Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 192335
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
635 PM CDT Sun Mar 19 2017
.AVIATION(00Z TAFS)...Elevated moisture advection currently over
wrn WI and ern IL will shift ewd with Cigs of 3.5-5.0 kft
developing this evening. Elevated CAPE is present above this level
but with only small chances of showers and tstorms with most of
the rain to develop across IA and IL late tonight. A slow moving
cold front will then move across srn WI for Mon AM. Weak flow
within a somewhat moist frontal zone may cause Vsbys to drop to
3-5SM while Cigs of 2-4 kft are forecast mainly along or south of
a line from Madison to Milwaukee. Though, cannot completely rule
out some stratus development to the north as well. Rain chances
will continue near the IL border through Mon AM with the passage
of the cold front. Nly winds will slowly bring drier air to the
area for Mon afternoon with VFR conditions eventually taking hold.
LLWS may be possible this evening into the early overnight via a
swly 35-40 kt LLJ.
.PREV DISCUSSION... (Issued 238 PM CDT Sun Mar 19 2017)
TONIGHT - Confidence...Medium Surface ridge axis will continue to
shift further away from the area. Upstream surface trough with a
flattening of the mid level ridge noted. Mid level ridging
dominates here for much of the night though the sfc/850 trough
axis will swing through later tonight. Meso models have trended
south with much of the precip though still some chances, but have
trended current pops a bit towards some of this newer data. Bufkit
soundings show quite a bit of elevated instability above 5k feet
with impressive mid level lapse rates. A mild night with a
sustained southerly wind ahead of the trough.
MONDAY - Confidence...Medium Looks like there may be a little
better phasing of the arrival of mid level vort max with the lower
level forcing across SE WI. So have somewhat higher POPS in the
SE Monday morning. With front passing to our southeast the LLVL RH
gradually decreases from NW to SE. NNE winds kick in with CAA
regime settling in.
Monday Night through Wednesday...Forecast Confidence is High:
High pressure will return for Mon night through Wed, bringing
mostly clear to partly cloudy skies. Could see little rain clip
the far sw Tue morning, but otherwise should be dry for this
period. Temps will be cooler Tue behind the departed cold front,
though still a couple degrees above normal. Below normal temps are
likely on Wednesday.
Thursday through Sunday...Forecast Confidence is Medium to High:
Models are in good agreement showing low pressure moving through
the region late in the week. This will likely bring a long period
of precip chances back into the area Thursday into Saturday.
Higher confidence in all rain for this system, as the ECMWF is
farther north again. Could see a little thunder Friday.
Near normal temps Thursday should warm back above normal Friday,
cooling again for the weekend as the low heads east and colder
air moves into the state.
AVIATION(18Z TAFS)...MVFR CU BKN-OVC field near the lake and
FEW-SCT inland will persist this afternoon. Surface high shifts
further east of WI and sets up SSE wind regime. Precip chances
tonight tied to surface cold front. Best surface based instability
is proggd to our south however BUFKIT soundings show impressive
mid level lapse rates and elevated CAPE values over 1000 j/kg, so
will retain the mention of thunder overnight. Meso models showing
various solutions with convection with latest HRRR blowing things
up just south of the WI/IL border and little or no precip in the
CWA. Potential for some post frontal lower cigs/vsbys (MVFR and
IFR) Monday morning. LLVL RH progs then show gradual drying from
nw/se as the day wears on.
MARINE...South/southeast winds ahead of a surface trough will
continue into the overnight hours. Expecting winds/waves to remain
below small craft levels though highest likely in the northern cuts
experiencing the longest fetch. On Monday winds shift to the NNE
with a favorable fetch however at this time winds and waves do not.
look like they will reach small craft criteria.
Tonight/Monday and Aviation/Marine...Collar
Monday Night through Sunday...DDV