Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 222311
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
611 PM CDT Fri Sep 22 2017

.SHORT TERM...(Tonight through Monday)
Issued at 310 PM CDT Fri Sep 22 2017

Precipitation chances, precipitation amounts and temperatures are
the main forecast concerns.

Water vapor satellite imagery in combination with recent RUC model
analysis showed a closed mid tropospheric low near the OR/ID/NV
border area, which was part of a large trough that stretched from
western Canada. A ridge extended from the eastern Great Lakes
region down into northern Mexico. 12 hour height falls at 500 mb
this morning were highest (around 60 meters) over northern AZ.
Winds at 300 mb were strongest (100 knots or higher) from northern
Baja CA up into WY. Thermal ridge at 700 mb (with temps as warm as
12 or 13 degrees C) extended from west TX into western and central
SD. A ribbon of higher 850 mb moisture, with winds at that level
mainly from 30 to 50 knots) was located just east of the mid
level thermal ridge. At the surface, a cold front extended from
low pressure over northeast SD down into southwest NE and
northeast CO. Temperatures east of the front in our area at 3 pm
were in the lower and mid 90s.

Tonight, will maintain some 20-30 percent chance of thunderstorms
in about the northwest half of northeast NE. There is a
conditional threat for severe storms, with damaging winds and
large hail. Chances are a bit higher prior to midnight. Southerly
flow across the area tonight should hold temperatures up, with low
expected to be mainly upper 60s and lower 70s. A few spots may
only drop to the mid 70s.

Frontal boundary will be nearly stationary near our northwest CWA
from Saturday through Saturday night, generally stretching from
southeast SD to southwest NE in that period. The chance for
showers and storms will be highest along and northwest of that
front. Temperatures ahead of the front should remain well above
normal, and went a bit higher than MOS for Saturday afternoon. For
Sunday, went mainly with highs of 85 to 90 ahead of the front and
70s behind the front. Precipitation should become likely Sunday in
the northwest part of northeast NE, then chances increase for the
rest of the area as the front slides to the southeast through
Monday. Expect at least some areas of locally heavy rain, but with
below normal rainfall recently, expect that if any flooding would
develop that it would be minor (at least for now).

Monday will be quite cool in northeast NE, with highs in the upper
50s to lower 60s, but ranging to 70s and lower 80s for the rest of
the area.

.LONG TERM...(Monday night through Friday)
Issued at 245 PM CDT Fri Sep 22 2017

The chance for showers and thunderstorms will remain high for
Monday night, but decrease on Tuesday from northwest to southeast.
That is based on current model timing, which could change.

At the start of this period, models are in good agreement that a
positively tilted trough at 500 mb should extend from Manitoba to
AZ. The northern end of that trough will trough to lift off to the
northeast, while a closed low forms back toward AZ Wednesday and a
ridge builds east from British Columbia. Right now, we will have a
mainly dry forecast from Tuesday night into Thursday, then carry
a low chance for showers around Thursday night.

Temperatures will start out below normal Tuesday, but moderate
back closer to normal by Thursday and Friday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 608 PM CDT Fri Sep 22 2017

VFR conditions are forecast through Saturday afternoon with mainly
scattered to broken mid and high level clouds. There is a small
chance thunderstorms could reach KOFK area before 06Z, then again
after 18Z, as storms continue to fire along a cold front that will
remain west of the TAF site. Otherwise strong southerly winds will
continue through 08Z, then increase again after 17Z, with speeds
averaging 15 to 25kt. Low level wind shear is also likely near
KOFK through the evening.

&&

.CLIMATE...
Issued at 616 AM CDT Fri Sep 22 2017

The records for today and Saturday are:

          Warm Max   Warm Min   Warm Max   Warm Min
          9/22       9/22       9/23       9/23

Omaha     99 (1937)  73 (2016)  96 (1892)  72 (1892)

Lincoln   99 (1937)  75 (1937)  97 (1921)  72 (1930,
                                               1892)

Norfolk   96 (1940)  67 (2016,  92 (1921)  69 (1958,
                         1937)                 1937)

&&

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

$$

SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Dergan


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