898 
fxus63 kapx 231642 
afdapx 


Area forecast discussion 
National Weather Service Gaylord Michigan 
1142 am EST Monday Nov 23 2009 


Synopsis.../issued at 429 am/ 


High pressure to our east will maintain mild and quiet weather 
through Tuesday. Low pressure will start to organize in the Central 
Plains tonight...and then slowly move toward northern Michigan through 
Thanksgiving day. This system will bring cooler and wetter weather 
by Wednesday and Thursday...though little in the way of snow is 
expected. 


Jz 


&& 


Short term.../issued at 1035 am/...today 


Departing high pressure will remain in control of northern Michigan/S 
weather through today before giving way to more unsettle weather 
over the next few days. Persistent with the last few mornings...low 
stratus/patchy fog once again widespread across northern Michigan. 
Shallow to be sure...less than 1000 feet in depth per 12z apx 
sounding. Difference today versus the last few days rests in warm 
advection high cloud cover which has inched into the state on the 
backside of the slowly departing high pressure system...as well as a 
slightly stronger inversion sitting at 900 mb. Combined...will be a 
bit more difficult to thin/erode the low stratus layer today versus 
the previous few days. Heating/mixing may ultimately thin out the 
low layer to some extent. But having serious doubts about that and 
plan for now is to nudge the forecast toward the cloudier side of 
things...today as well as through tonight. This will of course have 
obvious implications on today/S maximum temperatures and will tweak expected 
highs downward accordingly. 


Adam 


&& 


Long term.../issued at 429 am/...tonight and beyond 


High pressure and dry air over the eastern lakes to remain in control 
Monday night through Tuesday afternoon...while a Southern Plains storm 
system lifts into the Central Plains and an upper trough digs into 
the Central Plains. Model soundings and moisture forecasts show 850/500mb 
relative humidity lingering around 40 percent through 00z Wednesday. Will continue a dry forecast 
over the northern lakes Monday night and Tuesday. Low temperatures Tuesday in 
the middle 30s as airmass remains unchanged...afternoon temperatures in the 45 to 
50 degree range as some upper clouds increase over the state in 
advance of approaching surface and upper levels features. 


Tuesday night and Wednesday...Central Plains storm system lifts 
north into the upper Midwest Tuesday night before lifting north into 
The Straits and eastern Upper Michigan Wednesday. Model soundings and 
moisture forecasts showing moisture increase over the northern lakes through the period 
as the storm system lifts into northern Michigan. 850/500mb relative humidity will increase to 
around 80 percent while 850mb dew points increase from -8c Tuesday to 0c by 
12z Wednesday. Model soundings showing above freezing layer from the 
surface to around 4000 feet Tuesday night...extending to 5500 feet 
Wednesday. Therefore precipitation all in the form of rain through this 
period. Low temperatures in the 30s Tuesday night with highs in the middle 40s 
Wednesday. 


Wednesday night and Thursday...storm system over the northern lakes 
lingers but becomes stretched out across the state...as the low 
tries to lift north toward Hudson Bay. The digging 500mb trough drops 
south of the state and moves east over the Ohio Valley. Model 
soundings showing coldest 850mb air to linger west of the region and 
sweep south across the Ohio Valley. Over northern Michigan...850mb temperatures drop 
from around 0c/+1c Wednesday night to -3c Thursday. Model soundings 
showing above freezing layer extending from the surface through 4k feet 
Wednesday night dropping to around 2500 feet by 00z Friday. Will 
trend toward all rain event Wednesday night and much of Thursday 
afternoon. Will mention a mix rain/snow to all snow Thursday 
night...when vertical temperature profile on soundings show above freezing 
layer dropping under 1500 feet. Highs Thursday generally around 40 
most locations. 


Swr 


&& 


Marine.../issued at 429 am/ 


Winds and waves expected to remain below Small Craft Advisory criteria today 
through Tuesday...with winds primarily from the southeast. 
Strongest winds and highest waves today expected in The Straits 
and between the bridge and DeTour...however expected to remain below 
Small Craft Advisory. Fog this morning to diminish as surface high pressure and dry air 
linger across the eastern lakes. Clearing slowest over the eastern lakes 
once again today with overall southeast flow across the region and late 
Nov sun angle. Next chance of rain over the northern lakes nearshore 
waters...will be Tuesday night and Wednesday as a plains storm 
system lifts north into northern Michigan. 


Swr 


&& 


Aviation.../issued at 1142 am/...valid for 18z tafs 


Will trend considerably more pessimistic with the forecasts... 
particularly in regard to cloud cover. Low stratus (ifr) once 
again developed overnight and persists this morning. But unlike 
previous days...increasing warm advection/strengthening inversion 
and increasing high cloud cover limiting heating...will conspire 
to keep stratus layer intact through today and possibly through 
tonight. Thinning/lifting of the low clouds not completely out of 
the question...but not banking on it. Thus high IFR/low MVFR 
anticipated through the period. 


Adam 




&& 


Apx watches/warnings/advisories... 
Michigan...none. 
Lm...none. 
LH...none. 
Ls...none. 


&& 


$$