Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 170517

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1117 PM CST Thu Feb 16 2017

.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 300 PM CST Thu Feb 16 2017

The main story for the next 24-30 hours will be mild temperatures
tonight and unseasonably warm temperatures for Friday.

The north-south oriented warm front located across western IL early
this afternoon, will continue to push east this evening with a
modest surface pressure gradient persisting tonight, and continued
southwest winds/low level WAA. Low dew points will allow
temperatures to fall off a bit more than we typically see in this
type of flow regime, and mins will be closer to our normal highs for
mid February.

The upper low currently centered in west Texas will lift into the
southern Plains on Friday and this will bring some high clouds to
the area, however no more than we currently have in the northwest
flow aloft. The persistence of the WAA regime, veering southwest to
west low level winds, and the relatively "mild" overnight
temperatures will set the stage for another day of unseasonably warm
temperatures. Highs on Friday will be around 30 degrees above
average and some records highs are possible.


.LONG TERM...  (Friday Night through Next Thursday)
Issued at 300 PM CST Thu Feb 16 2017

Weak frontal boundary to slowly sink southeast across region Friday
night/Saturday, as upper level shortwave/cutoff low lifts northeast
and opens up. Even though low level moisture will be on the increase
ahead of this boundary, best chances of rain will be just south of
forecast area. Eventually the front will wash out over region and
upper level ridge to build in allowing much above normal temps
through the weekend and into early next week. So with warm south to
southwest winds, high temperatures through Monday will be in the mid
60s to mid 70s. High temps will be within 3 to 4 degrees of the
record highs each day through Monday.

As upper ridge shifts off to our east, clouds will be on the
increase Monday ahead of next system. Models are a bit stingy with
rain now due to split flow aloft, best chances of rain will be to
our north over Great Lakes region and to our south over Gulf Coast
states. So just have scattered chance pops through the extended
period. Temperatures will cool off just a bit but highs will remain
in the 60s through next Thursday.



.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1117 PM CST Thu Feb 16 2017

VFR conditions, dry wx, and S-SW surface winds will prevail at
the TAF sites thru the valid period. Main issues will be centered
around LLWS, with LLWS ongoing per latest VAD winds, and should
last until around 14z Friday.



Issued at 255 PM CST Wed Feb 15 2017

Critical fire weather conditions to persist through early this
evening. Winds are higher over more of the area, so expanded the
coverage of the Red Flag Warning to include most of our Missouri
counties and portions of west central Illinois through 6 pm.

As for Friday, will still have dry fuels, minimum afternoon RH
values below 25 percent, mainly along and west of Mississippi River.
However, winds will not be quite as strong. So will just have
elevated/heightened fire danger mention in products.


Record Highs

 2/17 2/182/19 2/20
STL: 77/1911 74/1971 77/2016 78/2016
COU: 74/2011 71/1930 76/1930 76/2016
UIN: 70/2011 68/1971 71/1930 72/2016




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