Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 291733
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1233 PM CDT Fri May 29 2015


...Update to near-term and aviation forecast discussion...

.UPDATE...
Issued at 1219 PM CDT FRI MAY 29 2015

Morning plume of rainfall has been very persistent and driven by
mesoscale features. Main axis of vertical motion in the local area
has been on the western edge of embedded mesoscale vorticity
maxima that have steadily translated northeast. When these
enhancements develop, the trajectory has caused 1-2 hours of
training of the higher reflectivity with embedded rainfall rates
greater than 0.5" per hour. One such vorticty maximum has just
passed east of the area while another is entering Anderson county.
The main vort max is moving almost due north through eastern
Oklahoma and has a broad area of heavy rain associated with it.
Expect the due north motion to eventually turn northeast as upper
level steering flow veers a bit. However, expect some of this
moderate to heavy rain to impact parts of east central KS through
the afternoon.

Another important feature of interest is what seems to be an axis
of drying that has very slowly proceeded east across the forecast
area this morning. This feature seems to bring some drying from
west to east but it is also clear that some of the northern
moisture flux overruns this feature to develop convection just to
the north and west (currently from MHK toward Holton). This
feature could also act as a forcing mechanism for the precip just
to the east of it by enhancing moisture convergence as the next
strong wave moves north from Oklahoma.

Bottom line of this short term forecast is that some heavy rain
potential remains through this afternoon, mainly south of an
Emporia to Lawrence line. This heavy rain potential will be
greatly enhanced if the energy in Oklahoma continues to move on a
more northerly track and brings its precipitation plume across
east central Kansas. A flash flood watch is in effect for the
areas of concern.

&&

.SHORT TERM...(Today and Tonight)
Issued at 356 AM CDT FRI MAY 29 2015

Very active and chaotic pattern in the short term. A moist and
somewhat unstable airmass covered the central plains early this
morning with southwest upper flow ahead of the main shortwave over
the central Rockies. A cluster of showers and thunderstorms
developed over southeast Kansas and eastern Oklahoma after 05 UTC.
The convection was supported by a decent low-level jet at 925 mb
modest moisture transport.  In the near term, forecasted the cluster
of storms over southeast Kansas to move through our southeast and
eastern counties early this morning.

The shortwave over the central Rockies moves into the central plains
today and tonight. A cold front extending from South Dakota
southwest into eastern Colorado at 06 UTC is forecast by all short
term models to move through northeast Kansas between 00 UTC and 06
UTC tonight. Given the abundant moisture and modest instability,
will continue showers and thunderstorms in the forecast until the
front moves through.  Will then end precipitation chances from
northwest to southeast the moisture is pushed out of the area and
cool advection takes over behind the front.

.LONG TERM...(Saturday through Thursday)
Issued at 356 AM CDT FRI MAY 29 2015

With upper trough passing through early Saturday, have doubts much
precip will be left in the morning and have lowered PoPs further.
Low cloud does look to remain rather prevalent and expect highs to
struggle to breach the upper 60s in moderate north wind. Weak
surface ridging then holds the area through the weekend with quiet
weather persisting into early next week as upper ridging builds into
the central ConUS. Models showing decent agreement in a shortwave
working its way through the Northern Rockies and into the Northern
Plains around Wednesday. Could see precip breach the northwest
counties with this and possibly drape a boundary farther southeast
by Thursday for modest precip chances. Temps gradually warm into the
mid week with uncertainty on specifics increasing with time.

&&

.AVIATION...(For the 18Z TAFs through 18Z Saturday Afternoon)
Issued at 1219 PM CDT FRI MAY 29 2015

Ongoing plume of precipitation continues to stream northeast, with
TOP and FOE on the fringe of the rain with VFR cig/vis. MHK is
west of the rain but low level moisture should keep an MVFR cig in
place through early afternoon before dissipating. A cold front
moves over TAF sites after 00Z with winds shifting out of the
north and scattered thunderstorms. Expect MVFR cigs to build in
1-3 hours behind the front and persist through the TAF. See some
potential for IFR cigs from 09Z-15Z, but confidence not high
enough to include at this time.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH through late tonight FOR KSZ054>056-058-059.

&&

$$

UPDATE...Barjenbruch
SHORT TERM...Johnson
LONG TERM...65
AVIATION...Barjenbruch






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