Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 231131

Area Forecast Discussion
National Weather Service Hastings NE
631 AM CDT Fri Mar 23 2018

...Marginal Risk for a Couple Low-End Svr Tstms This Evening...

.SHORT TERM...(Today and tonight)
Issued at 416 AM CDT Fri Mar 23 2018

Hazardous Weather Potential: Marginal risk for low-end svr hail
5-9 PM.

Aloft: A high-amplitude ridge was over the Plns at 09Z with a
longwave trof along the W coast. An embedded shortwave trof was
over CA/NV. The ridge will shift E today as large-scale height
falls cont to progress into the Nrn/Cntrl Plns. The shortwave trof
will be on our doorstep by 00Z and cross the CWA tonight.

Surface: A quasi-stationary front extended from MO to the KS/Neb
border then NW to low pres over WY. A Pac cool front was pressing
E thru the Wrn USA. Low pres will form over CO today and emerge
into Wrn KS by 00Z. The fronts will join the low as it heads E
across KS and into Wrn MO tonight.

Now thru sunrise: cldy with sct sprinkles.

Today: Highly variable depending on which side of the front
you`re on. Skies should be pretty cldy except the SW fringe of the
CWA...especially S of the front. Some sprinkles could fall from
the mid-lvl clds.

A major concern is the last 2 runs of the NAM/GFS fcstg low
stratus to surge N into the CWA. Am concerned that this is
overdone because there is very little of it in the obs over the
Srn Plns.

Because of cld cover uncertainty and the presence of the front...
temps are very low confidence. There will be a large gradient
across the CWA due to differing amts of cld cover. It could be
substantially warmer than we are indicating. Highest confidence is
over N-cntrl KS where we are fcstg the warmest day of the year
thus far (mid 80s).

Around 21Z CAMs/HREF are indicating that sct tstms will develop
over NE CO and SW Neb. These tstms should congeal and cross parts
of the CWA from W-E mainly between 00Z-03Z (6-9 PM). Best chance
will be S of I-80. These tstms may be sfc-based initially but
should become elevated as they move into and cross the CWA.

Severe: SPC has a marginal risk for most of the CWA. Believe the
modest threat for svr hail will primarily be a very narrow area S
of I-80 with the Srn extent limited by the capped warm sector. 03Z
SREF has 500-1000 J/kg of MUCAPE. Effective deep layer shear is
fcst 40- 50 kts. That combined with weak instability could support
more marginally svr hail.

Tonight: A cluster of tstms will quickly move E across the CWA
before midnight. Wrap-around clds should linger thru the night
over the NE 2/3 of the CWA.

.LONG TERM...(Saturday through Thursday)
Issued at 416 AM CDT Fri Mar 23 2018

Hazardous Weather Potential:

- A light wintry mix psbl late Sat night-Sun AM
- Possibly some non-svr tstms late Sun night-Mon

Aloft: A fairly high-amplitude shortwave ridge will move thru Sat
in the wake of Fri night`s trof. Then SW flow will prevail Sat-
Tue. The W coast trof will slowly advance into the Wrn USA with
the tail end cutting off over the Desert SW. The Nrn portion of
the trof will move thru the Nrn/Cntrl Plns Tue night with cyclonic
NW flow to follow Wed-Thu.

Surface: Strong 1040+ mb high pres over Ern Canada will build
into the rgn Sat...but low pres will form over CO Sun-Mon. This
will force a warm front to lift back N into KS Mon. The low is
fcst to weaken and ride up the front across MO into IL Tue. High
pres will form over the Cntrl Plns in its wake Tue.
arctic cold front will be plunging S out of Canada. This front is
fcst to move thru Wed followed by brief high pres Thu.

Temps: Cooler than normal temps Sat-Sun. Lots of uncertainty Mon
depending on the location of the warm front. Our temps are
probably way too warm N of the front (i.e., S-cntrl Neb). Mon
could be another chilly day with highs in the 40s over much of
S-cntrl Neb. Probably cooler than normal Tue...then near normal
Wed and then cooler than normal Wed.

Precip: A weak shortwave trof could bring some very light precip
Sat night into Sun. It will be dependent on sfc temps...but could
see a light wintry mix of frzg rain/sleet/snow from the Tri-
Cities N and E thru 10 AM Sun. Then more opportunities for shwrs
and possibly a few embedded non-svr tstms late Sun night into Tue
as the low rides up the front. Currently looking dry Wed-Thu.


.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Saturday)
Issued at 631 AM CDT Fri Mar 23 2018

Significant Wx: TSRA 00Z-03Z with IFR conds developing.

Today: VFR CIGs at or above 10K ft. There is significant model
disagreement/uncertainty on potential for MVFR or IFR stratus to
move in. For now kept a hint after 18Z with SCT025-030. E-ESE
winds 15-25 kts. Confidence: Medium

Tonight: Sct IFR +TSRAs 00Z-03Z with MVFR CIGs developing and
decaying to IFR. Winds diminish to 8-15 kts and become NE then N.
Confidence: Medium




LONG TERM...Kelley
AVIATION...Kelley is the U.S. government's official web portal to all federal, state and local government web resources and services.