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fxus63 kmqt 220029 aaa 
afdmqt 


Area forecast discussion...updated 
National Weather Service Marquette Michigan 
729 PM EST Sat Nov 21 2009 


Updated for 00z aviation discussion 


Discussion... 


Short term... 


Most of Upper Michigan experienced a sunny and mild day by late 
November standards with temperatures running 10 to 15 degrees above 
normal. The only exception was across eastern areas where low 
clouds/fog have been very persistent across Luce and eastern 
Schoolcraft counties. Low clouds/fog will continue to slowly 
dissipate through the remainder of the afternoon but stage will be 
set for a repeat performance tonight. 


Surface high centered over the Ohio Valley and Middle Atlantic States will 
still be the main player across the Great Lakes into this evening. 
Surface/upper trough making some progress through the northern plains will 
aid in tightening the pressure gradient across the area 
tonight...especially western sections. With clear skies and light 
winds early this evening temperatures will fall off quickly...likely 
reaching their night time lows by middle to late evening. After 
that...slowly increasing southerly winds should limit diurnal 
cooling. In addition...where winds remain lightest the longest in 
the east...anticipate areas of fog to develop once again. Further 
west...fog will not be as dense or widespread...but increasing 90h 
moisture with stronger southerly winds just off the surface will 
allow stratus to develop/move into the west towards daybreak. Clouds 
and perhaps even a little drizzle will persist through the 
morning...with some breaks likely by afternoon in the East. 


Lead shortwave associated with northern plains trough will shear out 
northeastward late Sunday afternoon and graze the far west. Will 
maintain a low chance pop for Western Lake Superior and expect most 
areas will remain dry during the day. 


Despite the clouds...temperatures on Sunday will continue to be well 
above normal with highs expected in the middle 40s to around 50. With 
no snow expected through tomorrow...it looks like we will break our 
record for the least snowiest start to the fall/winter season. In 
addition...if our high temperatures remain above 32 degrees through 
the 27th we will set a record for the longest period into the fall 
season without a high temperature at or below 32 degrees. 






Longer term...00z Monday Onward... 


NAM shows a trough in the northern rockies 00z Monday with a ridge over 
the eastern U.S. And Canada. NAM then takes the trough in The 
Rockies and digs it southeast on Monday and forms a closed low in it 
00z Tuesday and then continues to dig the low and trough southeast on 
Tuesday while having another shortwave moves across southern Canada at 
the same time. This shortwave in southern Canada will determine what 
this system will do...when it will kick out the 500 mb closed low 
and trough to the south of it...if they will merge or not or remain 
separate and this is what the models have been having a hard time 
figuring out the past several days. Will follow closer towards the 
NAM for this forecast which is a bit slower and blend towards the 
European model (ecmwf) later on. 


Frontal zone/trough gets sheared out and waits for this system to 
come in...but in the meantime...cannot rule out slight chance probability of precipitation 
along and near it across the far western County Warning Area Sun night through Tuesday 
before the system comes in from the SW. Not real impressed with rain 
chances though and will keep slight chance probability of precipitation in at this time. 
Will continue to be mild with fog at night especially over the 
central and east. 


In the extended...followed the 00z European model (ecmwf) for this forecast as it has 
been the model of choice for a while. The European model (ecmwf) has a closed 500 mb 
low near Kansas City 00z Wednesday which GOES to near Chicago 00z Thursday and 
to near Cleveland 00z Friday. Ridging then moves in for Friday and Sat. 
With system coming up from the south and it has to make its own cold 
air which it manages to do...looks like precipitation will be mixed with this 
system and start off as rain and then go to a rain/snow mix before 
going over to all snow Thursday night. One change is I bumped probability of precipitation up to 
likely for Wednesday through Thursday as deformation zone stays across the area 
and we are in favorable part of storm to get wet. Went dry then for 
Friday except across the east as wraparound is still there and Sat 
everywhere even as a cold front comes through then. One thing is 
that this system really does not have that cold of air for lake 
effect behind it as European model (ecmwf) only has -4c 850 mb air behind it and lake 
temperatures are running about 5c to 6c now. Temperatures look to 
still stay normal or slightly above normal this extended period. 


&& 


Aviation /for the 00z taf issuance/... 


Low level moisture trapped under a subsidence inversion has resulted 
in stratus and patchy fog over northern WI. Expect this stratus/patchy 
fog to spread into the taf sites late tonight or toward daybreak on 
the heels of increasing south winds. Diurnal mixing will cause south 
winds to pick up even more by late Sunday morning which should 
dissipate the fog but MVFR stratus ceilings should persist into 
afternoon. 


&& 


Marine /for the 4 PM Lake Superior forecast issuance/... 


With tightening pressure gradient overnight tonight and 
Sunday...could see a few southerly wind gusts up to 25 knots from 
late tonight into Monday morning. Winds will then remain under 20 
knots into Wednesday...when a storm system approaches the upper 
Great Lakes and winds begin to increase out of the north and 
northeast with gales possible late Wednesday into Thursday. 


&& 


MQT watches/warnings/advisories...none. 


&& 


$$ 


Short term...mz 
long term...07 
aviation...jv 
marine...mz