Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
352 AM EDT Tue Mar 14 2023

Valid 12Z Tue Mar 14 2023 - 12Z Thu Mar 16 2023

...There is a High Risk of excessive rainfall over parts of
Central/Southern California...

...Heavy snow over parts of the Northeast and the highest elevations of
the Sierra Nevada and the Northern/Central Rockies...

...A Nor Easter will develop along the Northeast Coast...

Low pressure south of Southern New England will deepen rapidly and move
northeastward into the Canadian Maritimes by Wednesday evening. The storm
will produce heavy snow over parts of the Northeast through Wednesday
evening. In detail, a coastal low will strengthen rapidly into a major Nor
Easter that significantly impacts the Northeast through Wednesday. The
greatest impacts are expected through Tuesday night. Heavy snow rates (2-3
inches plus per hour) and strong winds will produce dangerous to
impossible travel. The heavy-wet nature of the snow, combined with max
wind gusts of 55 mph, will result in scattered to widespread power outages
and tree damage. Snowfall totals 12 inches or higher are forecast over
large portions of New England and Upstate New York. Localized max totals
of 24-30 inches are possible, particularly in terrain. Widespread minor
and localized moderate coastal flooding and beach erosion are forecast
through Wednesday as the low pressure deepens and stalls off the New
England Coast.

Meanwhile, a front extending from the Northern Rockies to Central
California will have a wave of low pressure move onshore over California
on Tuesday. The system will move eastward to the Great Lakes to the
Central Plains and then westward to the Southwest by Thursday. The storm
will stream a plume of moisture into California through Wednesday morning.
The system will produce heavy rain and highest elevation heavy snow over
parts of California, Oregon, and the Great Basin. The storm will create
considerable to locally catastrophic flooding impacts below 5000 feet
elevation and is expected to shift south across much of the California
Coast, Central Valley, and the Sierra Nevada foothills. Heavy rain,
combined with snowmelt in terrain below 5000 feet to result in more
widespread flooding from Tuesday into Wednesday, particularly in low
elevations and areas with shallow snowpack. Creeks and streams will
continue to be vulnerable to flooding from additional rain and snowmelt.
Heavy rain absorbed into the particularly deep snowpack in the Sierra
Nevada, along with heavy snow, measuring in feet above about 7500 feet,
will further compound ongoing snow load impacts and issues.

Therefore, the WPC has issued a High Risk of excessive rainfall over parts
of Central/Southern California through Wednesday morning. Severe,
widespread flash flooding is expected. Areas that normally do not
experience flash flooding will flood. Lives and property are in great
danger from Tuesday into Wednesday. On Wednesday, the threat of excessive
rainfall decreases to a Marginal Risk over parts of Southern California
and the Southwest through Thursday morning.

Furthermore, as the wave of low pressure associated with the heavy rain
moves inland, snow will develop over parts of the Northern Intermountain
Region overnight Tuesday into late Wednesday evening. As the wave moves
eastward from the Northern Intermountain Region to the Upper Mississippi
Valley, light snow will develop parts of the Northern Plains/Upper
Mississippi Valley. On Wednesday evening, the snow and rain move into the
Upper Great Lakes. In addition, the system will create heavy snow over the
highest elevations of the Sierra Nevada and the Northern/Central Rockies
from Wednesday into Thursday morning.  



Ziegenfelder


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