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Area forecast discussion 
National Weather Service Milwaukee/Sullivan WI
447 am CDT Thursday Aug 21 2014

Today and tonight...forecast confidence medium to high.

850 mb warm advection and moisture transport has begun over the SW
County Warning Area where heavy rainfall is currently present. Precipitable waters are up to 1.8
inches and will overspread the area today. Radar rainfall totals are
over 2 inches with the hp like storm that moved through Lafayette
and SW green counties. This area of thunderstorms will continue to move
slowly east-southeastward and weaken toward sunrise as depicted by the hrrr
model. Thus only chances of rain this morning for the Milwaukee
area.

Over the next 18 hours the strongest portion of the low level
jet stream currently over Minnesota will gradually veer into and through
southern WI. This will bring the surface warm front into the area with a
strong cape gradient from SW to NE across the region. Thus expect
the showers and thunderstorms over Minnesota to move across the area this
afternoon with additional development expected on its back edge for
the evening hours. MLCAPE via warm...moist advection will rise to
1000-2500 j/kg with 30-40 kts of deep layer shear expected. In
addition the 0-1 km bulk shear will increase to 15-20 kts with 0-1
km srh over 100 m2/s2. Thus expect one to two severe mesoscale convective system/S but with the
potential for a few supercells as well. All severe threats are possible
as highlighted in Storm Prediction Center day 1 outlook. There will also be a flash
flood threat especially for urban areas. The mean storm motion will
be east-southeastward of 20-30 kts but any hp supercells will track southeasterly around
10 kts. Included severe and heavy rain potential in the grids and will
highlight in the severe weather potential statement.



Friday through Wednesday...forecast confidence...medium

A warm and wet pattern is expected to continue from Friday into
the first part of next week. There is some uncertainty with
precipitation chances Friday...as models are undecided with the location
of the low level frontal boundary. Kept some chance probability of precipitation going per
the the farther north and wetter models.

Went with mainly chance probability of precipitation from Saturday through Wednesday.
Models generally are building upper ridging into the area through
at least Sunday. After that...the European model (ecmwf) and Canadian flatten out
the flow...with the GFS hanging onto the ridge and warmer air a
bit longer. By Wednesday though...the GFS has a strong trough
moving through...with the European model (ecmwf) building ridging back in. Quite a
spread in model temperatures by middle-week as a result. Even given the
model differences...a consensus approach still supports some probability of precipitation
each day.

It looks pretty warm through at least Sunday...possibly into
Monday. Could see some heat index values up to around 100 away
from Lake Michigan...mainly Friday and Sunday. Should see temperatures
cool a tad by Tue/Wed...though possibly still a few degrees above
normal.

&&

Aviation/12z tafs/...kmsn and the southeast WI taf sites will see a round
of light to moderate rain showers or thunderstorms this morning with the
strongest storms staying to the south. A few areas of low stratus
and 3-5sm br will occur this am and may affect the taf sites. More
numerous thunderstorms are then expected for this afternoon and tonight as a
warm front lifts north into southern WI. 2-3 rounds of thunderstorms are
possible. Ceilings of cumulus clouds will range from 3.5-5.0 kft but
with much lowers ceilings and visibilities within thunderstorms. Once the majority of
the thunderstorms have ended late tonight...the moist conditions will likely
lead to some fog development.



&&

Mkx watches/warnings/advisories...
WI...none.
Lm...none.
&&

$$

Today/tonight and aviation...gehring
Friday through Wednesday...ddv

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