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fxus63 kdtx 151927 
afddtx 


Area forecast discussion 
National Weather Service Detroit/Pontiac Michigan 
327 PM EDT Monday Mar 15 2010 


Short term...tonight and Tuesday 


The advertised dry air originating from southern Quebec is punching 
into Southern Lower Michigan this afternoon...allowing for a slow 
north to south clearing trend...with temperatures climbing into the 
lower 50s (as of 3 pm)...even with the less than stellar insolation 
for a good part of the day. The amount of dry air is impressive...as 
the core of the dry air moves over Central Lake Huron tonight...with 
precipitable water values dropping to around 0.10 inches...and 1000-500 mb mean relative humidity 
down around 10 percent. This dry air will drop south into Southeast 
Michigan during the day Tuesday...which should assure a mostly sunny 
to sunny day. Noting the middle/high clouds over the eastern Great 
Lakes...and looking at the NAM forecasted 850-700 mb Theta-E 
fields/moisture advection...probably see scattered middle clouds 
brushing through the eastern areas this evening/tonight...but should 
exit by Tuesday morning. Inherited temperatures tonight (upper 
20s/lower 30s) and tomorrow (well into 50s) look fine...in line with 
latest mav guidance. 


&& 


Long term...Tuesday night through next Monday 


The weak upper ridge to our north/northwest will flatten as it moves 
south. This along with the surface high and northerly surface flow 
will bring in drier air through Friday. No real Big Warm air 
advection as 850 temperatures only warm to +3 to +5c through that entire 
period. High temperatures will be largely dictated by the height of 
the mixed layer. Those 850 temperatures are similar to early last week when 
highs reached middle to upper 50s. Think with an additional week off 
the calender...temperatures during this stretch to be a bit warmer in the 
middle 50s to around 60. With very light westerly flow on 
Wednesday...expect a more traditional lake breeze with cooler high 
temperatures within 10 miles of the Great Lakes. Thursday is likely to be 
the warmest day with west-southwest flow ahead a weak cold front...despite some 
ac around. Those high temperatures will be near MOS guidance. Lows will be 
a different story. With the mostly clear skies and dry air...will go 
toward the lower end of MOS guidance...if not a degree or two lower. 


Speaking of clouds...do not expect many through the middle term part of 
the forecast. Wednesday is very dry through the column and will go 
with sunny skies. Then on Thursday ahead of that weak front...there 
is moisture from about 700 mbs and above with some very modest warm 
air advection...especially in the north part of the forecast area. 
Partly sunny seems to be a good call for Thursday. 


Still some inconsistent models for this weekend. Really do not 
expect that to change until Wednesday or Thursday when the waves in 
question move into the Pacific northwest/Canadian rockies. There are 
three waves of interest...the first is in the northern stream that 
brings a weak cold front into the lakes region Friday. While this 
will be a dry front...it position will be a key to delineate between 
the warm Spring air and the more seasonably cool air. The next wave 
dives south into the Southern Plains. How this rotates around the 
developing central U.S. Trough will determine if it is an eastern 
lakes surface low or a coastal low. Behind that is a stronger 
northern stream system. How far south this moves across the lakes 
and northeast U.S. Will help determine the amount of cold air for 
Sunday and Monday. While inconsistencies exists...which make details 
tough for Saturday through Monday...the wide general synoptic 
pattern is there to support likely rain showers on Saturday or 
Saturday night...colder air moves in for a change to snow showers Sunday 
into Monday. MOS guidance is being strongly biased by climatology during 
this time period and will go well under its numbers. 


&& 


Marine... 


Large high pressure over the northern plains will slowly drop 
southeast over the next couple of days...with ridging extending into 
the Great Lakes region in the process. This will lead to light winds 
over the marine waters through the end of the work week. 


&& 


Previous discussion...issued 102 PM EDT Monday Mar 15 2010 


Aviation... 


Clearing will continue to take place from north to south this 
afternoon as drier air filters into the area...with skies mostly 
clear to clear by early evening. Outside of a few middle/high clouds 
glancing eastern areas through tonight...looking for clear skies 
and generally light winds. With favorable radiating 
conditions...do think there may be a touch of light fog (mvfr) 
around toward sunrise...as the ground remains saturated and the 
surface moisture may not fully mix out this afternoon. 


&& 


DTX watches/warnings/advisories... 
Michigan...none. 
Lake Huron...none. 
Lake St Clair...none. 
Michigan waters of Lake Erie...none. 


&& 


$$ 


Short term...sf 
long term....rbp 
marine.......sf 
aviation.....Sf 




You can obtain your latest National Weather Service forecasts online 
at www.Weather.Gov/Detroit (all lower case).