Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 231752
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1252 PM CDT Thu Mar 23 2017

.SHORT TERM...(Today and tonight)
Issued at 347 AM CDT Thu Mar 23 2017

Quiet conditions are in place across the area early this morning,
with cloudy skies. Upper air and satellite data showing more
southwesterly flow developing across the region, set up between a
ridge axis departing to the east and a low pressure system moving
across the CA/NV/AZ border area. At the surface, southerly winds
continue, with the region sitting between high pressure centered
over the Great Lakes and low pressure along the High Plains. Speeds
have generally been in the 10-15 MPH range, with an occasional
higher gust.

Through the rest of the early morning period and into the first
half of the day, hi-res models continue to show the potential
for scattered shower development across the area with warm
air/moisture advection driven by the increased LLJ. Some
difference with just how much there would be, kept the PoPs on the
low side. Models are also showing the continued northward
advection of an area of low level stratus this morning, with its
evolution through the rest of the day making for some forecast
headaches.

This afternoon, expecting there to be a bit of a lull in precip
between anything that develops this morning and the next chance
later in the afternoon. Confidence in the temperature forecast is
not high, especially thanks to models like the NAM, which hang
onto this lower level stratus a lot longer than other models.
Forecast highs reach the lower 80s in southwestern portions of the
CWA, but if the models which show that stratus being less of an
issue into the mid/late afternoon are right, temps like that are
going to reach further east than what is currently in the grids.

Through the day/evening hours, the main upper level system
continues pushing east through the four corners region, with
increasing larger scale lift out ahead across the Plains. At the
surface, low pressure deepens near the CO/KS border, with a
dryline developing over wrn KS/swrn NE and cold front pushing into
nwrn NE. While some isolated activity is not out of the question
during the late afternoon hours, the better chances for
thunderstorms comes after 00Z, with storms moving in from the
southwest. Deep layer shear/instability values keep strong/severe
thunderstorms a concern, and the western 2/3rds of the CWA is
included in the SPC Day 1 slight risk area. Large hail/damaging
winds would be the primary hazards.

Once that initial wave of thunderstorms pushes east/tapers off,
the main precipitation chances through the overnight hours focus
to the northwestern portions of the CWA. The main upper level low
pressure system continues its eastward push, by 12Z ending up
near the southern CO/KS border. The better frontogenetical forcing
lies across NErn CO up through SErn SD, clipping our northwest. A
bit of instability lingers, so kept an isolated mention of
thunder going after 06Z.

.LONG TERM...(Friday through Wednesday)
Issued at 347 AM CDT Thu Mar 23 2017

Overall models are in decent agreement with a stacked low pressure
system tracking along the KS and Oklahoma border Friday/Friday
night, with the NAM on its own trending a little farther north
with the track. The initial round of warm air advection
precipitation is expected to move east of our area early Friday
morning, with the dry slot of the system nosing north near I80 mid
morning and shifting east in the afternoon. The cold frontal
boundary aligns across our northwest cwa through the morning, then
slowly pushes southeast Friday afternoon/evening as the system
tracks east. This deformation/frontal zone will be the focus for a
swath of precipitation near or along our western zones during the
day on Friday, which generally speaking should predominantly fall
as rain given the forecasted high temperature in the 40s in our
northwest areas. This being said, the NAM is the most aggressive
with cold air and strong mid level frontogenesis is progged along
our northwest zones and NAM thermal profiles suggest the potential
for a brief mix or transition to sleet/snow before ending (and
potential for half inch of sleet/snow). Since the NAM does not
have support from other models, have kept this a rain event.
Instability remains present Friday/Friday evening and a
differential heating boundary and the front may focus convection
and have kept thunder in the forecast.

The precipitation looks to wind down pretty quickly by midnight
Friday night but left a lingering small chance for wraparound
precipitation in our eastern areas overnight. Not real excited
about pops lingering into Saturday morning, but they are in there
in case system slows any.

Saturday dries out quickly behind the departing upper low, with
height rises and shortwave ridging in between systems. Flow
transitions southwest Saturday night ahead of another upper low
pressure system emerging from the south central Rockies. This
system is progged to track across Kansas, bringing good chances
for rain for our southern zones Sunday evening and night.

In a similar regime, the forecast dries out again for the first
part of next week, then in a progressive pattern precipitation
chances return for the middle of the week. Extended models are not
in agreement on the track of the this system a week from now and
did not deviate from ensembles at this point.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Friday afternoon)
Issued at 1252 PM CDT Thu Mar 23 2017

Difficult aviation forecast with multiple rounds of precipitation
possible as well as low ceilings/visibilities that will impact
flight conditions. This morning drizzle and light rain was fairly
widespread causing IFR to LIFR conditions across the area. As of
this issuance, scattered thunderstorms are moving northeast across
the area and may impact the terminals...but currently am thinking
they will remain away, so have left them out of the forecast, so
will need an amendment if they do continue to track that way. This
evening, really think the majority of the precipitation and
thunderstorms will remain west of the area until 4-6z. Then
another lull until towards morning.

Another couple of challenges include, ceilings and low level wind
shear.  Ceilings are expected to improve over the next few hours
and then deteriorate again as the cold front moves in towards
morning. Low level wind shear will be a concern after 00z tonight
and has been included at both terminals between 03-09z.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&

$$

SHORT TERM...ADP
LONG TERM...Fay
AVIATION...Billings Wright


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