US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
433 PM EDT Wed Sep 30 2020
 
Valid Saturday October 03 2020 - Wednesday October 07 2020
 
Hazards:
- Heavy rain across portions of the Florida Peninsula and North Carolina coast, Sat-Sun, Oct 3-Oct 
4.
- Heavy rain across portions of the northern Mid-Atlantic to central and coastal New England, 
Mon-Tue, Oct 5-Oct 6.
- Flooding occurring or imminent across portions of northeastern Florida.
- Flooding likely across portions of northeastern Arizona.
- Much above normal temperatures across portions of northern California, northern Nevada, and 
interior Pacific Northwest, Sat-Wed, Oct 3-Oct 7.
- Heavy precipitation across portions of the Alaska Panhandle and southern coast of Alaska, 
Sun-Mon, Oct 4-Oct 5.
- Heavy precipitation across portions of the Kenai Peninsula, Sat, Oct 3.
 
Detailed Summary:

At the start of the medium range period (Saturday, Oct 3 - Wednesday, Oct 7), global models show 
very good agreement that a longwave trough will be the dominant feature across the central to 
eastern U.S. as an upper-level ridge lingers across the West.  However, solutions quickly diverge 
thereafter as the ECMWF and CMC continue to predict a rather significant low pressure system to 
develop near the New England coast early next week.  On the other hand, the GFS continue to show 
very little of such development.  What the ECMWF and CMC indicate is the phasing of an Alberta 
clipper with a coastal low forming near the Mid-Atlantic coast.  Given the rather amplified upper 
pattern to start with, it appears that the ECMWF/CMC solutions represent a more reasonable outcome 
than that of the GFS which shows a gradual weakening of the Alberta clipper as it moves toward the 
Great Lakes.  Therefore, a heavy rain area has been introduced across portions of the northern 
Mid-Atlantic to central and coastal New England for Monday and Tuesday.  In addition, it would be 
possible that the coastal sections will be impacted by increasing winds and waves depending on the 
eventual strength of the low pressure system.

Meanwhile, a continued feed of tropical moisture ahead of and along a stalled front will keep a 
good chance of heavy rain for the central to southern portion of the Florida Peninsula likely 
through the middle of next week.  The National Hurricane Center is also watching the potential for 
a tropical cyclone to develop and move across the western Caribbean for early next week.  In 
addition, there is increasing model support for a wave of low pressure to form along the stalled 
front off the Carolina coasts which is forecast to phase with the Alberta clipper as mentioned 
earlier.  This low pressure wave is forecast to bring heavy rain near the coast of North Carolina 
during the weekend.

Much of the western U.S. will see warmer than average temperatures through the period under the 
influence of the upper-level ridge.  Temperatures across portions of northern California, northern 
Nevada, and interior Pacific Northwest are forecast to remain more than 12 degrees above normal 
through the medium-range period.  This could keep the fire risk high across these areas.  The warm 
air will then work its way eastward across the Plains behind a warm front early to middle of next 
week.  Meanwhile, the chilly air that covers much of the eastern two-thirds of the country this 
weekend will gradually moderate to around normal by the middle of next week.

Over Alaska, an active pattern will lead to fast and frequent energetic oceanic cyclones to push 
onshore across the southern part of the state through early next week.  Heavy precipitation will be 
likely over the Kenai Peninsula on Saturday in association with the first cyclone, spreading 
eastward into the northern part of the Alaska Panhandle Sunday and Monday associated with the 
second cyclone.  The second cyclone is expected to bring gale-force winds to the coastal sections 
of southern Alaska on Sunday.  By the middle of next week, a strong front could be moving through 
the Aleutian Islands.

Kong