Valid Thursday May 02, 2019 to Wednesday May 08, 2019
US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM
EDT April 24 2019
Synopsis: Mid-level low pressure is forecast
over the Western U.S. in week-2 favoring periodic impulses of shortwave energy
to eject out of the Rockies. These disturbances are favored to rotate around
the periphery of surface high pressure over the East, resulting in intermittent
chances of unsettled weather throughout the period.
Moderate risk of heavy precipitation for portions of the Central and
Southern Plains, and the Middle and Lower Mississippi Valley, Thu-Fri, May
Slight risk of heavy precipitation for portions of the Central and Southern
Plains, the Mississippi Valley, the Central and Southern Appalachians, the
Great Lakes, the Ohio Valley, the Tennessee Valley, the Northeast, and the
Mid-Atlantic, Thu-Wed, May 2-May 8.
Slight risk of much below normal temperatures for Montana and adjacent
areas, Thu, May 2.
For Thursday May 02 - Wednesday
May 08: A noticeable shift in model guidance today has resulted in some
changes to the hazards outlook compared to yesterday. A stronger trough is now
favored in the Western CONUS early in week-2, along with an eastward
displacement of the mid-level ridge and surface high pressure in the East.
Because of the increased troughing in the West, there is an increased risk for
cooler temperatures early in week-2, with a slight risk for much below normal
temperatures (20% chance of minimum temperatures in the lowest 15th percentile
of the climatological distribution) now posted over much of Montana, Northern
Wyoming, and the far Western Dakotas on 5/2 given the potential of a hard
freeze in some areas. This is based on guidance from the GEFS reforecast tool.
Snow is also possible early in the period over this region as shortwave energy
may interact with the cold air in place.
With the eastward shift in the ridge axis, the precipitation axis is also
shifted southward and eastward compared to yesterday. A disturbance ejecting
out of the Rockies early in the period favors a heightened chance for heavy
precipitation across the Plains early in week-2. The GEFS focuses the heaviest
precipitation across portions of the Central Plains and adjacent parts of the
Mississippi Valley, while the ECMWF ensembles favor the Southern Plains to have
the highest precipitation totals. Synoptically, the overall set-up looks
conducive for a convective event, and therefore a moderate risk of heavy
precipitation (40% chance of precipitation in the highest 15th percentile in
the climatological distribution) is highlighted for parts of the Central and
Southern Plains along with western parts of the Middle and Lower Mississippi
Valley. Throughout week-2, this along with other disturbances are favored to
track around the periphery of surface high pressure over the Southeast and
Western Atlantic, resulting in intermittent chances of heavy precipitation.
Therefore, a slight risk of heavy precipitation (20% chance of precipitation in
the highest 15th percentile in the climatological distribution) is posted for a
broad area extending from the Central and Southern Plains northeastward through
parts of the Mississippi Valley, the Ohio Valley, and into the Mid-Atlantic and
Northeast for the entire period. No areas of hazardous winds are posted,
although some gusty winds are possible in parts of the High Plains during
Ridging is forecast over Alaska in week-2 with some troughing forecast to
develop over the Bering Sea toward the middle of week-2. Precipitation threats
look minimal and therefore, no hazards are posted for the
Forecaster: Thomas Collow
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.