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FXUS63 KMKX 300837

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
337 AM CDT Tue May 30 2017


Today and Tonight...Forecast confidence high.

A few vorticity maximums will move across central and srn WI this
afternoon and tonight as they rotate around the large low pressure
area over nrn Ontario, Canada. At the sfc, a weak sfc trough will
affect srn WI for the afternoon and early eve. CAPE values may
rise to a few hundred joules for the afternoon. Went with 40-50
PoPs for showers and slight chances of thunder. Temps will be
several degrees cooler than yesterday with 1000-500 mb thicknesses
only from 546-549 DM. A few showers will linger into the evening
but then likely dry the remainder of the night. 


Models suggest quiet weather for Wednesday into Thursday morning
across the area, with steady warm air advection developing. Highs
should climb from the upper 60s Wednesday into the lower to middle
70s on Thursday. 

Models then are in decent agreement with a warm front approaching
the area Thursday night from the southwest. Focused warm air
advection and low level frontogenesis response increase during 
this time across the area. Area forecast soundings are showing 
modest elevated CAPE as well. 

Went with high chance to low end likely PoPs for Thursday night, 
highest in the southern counties. May need to go higher with PoPs 
in later forecasts if consistency remains with the models.


FRIDAY THROUGH MONDAY...Forecast Confidence Is Medium.

00Z ECMWF keeps the warm front over the area Friday into Friday
night, before low pressure slides southeast along it and through
the area on Saturday. The 00Z GFS is a little further south with
these features Friday, then sags south into northern Illinois on
Saturday. The 00Z Canadian keeps the front mainly in northern 
Illinois Friday into Saturday. 

Despite the differences in the models during this time, this 
appears to be a potentially active period with showers and 
thunderstorms across the area. If the ECMWF is correct, there is 
potential for strong to severe storms on Friday, as mean layer 
CAPEs rise with increasing deep layer shear. Training convection 
may occur as well into Saturday, given the movement of the low 
along the warm front. The other model solutions would bring a
lower severe weather and heavy rainfall risk, especially the GFS.
For now, kept the blended model PoPs going. 

Models are then generally showing cold air advection for Sunday
into Monday, as the previous system departs. This would bring
cooler temperatures into the area for this period.


.AVIATION(06Z TAFS)...VFR conditions today and tonight but sct
showers and isold tstorms are forecast for the afternoon.
Bkn050-070 will develop by late morning or early afternoon and
continue into the evening due to instability. Skies becoming
partly cloudy later tonight.  


.MARINE...A Small Craft Advisory is in effect from 11 AM until 7 
PM for breezy westerly winds. A large low pressure area over 
Ontario, Canada will continue to bring breezy wly winds during the
daylight hours. 


LM...Small Craft Advisory from 11 AM this morning to 7 PM CDT this 
     evening for LMZ643>646.


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