Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 300824
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
324 AM CDT THU JUN 30 2016
.TODAY AND TONIGHT...Forecast Confidence - Medium.
Focus of this period on shower and thunderstorm threat today into
this evening. Best time for precipitation will be from mid-
afternoon through mid-evening as sharpening mid-level low pressure
trough swings through WI. At this time, the trough is still well
upstream from the area, and is currently crossing the border into
nrn MN. As the trough approaches, column precipitable water values
increase to 1-1.25 inches later today. As the trough sharpens, the
left exit region of an increasing upper jet briefly affects srn WI
during this time. Hence enough confidence to beef up pops to low
categorical for several hours in the late aftn and early evening.
Although dewpoints will not get quite as warm as depicted by the
GFS, using more of a short term model blend wl result in dewpoints
getting into the low 60s ahead of passing cold front tied to upper
low pressure trough. This will result in MU CAPE values anywhere
from 500 to 1500 j with 0-6km bulk shear around 30 kts. Mid-level
lapse rates increase to 6-6.5 degrees. So not a terrible setup and
agree with SPC Marginal Risk for an isolated severe storm,
considering strong synoptic forcing. Short wave trough quickly
exits the area during the evening so expect a rapid end to the
shower and thunderstorm threat by 06z. Cooler air surge behind
front may bring a period of low clouds to eastern CWA late tonight.
Friday Lake Michigan beach goers will need to check on the swim risk
before heading to the beach.
.FRIDAY THROUGH SUNDAY...Forecast Confidence...High
High pressure will slowly slide through the region Friday through
the weekend. This will bring very pleasant weather to southern
Wisconsin for the holiday weekend. Skies will be mostly sunny during
this period, with highs mainly in the 70s, possibly cracking 80 by
.INDEPENDENCE DAY THROUGH WEDNESDAY...Forecast Confidence...Medium
Models are showing low pressure passing by to the south on
Independence Day. The Canadian is the farthest north, bringing
precip into the forecast area. Did end up with some low pops on the
4th per a consensus blend of models, though think the dry easterly
flow on the north side of the low will probably keep it dry across
It looks dry Tuesday behind the departing low. Have some low pops
Wednesday as a trough may approach the area, though not great run to
run consistence among models for this period.
Models suggest temps should be near to a few degrees above normal
for the first half of next week.
.AVIATION/12Z TAFS/...VFR conditions are expected today, however a
passing cold front will bring numerous thunderstorms to the area
between 22z and 04z. A few of these storms will affect TAF sites
with briefly lower cigs and vsbys. Cold air surging southward
behind the front may result in a period of MVFR/IFR cigs later
tonight into early Friday at eastern TAF sites.
.MARINE...A cold front will sweep across Lake Michigan this evening
triggering thunderstorms. A few thunderstorms may contain gusty
winds in excess of 33 kts and hail. Mariners will need to keep an
eye on the sky and be ready to seek harbor this evening.
Gusty north winds will develop later tonight behind the departing
cold front. Gusts may reach 25 knots after midnight through Friday
morning. A Small Craft Advisory may be issued by later shifts for
.BEACHES...Thunderstorms are expected to affect some Lake
Michigan beaches late this afternoon and evening as a cold front
moves across southeast WI and Lake Michigan. North winds behind the
front will increase to 10 to 20 mph later tonight and continue into
Friday morning. These winds may cause waves to increase to 3 to 5
feet resulting in a high swim risk at beaches along Lake Michigan
for a time on Friday. If this trend continues, a Beach Hazard
Statement may be issued later today or tonight. Life guards and
beach managers should be prepared for potential hazardous swim
conditions on Friday.
TODAY/TONIGHT AND AVIATION/MARINE/BEACHES...MBK
Friday THROUGH Wednesday...DDV