US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
340 PM EST Wed Jan 13 2021
 
Valid Saturday January 16 2021 - Wednesday January 20 2021
 
Hazards:
- Heavy precipitation across portions of the Northeast, Sat, Jan 16.
- Heavy rain across portions of the Southeast, the Lower Mississippi Valley, and the Southern 
Plains, Tue-Wed, Jan 19-Jan 20.
- Flooding occurring or imminent across portions of the Southeast, the Pacific Northwest, and the 
Northern Great Basin.
- Flooding likely across portions of the Pacific Northwest.
- High winds across portions of southern mainland Alaska, Sat, Jan 16.
- High winds across portions of northern mainland Alaska, Sat-Sun, Jan 16-Jan 17.
- Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sat-Tue, Jan 
16-Jan 19.
- High winds across portions of the Alaska Panhandle and mainland Alaska, Mon, Jan 18.
 
Detailed Summary:

Throughout the medium range period (Saturday, January 16 - Wednesday, January 20) the upper-level 
pattern will be dominated by a pair of deep lows and significant troughing on both sides of the 
CONUS. An upper-level low positioned over the Ohio Valley and Lower Great Lakes is forecast to 
propagate northeast Saturday into Sunday, deepening in the process. Concurrently at the surface, an 
occluded low pressure/frontal system is expected to sweep through the Northeast, bringing a mix of 
heavy rain and snow as well as moderately gusty winds to the region through early Sunday morning. 
Similarly to yesterday, guidance suggests areas closer to the coastline and at lower elevations 
will likely receive heavy rain, while snow is expected to be the main form of precipitation at 
locations inland, at higher elevations, and downwind of Lake Ontario in northern New York where 
there is potential for lake effect snow. Models also indicate that precipitation type changes and 
rain/snow mixes are possible throughout the Northeast, making it unlikely that any one region will 
experience either rain or snow exclusively. Therefore, the whole region will be marked as at risk 
for heavy precipitation. As the low pressure/frontal system moves through the Northeast, 
temperatures in interior New England and Maine are expected to be between 12 and 15 degrees above 
normal, bringing daily temperatures above freezing. This could serve to melt some of the snow pack 
already in place and, mixed with the heavy precipitation event and above average streamflow, may 
cause or exacerbate flooding along streams and rivers.

In the beginning of next week, troughing over the western half of the country is forecast to 
precede the development of a second deep upper-level low over the Southwest. As this feature starts 
to develop, shortwave energy at the surface will fuel mountain snows in the Rockies on Monday and 
Tuesday and in the Washington Cascades on Wednesday. While the snowfall is not expected to be heavy 
enough to be hazardous, there are isolated areas that may see up to 8" of snow. Simultaneously, a 
new low pressure/frontal system will emerge in southern Texas on Sunday and remain relatively 
stationary throughout the remainder of the period, kept in place by high pressure to the northeast. 
Once the deep low over the Southwest is formed a change in the upper-level flow pattern will force 
the surface high pressure to recede Monday into Tuesday. No longer impeded by high pressure, the 
low pressure/frontal system is expected to bring heavy rain to the Gulf Coast states Tuesday into 
Wednesday. The heavy rain will be especially hazardous along the western Texas and Louisiana coasts 
where high rainfall totals that could reach 2+" in 24 hours mixed with highly saturated soils could 
enhance the potential for rain-induced flooding.

Non-hazardous above normal temperature anomalies for both maximum and minimum temperatures will be 
present all around the CONUS throughout the period.
Most notably, the northern Great Plains will experience above normal highs throughout the period, 
while the entire Northern Tier is forecast to have daily lows significantly higher than normal, 
with some isolated areas exceeding their normal lows by 25 to 30F over the weekend.

In Alaska, a tight pressure gradient is forecast to develop over the northern Mainland between a 
deep low in the Gulf of Alaska and a strong high in the Arctic Ocean Saturday and Sunday, producing 
high winds over and around the Lisburne Peninsula. Additionally, a series of frontal systems are 
forecast to move through the Gulf of Alaska during the period, bringing a virtually constant string 
of heavy precipitation to the coast from the Southcentral region through the Alaska Panhandle until 
a lull on Wednesday. While these systems may generate significant waves, they are expected to 
remain predominantly offshore. Onshore winds associated with these systems will also pose a threat 
to coastal regions, specifically to the southern Mainland on Saturday and northern Panhandle on 
Monday, where wind gusts could potentially reach and exceed hazardous levels. Similarly to the 
CONUS, maximum and minimum temperatures are forecast to be well above normal throughout Mainland 
Alaska. While maximum temperatures may reach 25F above normal, minimum temperatures will likely 
reach or exceed 40F above normal in some areas, a significant reprieve from the cold!

Zavadoff