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Valid Monday September 25, 2017 to Friday October 06, 2017
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EDT September 22 2017Synopsis
: Strong mid-level high pressure is
anticipated over the eastern U.S., while strong mid-level low pressure is
expected over the west. A frontal system over the Upper Mississippi
Valley/Great Plains/Southwest U.S. is forecast to move very slowly
east-southeastward. Hurricane Maria is expected to move northward over the
Western Atlantic. Surface low pressure is forecast to develop over the Gulf of
Alaska. During the beginning to middle of week-2, areas of mid-level low
pressure are anticipated over the eastern U.S. and western and central mainland
Alaska, while mid-level high pressure is expected over the western U.S. and
southeastern Alaska. The middle to end of week-2 is anticipated to be dominated
by a more zonal pattern across the lower 48 states. Hazards
Summary For Monday September 25 - Friday
- Heavy rain across portions of the Central Plains and Southern Plains,
Mon, Sep 25.
- Heavy rain across portions of the Southern Plains, Tue-Fri, Sep 26-Sep 29.
- High significant wave heights for coastal portions of the Mid-Atlantic and
the Northeast, Wed, Sep 27.
- Heavy rain across portions of the Alaska Panhandle, Tue-Wed, Sep 26-Sep 27.
- Much above normal temperatures across portions of the Northeast, the
Central Appalachians, the Mid-Atlantic, the Upper Mississippi Valley, the Great
Lakes, and the Ohio Valley, Tue-Wed, Sep 26-Sep 27.
- Flooding occurring or imminent across portions of the Southeast.
- Severe Drought across the Central Plains, the Northern Plains, Hawaii, the
Northern Rockies, the Middle Mississippi Valley, California, the Upper
Mississippi Valley, and the Southern Plains.
Strong ridging over the east-central CONUS favors much above
normal temperatures (positive anomalies exceeding 20-24 degrees F) across
portions of the Northeast, the Central Appalachians, the Mid-Atlantic, the
Upper Mississippi Valley, the Great Lakes, and the Ohio Valley, Sep 26-27. Day
time maximum temperatures are expected in the upper 80's/low 90's F for parts
of these regions.
A strong mid-level trough over the western CONUS, in combination with a
frontal system forecast to move east-southeastward from the Upper Mississippi
Valley/Great Plains/Southwest to the east-central CONUS increases the
likelihood for heavy rain (amounts of 3-4 inches over 48 hours) for portions of
the Central Plains and Southern Plains Sep 25, shifting southeastward to the
Southern Plains from Sep 26 to 29.
Hurricane Maria is forecast to move northward over the Western Atlantic.
High significant wave heights (in excess of 20 feet) are forecast for coastal
sections of the Mid-Atlantic and Northeast Sep 27. Please consult the latest
advisories from the National Hurricane Center at http://www.nhc.noaa.gov/ for
the latest forecasts regarding this system.
Surface high pressure is anticipated to build across the Great Basin at the
beginning of the period. This pattern may support several days of increased
probability for windy conditions. High temperatures, low relative humidity, and
dry fuels may lead to increased chances for wildfire risk. However, due to
forecast surface wind speeds not reaching critical criteria, a specific area is
not highlighted at this time.
River flooding is forecast to continue for parts of Florida due to
antecedent rainfall from Hurricane Irma.
A surface low pressure system is predicted to develop over the Gulf of
Alaska early in the period. Heavy rain (amounts in excess of 2 inches in 24
hours) is anticipated across portions of the Alaska Panhandle Sep 26 to
For Saturday September 30 - Friday October 06:
The 6Z Deterministic GFS
indicates the potential for a surface low to develop off the coast of the
Carolinas by Oct 1. This model solution then indicates the low would intensify
and track along the coast of the Mid-Atlantic, bringing heavy rain to coastal
areas. However, the 6Z GEFS and 0Z Deterministic and Ensemble ECMWF does not
show development of this storm, precluding any related hazards from being
determined at this time.
Some model solutions indicate the possibility of tropical activity over
parts of the Caribbean late in the week-2 period so this region will need to be
The U.S. Drought Monitor, valid on Sep 19, indicates that severe to
exceptional (D2-D4) drought covers 5.60 percent of the continental
Forecaster: Melissa Ou
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.