708 
FXUS64 KHUN 072315
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
615 PM CDT Fri Oct 7 2022

...New AVIATION...

.NEAR TERM...
(Remainder of today and tonight)
Issued at 247 PM CDT Fri Oct 7 2022

Amplification of a broad longwave trough across central/eastern 
North America will continue this afternoon, as a progressive 
shortwave trough currently dropping into the Lower Great Lakes 
region begins to lift northeastward into New England. As this 
occurs, a fairly cold/dry airmass of Canadian origin building 
southward through the northern Plains will spread southward into 
the region, although this airmass will likely not arrive in the 
local area until late this evening/early Saturday morning. Thus, 
after a warm afternoon with highs in the u70s-l80s, strengthening 
low-level cold advection through persistent northerly flow around 
10 MPH will drive temperatures down into the 40s for most of the 
area by sunrise, with lows ranging from the lower 40s in our TN 
counties to the upper 40s across southern Cullman County.

&&

.SHORT TERM...
(Saturday through Sunday night)
Issued at 247 PM CDT Fri Oct 7 2022

Latest short term model consensus suggests that the longwave 
trough noted above will be reinforced over the course of the 
weekend, as an upper low predicted to dig southeastward across 
Hudson Bay overnight opens into a trough and travels cyclonically 
through southern Ontario and into the Canadian maritime provinces 
by the end of the short term period. Our forecast area will remain
along the southern edge of stronger mid-level cyclonic flow to 
our north, with this expected to result in sunny/dry conditions 
tomorrow and highs ranging from l-m 60s in elevated terrain to the
u60s-l70s in the valley. Although northerly winds will remain 
rather brisk during the morning hours, the pressure gradient will 
relax by late Saturday afternoon as a surface ridge builds 
eastward into the TN/OH Valleys, and remains centered to our 
immediate north/east through Monday morning. The combination of 
light-calm flow in the boundary layer and dewpoints in the l-m 30s
will be favorable for radiational cooling both Saturday and 
Sunday night, with a patchy-areal coverage of frost possible 
during the morning hours, particularly across our TN zones and in 
far northeast AL. However, one potential negative factor regarding
frost development at least on Saturday night could be an increase
in high-level cloudiness associated with a mid-level vort max 
crossing the Ozarks/Mid-South region.

&&

.LONG TERM...
(Monday through Friday)
Issued at 247 PM CDT Fri Oct 7 2022

Global models suggest that a change in the synoptic flow pattern 
will begin early next week, as a low-amplitude ridge at the 500-mb
level translates eastward across the southern CONUS in response 
to deepening northern stream trough digging across the Canadian 
Rockies. Present indications are that the ridge axis aloft will 
shift to the east of the region by Monday night, allowing west- 
southwesterly flow to resume by Tuesday morning. Although guidance
indicates that the west-southwesterly flow will steadily 
strengthen through the mid-week period as the height gradient 
contracts between the trough to our northwest and a subtropical 
high to our southeast, it will not be until Tuesday when low- 
level return flow becomes sufficient to result in a notable 
increase in boundary layer moisture.

Chances for showers will begin to increase early Wednesday 
morning, as both deep-layer moisture advection and synoptic scale 
ascent increase in the strengthening warm advection regime 
downstream from the amplifying trough to our northwest, with a few
thunderstorms possible by by Wednesday afternoon as dewpoints 
rise into the u50s-l60s in the warm sector airmass ahead of the 
related surface cold front. This regime will become even more 
robust during the period from Wednesday night-Thursday morning, as
the south-southwesterly low-level jet increases to 35-45 knots 
and PWAT values rise into the 1.6-1.8 inch range, setting the 
stage for a fairly widespread coverage of showers and 
thunderstorms in what could be our first Autumn severe convective 
event. A cooler and drier airmass of North Pacific origin will 
spread into the region in the wake of the front, with pleasant 
weather conditions returning by the end of the work week.

&&

.AVIATION...
(00Z TAFS)
Issued at 615 PM CDT Fri Oct 7 2022

Even with the passage of a dry cold front, VFR conds are generally
expected thru the TAF period. Mid/high clouds filtering into the
area from the west will also linger into much of Sat. Light/var
winds will become north around 10kt with higher gusts Sat morning
as well.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.
&&

$$

NEAR TERM...70
SHORT TERM....70
LONG TERM....70
AVIATION...09