Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 AM EDT Thu Oct 01 2020 Valid 12Z Thu Oct 01 2020 - 12Z Sat Oct 03 2020 ...October to open on a cool and crisp note from the Plains to the East Coast, hot and smokey on the West Coast... ...Slight Risk for flash flooding in portions of South Florida, scattered showers across the Great Lakes today, passing showers over the Northeast tonight into early Friday... An amplified jet stream pattern over North America will make for a tale of two contrasting air-masses across the Lower 48 to kick off October. Much of the eastern half of the country can expect a cool and dry autumn-like regime with the coolest temperatures versus normal located in the Midwest where temperatures look to range between 10 and 15 degrees below normal. A seasonally mild Thursday is on tap from the Mid-Atlantic to the Northeast before a cold front swings through early Friday, setting the stage for a cool and dry Saturday up and down the East Coast. Meanwhile out west, a strong upper level ridge is responsible for the ongoing heat wave in California. Excessive Heat Warnings and Heat Advisories extend from San Diego to San Francisco today and sizzling temperatures look to stick around in Southern California through Friday. In addition to the heat, elevated fire weather conditions persist along the Transverse Ranges and Red Flag Warnings up the California coast. Air Quality Alerts remain in place over portions of the West Coast and central High Plains due to ongoing bouts with wildfire smoke causing poor air pollution. Precipitation-wise, much of the CONUS is forecast to be mostly dry thanks to the strong upper level ridge out West and an expansive area of high pressure from the Plains to the Southeast. A cold front will set off scattered showers across the Great Lakes today and a wave of low pressure looks to produce showers from the Mid-Atlantic to to the Northeast Thursday night into Friday. The heaviest rainfall over the next couple days will be focused along a frontal boundary draped over South Florida. Showers and thunderstorms tapping into a tropical moisture allows the more intense storms to inflict excessive rainfall rates over the heavily urbanized portions of South Florida. As a result, a Slight Risk for flash flooding is in place along the southeast coast of Florida today and Friday. Mullinax Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php