Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 312025
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
325 PM CDT Fri Oct 31 2014

.SHORT TERM...(This Evening through Saturday)
Issued at 306 PM CDT FRI OCT 31 2014

Mid/upper level shortwave continues to dig southeast across the OH
river valley the rest of today and into tomorrow. Behind this wave
is a surface high pressure slides southward through the region
overnight. This will allow the pressure gradient to relax resulting
in a gradually decrease in winds this evening. The clear skies and
calm winds will set the stage for widespread frost and low
temperatures in the low 20s and possibly upper 10s in favorable
areas tonight. Tomorrow an upper level ridge moves over the central
US as the surface high retreats eastward. Although strong upper
level shortwave is forecast to progress over the west coast, which
will shove the upper ridge eastward allowing southwest flow aloft to
take control. Southwest flow aloft will cause a lee side trough to
develop over the high plains causing an increasing pressure gradient
within the return flow. Warmer temps advecting in from the western
US will help highs tomorrow reach the upper 40s and low 50s. Wind
gusts tomorrow afternoon could approach 30 mph out of the south.

.LONG TERM...(Saturday Night through Friday)
Issued at 306 PM CDT FRI OCT 31 2014

Upper ridging will gradually shift east as a deep Rocky Mountain
trough makes an eastward shift through Monday as well. Surface
cyclogenesis will develop in the lee of the Rockies with a
strengthening pressure gradient and low level winds across the
local forecast area Saturday night through Sunday night. This will
keep low temperatures warmer both Sat and Sun night, and highs on
Sunday should be well into the 60s to around 70 if clouds remain
limited.

Rain chances begin to increase by late Sunday night into Monday as
the upper level jet moves overhead and low level moisture
continues to advect into the forecast area. Vertical motion will
continue to increase into the day on Monday in the vicinity of the
upper jet divergence and a slow moving frontal zone. This will be
further amplified by an intensifying low level jet Monday evening
in the vicinity of the frontal zone. Overall, rain chances look
quite good across the entire area at some point during the Monday
to Monday night time frame. The chances may increase slightly with
southeastward extent in the forecast area though. Any uncertainty
lies in the eventual evolution of the northern stream trough
scheduled to bring a surge of dry air south into the region and
impacting the speed of the surface front. All told, expect rain,
with a widespread 0.25 to 1.5 inches across the area through
Monday night.

All signs point to a fast drying trend from northwest to southeast
starting early on Tuesday, with the whole area precipitation free
by Tuesday afternoon. A secondary dry cold front will bring
temperatures colder yet for Wednesday night into Thursday. Model
guidance diverges considerably by next Friday with significant
differences in the evolution of a tropic Pacific storm system as
it moves north and becomes absorbed into the main upper flow.
Thus, low confidence at the end of the forecast but see some
potential for another round of rain so have kept some chances
mentioned for Friday.

&&

.AVIATION...(For the 18Z TAFs through 18Z Saturday Afternoon)
Issued at 1124 AM CDT FRI OCT 31 2014

VFR conditions expected through the taf period. Occasional gusts
this afternoon especially at TOP/FOE as winds gradually decrease
and become calm by sunrise only to eventually veer overnight.
Winds pick up late morning out of the southeast with gusts
occurring by the end of the period.


&&

.TOP WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from 9 PM this evening to 9 AM CDT Saturday FOR
KSZ011-012-021>024-026-034>040-054>056-058-059.

&&

$$

SHORT TERM...Sanders
LONG TERM...Barjenbruch
AVIATION...Sanders






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