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. Tropical Storm Matthew, currently over
the 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:
- Heavy rain for the northern high Plains,
Mon-Tue, Oct 3-4.
- Heavy snow at the higher elevations of Montana and Wyoming, Mon-Tue, Oct
- High winds for parts of the western and central U.S., Mon-Tue, Oct 3-4.
- Severe weather for parts of the central and southern Great Plains, Tue, Oct
- High winds and waves for parts of the East Coast, Tue-Thu, Oct 4-6.
- 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 the mountains
of Montana and 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 model 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 5am EDT on September 29, Tropical Storm Matthew is located at
14.1N/65.5W in the Caribbean as it nears hurricane strength. 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 exact track of Matthew, an increase in surf and
wave heights is expected from the Atlantic coast beaches of Florida north to at
least Long Island, beginning on October 4. 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. A heavy rain hazard is not posted due to the
continued large differences 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
To be completed later.
Forecaster: Brad Pugh
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.