Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 021151
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
651 AM CDT WED SEP 2 2015

...Update to aviation forecast discussion...

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 311 AM CDT WED SEP 2 2015

Early this morning an upper level trough extended from southwest MN,
south-southwest across eastern NE and extreme north central KS. Weak
isentropic lift and ascent ahead of the upper trough was causing
scattered showers and isolated thunderstorms to move east across
extreme northeast KS. Several models show this band of elevated
showers and isolated storms developing farther southwest across east
central KS. Therefore...I will keep slight pops this morning across
east central KS with chance pops across northeast KS. The MUCAPE
will be below 400 j/kg, may be just enough instability for an
elevated thunderstorm. Once the H5 trough moves east into northern
MO the chances for showers should end during the mid and late
morning hours and the mid and high clouds should shift to the east.
Highs Today will range from the upper 80s to lower 90s.

Tonight, The NMM and GFS are the only two model runs that show the
weak isentropic lift generating isolated showers or elevated
thunderstorms after 9Z across the western and northern counties of
the CWA. At this time I will only place 14 pops across the northwest
counties late Tonight. Lows will drop off to around 70 degrees
across much of the area.

.LONG TERM...(Thursday THROUGH Tuesday)
ISSUED AT 311 AM CDT WED SEP 2 2015

Thursday and Friday will be quiet weather with high temperatures in
the low to mid 90s and low temperatures in the low 70s. Surface
winds will continue out of the south around 10 to 20 mph with gusts
up to 30 mph especially in central KS on Thursday. Into the weekend
a strong mid/upper level low pressure will dig across the Pacific
northwest keeping the plains in southwest flow aloft. The models
depict several weak shortwaves embedded within this southwest flow
aloft that track north and west of the forecast area. This could
bring showers and storms close to north central KS. On Saturday
night the GFS shows a slightly stronger shortwave will track towards
the area from the desert southwest along with increasing isentropic
ascent. There is also some GFS ensemble members that track a mid-
level shortwave close to the area, which may provide lift for precip
Sunday morning. Meanwhile there is better model agreement that the
Pacific NW system lifts northeastward over the northern Rockies and
northern plains. This will drive a cold front southward into eastern
KS Sunday night and Monday. This front is then forecast to stall out
as the main systems continues northeastward over southern Canada.
This opens the door to several weaker shortwaves from the desert
southwest to pass over the frontal boundary on Tuesday and
Wednesday. Therefore the chance for precip continues through
midweek.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z Thursday MORNING)
ISSUED AT 646 AM CDT WED SEP 2 2015

Isolated shower or storms will be possible at the terminals
through 16Z. KTOP may have marginal low-level windshear through
15Z. Otherwise, expect VFR conditions.

&&

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

$$

SHORT TERM...Gargan
LONG TERM...Sanders
AVIATION...Gargan


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