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fxus63 kiwx 051957 
afdiwx 


Area forecast discussion 
National Weather Service northern Indiana 
357 PM EDT Sat Jul 5 2008 


Short term... 


High pressure established at surface providing a fine sunny day for the 
County Warning Area with high clouds to our south associated with deepening 500 mb trough 
and cumulus development beginning over southern counties where dewpoints are 
highest. Deep surface low located over Manitoba sliding west while 
trailing cold front moving into Dakotas and strong upper flow 
situated off to the north. Temperatures running similar today...just a 
couple of degrees warmer in most places except for southeast counties 
where it was cloudy/cooler yesterday. Light winds turning 
southerly overnight with mostly clear skies should once again allow 
for some patchy fog in the early morning hours. 


Models close off 500 mb low Sunday with good agreement on location to 
our southeast near KY/OH. County Warning Area remains northwest of low/back side of 500 mb trough in 
area of subsidence resulting in another nice dry Sunday. Temperatures 
will warm another few degrees under July sun. Southerly ll flow 
increases moisture through the day...with Sunday night low temperatures 
several degrees warmer as a result. As low over Canada moves east 
associated surface front will dip into the upper Midwest. Convection 
is indicated in models ahead of the front which 12z runs try to 
sneak into northern Illinois/southern Wisconsin by Monday 
morning...but at this time believe it will hold to the west 
through this period even if the more easterly propagation occurs 


&& 


Long term... 


Very little adjustment needed...models have been fairly consistent 
early in the period...and are starting to be slightly more 
consistent later. Higher confidence Monday and Tuesday (4 of 5)...with 
near average confidence from Wednesday on into the weekend (3 of 5). 


Monday through Tuesday... 


Continued concerns of possible mesoscale convective system activity as frontal boundary 
pushes east towards the region...and weak ridging nudges into the 
region allowing for west-northwest or west flow across the region. Decent 
instability seen through the afternoon/early evening Monday allowing 
for moderate convective available potential energy near 1500-2000 j/kg...and the bit of capping 
looking to break in the late afternoon most likely. Will alter 
wording to scattered as the showers/thunderstorms will most likely be hit and 
miss. Main concern would be threat of locally heavy rainfall with 
high precipitable waters  near 1.7 inches and decent warm cloud layer around 11.5 k 
feet. 


Frontal boundary pushes into the region Tuesday. Signal there for 
all the ingredients necessary for storms...boundary as a 
trigger...significant moisture with precipitable waters  nearing 2 inches...and 
instability with heating producing convective available potential energy near 2000-2500 j/kg by late 
afternoon/early evening and decent middle level speed maximum pushing through 
the area. Bumped up the probability of precipitation to very low end likely for the Tuesday 
18z to 00z Wednesday timeframe. Modest unidirectional flow along the 
boundary...warm cloud layers at or above 13 kft...decent low level jet...main 
concern will be training storms producing larger rainfall totals and 
possible flooding. With that said...as previously mentioned in the 
last discussion wet microbursts can not be entirely ruled out. Will 
mention both of these threats in the severe weather potential statement. 


Wednesday through Saturday... 


Surface high pressure will start to work into the region...with 
troughiness developing across the northeastern Continental U.S. And Great 
Lakes. Trended temperatures cooler for the Wednesday-Thursday period...then warming as 
the surface high pushes east and warmer southerly flow strengthens 
Friday into the weekend and more zonal flow develops with 
significant ridging across the southeastern Continental U.S. And much of the 
Ohio Valley. H850 temperatures around 8 to 10c Wednesday/Thursday climb to about 15c 
for Friday...and push near 18 to 20c by Saturday. 


Have the entire period dry with Little Signal for precipitation in any 
model...the only possible debate may be how fast the front pushes 
through Tuesday night. If slower solution were to develop then a slight 
chance of precipitation may exist for the first half of Wednesday... 
experience is that these Summer systems can be tricky as they can 
stall a bit more northerly than expected some times as they push 
into a southeast Continental U.S. Ridge...strong model support here that this will not 
be the case and push well into the Ohio and Tennessee Valley by early Wednesday 
morning. 


&& 


Aviation... 


VFR conditions will prevail with another period of patchy fog early 
Sunday morning which could reduce visibilities to MVFR primarily 
between 8z-12z. Winds will remain light overnight turning southerly 
into Sunday. 


&& 


Iwx watches/warnings/advisories... 
in...none. 
Michigan...none. 
Ohio...none. 
Lm...none. 
&& 


$$ 


Short term...Ludington 
long term...schott 
aviation...Ludington