Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 152331
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
631 PM CDT Mon May 15 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Tuesday)
Issued at 305 PM CDT Mon May 15 2017

Southerly flow continues over northeast Kansas tonight ahead of a
deepening longwave trough moving towards the central plains.  The
majority of models keep chances for thunderstorms limited to
tomorrow afternoon and evening, although the GFS does move in some
precipitation across north central Kansas early tomorrow morning
near sunrise associated with a weak shortwave.  With some elevated
CAPE, could see some thunder with any early morning activity and
have added in slight chances for storms during this period.
Continued warm air advection keeps temperatures warm tonight with
lows similar to that of previous nights, in the upper 60s.

Main focus for tomorrow will be the potential for strong to severe
thunderstorms to form in the late afternoon and evening.
Temperatures look to warm up tomorrow into the low 80s, with
dewpoint temperatures reaching into the mid-60s during the afternoon.
Models show CAPE upwards of 2000 J/kg tomorrow along with increasing
deep layer shear between 30-40 knots.  A cap does look to be in
place most of the day and into the afternoon aiding in steep lapse
rates near 8-8.5 C/km.  This cap will begin to weaken through the
afternoon and clusters of storms may form in the late afternoon
continuing into the evening.  The main threat with any storm will be
large hail and damaging winds.  While on the low side, a tornado
threat cannot be ruled out with low level bulk shear values near 20
knots. This threat will be most pertinent if any singular supercells
can form before storms become more clustered. The threat for severe
weather looks to continue into the evening.

.LONG TERM...(Tuesday night through Monday)
Issued at 305 PM CDT Mon May 15 2017

Extended period focuses heavily on the severe weather potential
continuing Tuesday evening and perhaps again on Thursday afternoon
and evening. Picking up from the short term period, ongoing
convection is likely after 00Z, especially over north central areas
where CAPE and shear values are maximized. Speed jet maxima in the
low levels from the lee sfc trough surging east may generate the
multi cellular clusters, capable of large hail and damaging winds.
While this signal is evident in all CAMS, there is also a
conditional threat for an isolated tornado or two as supercells form
near the dry line in west central KS. If these cells make it to our
western border after 6 PM, low level shear increases and enhances
the potential. As storms progress northeastward overnight into
southeast NE, additional development is anticipated from western OK
into southern KS as the main upper trough lifts out into the central
plains. A few storms may be strong to severe with this round
shifting into east central areas into Wednesday morning. Hail and
gusty winds would be the main threats.

As the trough exits the region, subsidence fills in for the
remainder of Wednesday into portions of Thursday before the next
upper trough digs into CO. Latest runs from guidance are fairly
similar with the frontal boundary setting up over the CWA, being the
focus for convection in the late afternoon and early evening.
Generous amounts of MLCAPE and minimal inhibition combine with
effective shear values in excess of 30 kts within the warm sector.
While this event is still several days out, there remains the
potential for severe weather in our area for the early evening.

Friday is looking to be cooler, cloudy, however mostly dry as the
sfc trough lifts out, leaving northerly sfc winds around 10 to 15
mph. The upper low meanders around the northern plains Friday and
Saturday, leaving the potential for additional showers and
thunderstorms, especially on the ECMWF. Meanwhile the GFS is quicker
with the track of the low and ending precip on Saturday. For now,
will leave in low pop chances. Temps are also trending cooler with
highs in the upper 60s for the weekend and lows in the 40s and

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 623 PM CDT Mon May 15 2017

VFR conditions expected through tonight along with low level wind
shear. Tomorrow the models are suggesting that daytime cumulus
could be around 3 kft and possibly broken. Given the uncertainty
have left it as a scattered deck for now which may need to
revisited for a later issuance.

&&

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

$$

SHORT TERM...Heller
LONG TERM...Prieto
AVIATION...Sanders



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