delayed in updating graphics.
most up to date graphics.
Valid Saturday May 26, 2018 to Wednesday June 06, 2018
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EDT May 23 2018Synopsis
: An active pattern is expected to bring
wet weather to much of the eastern U.S. during the forecast period and the
highest rainfall is expected to be in the Southeast. A low pressure system with
tropical origins is forecast to bring significant rainfall to the Southeast
this weekend and residual rainfall is likely to spread to the mid-Atlantic by
the beginning of next week. A series of upper-level low pressure systems will
move through the Gulf of Alaska this week and could bring significant rainfall
to the Alaskan Panhandle on Saturday. Hazards
Summary For Saturday May 26 - Wednesday May 30:
- Heavy rain
across portions of the Southeast, the Southern Appalachians, the Lower
Mississippi Valley, the Southern Plains, and the Tennessee Valley, Fri-Sat, May
- Heavy rain across portions of the Lower Mississippi Valley, the Central
Appalachians, the Tennessee Valley, the Mid-Atlantic, the Southern
Appalachians, the Southeast, the Southern Plains, and the Ohio Valley, Sun-Tue,
May 27-May 29.
- Flooding possible across portions of the Mid-Atlantic, the Pacific
Northwest, and the Upper Mississippi Valley.
- Flooding occurring or imminent across portions of the Northern Plains, the
Northern Rockies, and the Northern Great Basin.
- Flooding likely across portions of the Northern Plains, the Northern
Rockies, and the Northern Great Basin.
- Heavy rain across portions of the Alaska Panhandle, Sat, May 26.
- Slight risk of much above normal temperatures for portions of the Central
Plains, the Central Rockies, the Lower Mississippi Valley, the Southern
Rockies, the Southern Plains, and the Southwest, Thu-Sat, May 31-Jun 2.
- Moderate risk of much above normal temperatures for portions of the
Southern Rockies, the Southern Plains, and the Southwest, Thu-Sat, May 31-Jun 2.
- Slight risk of heavy precipitation for portions of the Lower Mississippi
Valley, the Tennessee Valley, the Middle Mississippi Valley, the Mid-Atlantic,
the Southern Appalachians, the Southeast, and the Ohio Valley, Wed-Sun, May
- Moderate risk of heavy precipitation for portions of the Southeast, the
Mid-Atlantic, the Lower Mississippi Valley, the Southern Appalachians, and the
Tennessee Valley, Wed-Fri, May 30-Jun 1.
- Severe Drought across the Central Plains, the Central Rockies, the Central
Great Basin, the Northern Plains, the Southern Rockies, California, the
Southeast, the Southern Plains, and the Southwest.
The upper-level pattern over the CONUS is forecast to feature two large
troughs over the western and eastern U.S., leading to a likely unsettled
pattern for much of the lower 48. The National Hurricane Center has upgraded
the tropical system in the Gulf to a 60% chance of formation in the next 5
days. This tropical system is likely to bring heavy rain to the Southeast and
Florida for the duration of the 3-7 day period, May 26-30. Most model guidance
has continued to support the tropical low moving up the western side of the
Florida peninsula, except for the deterministic GFS, which has the system
moving up eastern side. Due to model agreement in the other models, the
deterministic GFS solution was not favored in this forecast. The Gulf coast is
likely to see the heaviest precipitation in the early part of the period, May
26-28, with localized totals possibly reaching up to 4 inches. As the tropical
system moves over land, the region of heavy rain is forecast to expand
northward to Tennessee and the Carolinas. Many of these regions have been
impacted by heavy rain in the past few weeks, so continued heavy rain could
elevate certain localized hazards.
Several surface low pressure systems are expected to transverse the central
U.S. over the 3-7 day period. Heavy rain is likely in Nebraska in association
with these systems, from May 28-29. Both GFS and ECMWF models show 24-hour
rainfall totals from 1.5-2.5 inches for localized regions.
Upper-level ridging and southerly flow are expected to impact the central
CONUS, causing widespread much above normal temperatures over the Plains, May
26-28. Several areas in the central Plains are forecast to break or tie daily
temperature records with temperature anomalies up to 16 degrees F. Highs in
these regions are expected to reach the upper 90ís, with localized areas
surpassing 100 degrees F. Heat index values along the western Gulf Coast are
forecast to reach 105 degrees F, with some regions in southern Texas reaching
110 degrees F on Monday.
Persistent upper-level troughing is expected for Alaska throughout days
3-7. At the start of the period, a storm system associated with an upper-level
trough is forecast to move inland over the Panhandle from the Gulf of Alaska.
This will bring heavy rainfall to the Alaskan South Coast and Panhandle.
Although most of the South Coast rainfall should stay below our hazardous
criteria, models indicate that isolated areas along the Panhandle could see
more than 3 inches of rain on Saturday, May 26. For Thursday May 31 - Wednesday
Broad upper-level ridging is forecast over the CONUS for much of
Week-2. This upper-level pattern is likely to continue warmer temperatures over
the central and southern Plains in the early part of Week-2. A slight risk for
much above normal temperatures has been issued for the southern Plains up
through parts of Kansas for May 31-June 3. Southern Texas and parts of the
Panhandle are likely to experience the warmest temperatures. Model guidance
from the GEFS indicates a 40% chance that temperatures in these regions will
surpass the climatological 85th percentile, so there is a moderate risk for
much above normal temperatures in Southern Texas from May 31-June 2. Toward the
end of the period, the upper-level pattern is forecast to weaken and begin to
For the Southeast, a weak upper-level trough is likely over the region for
the early part of Week-2. Heavy rainfall is expected to continue for the
Southeast through the period. The GFS and ECMWF ensembles support heavy rain
throughout the entire period, with a 20% chance of reaching the 85th percentile
of the climatological normal. A slight risk of heavy precipitation is forecast
for the region May 31-June 6. Model guidance shows the highest chances (above
40%) of reaching the 85th percentile mid-period, so a moderate risk of heavy
precipitation has been issued from June 2-4 for the central Gulf Coast states.
Upper-level ridging is expected to replace most of the troughing from the
day 3-7 period for Week-2 over Alaska. This will likely bring some warmer
temperatures to interior Alaska, though none are currently forecast to reach
above hazardous thresholds.
The US Drought Monitor, valid on May 15, indicates that the coverage of
severe to exceptional drought increased slightly from 15.92 percent last week
to 16.71 percent this week.
Forecaster: Christina Finan
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.