Valid Thursday, February 28, 2019 to Monday, March 11, 2019

Summary of Forecasts and Hazards

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT October 23 2020

Synopsis: *** Week-2 U.S. Hazards will be updated by mid-afternoon ET today ***

The Week-2 U.S. Hazards Outlook features mid-level low pressure over Alaska and near the Eastern Seaboard of the contiguous U.S., with moderately strong mid-level high pressure over the western and central CONUS. A weak, low-amplitude ridge is predicted across the Bering Sea.

Hazards

• *** Week-2 U.S. Hazards will be updated by mid-afternoon ET today ***
• Moderate chance of much below normal temperatures over the Great Lakes, Northeast, and the northern Mid-Atlantic, Fri-Sat, Oct 30-31.
• Slight chance of much below normal temperatures from the Middle and Upper Mississippi Valley eastward to the Northeast and the Mid-Atlantic Coast, Fri-Tue, Oct 30-Nov 3.

Detailed Summary

For Monday October 26 - Friday October 30: WPC Days 3-7 U.S. Hazards

For Saturday October 31 - Friday November 06: *** Week-2 U.S. Hazards will be updated by mid-afternoon ET today ***

Today’s GFS and ECMWF ensembles predict more progressive solutions compared to yesterday, backing off on the idea of a closed low developing across the Southwest CONUS. The ECMWF ensemble is significantly more progressive today than the GEFS. A moderately strong 500-hPa ridge is predicted to extend across the western and central CONUS during Week-2, and a mid-level trough is forecast to propagate rapidly eastward, with the mean location of its axis near the Atlantic Coast. Most of Alaska is forecast to be under a trough, with heights within 30 meters of normal for the Week-2 period.

The more progressive model solutions today favor the eastward advection of anomalously cold air into the Great Lakes and Northeast during Week-2, and a rapid retreat of anomalously cold air from the Southwest and Great Plains. Accordingly, a slight chance (20%) of much below normal temperatures (15th percentile or lower) is indicated from the Middle and Upper Mississippi Valley eastward to the Northeast and Mid-Atlantic Coasts, from Oct 30-Nov 3. A moderate chance (40%) of much below normal temperatures is specified for the Great Lakes region, the Northeast, and northern Mid-Atlantic, from Oct 30-31. For the Northeast CONUS, both the ECMWF and GFS reforecast tools indicate temperatures could reach the 5th percentile of the historical minimum temperature distribution. There is also at least a 60% chance of minimum temperatures falling below 28 deg F for most of the Northeast, which qualifies as a hard freeze. Possible exceptions could include Long Island, NY, and the immediate southern New England coast.

Early in the Week-2 period, a lingering frontal zone is forecast to bring precipitation to parts of the Mid-Atlantic and Northeast, but the amounts are expected to fall short of hazardous criteria. Similarly, onshore flow ahead of a mid-level trough over Alaska is expected to bring precipitation to the Southeast Panhandle region (2 inches over a 3-day period), but this amount is not considered hazardous for this region during this time of year.

The first significant Santa Ana wind event of the season is expected in southern California early next week, however this event is likely to time off before the beginning of the Week-2 Hazards period. The high wind event was therefore removed from today’s Outlook map.



Forecaster: Anthony Artusa

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