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Valid Monday May 28, 2018 to Friday June 08, 2018
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EDT May 25 2018Synopsis
: The summer season is expected to move
in quickly for much of the contiguous U.S., with two high impacts events in the
day 3-7 forecast. Subtropical storm Alberto in the Gulf of Mexico is expected
to bring unsettled weather to the southeastern U.S, while intense upper-level
high pressure is forecast to dominate the central region. Impacts from this
anomalous high pressure are expected to last into Week-2 for the middle third
of the U.S. Upper-level ridging over Alaska in Week-2 is likely to quiet the
previously active storm track along the southern Coast.
Detailed Summary For Monday May 28 -
Friday June 01:
- Heavy rain across portions of the Central
Plains, the Upper Mississippi Valley, and the Northern Plains, Mon-Tue, May
- Heavy rain across portions of the Lower Mississippi Valley, the Central
Appalachians, the Tennessee Valley, the Mid-Atlantic, the Southern
Appalachians, the Southeast, and the Ohio Valley, Mon-Fri, May 28-Jun 1.
- Flooding possible across portions of the Northern Rockies.
- 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 and the Northern
- Excessive heat across portions of the Middle Mississippi Valley, the Lower
Mississippi Valley, and the Southern Plains, Tue-Thu, May 29-May 31.
- High winds across portions of the Southeast and the Lower Mississippi
Valley, Mon, May 28.
- Much above normal temperatures across portions of the central U.S.,
Mon-Fri, May 28-Jun 1.
- High significant wave heights for coastal portions of the Southeast and the
Lower Mississippi Valley, Mon, May 28.
- Moderate risk of excessive heat for parts of Texas and the Lower
Mississippi Valley, Sat-Sun, June2-3.
- Slight risk of excessive heat for parts of Texas and the Lower Mississippi
Valley, Sat-Sun, June2-3.
- Slight risk of much above normal temperatures for portions of the central
U.S., Sat-Tue, Jun 2-Jun 5.
- Moderate risk of much above normal temperatures for portions of the Central
Plains, the Mississippi Valley, the Southern Plains, and the Southwest,
Sat-Mon, Jun 2-Jun 4.
- High risk of much above normal temperatures for portions of the Southern
Plains, Sat-Sun, Jun 2-Jun 3.
- Severe Drought across the Central Plains, the Central Rockies, the Central
Great Basin, the Northern Plains, the Northern Great Basin, the Southern
Rockies, California, the Southern Plains, and the Southwest.
The Southeast is a focal point for this forecast, as
subtropical storm Alberto has formed in the Gulf of Mexico. The National
Hurricane Center currently is forecasting a track through the Gulf of Mexico
and into the central Gulf Coast through the day 3-7 period. Model guidance
shows this system moving overland in the Southeast during days 3-7, first
impacting the Southeast before moving northward toward the mid-Atlantic. High
winds (sustained winds exceeding 35 knots) and significant wave heights are
likely for the central Gulf Coast in conjunction with the track of the tropical
system. Heavy rain is forecast from the Southeast to the Mid-Atlantic, May
28-Jun 1. The highest totals are likely to be in the Southeast early in the
period, with some areas receiving more than 2 inches of rain in 24 hours.
Upper-level ridging over the central U.S. during the day 3-7 period is
forecast to cause widespread warm temperatures over the region. Today's model
guidance shows the peak intensity of this ridge toward the end of this period
into Week-2. Much above normal temperature (anomalies of +16 degrees F) are
forecast over the Plains region and into the Mid-west for May 28-Jun 1. A
shortwave trough early in the period is forecast to quickly weaken as it moves
eastward over the northern tier of the U.S.; this pattern likely will interrupt
the warmer temperatures for parts of the north central Plains, so the area of
concern for the high temperatures has shifted eastward from yesterday's
forecast. The forecast extreme heat index values for the Southern Plains are
not quite as widespread as yesterday; however, excessive heat (heat index
values exceeding 105 degrees F) is still likely for parts of the lower
Mississippi River Valley and Southern Plains for Jun 1, as the ridge
Surface low pressure systems moving over the northern Plains and Rockies
early in the period are likely to cause heavy rain from May 28-30. The storm
system is expected to cause localized heavy rain, first in the Dakotas on May
28 and then moving eastward over the central Plains and also northeastward into
Minnesota, May 29-30. The GFS model shows several localized regions of heavy
rainfall (1.5 inches in 24 hours) over the entire highlighted region, while the
ECMWF focuses the higher rainfall totals in the central Plains.
An upper-level ridge is forecast to build in the Gulf of Alaska, while
upper-level troughing is expected for mainland Alaska throughout days 3-7. A
few surface low pressure systems are forecast in the region, one in the Bering
Sea and another moving north along the southern coast from the Gulf of Alaska;
however, impacts from these systems are forecast to remain below hazardous
thresholds. For Saturday June 02 - Friday
With model guidance forecasting the upper-level ridge over the
central U.S. to amplify late in Week-1 and into Week-2, the early season heat
wave in the southern and central Plains, as well as parts of the Midwest, is
likely to peak during the early part of Week-2. The axis of this ridge is
forecast to be more positively tilted over the Southern Plains in to the Great
Lakes region. A slight risk for much above normal temperatures is forecast over
this general region, as warm temperatures are likely to penetrate into the
upper Midwest, Jun 2-5. A moderate risk is forecast for parts of the southern
Plains and lower Mississippi River Valley, Jun 2-4, while a high risk is
forecast for parts of Texas, Jun 2-3, when upper-level ridging is likely to
be most intense. The GFS ensemble forecasts a 20% chance of exceeding the 90th
percentile of climatological normal over the entire highlighted region, and a
40-60% chance of exceeding the 85th percentile for the southern portion of this
region. Warm temperatures are most likely to affect the northern extent of the
highlighted region early in the period, before upper-level troughing moves
south from Canada, pushing the ridge further south.
A slight risk for excessive heat (heat index values exceeding 105 degrees
F) has also been issued for parts of the southern Plains in the early part of
Week-2, Jun 2-3, during the peak of the warm temperatures. For the regions with
the where heat index values have a 50% chance of exceeding the 90th percentile
of climatological normal, a moderate risk for excessive heat has been issue.
The upper-level trough moving through the northern tier of the U.S. is
likely to cause an unsettled pattern over the northern Plains, with the
possibility of heavy rain and severe weather toward the middle of Week-2.
Confidence in this forecast is low though, as model guidance is not showing a
strong signal as of yet, so this hazard has been currently kept off the map.
Persistent upper-level ridging is expected for Alaska in Week-2. This will
likely bring some warmer temperatures to interior Alaska, though none are
currently forecast to exceed hazardous thresholds. The recently active storm
track along the southern coast of Alaska is forecast to be quieter in Week-2.
The US Drought Monitor, valid on May 22, indicates that the coverage of
severe to exceptional drought has again increased slightly this week, from
16.71 percent last week to 16.84 percent. Parts of the Southwest improved from
D4 to D3 drought, while conditions in the Oklahoma panhandle and northern Texas
continue to degrade.
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.