Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 317 AM EST Tue Dec 17 2019 Valid 12Z Tue Dec 17 2019 - 12Z Thu Dec 19 2019 ...Winter weather spreading from the Ohio Valley into New England today... ...Strong to severe thunderstorms with locally heavy rains across the South will taper off behind a cold front this morning... ...Arctic air expected to surge across the northern Plains toward New England, while mild temperatures spread eastward from the lee of the northern and central Rockies... ...High winds likely from Santa Ana conditions across southern California today... A low pressure system continues to intensify along a sharp front as it moves northeastward toward the central Appalachians this Tuesday morning. An extended swath of snow and wintry precipitation is currently impacting areas from the Mid-Mississippi Valley through the Ohio Valley into the central Appalachians. Much of New England will see the wintry precipitation continue through tonight as the low pressure center is forecast to pass just south of Long Island. Snow is expected across the interior sections while freezing rain will be the primary threat for southern New England today. The storm will move rapidly away from the Northeast on Wednesday as the snow tapers off to flurries in interior New England. In the wake of this storm, an arctic blast from central Canada is forecast to impact areas from the northern Plains eastward into New England for the next couple of days. Sub-zero temperatures are forecast for the upper Midwest Wednesday morning; single digits by Thursday morning for northern New England. These temperatures are 15 to 25 degrees below average. The arctic air flowing over the warm waters of the Great Lakes will also ignite lake-effect snows across the upper Lakes today and over the lower Lakes on Wednesday. Locally heavy snows are likely with these lake-effect snow squalls. In contrast to the very cold temps across eastern portions of the northern Plains, the upper Mississippi Valley and the upper Great Lakes, downslope/Chinook winds will spread eastward from the lee of the northern Rockies and across the Northern High Plains today, then southward into the lee of the central Rockies and across the central Plains Wednesday. These downslope winds will support much above average temperatures across the northern High Plains today and across much of the northern and central Plains Wednesday. Across the South, strong to severe thunderstorms with locally heavy rains will taper off behind a strong cold front this morning. The rain is expected to overspread much of the East Coast today before moving out to sea later tonight. Strong Santa Ana wind conditions will persist through today across southern California. Winds gusts of 35 to 55 mph are possible, resulting in potential of downed trees and power lines, along with an increased fire weather threat. These Santa Ana wind conditions will diminish significantly by Wednesday as an area of low pressure moves toward northern California. Rain is possible across northern California with this low on Wednesday, but amounts are not expected to be heavy. In contrast, an extended period of unsettled weather is expected to reach the Pacific Northwest beginning on Wednesday. Kong/Oravec Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php