Area Forecast Discussion
Issued by NWS Hastings, NE

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930
FXUS63 KGID 221356
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
856 AM CDT THU SEP 22 2016

.UPDATE...
Issued at 855 AM CDT Thu Sep 22 2016

A few comments/updates regarding the rest of today:

Normally hate to make many forecast changes so early in a shift,
but the bank of low stratus currently approaching the WFO from the
northwest as evident out our north window has already necessitated
some modest adjustments. Briefly getting into over these:

1) As of this writing, the leading edge of a solid blanket of low
stratus extends roughly along a Fullerton-Hastings-Alma-Norton KS
line, and continues making very slow progress to the south and
east. Although most areas under this stratus are experiencing
light fog (visibility generally 2-3 miles or greater), a narrow
corridor of thicker fog and even dense fog extends a short
distance behind the leading edge (as evidenced by 1/4 mile ob at
KGRI). As a result, have beefed up morning fog wording a bit from
"patchy" to "areas with less than 1 mile visibility" behind the
advancing stratus. Any truly "impactful" fog is not expected to
last much beyond 10-11 AM or so.

2) Going forward, the million dollar question today largely
surrounds what this stratus deck does. Based on the latest RAP13
low level RH progs, it is not expected to advance more than
roughly another 20 miles, before stalling out and likely
retreating back northward/eroding somewhat during the afternoon.
Of course, the exact position of its southern edge will be tough
to predict more than 1-2 hours in advance. That being said, far
northern parts of the CWA seem to stand an increasing chance of
staying "socked in" for much of, if not the entire day.

3) Obviously the aforementioned "stratus problem" for today
greatly affects the sky cover and resultant high temperature
forecast, and if anything makes it more difficult than it already
looked before. Did not make "major" changes, but did feel
compelled to knock down much of the northern 1/2 or so of the CWA
a few degrees, now aiming for a healthy gradient from only 70s
far north (places such as Ord), low-mid 80s central (including Tri
Cities) and still upper 80s to low 90s along and especially south
of the state line. Stay tuned for more fine tuning as the day
wears on...

&&

.SHORT TERM...(Today and tonight)
Issued at 320 AM CDT Thu Sep 22 2016

Showers and thunderstorms developed over the northeast part of the
forecast area early this morning. At this time, they have moved out
of the forecast area. Surface analysis shows a nearly stationary
front across the northwest part of the forecast area.

An upper level wave moving through the area early this morning will
push to the northeast today. The boundary across the northwest is
forecast to sag to the south during the day today. First concern for
the day is how much precipitation will be lingering into the morning
hours. With most of the precipitation out of the area already this
morning the first thought is none, but there is a weak wave still
moving into the area during the morning hours. A couple of the
models bring a little precipitation into the area as the wave moves
through. Have kept some low PoPs in the east during the morning. The
next concern is how far south will the front sag. This will affect
the temperatures across the north. Have cooled temperatures a little
this afternoon in the far north.

Tonight the boundary that sags south, moves back to the north. There
is an upper level ridge that drifts to the east over the area. A few
of the models develop some precipitation across the north near the
front as it is moving to the north. The ridge keeps the energy to
the north of the area. Will have to watch to see if anything
develops along the front before it gets out of the area. The front
moving north will allow for warm temperatures again tonight.

.LONG TERM...(Friday through Wednesday)
Issued at 403 AM CDT Thu Sep 22 2016

A ridge of high pressure will build across the Mississippi river
valley as a trough of low pressure deepens across the intermountain
west. This will result in a generally west southwesterly flow aloft
across the local area...with continued above normal temperatures to
start the extended periods.

Expect the aforementioned upper level low to lift northeast over the
ridge over the upcoming weekend...shifting the ridge further east by
Saturday afternoon...as a cold front moves across the local area.
While the trajectory of this low is less favorable for rainfall than
a few days ago...there will be plenty of instability in the
atmosphere to tap...so if some storms are able to develop along the
passing cold front...expect the possibility for a few of these
storms to become marginally severe...with quarter size hail and 60
mph wind gusts being the primary concerns. While only a very small
portion of the local area is highlighted in a marginal risk for
severe weather over the time period...opted to introduce a mention
for severe thunderstorms to the HWO for all areas over this time
period...as there will be plenty of instability to work with along
with marginal 0-6 KM shear values.

Once the aforementioned front crosses the local area Saturday...
expect a return to more seasonal temperatures...with many locations
not climbing out of the upper 60s on Sunday. In addition...available
instability will decrease significantly behind this front...and
while several small chances for precipitation exist through the
extended periods...opted to keep out the mention of thunder.

Temperature wise...expect these near to slightly below normal
temperatures to persist across the local area for much of the work
week, with a slight warning trend expected towards the later half of
next week.

&&

.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Friday morning)
Issued at 610 AM CDT Thu Sep 22 2016

Low clouds and some patchy fog are moving toward the terminals
this morning. Have LIFR ceilings for a time this morning. Not
completely sure how long it will last, so have a few hours. As the
sun comes up this morning it should push the lower clouds out of
the area.


&&

.GID Watches/Warnings/Advisories...
NE...None.
KS...None.
&&

$$

UPDATE...Pfannkuch
SHORT TERM...JCB
LONG TERM...Rossi
AVIATION...JCB



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