Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 01/23/20
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
908 PM CST Wed Jan 22 2020
Issued at 908 PM CST Wed Jan 22 2020
Dense fog is moving westward, especially in North Central Kansas
over the past hour or so. Most model guidance indicates that the
surface trough will continue to slide eastward moving the fog
potential to the east as well, so am forgoing a Dense Fog Advisory
at this time. Will continue to monitor though and an Advisory may
be needed if things do not improve.
.SHORT TERM...(This evening through Thursday)
Issued at 338 PM CST Wed Jan 22 2020
Aloft: Aircraft winds/RAP tropopause analyses and WV imagery
indicated fairly low-amplitude flow over the CONUS. The wk shrtwv
trof that brought the precip was over IA/MO and moving away. A
more potent shrtwv trof extended from AB-MT-WY. This trof will
dig/deepen over the the Cntrl Plns tonight with a low forming over
Ern KS tomorrow. Overall the CWA will remain in an upr trof thru
Surface: 1030 mb high pres was over the Ern USA with return flow
over the Plns. A sfc trof extended from Nrn MN acrs Wrn NEB to W
TX. This trof was moving E and it will cross the CWA the rest of
this afternoon and early eve. Wk low pres will form within this
trof tonight...over Wrn IA. Meanwhile...a wk cool front stretched
from SD-NV. This front will move thru this evening. The low will
then sink into MO tomorrow. Canadian high pres will then begin
nosing into NEB/KS tomorrow afternoon.
Rest of this afternoon: Satellite shows clearing line is heading
E as warmer/drier air moves in from the NW. It is highly uncertain
how far E this line gets before sunset. It is highly doubtful it
clears the entire CWA...despite the trof contg to move E. Once
sunset occurs...E progression of the stratus/fog should cease and
it will probably begin moving W again.
Tonight: Any areas that aren`t already cldy (W of Hwy 183) will
become cldy. We may not lose the fog from the daytime hrs...and it`s
likely that it will expand during the evening. Just not sure how far
W. Dwpt depressions have dropped off nicely at LXN/BBW...but that
will not occur where stratus remains. Fog
coverage/intensity/location is low confidence.
The area of light reflectivity on radar over SD will move SE and
cross the CWA mainly as light snow. It could mix with or begin as
light rain at the onset until wetbulb cooling lowers the warm nose
aloft to 32F. Current expectation is that there should be about
1" of accum by sunrise.
Coord with LBF and OAX to issue a Winter Wx Advisory.
Temps will remain up tonight (mainly holding steady a little
Thu: Light snow will be on-going at sunrise and cont thru the
morning...mainly E of Hwy 183. There is significant uncertainty
with when the precip will end. The NAM and its nest as well as the
NMM indicates light precip will cont well into the afternoon
while the RAP/GFS bring it rapidly to an end. Don`t have a good
feel for which scenario is right. If precip does linger past
midday...it will probably mix with or change to rain...espcly S of
I-80. Little or no additional accum is expected though.
Snow: 2-3" in the advisory area (E of Loup City-Hastings-Nelson
with the best chance for 3" from GRI-OLU. W of that line a dusting
up to 1 inch or so.
Temps: Near normal.
Winds will not be a big deal until 12 PM. Thereafter...winds will
incrs with gusts 30-35 mph at times. This should be a wet snow. So
blowing/drifting will not be a significant concern.
.LONG TERM...(Thursday night through Wednesday)
Issued at 338 PM CST Wed Jan 22 2020
Aloft: The last 2 runs of global mdls indicate low-amplitude flow
will cont thru Mon. NW flow will cont over NEB/KS. A wk shrtwv
trof is fcst to move thru Sat night into Sun AM with little
consequence. A shrtwv ridge will arrive Mon...ahead of a trof that
the mdls have been fcstg to move from the Wrn USA into the
Cntrl/Srn Plns Tue-Wed. There are substantial diffs with how the
EC and GFS runs have been handling this system. How it shakes out
will affect how much of an impact it has on the rgn.
Surface: Fri high pres will drift acrs the rgn. A wk sfc trof
will follow Sat. A warm front is then fcst to form and cross the
CWA Sun night. A wk cold front is then fcst to arrive and move
thru Tue while low pres organizes over the Srn Plns (probably OK).
Temps: Near normal Fri-Sat. Then warmer than normal Sun-Mon. Back
to near normal Tue-Wed.
Precip: The next wx-maker of significance will arrive next Tue-
Wed. With a lack of substantially cold air around...this system
too will probably feature a wintry mix. Marginally cold enough
will be wrapping into this system as precip is falling.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 542 PM CST Wed Jan 22 2020
The dense fog that moved through the terminals is moving off to
the east with clear skies at KEAR for a brief period of time.
IFR ceilings at KGRI is expected to improve at KGRI before
decreasing again this evening. Ceilings are also expected to
become IFR at KEAR as the next system moves in tonight. Snow is
expected to develop between 03-06z and impacting KGRI more than
KEAR. Snow is expected to persist into the morning hours before
diminishing. IFR to LIFR ceilings are expected into the morning
hours, improving to MVFR to VFR later in the day Thursday.
NE...Winter Weather Advisory until 6 PM CST Thursday for NEZ039>041-