Area Forecast Discussion
Issued by NWS Hastings, NE

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863
FXUS63 KGID 302023
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
323 PM CDT MON MAY 30 2016

...Much Quieter and Drier Weather is in the Offing After We Get
Past the Tstm Threat Tonight...

.SHORT TERM...(This evening through Tuesday)
Issued at 323 PM CDT Mon May 30 2016

Aloft: Meteorological summer begins Wed and the 500 mb charts
from 00Z and 12Z show it. The main belt of Westerlies was over the
Nrn USA and it was weak. The strongest jet streak was over the Pac
NW associated with a shortwave trof. A small associated low has
developed along the MT/AB border. This low will advance across the
Dakotas tomorrow with the trof crossing the Cntrl Plains Tue
night.

Surface: As is typical of summer...most sfc features are weak and
poorly defined. Occluded/weak low pres was over Srn Sask with a
subtle warm front from SD-IA. A fairly decent cool front was
making its way thru the Pac NW/Nrn Rockies. Cyclogenesis will
occur over WY/SD today with a well-defined triple pt low taking
over and lifting to near FAR by 12Z/Tue. Meanwhile...the cool
front will surge S and cross the fcst area tonight. Weak high pres
will build in tomorrow.

Now: Svr Tstm Watch #232 is in effect until 10 pm. It will be svrl
hrs before tstms move into the fcst area. So Memorial Day
activities thru early evening should be fine. Suggest everyone
from Beaver City-Lexington-Ord keep an eye to the W after 8 pm.

Observed 12Z soundings show fairly dry air over the region in the
low-lvls...with dwpts in the mid-upr 50s. Combined with mid-lvl
lapse rates around 7.5 C/km and temps around 80F...this has
resulted in MLCAPE around 1500 J/kg. 0-6 km shear is around 25
kts.

Tstm development should be most widespread over the Panhandle/Wrn
Neb and along the CO/KS border before 8 pm. Given the dry sub-
cloud layer...these storms should rapidly form a common cold pool
and accelerate E as one or more lines. While hail up to the size
of 1.5 inches will be possible early...believe the main threat
will be winds of 50-60 mph. This line should cross much if not all
of the fcst area from W-E between 10 pm and 4 am. The back edge
could linger S and E of the Tri-Cities thru dawn...but with
minimal severe threat expected after midnight.

Tomorrow: could see a little tstm activity linger into the morning
hrs...S and E of the Tri-Cities. Otherwise...decreasing clouds and
cooler.


.LONG TERM...(Tuesday night through Monday)
Issued at 323 PM CDT Mon May 30 2016

Aloft: WNW flow Wed-Fri will become NW and the longwaves amplify.
Significant adjustments upstream over the Pac will send heights
rising over the Wrn USA as a +2 standard deviation ridge/high
builds. This ridge is then fcst to deamplify and overtake the
Plains the middle of next week per the EC and N American ensemble
means.

Surface: A stronger cool front will move thru Tue night with high
pres overtaking the region Wed. This high will depart to the E and
S Thu-Fri. The next Pac cool front will be making its way thru Wrn
Canada and the Nrn Rockies. This weak front is fcst to move thru
here Fri night-Sat followed by weak high pres Sun-Mon.

A few daily details...

Tue night: another passage of a cool front. No rain expected.

Wed: Wonderfully pleasant. Low humidity and winds.

Thu: Similar but a little warmer. Close to 80F.

Fri: A little warmer yet as the thermal ridge pokes NE across the
Cntrl Plains ahead of the approaching cool front. The 06Z/12Z GFS
runs were the most aggressive developing scattered tstms while the
00Z/12Z EC suggest maybe a lone tstm or two. The GFS is as much as
10F higher with its dwpts than the EC. There will be a lot of tstm
activity processing Gulf moisture over the Srn/Gulf Coast States.
Therefore...am not buying the GFS runs. The 00Z EC ensemble QPF
probabilities support this thinking with barely a 10% prob for
.10" in the 24 hr period from 7 am Fri - 7 am Sat. So POPs in the
fcst were clipped to only 20%.

Sat-Mon: Looks dry for now and very nice with highs around 80 and
lows 55-59F.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Tuesday)
Issued at 1234 PM CDT Mon May 30 2016

Significant Weather: A period of IFR tstms likely tonight with G45
kts possible.

This afternoon: VFR with sct patches of altocu and cirrostratus at
or above 12K ft. Winds will be vrbl between SE-SW 8-12 kts. A gust
up to 20 possible...but should not be persistent enough to include
in the TAFs. Confidence: High

Tonight: VFR to start...but a period of tstms with IFR VSBYs
appears likely as a cool front crosses the terminals. The exact
timing of its passage will be masked by a wind shift to NW as the
storms move in. G45 kts possible. Confidence: Medium

Tue thru 18Z: Multi-layered VFR clouds likely in the morning
behind departing tstms. Decreasing clouds thru the morning. NW
winds 10 kts or less shift to N-NNE. Confidence: Medium

&&

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

$$

SHORT TERM...Halblaub
LONG TERM...Halblaub
AVIATION...Halblaub



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