Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 292048
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
348 PM CDT Wed Oct 29 2014
.SHORT TERM...(This Evening through Thursday)
Issued at 340 PM CDT WED OCT 29 2014
Water vapor imagery showed a mid-level trough progressing toward the
east coast with a shortwave trough noted over Montana early this
afternoon. Surface high pressure was centered over the region today,
gradually shifting to the east. Mostly sunny skies along with winds
shifting to the southeast helped to warm temperatures into the upper
50s to mid 60s this afternoon. Models show the shortwave trough
dipping southward and skimming across the forecast area overnight
into Thursday morning. This advancing trough will help to push an
area of surface low pressure and associated weak cool front eastward
across the area Thursday morning. While some isentropic lift will be
present with this passing wave, model soundings show little in the
way of available moisture so have kept the forecast dry with only
some mid-level clouds expected. These mid-level clouds along with
light southerly winds should keep overnight low temperatures a few
degrees warmer with readings in the low/mid 40s. Surface high
pressure will surge into the central U.S. behind the exiting surface
low. Despite northerly surface winds through the day, do not
anticipate caa behind the low so mostly sunny skies should aid in
afternoon high temperatures reaching into the mid/upper 60s.
.LONG TERM...(Thursday Night through Wednesday)
Issued at 340 PM CDT WED OCT 29 2014
An upper level trough digging southeast out of central Canada into
the Great Lakes States will amplify the longer wave length trough
across the eastern US. Strong low-level CAA will spread southward
across the plains late Thursday and Thursday night. Temperatures on
Friday will struggle into the mid 40s for highs as a 1036 MB surface
ridge will build southward across the MO river valley from central
Canada. North winds of 15 to 25 MPH during the morning hours of
Friday will gradually diminish through the afternoon hours.
Friday night, clear skies and light winds will cause overnight lows
to drop into the lower to middle 20s. This will cause the first
widespread hard freeze across the CWA. The official end of the
growing season across the CWA is October 31st. We may issue a freeze
warning for Friday morning, even though it will be November 1st.
Saturday, the cold surface ridge will gradually shift east into the
MS river valley. After a cold start temperatures will only warm into
the mid 40s to around 50. The deeper longer wave-length trough will
move east across the eastern seaboard. An upper level ridge will
amplify across the plains.
Saturday Night through Sunday night, an upper level trough will move
into the western US. The upper trough will shear apart with the
northern section of the H5 trough lifting northeast across the
northern plains. The southern sections will dig into the four
corners region. A deepening lee trough across the central and
southern high plains will cause southerly low-level winds to
increase across the southern and central plains. The southerly winds
will transport deeper moisture north. Isentropic lift ahead of the
moisture return may cause isolated showers to develop Sunday Night.
Highs on Sunday will warm into the upper 50s to lower 60s.
Monday through Tuesday. The H5 trough across the four corners region
will lift northeast across the plains. The combination of stronger
ascent, deeper moisture and surface convergence ahead of surface
front will provide for a good chance of showers and perhaps isolated
thunderstorms Monday into early Tuesday morning. The front should
push southeast of the CWA Tuesday afternoon bringing and end to the
showers. Highs Monday will reach the lower 60s.
Tuesday night through Wednesday, The eastern US longer wave length
trough will amplify across the eastern US. The coldest air mass
should remain across the upper Midwest. Highs on Tuesday will reach
the lower 60s.
.AVIATION...(For the 18Z TAFs through 18Z Thursday Afternoon)
Issued at 1251 PM CDT WED OCT 29 2014
For the 18z TAFs, VFR conditions are expected through the period.
Surface winds will be light through Thursday morning, gradually
veering from southeast to northwest. As a shortwave trough skims
southward over the region overnight into Thursday morning, the
low-level jet will increase over the TAF sites, resulting in the
potential for some LLWS concerns overnight as southwesterly winds at
around 1000ft may reach upwards of 35-40kts.