064 
FXUS63 KLSX 161201
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
701 AM CDT Mon Oct 16 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 330 AM CDT Mon Oct 16 2017

High pressure centered over northern Texas will move northeast 
across the Mississippi Valley into the Mid Atlantic Region by early 
Tuesday morning.  The high will bring our area tranquil weather and 
temperatures near seasonal normals in the mid 60s today.  Should see 
temperatures a few degrees warmer in the mid 40s over northern 
portions of the forecast area tonight as light southerly flow 
develops northwest of the ridge axis.  Temperatures will be 
cooler in the upper 30s to around 40 under the ridge axis 
across southeast Missouri.

Carney

.LONG TERM...  (Tuesday through Sunday)
Issued at 330 AM CDT Mon Oct 16 2017

Northwest flow aloft will continue thru Wednesday, gradually de-
amplifying with time.  A RIDGE aloft is then expected to build over 
our region on Thursday and then shift eastward, resulting in a SW 
flow aloft heading into next weekend with a TROF approaching on 
Sunday.  At the surface, a southerly flow will prevail for much of 
this period, with a weak cold front edging our region to the north 
Wednesday night and early Thursday.  A more meaningful cold frontal 
passage looks slated for Sunday. 

The atmospheric column will begin the period quite dry thanks to NW 
flow aloft and a RIDGE axis extending along the Gulf Coast 
effectively choking off any moisture return.  Any upper level 
disturbances set to slide thru will struggle mightily to generate 
any clouds or pcpn and dry weather is favored thru at least Friday.

The southerly low-level flow during this period will result in 
temperatures above average thru the period with some 80s possible in 
places for Friday and Saturday. 

The models continue to signal support to the breakdown in the dry 
stranglehold on our weather by Saturday, with flow from the Gulf of 
Mexico opening up and flow aloft having gone SW some time earlier. 
With weak upper level disturbances anticipated to stream into our 
region on Saturday ahead of the approaching upper TROF, have 
mentionable PoPs beginning on Saturday afternoon and then trend them 
into likely category with a much stronger signal with cold frontal 
passage on Sunday.

TES

&&

.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 643 AM CDT Mon Oct 16 2017

VFR flight conditions are expected to prevail across the area
today. Visibility will be reduced locally this morning due to 
steam fog in the vicinity of area rivers. The steam fog will 
dissipate by 13-14Z. Light wind will turn to the south across the
area tonight as the surface ridge drifts east of the region.

SPECIFICS FOR KSTL: 

VFR flight conditions will prevail at Lambert through Tuesday
morning. Expect light and variable wind to become southerly this
evening as a surface ridge moves east of the area.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX