Valid Monday May 02, 2016 to Friday May 13, 2016
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EDT April 29 2016Synopsis
: A series of low pressure systems are
expected along a front that is expected to be located near the East Coast
through mid-week. An area of upper-level high pressure is expected to briefly
build across the west-central U.S. during the beginning of May. An area of
upper-level low pressure is forecast to move inland from the east Pacific prior
to the Week-2 period. Multiple surface lows are expected to affect southern
Alaska and the Alaska Panhandle during the next two weeks.
Summary For Monday May 02 - Friday May 06:
- Heavy rain for southwest Louisiana and southeast
Texas, Mon, May 2.
- Heavy rain for the eastern Carolinas, Tue-Wed, May 3-4.
- Flooding occurring, imminent, likely, or possible across parts of the
central U.S., Mon-Tue, May 2-3.
- Much below-normal temperatures for parts of the Rockies and high Plains,
Mon, May 2.
- Much above-normal temperatures for parts of the Pacific Northwest, Mon, May
- Much above-normal temperatures for parts of eastern Washington, Tue-Wed,
- Much above-normal temperatures for the desert Southwest, Wed, May 4.
- Heavy precipitation (rain and high-elevation snow) for parts of the Sierra
Mountains, Great Basin, north-central Rocky mountains, and north-central high
Plains, Sat-Sun, May 7-8.
- Slight risk of much-above normal temperatures for much of the Great Plains,
Sat, May 7.
- Severe drought across parts of California, the Great Basin, Southwest,
Wyoming, southern Great Plains, Hawaii, and Puerto Rico.
continued risk of heavy rainfall (locally more than 2 inches) along a trailing
front is expected to persist for the western Gulf Coast through Monday, May 2.
The deterministic 6Z GFS and 0Z ECMWF models on April 29 indicate precipitable
water values remaining around 1.75 inches across this region until drier
northerly flow arrives on Tuesday, May 3. Meanwhile, waves of low pressure are
expected to develop along a front near the East Coast and result in heavy
rainfall across the eastern Carolinas on Tuesday and Wednesday, May 3 and 4.
The heaviest rainfall amounts (2 inches or more in the 48-hour period) are
expected across the Outer Banks of North Carolina.
An upper-level trough is expected to bring a brief period of much-below
normal temperatures to parts of the south-central Rockies and high Plains on
Monday, May 2. Maximum temperatures are forecast to average more than 15
degrees F below-normal and minimum temperatures could fall below freezing in
the highlighted area on the map.
A strong ridge aloft is expected to promote much above--normal temperatures
(12 to 30 degrees F) across the Pacific Northwest from May 2 to 4. The
summer-like warmth, with maximum temperatures into the 80s, is expected to end
later in the week when 500-hpa heights decrease.
Elsewhere, much above-normal temperatures are posted for the desert
Southwest on Wednesday, May 4, when maximum temperatures are forecast to peak
near 10 degrees F above-normal and could reach 100 degrees F in the lower
Model guidance remains consistent that a vigorous upper-level trough shifts
east into the western U.S. by Friday, May 6. The deterministic 6Z GFS model on
April 29 is most progressive with this upper-level trough and indicates heavy
rain and high-elevation snow developing over the north-central Rockies on May
6. However, the deterministic 0Z ECMWF model is slower with the progression of
this upper-level trough and delays the risk of heavy rain and high-elevation
snow across the interior West until Week-2. Due to these model differences, a
heavy precipitation hazard is posted in the Week-2 period.
Antecedent heavy rainfall results in areas of flooding occurring, imminent,
likely, or possible across portions of the central U.S. Multiple rivers are
currently in minor to moderate flood stage from Louisiana and Texas north to
the Missouri River Valley.
A series of low pressure systems are expected to bring periods of rain to
the southern coastal areas of Alaska and the Alaska Panhandle. However,
rainfall amounts are forecast to remain below hazards criteria. For Saturday May
07 - Friday May 13:
A vigorous upper-level trough is likely to be centered
over the Rocky Mountains early in the Week-2 period. Based on model consistency
and reasonably good agreement among the deterministic model solutions and their
ensemble means, heavy precipitation (rain and high-elevation snow) is most
likely across parts of the Sierra Mountains, Great Basin, north-central Rocky
Mountains, and high Plains on May 7 and 8. The 0Z ECMWF ensemble mean on April
29 indicates a 48-hour max of more than 1 inch (liquid equivalent) in Wyoming
from May 7-8.
Downstream of the upper-level trough entering the western U.S., a slight
risk of much above-normal temperatures is posted for parts of the Great Plains
where the GEFS reforecast temperature tool indicates that maximum temperatures
have at least a 20 percent chance of exceeding the 85th percentile compared to
According to the U.S. Drought Monitor valid on April 26, severe, or greater
intensity, drought covers 5 percent of the U.S. Drought Monitor areas with a
continued decrease in coverage during the past six months.
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.