Valid Sunday March 01, 2015 to Thursday March 12, 2015
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EST February 26 2015Synopsis
: Several arctic Highs are predicted
to bring unseasonably cold temperatures to much of the contiguous U.S. during
the first half of the Outlook period. The coldest temperatures, relative to
normal, are expected to be in the Great Plains and Mississippi Valley. For the
6-10 day period, warmer than normal temperatures are anticipated in parts of
the Southeast, and perhaps coastal portions of California and Oregon. Several
precipitation events are forecast across much of the central and eastern lower
48 states by the early and middle portions of the Outlook period, with a range
of precipitation types expected. Relatively mild and wet conditions are
predicted for a large portion of Alaska, as a series of Pacific storm systems
moves across the state. Hazards
Detailed Summary For Sunday March 01
- Thursday March 05:
- Much below-normal
temperatures for most of the central and eastern CONUS, Sun-Thu, Mar 1-5.
- Periods of heavy snow for the Four Corners region, Sun-Wed, Mar 1-4.
- Periods of heavy snow in a swath from western Kansas east-northeastward
across the middle Mississippi Valley, northern Ohio Valley, lower Great Lakes
region, and much of the Northeast, Sun-Wed, Mar 1-4.
- Periods of freezing rain/sleet in a band stretching from the Texas
Panhandle and Oklahoma east-northeastward across southern portions of both
Missouri and Illinois, the southern Ohio Valley, most of the interior
mid-Atlantic, Long Island, and extreme southern New England, Sun-Wed, Mar 1-4.
- Periods of heavy rain for far eastern Texas, the lower Mississippi and
Tennessee Valleys, northern Alabama, northern Georgia, portions of the
Carolinas, and from most of Virginia northeastward into New Jersey, Sun-Thu,
- High Waves for the western Aleutians, Sun, Mar 1.
- Flooding possible in central Mississippi, Sun-Tue, Mar 1-3.
- A slight risk of much below-normal minimum temperatures from the eastern
Intermountain region eastward across the Rockies, Great Plains, Mississippi
Valley, the Great Lakes region, Ohio and Tennessee Valleys, the Appalachians,
and the Atlantic Coast states from Virginia to Maine, Fri-Sat, Mar 6-7.
- A moderate risk of much below-normal minimum temperatures for much of the
central and southern Plains, the upper and middle Mississippi Valley, the Great
Lakes region, Ohio Valley, and from northern West Virginia and northern
Maryland northeastward to western New England, Fri-Sat, Mar 6-7.
- A high risk of much below-normal minimum temperatures from the central
Plains northeastward across the Midwestern states to lower Michigan, Fri-Sat,
- Severe drought for the Central and Southern Great Plains, Southwest, Great
Basin, California, the Pacific Northwest, and Tennessee Valley.
At the start of this period, an arctic air mass is
forecast to be in place across the central and eastern CONUS. Some of this
colder air is expected to spill west of the Continental Divide, reducing
daytime high temperatures by as much as 8-12 degrees F. However, the largest
departures from normal are anticipated east of the Divide, ranging from 12 to
as much as 28 degrees F below-normal across portions of the Great Plains.
Periods of heavy snow are predicted for the Four Corners region from Mar
1-4, as a surface low pressure system traverses the area and interacts with
arctic air. A positively tilted 500-hPa trough, expected to be just west of
this region, will help provide a favorable environment for precipitation with
its associated large-scale ascent of air.
Significant wave heights of 23-26 feet are forecast by the NOAA Wavewatch
Model for the western Aleutians on March 1, as a storm approaches from the
As an arctic high pressure center (1040 hPa) moves off the mid-Atlantic
Coast, southeasterly surface flow is predicted to briefly develop across the
southern Plains and lower Mississippi Valley prior to the next southward push
of cold air. Current thinking is that the boundary separating the warm, moist
air from the cold, dry air (initially stretching from the southern Rockies to
the middle Mississippi Valley to the central Appalachians) will advance and
retreat several times during this period. Rather than have a single, major
storm system to contend with, it appears the associated precipitation will be
distributed among two, weaker storm systems, which generally track from the
southern Plains northeastward towards the mid Atlantic region. This complex and
very dynamic setup makes it extremely difficult to accurately determine where
the swaths of rain, snow, freezing rain, and sleet will be, and how they will
shift with time. At this time, the area most likely to experience significant
snowfall with these back-to-back storm systems is from western Kansas
east-northeastward across the middle Mississippi Valley and northern Ohio
Valley to New England. The area most likely to experience heavy rainfall is
from far eastern Texas and the lower Mississippi and Tennessee Valleys eastward
across portions of the Carolinas, and from most of Virginia into New Jersey.
In-between these predicted snow and rain areas is where a transition zone of
freezing rain and ice pellets is expected to set up. However, what the map
cannot show is how these three bands of precipitation are expected to shift
northward or southward with time, so these depicted areas should be interpreted
only as a general guide. Icy precipitation events are common in winter on the
northern and western sides of an upper-air ridge forecast to be located across
the Southeast U.S.
Another consideration associated with the anticipated precipitation events
over the central and eastern CONUS is severe weather. With so much uncertainty
as to whether arctic air or maritime tropical air dominates the southern
Plains, the lower Mississippi Valley, and the Ohio and Tennessee Valleys, no
area of severe weather is indicated on the map. If warm advection of moist,
unstable Gulf air dominates, the chances for severe weather will increase in
this area. However, if cold, dry arctic air dominates, the boundary layer will
be very stable, with winds blowing offshore, effectively shutting down the
potential for severe thunderstorm activity.
Flooding is possible in central Mississippi from Sunday to Tuesday,
especially in regards to the Big Black River at Bentonia and West. Several
hydrographs (U.S. Army Corps of Engineers) indicate this river will remain
above flood stage at least into Tuesday. According to the Advanced Hydrologic
Prediction System (AHPS), 3-5 inches of rain has fallen in this area during the
past 7-days. For Friday March 06 - Thursday
There is a slight risk of much below-normal temperatures from
the eastern Intermountain region eastward across the Rockies, Great Plains,
Mississippi Valley, the Great Lakes region, Ohio and Tennessee Valleys, the
Appalachians, and the Atlantic Coast states from Virginia to Maine, Fri-Sat,
Mar 6-7. A moderate risk of much below-normal minimum temperatures is indicated
for much of the central and southern Plains, the upper and middle Mississippi
Valley, the Great Lakes region, Ohio Valley, and from northern West Virginia
and northern Maryland northeastward to western New England, Fri-Sat, Mar 6-7. A
high risk of much below-normal minimum temperatures is depicted from the
central Plains northeastward across the Midwestern states to lower Michigan,
Fri-Sat, Mar 6-7.
The most recent U.S. drought monitor, released today, February 26, 2015,
indicates a slight decrease in the areal coverage of severe to exceptional
drought (D2 to D4) in the past week from 16.44 to 16.42 percent across the
continental U.S. Forty percent of California remains designated in the
exceptional drought (D4) category. Although most revisions made to the Monitor
this week are fairly small, the more notable changes include a general
1-category improvement in Kentucky and western Tennessee, and a 1-category
degradation across the central Gulf Coast area.
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.