Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

000
FXUS63 KOAX 271725
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1125 AM CST Sun Nov 27 2016

.SHORT TERM...(today through Tuesday)
Issued at 309 AM CST Sun Nov 27 2016

Increasing chances for showers and thunderstorms today, then colder
temperatures by Tuesday, are the primary forecast concerns.

Mainly clear skies and light winds earlier tonight allowed
temperatures to dip into the 20s and lower 30s for much of northern
parts of our area during the evening. Increasing mid and high level
clouds pushing in from the southwest ahead of our next system was
putting a halt to falling temperatures this morning, with south
winds beginning to pick up to our south and west.

Cloud cover moving overhead was in response to diffluent mid level
flow pattern in the Plains, ahead of upper trough pushing toward the
Rockies. Strong 150+kt upper level jet segment was rounding base of
trough in northern Arizona, and will punch northeast helping to
close off upper low in Wyoming by mid day. Meanwhile mid level jet
is expected to approach southeast Nebraska this afternoon, enhancing
lift across most of eastern Nebraska and southwest Iowa into
tonight. Strong flow and diffluent flow suggests strong isentropic
upglide will result in potent lift and moistening in our area this
afternoon. Low level moisture is scant now, and surface dew points
are only forecast to approach 50F this afternoon and evening. Thus
forecast soundings showing limited CAPE values less than 500 j/kg
are believable. However, strong and veering flow in lower half of
the atmosphere will result in strong shear near 50kt. So while
convection will likely be limited, an isolated strong thunderstorm
is possible if convection can get going.

Onset of precipitation has slowed down a bit from previous forecasts
with slightly delayed arrival of lift/moisture. Much of the morning
should remain dry for much of our area with showers expected to move
into our western areas by late morning before spreading quickly
northeast across the rest of eastern Nebraska and southwest Iowa
during the afternoon. Jet segment rotating around upper low moving
into central South Dakota by midnight will knife through our CWA
by or shortly after midnight, taking most of the precipitation
with it.

Beyond tonight, chances for precipitation will be generally low
and focused over northeast Nebraska where mid level impulses
rotating around upper low meandering in the Northern Plains will
skirt that area from time to time through Tuesday. Will maintain
slight chances for rain or snow there with phase dependent on
temperature profile at time of occurrence. Any snow accumulations
should remain light.

Temperatures this afternoon should reach the 50s all areas with
strong southerly winds pumping warmer temperatures north despite
thickening clouds and increasing precipitation chances. Cool
advection begins Monday, but won`t really kick in until Monday
night. So with more sunshine Monday, expect highs will top 50
again most areas with northeast Nebraska remaining cooler. Much
cooler airmass will be in place for Tuesday when highs remain in
the upper 30s north to the 40s south.

.LONG TERM...(Tuesday night through Saturday)
Issued at 309 AM CST Sun Nov 27 2016

Colder temperatures will be the main weather story for the rest of
the work week into the weekend. Upper low in the Northern Plains to
begin the longer term period will drift east into the Great Lakes
region by Thursday. Models may not agree exactly with the speed of
that departure, but all suggest the middle of the country will
remain under broad mid level trough regime, keeping colder surface
airmass in place all week. Airmass will be characterized by 850
temperatures in the 5-10C below range through the period, suggesting
high temperatures in the 30s will be common Wednesday through
Saturday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1124 AM CST Sun Nov 27 2016

MVFR conditions early in the period, but becoming VFR by 01-03z.
Scattered showers will affect all TAF sites through about 00-02z.
Thunderstorms could affect KLNK/KOFK 23-02z. Southeast winds at 12
to 23 knots, becoming less than 12 knots from the southwest by
03-07z.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...DeWald



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.