Valid Tuesday June 09, 2020 to Monday June 15, 2020
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EDT June 01 2020Synopsis
: An active start to the tropical season
is becoming more likely toward the end of Week-1 and heading into Week-2, as
models favor the development of a tropical low in the Gulf of Mexico elevating
the risk of heavy precipitation and high winds for the southern U.S. Mid-level
high pressure forecast over the southwestern U.S. and the Southern Plains is
expected to lead to anomalously warm temperatures into the middle of June.
- Slight risk of heavy precipitation for portions
of the Southern Plains, the Lower and Middle Mississippi Valley, and the
Southeast, Tue-Fri, Jun 9-Jun 12.
- Moderate risk of heavy precipitation for portions of the Southern Plains,
the Lower Mississippi Valley, and the Southeast, Tue-Thu, Jun 9-Jun 11.
- Slight risk of high winds for portions of the Southern Plains, the Lower
Mississippi and Tennessee Valleys, and the Southeast, Tue-Thu, Jun 9-Jun 11.
- Slight risk of high winds for portions of the Central and Northern Plains,
Tue-Sat, Jun 9-Jun 13.
June 04 - Monday June 08: WPC Days 3-7 U.S.
Hazards For Tuesday June 09 - Monday
Today marks the first day of the Atlantic hurricane season and it
appears likely to hit the ground running. Since late last week, model guidance
has been consistent in the formation of a tropical low in the Gulf of Mexico
associated with the remnants of tropical cyclone Amanda which originated in the
East Pacific. The National Hurricane Center is currently monitoring an area of
convection over the Yucatan region of southern Mexico that is expected to move
northward in the Gulf later this week. Anomalously warm sea surface
temperatures and low vertical wind shear predicted by the models remain
conducive for the low to deepen into a new tropical depression throughout
Week-1, with possible adverse impacts over the Gulf States heading into Week-2.
Despite the consistency in the models for development, there are some
notable differences during the beginning of Week-2. Compared to this morning's
GEFS guidance, the ECMWF favors a more westerly mean solution in bringing the
closed low over parts of southeastern Texas prior to the start of Week-2. This
is reflected in the 0z ECMWF deterministic solution which depicts a slower, and
weaker northerly component to the track, as the low moves westward into
southeastern Texas by Jun 9. Additionally, there are large differences in the
24-hour ensemble mean precipitation amounts ending on Jun 10. The GEFS places
the bulk of the heavy rainfall east of the southern Plains, whereas the ECMWF
is drier over the Southeast and depicts much higher amounts over eastern Texas
and into Oklahoma as the low is expected to begin its extratropical transition.
The GEFS reforecast tool indicates many coastal regions from the Lower
Mississippi Valley and the Southeast at risk for heavy rainfall, whereas the
ECMWF reforecast tool focuses this tropically related rainfall extending across
the southern Plains and into the middle Mississippi Valley. As a result, a
broad slight risk of heavy precipitation is posted to account for these
differences, and a moderate risk is posted from eastern Texas along the coast
to the Florida Panhandle for the early portion of Week-2. Additionally, a
slight risk of high winds is issued mainly over the Lower Mississippi Valley.
Regardless of the location of potential landfall, deep southerly flow and the
advection of ample tropical moisture may lead to flooding across the Gulf coast
and inland areas particularly if this system were to slow.
Across the higher latitudes, the 0z and 6z GEFS ensemble means feature
anomalous troughing over the northwestern CONUS that is predicted to shift over
the Great Plains, while anomalous ridging is expected to develop over the
western and northeastern CONUS. Over the Central and Northern Plains, model
surface analysis depicts periods of strong pressure gradients and there is
agreement in reforecast tools highlighting a region with at least a 20% chance
maximum sustained winds exceed the 85th percentile and 25mph. A slight risk for
high winds is posted for Jun 9 to Jun 13. Relative to the predicted ridging
aloft over the eastern CONUS, anomalously warm maximum temperatures are likely
to persist from late in Week-1 into early Week-2, however, reforecast tools
indicate the increase in temperatures are not likely to exceed hazards
criteria. Although the ECMWF is more bullish with the prospect of daytime
temperatures exceeding the 85th percentile, there is reduced likelihood that
these temperatures will exceed 95 degrees F early in Week-1.
Over the southern CONUS, anomalously warm temperatures are also likely over
parts of southern and western Texas early in Week-2. Reforecast tools highlight
an area with at least a 20% chance maximum temperatures exceed 100 degrees F,
and heat index tools also support elevated chances of values exceeding 105
degrees. However, given the uncertainty between the GEFS and ECMWF relative to
the location of the predicted tropical system in the Gulf of Mexico to
potentially impact the region, no temperature related hazards are included in
the outlook. In the Southwest, ECMWF ensemble guidance favors the development
of positive height departures over the southwestern CONUS to also increase the
risk of excessive heat during late in Week-2. Reforecast tools reflect the
increase in anomalous warmth, with at least a 20% chance daytime temperatures
exceed the 85th percentile, however there is currently a low probability that
these temperatures will exceed heat advisory thresholds for the region (110
degrees F). This area will continue to be monitored for excessive heat in the
upcoming forecasts this week.
Forecaster: Nick Novella
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.
Week-2 Probabilistic Extremes Tool
GFS Ensemble Forecasts