Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 241112
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
612 AM CDT Thu May 24 2018

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 315 AM CDT Thu May 24 2018

A midlevel shortwave trough is currently lifting northeastward over
the northern high plains with a trough axis stretching southward
over UT and CO. As this trough lifts over the front range it will
support convective initiation on the Palmer Divide in the early
afternoon. Another area for convective development is along a
trailing cold front in central NE during in the afternoon. The deep
layer shear is expected to be marginal across the region therefore
multicell mode is favored at least initially, and congealing cold
pools could result in MCS development during the evening. The MLCAPE
should range between 2500-3500 J/kg across western KS and central
NE, so the convection moving out of CO has an increased chance
maintaining intensity. During the evening the strengthening
nocturnal low-level jet may support MCS maintenance. There is some
model discrepancy as to whether the potential NW KS or central NE
MCS becomes favored, but both have a chance of reaching north
central KS in the evening with damaging wind gusts as the main
threat. How far east this threat will extend should be governed by
the strength of the nocturnal surface inversion, and the speed of
the complex. As of now it appears the threat should decrease across
east central KS since the MCS would likely arrive after midnight.
The speed and locations of these potential complexes is still not
certain especially given the overall lack of synoptic forcing.

Late this morning isentropic lift centered around 700 mb is possible
in north central KS, which could support isolated showers and
storms. Around mid day surface heating will erode the cap across the
area. With the lack of low-level features to focus convective
initiation confidence on storm development remains low. There is
currently a complex of storms in the Texas Panhandle, which could
result in an MCV/wave tracking over eastern KS this afternoon. This
has been advertised by a few HRRR runs and could explain the several
CAM solutions. These CAMs show storms forming mid day right around
when that potential MCV/wave would arrive. By this time MLCAPE could
approach 2500 J/kg with minimal deep layer shear, and the RAP is
forecasting DCAPE ranging from 800-1000 J/kg. Given this environment
there is a slight chance for hail and localized downburst with the
strongest cells. In fact, some CAMs are producing updraft helicity
tracks in portions of central KS. Overall the instability and
vertical wind shear supports mainly a multicell mode and the
resulting convective outflows could become the focus for further
development with the lack of CIN. High temperatures are forecasted
to reach the upper 80s to lower 90s, but with the chance for storms
and cloud debris temperatures could be slightly cooler.

.LONG TERM...(Friday through Wednesday)
Issued at 315 AM CDT Thu May 24 2018

Fridays forecast will be contingent on boundaries that remain and
recovery during the afternoon hours. Models show atmosphere becomes
unstable in the afternoon hours with little to no inhibition for
surface based parcels. During the afternoon hours mid level PV
anomaly is forecast to move southeast out of Nebraska in the
northwest flow aloft which will aid in forcing for ascent across
eastern Kansas. In addition a theta-e ridge is forecast to extend
from north central Oklahoma into northeast Kansas which will aid in
precipitation efficiency yielding the potential for locally heavy
rainfall to occur. Weak to moderate shear amid steepening lapse
rates in northwest flow along with peak heating in the afternoon
hours will promote a few strong to severe storms in the afternoon
and evening hours with strong wind gusts and hail the main hazards.

An upper level ridge will build into the Plains as the western U.S.
upper trough moves eastward into Nevada and western Utah for the
Memorial Day Weekend. This should keep much of the area dry and very
warm, however the GFS ejects out energy Sunday evening out of the
base of the trough and sends it northeast across north central
Kansas. The ECMWF ejects out some energy out into western Kansas.
This will bring a chance of showers and thunderstorms to mainly
north central Kansas Sunday night, but confidence is not very high
at this time. The next better chance of convection looks to be
Tuesday as the upper trough in the west becomes an open wave and
moves northeast across the Plains. Highs in the 90s are expected to
continue with lows in the 60s to around 70.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 607 AM CDT Thu May 24 2018

Confidence in location and timing of storms today is low. As of
now there are two possible rounds with one in the afternoon and
another one tonight. Storms may be capable of producing heavy
rainfall, hail, and damaging wind gusts. These storms could
restrict flight categories for a brief period.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Sanders
LONG TERM...53
AVIATION...Sanders


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