Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/08/19

Area Forecast Discussion

National Weather Service Hastings NE

 640 PM CDT Mon Oct 7 2019

...Aviation Update...

.SHORT TERM...(This evening through Tuesday)
Issued at 222 PM CDT Mon Oct 7 2019

Aloft: Low-amplitude NW flow was over NEB/KS at 19Z per RAP
tropopause analyses and aircraft wind data. A trof extended from
Ern Can to TX. A modest shrtwv rdg extended from Cntrl Can to
UT/CO. A small/weak shrtwv trof was along the CA/NV border. The
shrtwv rdg will crest over the Cntrl Plns tonight while the CA/NV
trof conts moving E. The flow over the CONUS will remain low-
amplitude thru tomorrow with winds shifting to WSW over NEB/KS.
The small/weak trof will cross CO tomorrow and will be moving into
NEB/KS by 00Z.

Surface: 1026 mb high pres was over KS/OK. Widespread downslope
flow was occurring to its N to the lee of the Rckys. The high will
head into the GtLks tonight and New Eng tomorrow. Downslope/
return flow will cont over NEB/KS thru then. Meanwhile...an
unseasonably strong cold front will sink out of SW Canada into the
Pac NW.

Tonight: Mostly clr. Not as cold as winds will remain up. Lows in
the 40s.

Tue: Sunny and very comfortable...but brzy. S winds will gust
25-35 mph. Near normal temps with highs low-mid 70s. Incrsg
cirroform clds in the afternoon ahead of the aprchg trof.

.LONG TERM...(Tuesday night through Monday)
Issued at 222 PM CDT Mon Oct 7 2019

Aloft: An unusually deep trof (-2 SD) was over Wrn Can. The flow
over the CONUS will become highly-amplified this wk as this trof
sinks into the Wrn USA and deepens...along with a shortening
wavelength. The flow will become SW over NEB/KS Wed-Thu as the
trof gradually drifts E. Most mdl runs and the EC ensemble mean
suggest a low will form within the trof and intensify as it heads
NE acrs the Dakota`s Fri. The -2.5 SD trof will cross the CWA in
its wake Fri with cyclonic NW flow cont into Sat as the low slows
over MN. Mdl spread increases Sun-Mon...but it appears cyclonic NW
flow will remain over the CWA Sat-Sun. There will probably be a
wk shrtwv trof moving thru the Wrn USA...with a modest rdg
preceding it. Not sure how this will play out for next Mon.

Surface: With the incrsg amplitude/shortening wavelength of the
upr trof...the strong cold front is now fcst to cross the CWA
Thu... slower than expected earlier. So the CWA will remain in the
warm sector thru Wed night. Strong 1036 mb high pres over the Nrn
Rckys will begin bldg in behind the front Thu. Deepening low pres
will move up the front and occlude over the Nrn Plns Fri. Mdl
diffs dvlp Sat. The Wrn USA high will probably emerge into the Srn
Plns...but will the thermal trof lift out and return flow dvlp?
Or will the large circulation with the departed (and probably cut-
off) low still influence the wx here? Too soon to determine.

Temps: Wed the NAM/GFS suggest low stratus could dvlp around
sunrise and linger thru much of the day for portions of the CWA.
This will suppress temps if it doesn`t break apart. So parts of
the CWA may not be as warm as we`ve indicated. Temps should
average near normal. Thu highs will occur at midnight. Temps will
fall...espcly in the AM...then hold steady or fall slowly in the
afternoon. Fri unseasonably cold. Much of S-cntrl NEB will only
reach the 30s! Sat some recovery into the 40s/50s...but still much
chillier than normal. Sun-Mon are uncertain. Probably still
cooler than normal.

Confidence is high that widespread/killing freezes will occur Fri
and Sat mornings. Lows in the 20s to low 30s expected. A Freeze
Watch/Warning will be required.

It is psbl Valley/Greeley counties may see 4 consecutive mornings
with subfrzg temps Fri-Mon! See 00Z and 12Z MEX guidance.

Precip: There is a slgt chance a cpl shwrs or tstms could skirt
the far SE fringe of the CWA toward dawn Wed thru mid-morning.
Most of the activity should remain over Cntrl/Ern KS. A few more
isolated shwrs/tstms are psbl Wed night into Thu AM along and
ahead of the cold front. Believe our POPs are too high over
S-cntrl NEB (60-70% N of I-80). Would feel more comfortable with
30-40%.

There could be a little light rain Thu night into Fri AM as the
potent upr trof moves thru. Temp profiles will gradually become
cold enough from NW-SE to change the rain over to wet snow...if
precip is occurring. Not all areas will see rain/snow. The mdl
consensus is unanimous that the upr low will track W of the CWA.
That means little or no snow accum.

Wind: As is typical for these situations...N winds will be
howling 20-30 mph Thu and Fri...with gusts of 35-45 mph.

Will issue a SPS to raise awareness of the upcoming end to the
growing season.

&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 628 PM CDT Mon Oct 7 2019

VFR conditions are expected with dry weather throughout the TAF
valid period. The primary aviation concern centers around strong
low level wind shear primarily after midnight through around 10 AM
CDT Tuesday.

&&

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

$$

SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Wesely