Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
345 AM EDT Fri Oct 15 2021

Valid 12Z Fri Oct 15 2021 - 12Z Sun Oct 17 2021

...Severe weather and Excessive Rainfall on tap from the Mid-South to the
Great Lakes today; severe storms possible in the Northeast on Saturday...

...Fresh injection of cooler than normal temperatures overtaking the
Rockies and Heartland arrives in the Tennessee and Ohio Valleys on
Saturday; abnormally warm along the East Coast...

...Elevated fire weather conditions in Southern California; wet pattern
returns to the Pacific Northwest

The primary weather maker to close out the week is an elongated frontal
boundary stretching from southeast Canada to South Texas that contains a
couple waves of low pressure embedded along the front. The front is set to
ignite areas of showers and thunderstorms throughout the day with some
storms potentially becoming severe. The Storm Prediction Center has issued
a Slight Risk for severe storms from northern Arkansas and through the
Ohio Valley into the eastern Great Lakes today. There is also a Marginal
Risk for Excessive Rainfall in some of these areas that could lead to
localized areas of flash flooding. As an upper trough tracking through the
Midwest amplifies Friday night, one particular area of low pressure will
rapidly deepen as it tracks from the eastern Great Lakes Friday evening
into southeast Canada on Saturday. The storm system's cold front will
swing through the Northeast and Mid-Atlantic producing areas of showers
and thunderstorms on approach. Some storms could be severe in the
Northeast, which has led SPC to issue a Marginal Risk for parts of the
region. The front races into the northwest Atlantic Saturday night and a
dome of high pressure builds in behind it, leading to the arrival of a
drier and seasonally cooler temperatures on Sunday.

Farther west, a chilly and dry air-mass lies in wake of this elongated
cold front tracking through the eastern half of the Lower 48. Today, much
below normal temperatures are engulfing the Intermountain West and the
Heartland while east of the front, an air-mass bordering on one observed
in late summer remains entrenched east of the Mississippi River. Numerous
daily record warm minimum temps are likely to be challenged this morning
from South Texas to the Northeast with some daily record highs possible in
the central Appalachians. While the cooler temperatures are not likely to
break many (if any) records, daily temperature departures of 10 to 20
degrees below normal are anticipated in the Rockies and the High Plains.
The front quickly pushes east on Saturday, ushering in that drier and more
autumn-like temperature regime from the Great Lakes to the western Gulf
Coast. Most of the East Coast receives a dose of much cooler temperatures
by Sunday.

Elsewhere, a strengthening upper level ridge allows for drier and milder
temperatures to set up shop over the western third of the CONUS. Santa Ana
winds in Southern California combined with low relative humidity levels
have led to the issuance of Red Flag warnings and an Elevated Risk for
fire weather conditions. Ridging over the Intermountain West will keep
Santa Ana winds in the forecast into Saturday, prolonging the favorable
fire weather conditions in place there. Farther north, the coastal areas
of the Pacific Northwest begin to feel the affects of a deepening upper
trough in the northeast Pacific as it delivers subtropical moisture into
western Washington. The Olympics and northern Cascades are likely to
contend with periods of rain just before an approaching frontal system
brings additional rainfall to western Washington and Oregon on Sunday.

Mullinax


Graphics are available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php