Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 251112
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
612 AM CDT Sat Oct 25 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 309 AM CDT SAT OCT 25 2014

Upper flow over the Central Plains is transitioning to northwest as
upper low moves through the eastern Canadian provinces, with another
upper low moving onshore the Pac Northwest, boosting high pressure
over the Rockies.  Warm temperatures aloft also have moved eastward
over our forecast area as seen on past evening sounding.  A weak
surface high is nosing into northeast Kansas, creating a boundary
for moisture to pool on and bringing haze and fog to portions of the
area. Think this will diminish from NW to SE as southwest flow moves
overhead and drier air continues to undercut from the north.  Will
carry some patchy morning fog with areas in the low spots and river
valleys once again.

Temperatures warm nicely back toward the 80 degree mark for this
afternoon. Surface winds slowly shift around to the southeast as the
lee trof redevelops through early Sunday - which should keep mixing
up overnight enough for lows to remain in the 50s.

.LONG TERM...(Sunday through Friday)
Issued at 309 AM CDT SAT OCT 25 2014

On Sunday the upper level trough will continue to progress eastward
across the US Canada border. The southwesterly flow and deeper
mixing during the day should allow highs to reach the low to mid
80s. Ahead of the approaching system the lee side trough will
deepen increasing the southwesterly flow across the area. Surface
winds pick up late morning to around 15 to 25 mph with gusts up to
30 mph, and last until sunrise especially in east central KS. The
trailing cold front is still forecast to move through the region on
Monday. The models agree well with the timing of the front, but
disagree on the development and placement of precip. Soundings show
mid level capping may prevent most areas from getting any rain
although the better chances remain in east central KS Monday
evening. Slight instability aloft keeps the potential for maybe some
isolated thunder within the activity. The only model which keeps
precip around through Tuesday morning is the ECMWF as the southern
extent of the shortwave energy within the trough axis passes
overhead. The only moisture available at that point will be in the
mid levels and associated with the trough itself.

Cooler air filters in behind the system on Tuesday with highs only
in the 60s as northwest flow aloft becomes well established. A few
embedded shortwaves within the flow will pass over the central US
mainly on Wednesday night and Thursday, but limited moisture, dry
low levels, and weak lift prevent any good chances for precip. It
will likely result in another front to move through the area. The
00Z ECMWF then takes a drastic change and drops a strong closed mid
level low from southern Canada into the mid MS valley. This results
in a strong push of cold air, and 850 mb temps around -5 C. The GFS
takes this system and deepens it over the eastern Great Lakes. It
does appear the cold front will bring another shot of cooler air
into the region none the less, therefore the temps for Friday
could be cooler than normal.

&&

.AVIATION...(For the 12Z TAFs through 12Z Sunday Morning)
Issued at 610 AM CDT SAT OCT 25 2014

Fog at TAF sites is patchy, but dense. Fog banks drifting over the
airfields at times will make for prevailing visby less than 3
miles with patchy dense fog at TAF sites. Will carry a tempo for
TOP/MHK given proximity of airfield to water. Winds north through
southeast become more southerly overnight and will not add a group
for that at this time.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until 10 AM CDT this morning FOR KSZ012-024-
026-035>040-054>056-058-059.

&&

$$

SHORT TERM...67
LONG TERM...Sanders
AVIATION...67






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