Area forecast discussion
National Weather Service Green Bay WI
541 PM CDT Sat may 25 2013
Updated aviation portion for 00z taf issuance
Short term...tonight and Sunday
issued at 305 PM CDT Sat may 25 2013
Frost potential is the main concern during this part of the
forecast.
An upper level short wave that managed to pass through an upper
ridge axis is forecast to continue to move southeast...taking the
precipitation that was over the middle Mississippi Valley along with
it. Middle and high clouds from the system spread across the area
during the day...but they should start to clear out during the
night as the system departs. A surface ridge that was over the
upper Great Lakes region today is expected to move little through
00z Monday.
A weak surface pressure gradient...dew points mainly in the
30s...and little cloud cover will allow temperatures to at least
fall into the middle 30s across the northern part of the forecast
area. 12z MOS guidance for Rhinelander had lows of 33 from the GFS
and 37 degrees from the NAM. Have gone closer to the NAM but am a
bit concerned since the 19z dew point was only 32 at rhi. There
should be at least areas of frost over much of the north...with
widespread frost in the far north. Thus...have a frost advisory for
Oneida County and along the Upper Michigan border late tonight
through early Sunday morning.
Long term...Sunday night through Saturday
issued at 305 PM CDT Sat may 25 2013
500mb ridge is expected to build across the eastern United States
by the middle of next week...while West Coast trough deepens.
This pattern change will lead to unsettled weather... starting
Monday night and continue through much of next week. Overall
forecast confidence in smaller scale features/sensible weather low
with expected rounds of convection.
Will stay dry through Monday as low level jet/strong warm air advection focused into
western Minnesota. 12z NCEP models have trended this way. Overnight
temperatures Sunday night still to run on cool side...especially
far northeast WI with lingering dry air and light winds.
Have gone with sref/ensemble forecast Monday night through Tuesday
given run to run differences in convective details. Look for increasing
probability of precipitation through the period as low level jet shifts into WI and warm front
over southern Illinois/Iowa begins to move north as short wave/s? Moves
into/through plains. Increasing moisture with precipitable waters 1.5 in or
greater...instability and height falls to lead to rounds of
convection over upper Midwest and western lakes. Each with
potential for heavy rain.
For later periods...question is where warm front will end up. Will
stay with blend/ensembles to avoid differences between models. Models
suggest front to lift north of state...with continued warm/humid
air over WI. Temperatures above norms with potential highs in the
80s/lows in the 60s into Sat. Though again high temperatures each
day to be problematic due to possible cloud cover...rain and
position of the surface front.
&&
Aviation...for 00z taf issuance
issued at 541 PM CDT Sat may 25 2013
Excellent flying weather with just a few middle and
high clouds tonight and Sunday. Frost possible early Sunday
morning in far northern Wisconsin.
&&
Grb watches/warnings/advisories...
frost advisory from 1 am to 7 am CDT Sunday for wiz005-010>013.
&&
$$
Short term.....Mg
long term......te
aviation.......rdm
