also helping 
the ridge to build will be Gustav making its way into the Gulf of 
Mexico. All of these factors will lead to plenty of dry weather and 
temperatures warming well above normal through the Holiday weekend 
and into the first portion of next week. 


12z GFS is trying to bring the next system and chance of rain into the 
area next week around the Wednesday time frame. Previous run of the 
GFS was a little slower...and the 27/00z Euro holds the front and 
any precipitation potential off until Thursday. With the amplified upper flow 
developing and the tropical systems in the mix...we feel that slower 
is better. We have kept the warm temperatures in and the forecast dry through 
next Wednesday with this in mind. 


&& 


Marine...(318 PM EDT Wednesday Aug 27 2008) 
light winds tonight will see south winds increasing ahead of the 
cold front Thursday night. However the gradient is not all that 
strong so waves will remain below small craft criteria. Once the 
front comes through there should be enough wind to build waves to 
the 4 foot range on Friday. Some thunderstorms are possible with the 
cold front after midnight Thursday night. 


&& 


Aviation...(1147 PM EDT Wednesday Aug 27 2008) 
east to northeast low level flow will become more southeast 
overnight which is expected to bring in enough low level moisture to 
cause some reductions to visibility and ceilings across Southern 
Lower Michigan. MVFR ceilings and visibilities will be possible between roughly 
07z and 14z at lan...jxn and btl. The best chance for this will be 
at jxn where IFR conditions cannot be ruled out. Conditions will 
improve after daybreak on Thursday as low level moisture mixes out. 
A cold front will bring lowering ceilings Thursday night with the 
potential for some rain showers and thunderstorms by 06z at mkg. 


&& 


Hydrology...(318 PM EDT Wednesday Aug 27 2008) 
another feeble rain producing front will cross the area Thursday 
night. Most areas will see less than a quarter inch or precipitation 
with it. This will have little Hydro impact. 


&& 


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


&& 


$$ 


Synopsis: wdm 
short term: wdm 
long term: njj 
marine: wdm 
aviation: ostuno 
hydrology: wdm