Valid Sunday October 02, 2016 to Thursday October 13, 2016
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EDT September 29 2016Synopsis
: An area of upper-level low
pressure is expected to weaken as it progresses slowly north into southeast
Canada early in the period. A strong area of upper-level low pressure is
forecast to enter the western U.S. this weekend, resulting in a cold front
pushing east across the Great Plains to the Mississippi Valley on October 4 and
5. An area of upper-level high pressure is forecast to persist across mainland
Alaska through the early part of Week-2. Hurricane Matthew, currently over the
eastern Caribbean Sea, is forecast to strengthen and turn north during the next
five days and could eventually result in multiple hazards along the East Coast.
Detailed Summary For Sunday
October 02 - Thursday October 06:
- Severe weather for parts of the central and
southern Great Plains, Tue, Oct 4.
- Heavy rain for the northern high Plains, Mon-Tue, Oct 3-4.
- Heavy snow at the higher elevations of Wyoming, Mon-Tue, Oct 3-4.
- High winds for parts of the western and central U.S., Mon-Tue, Oct 3-4.
- High winds and significant waves for parts of the East Coast, Tue-Thu, Oct
- Flooding is occurring across parts of the Midwest and south Texas, with
possible flooding for parts of the mid-Atlantic.
- Severe Drought across parts of the Eastern CONUS, Missouri River Valley,
Great Plains, Northern Rockies, Intermountain West, Arizona, California, and
The closed 500-hpa low, initially
centered over the Ohio Valley and central Appalachians, is forecast to
gradually fill as it moves north into southeast Canada. Rainfall intensity over
the eastern U.S. is likely decrease in time, but river flooding may linger into
the beginning of this period across parts of the mid-Atlantic. Elsewhere, heavy
rainfall prior to this period triggered moderate to major flooding along the
Cedar, Iowa, and Wapsipicnic Rivers in southeast Iowa, middle Mississippi
River, and Nueces River in south Texas.
Model guidance remains in reasonably good agreement with the evolution of
an amplifying 500-hpa trough entering the western U.S. during the weekend. As
the vigorous trough aloft progresses inland to the Rockies, heavy snow (more
than 6 inches in 24 hours) is most likely above 6,000 feet across Wyoming on
October 3 and 4. Heavy rain (around 1 inch per 24 hours) associated with the
surface low is expected across the northern high Plains at the same time. The
deterministic 0Z GFS and 0Z ECMWF models indicate 48-hour precipitation
amounts, ending at 12Z October 5, of 1 to 4 inches (liquid equivalent) centered
on southeast Montana and northern Wyoming on October 3 and 4.
A lee side surface low is expected to develop across the north-central high
Plains on Monday, October 3, due to the approaching 500-hpa trough. Although a
few severe thunderstorms may affect the Dakotas and Nebraska on Monday
afternoon and evening, coverage is expected to be limited by marginal
instability. On October 4, instability is expected to be sufficient to support
severe thunderstorms along the dryline, extending from Kansas south to the
Texas Panhandle and southwest Texas. The amplifying trough and the development
of the lee side low pressure system are likely to result in high winds (gusts
above 40 mph) across parts of the Great Basin, Rockies, and high Plains on
October 3 and 4.
As of 11am EDT on September 29, Hurricane Matthew is located at 14.2N/65.3W
(eastern Caribbean Sea). Matthew is expected to turn north as it moves to the
western edge of a subtropical ridge and perhaps begins to be influenced by a
mid-level trough over the Gulf of Mexico. Model solutions continue to differ on
where and how fast this northward turn occurs. Regardless of the eventual
track, a tight pressure gradient between a 1032-hpa surface high over New
England and tropical cyclone Matthew is forecast to bring the potential of high
winds (gusts above 40 mph) to coastal areas of the Southeast and mid-Atlantic.
An increase in swells and wave heights are also expected from the Atlantic
beaches of Florida north at least to Long Island. A heavy rain hazard is not
posted due to the continued large differences among the deterministic models
and large spread among the 0Z ECMWF ensemble members on the track of Matthew.
Please refer to the latest statements and forecasts from the National Hurricane
Center at www.nhc.noaa.gov. For Friday October 07 - Thursday
The forecast along the East Coast during the early part of
Week-2 remains highly uncertain due to the large model spread with the eventual
track of tropical cyclone Matthew. The 0Z/6Z GFS and 0Z ECMWF ensemble means
feature a weak upper-level trough over the northwestern conus and a subtropical
ridge centered over the south-central conus. The ECMWF model favors
below-normal temperatures across the northern Great Plains, but minimum
temperatures are not expected to be too anomalous. An upper-level trough over
the Bering Sea is expected to maintain above-median precipitation across
According to the latest U.S. Drought Monitor (USDM) valid on September 27,
the coverage of severe or greater drought (for the CONUS) increased from 7.76
to 8.10 percent during the past week. Less than 1 percent of the Hawaiian
Islands is designated with severe drought.
Click here to see a display of the GFS Ensemble Forecasts
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.