Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 222316
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
616 PM CDT Sun Oct 22 2017

.SHORT TERM...(Tonight through Wednesday)
Issued at 255 PM CDT Sun Oct 22 2017

Quiet weather today across the area. Subjective 12Z upper-air
analysis indicates an upper-level trough extending through the
Plains from near the Dakotas-MN border to eastern NE/central
KS/central OK. A shortwave was noted in southern BC/AB. A 150kt
upper-level jet extended into northern WA. A low at 850mb was
centered in northern MB, with front extending through WI/IL-IA
border through MO and into AR. Moisture was shunted ahead of that
front, with a ribbon of 8C+ dewpoints from TX/LA through MI, and a
cool pocket behind the front had brought single digit 850mb
temperatures into the central/northern Plains to upper Midwest.
Surface high at 19Z was located in western OK to southwest TX, with
ridge axis through eastern KS to western IA to central MN. A surface
low was noted upstream in southern SK.

Main forecast concern in the short term is wind potential on Monday.
As the upper-level shortwave in western Canada moves across the
northern Plains to upper Midwest. it will draw a cold front through
the central US, along with a tightening pressure gradient. Strong
winds from the mid-levels downward are indicated from morning
through around sunset. Core of the troposphere fold is progged to
descend from the Dakotas through northeast NE/western IA during peak
heating and mixing, which should optimize the wind gusts. Have high
confidence in reaching wind advisory criteria for at least areas
north of I-80, with moderate confidence south of there. In
coordination with neighboring offices (and keeping in mind that
offices to our west do not issue wind advisories), will include the
entire CWA in an advisory on Monday.  Latest information indicates
grassland fuels are still rather green, with wet surface conditions;
only the dried fields are really brown right now. Fire risk is
higher tomorrow because of the wind and the 25-35% RH, but because
it is limited to farm fields with harvest activity that could spark
fires, will mention the risk as a part of the wind advisory
information and opt to not issue fire weather headlines.

Winds will remain somewhat gusty out of the north to northwest on
Tuesday as tight mid-level to surface gradient persists, though it
should weaken through the afternoon. 850mb temperatures take a dip
to the low single digits on Tuesday, and thus have kept highs in the
50s despite quality mixing. Winds turn more westerly on Wednesday,
allowing some warm-air advection and a bump in surface temperatures
as dry northwesterly upper-level flow continues.

.LONG TERM...(Wednesday night through Sunday)
Issued at 255 PM CDT Sun Oct 22 2017

An upper-level trough, deepening to a low, will descend into the
central US on Thursday-Friday. With this low, a significant cold
push will plow into the central US, bringing sub-0C 850mb
temperatures to a wide swath of the central US. Frontal passage on
Thursday actually looks dry for our area, with more coherent precip
signature closer to the mid-level low in the northern Plains and
also closer to better moisture in the southern Plains. Have bumped
up winds on Thursday behind the front, given strong cold air
advection. If precipitation did brush the area on Thursday
night/Friday morning (which is no longer in our forecast, per
coordination with neighboring offices), there is a good chance that
it could at least mix with something frozen. For now, those chances
are very low and mainly on the fringes of the forecast area, with
even lower chance of anything that accumulates or sticks - so don`t
hit the panic buttons just yet.

That said, temperatures on Friday morning are likely to be near or
below freezing, though winds should keep temperatures from bottoming
out. Highs on Friday will reluctantly recover only into the 40s as
coldest air is overhead. With clearing skies and lighter winds on
Friday night, temperatures may plunge pretty far on Saturday
morning, with current lows forecast in the 20s everywhere and even
in the lower 20s in northeast NE. That would be a killing freeze for
sure and would finish off whatever is left of the growing season.
Temperature recovery may only be a little better on Saturday as the
tail end of cold air lingers, with highs maybe approaching the 50s.
Subfreezing temperatures are possible again on Sunday morning as the
cool airmass lingers, though some moderation should begin around
Sunday as the upper low moves eastward and 500mb heights rise, with
surface to mid-level winds returning to the west/southwest and
providing warm air advection.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 615 PM CDT Sun Oct 22 2017

A surface cold front currently moving out of the northern Rockies
will push through the TAF sites between 09z and 11z on Monday
with southwest winds veering to northwest. Strong tropospheric
flow within the post-frontal environment will translate to
intensifying surface winds on Monday with gusts approaching 40 kt
at the peak of the diurnal heating cycle. Mid and high-level
cloudiness will increase overnight with potential for boundary-
layer-based stratocumulus (FL040) on Monday afternoon.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Wind Advisory from 10 AM to 7 PM CDT Monday for NEZ011-012-
     015>018-030>034-042>045-050>053-065>068-078-088>093.

IA...Wind Advisory from 10 AM to 7 PM CDT Monday for IAZ043-055-056-
     069-079-080-090-091.

&&

$$

SHORT TERM...Mayes
LONG TERM...Mayes
AVIATION...Mead


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