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Area forecast discussion 
National Weather Service La Crosse WI
308 PM CDT Friday Aug 22 2014

Short term...(tonight through Saturday night)
issued at 308 PM CDT Friday Aug 22 2014

Low clouds hanging tough across the area as lower level boundary
layer moisture on the increase. Surface dew points early this
afternoon were in the Lower/Middle 70s...pretty sticky. Surface map
depicting an area of low pressure located over north central
Wisconsin with a boundary laid up from the low through La Crosse
into northeast Iowa. Meanwhile...surface cyclogenesis taking place
over western Kansas with a warm front extending through northern Kansas into
northern MO and central Illinois.

For tonight...main shower/thunderstorm action will take place along
the warm front to our south as low level jet impinges on it. There
could be a few showers and storms as well along the frontal boundary
in place across our south but moisture transport is lacking. As
such...will keep a slight shower/thunderstorm chance in across
portions of northeast Iowa/far southwest WI. With weak pressure
gradient to drive surface winds tonight and abundant low level
moisture...expect areas of fog to form overnight. Not confident at
this point whether reduction in visibility will be low enough for a
headline. Will have to monitor this as the evening progresses.

Attention then turns to the warm front which will start making a
northward push into the area Saturday/Saturday night. Models in good
agreement in keeping best axis of moisture transport west of the
area into western Iowa/Minnesota and eastern Dakotas as the surface low lifts
northward from the central into the northern plains. Will still be
watching for a slight severe threat Saturday afternoon into Saturday
evening as the NAM is producing some elevated MUCAPE in the 2500-
4000j/kg range. 0-3km bulk shear rather weak in the 10-20 knots expecting pulse-type nature to thunderstorm activity.
Heavier rainfall potential will also have to be watched with
precipitable water values in the 1.5-2 inch range. After 06z
Sunday...looking for convection to get pulled north/westward out of
the area as the warm front progresses out of the area.

Otherwise...getting increasingly steamy going into Saturday mainly
south of I-94 with highs topping off in the Lower/Middle 80s and dew
points in the 70s. Plan on heat indices by later in the afternoon in
the 90-95 degree range.

Long term...(sunday through friday)
issued at 308 PM CDT Friday Aug 22 2014

Hot and humid day on tap for Sunday with the area entrenched in
strongly capped warm sector. NAM very consistent indicating 26-30c
925mb air getting pulled northward into the area...with the hottest
axis of this air along/west of the Mississippi River. Plan on highs
ranging from the 85-90 degree range across central
the lower 90s along and west of the Mississippi River. These
temperatures combined with dew points in the 70s expected to produce
heat indices in the 90s to around 100 degrees. A heat advisory may
be needed for portions of the area Sunday and will continue to be

A cold front will then push into the area Sunday night for a good
chance of showers and thunderstorms. Models in good agreement in
this boundary will lay up across the area through Thursday for
continued showers and thunderstorm chances...with highest likelihood
Tuesday into Wednesday. Will have to keep a close eye on heavy rain
potential in this scenario given precipitable waters in the 1.5-2 inch
range along with upper jet dynamics. Otherwise...looking like
temperatures will be dependent on cloud cover and rain coverage. So
far...looking like highs in the middle 70s to middle 80s on
Monday...cooling into the 70s Tuesday through Thursday.

Looks like some drying Thursday night/Friday as high pressure builds
in from Canada. Highs Friday expected to remain in the 70s.


Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 1232 PM CDT Friday Aug 22 2014

MVFR/local IFR ceilings/visibilities will continue to be a problem across the taf
sites this afternoon into Sat. Plenty of boundary layer moisture
from recent inversion near 900mb and little for winds in
the surface-850mb layer will keep the lower levels across the area quite
moist into Sat. Little change of the lower level airmass will mean
scattered to broken/overcast strato-cumulus clouds will remain across much of the area
through tonight into Sat.

Br/fog was slow to lift/burn off this morning...with some MVFR visibilities
still persisting as of 17z. Lower clouds this afternoon will
suppress high temperatures again...with temperature-dew point spreads on the lower
side going into tonight. With higher boundary layer dew points and
diurnal cooling...more MVFR/IFR br/fog expected again especially
later tonight/early Sat morning in the 08-14z time-frame. Previous
taf cycle already added IFR visibilities in br/fog to both krst/klse in this
time frame. Any br/fog will again be slow to burn off and lingered
MVFR visibilities through the middle/late morning hours.


Arx watches/warnings/advisories...



Short term...das
long term....das

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