Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 142113

Area Forecast Discussion
National Weather Service Topeka KS
313 PM CST Thu Dec 14 2017

.SHORT TERM...(This evening through Friday)
Issued at 304 PM CST Thu Dec 14 2017

A weak disturbance will continue to bring light precip to the
region this afternoon and evening before exiting overnight.

Afternoon water vapor imagery showed a compact H500 wave/PV lobe
tracking southeastward through Nebraska. Enough attendant lift and
moisture was present with this feature to generate a broad but
rather patchy region of light rain and snow, though accumulations
were very light. An overall drying trend has been noted in MRMS
data over the last few hours and most model guidance support this
evolution. Did keep the mention of light sprinkles/flurries east
of Manhattan through midnight given upstream echos extending as
far as the Black Hills and recent runs of the HRRR generating
light POPs through that same time range. Broad upper level ridging
builds in the wake of this system for Friday with increasing H850
WAA aloft setting the stage for a warm start to the weekend.

.LONG TERM...(Friday night through Thursday)
Issued at 304 PM CST Thu Dec 14 2017

The long-term remains mostly quiet with the best chance of
precipitation coming on Sunday morning.

The aforementioned upper level ridge will give way to a sharp
longwave trough digging southeastward along the West Coast
Saturday morning, placing Kansas in broad WSW flow. Saturday will
feature yet another round of unseasonably warm weather with H850
temps soaring to +11 to +13 C. The NAM is a surprisingly cool
solution and places the stationary surface boundary further
southeast than the other solutions, so leaned toward the
EC/GFS/GEM consensus for highs on Saturday. Gusty southwest winds
of 15 to 25 kts combined with afternoon RH values around 25 to 30
percent will present a very high fire danger throughout northeast
Kansas given the dry state of fuels.

A sharp, negatively-tilted H300 wave lifts through Kansas between
06 and 18Z on Sunday morning with a weak 1005 mb surface cyclone
pulling off the Front Range after 06Z Sunday. The evolution of the
surface trough/low as the upper level wave outruns it during the
day on Sunday is somewhat uncertain. In either case, most guidance
have backed off on the coverage of precip Sunday morning and the
thermal profiles would support mostly rain with maybe a wintry mix
in the early morning along the NE border. The NAM is, once again,
the outlier in holding the surface trough further south and
advecting cool/moist near-surface air along the KS/NE border.
Should this solution pan out, there may be a brief window of
freezing drizzle near the NE border Sunday. However, given the
NAM`s high moisture bias and the lack of support from other
solutions with warmer and drier profiles, did not include any
mention of freezing precip in the updated forecast.

A second lobe of energy follows on the heels of this system late
Sunday night, but the sensible weather effects look to be minimal.
Broad quasi-zonal upper ridging then prevails for Tuesday and
Wednesday and will bring above average temperatures and dry
conditions. A pattern change does shape up for the end of the
week. Upper level ridging builds along the west coast with a
potent trough digging southward along the downstream flank of the
ridge for Thursday and Friday. The 12Z GFS/EC/GEM vary greatly in
the evolution of this wave and this evolution will play directly
into the region`s weather around the Christmas holiday.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1129 AM CST Thu Dec 14 2017

A region of light rain/snow will drop southeastward this
afternoon/evening, possibly bringing MVFR ceilings west of MHK.
Northwesterly winds of 5 to 10 kts will gradually back to the WSW
by Friday morning.




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