Valid Monday July 25, 2016 to Friday August 05, 2016
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EDT July 22 2016Synopsis
: A surface low and its trailing cold
front are forecast to progress across the east-central U.S. early in the
period. A stationary front is expected to extend across the Missouri River
Valley from July 25 to 28. An area of upper-level high pressure is forecast to
strengthen over the western U.S. during the next week, while an area of
upper-level low pressure persists over mainland Alaska through at least the end
of July. During Week-2, upper-level high pressure is expected to remain
anchored along the 35th parallel. Hazards
Detailed Summary For Monday
July 25 - Friday July 29:
heat for parts of the mid-Atlantic, Mon, Jul 25.
- Much above-normal temperatures for parts of the western U.S., Mon-Fri, Jul
- Periods of locally heavy rain for parts of the northern and central Plains
and middle to upper Mississippi Valley, Tue-Thu, Jul 26-28.
- Heavy rain for coastal southeast Alaska, Mon and Thu-Fri, Jul 25 and Jul
- Slight risk of much above-normal temperatures for much of the western U.S.,
Sat-Mon, Jul 30-Aug 1.
- Moderate risk of much above-normal temperatures for parts of northern
California, the Great Basin, and Pacific Northwest, Sat-Sun, Jul 30-31.
- Slight risk of much above-normal temperatures for parts of the mid-Atlantic
and Southeast, Sat-Mon, Jul 30-Aug 1.
- Severe Drought across parts of the Central Great Basin, California,
southern Arizona, Northern Plains, Southeast, lower Great Lakes, Northeast, and
Excessive heat is expected to persist across
parts of the mid-Atlantic through Monday, July 25. Maximum heat index values
are forecast to be near or above 105 degrees F in the outlined area for
excessive heat on the map. Excessive heat is expected to ease after Monday,
July 25 as 500-hpa heights decrease slightly across the east-central U.S.
An upper-level ridge is forecast to amplify across the western U.S. during
the next week. Much above-normal temperatures, with maximum temperatures
averaging around 10 degrees F above-normal, are expected to expand north from
California and Nevada to eastern Washington and Oregon from July 25 to 29.
Shortwave troughs embedded within increasing northwest flow aloft and a
stationary front is likely to result in the development of mesoscale convective
systems (MCSs) across the north-central Great Plains, beginning on July 26.
These MCSs are likely to bring periods of heavy rain (more than 1 inch per 24
hours) to parts of the Missouri and middle to upper Mississippi Valleys from
July 26 to 28. Low predictability in timing and exact location precludes
designation of a severe weather hazard across the central U.S. at this time.
A steady increase in monsoon moisture is expected across the Southwest as
the mid-level ridge axis shifts north and deep easterly flow becomes
established. Tropical Storm Frank in the east Pacific is forecast to become a
hurricane this weekend and track south of the Baja Peninsula. A northward shift
in the track of Frank would also enhance low-level moisture across the desert
Southwest. Although no heavy rain hazards are posted on the map, the risk for
convection capable of triggering flash flooding seems to be increasing across
the desert Southwest during the final week of July.
An amplifying upper-level trough coupled with onshore flow is expected to
result in heavy rainfall (2 inches or more per 24 hours) across coastal
southeast Alaska during this time period. Based on model guidance, heavy rain
is most likely on July 25 and then again on the 28th and 29th.
Tropical Storm Darby in the central Pacific is forecast to affect the
Hawaiian Islands this weekend with increased rainfall and winds. The predicted
track takes Darby north of the Hawaiian Islands early next week. Please refer
to the Central Pacific Hurricane Center (CPHC) at:
http://www.prh.noaa.gov/cphc/ for the latest updates. For Saturday July 30 - Friday
The 6Z GFS and 0Z ECMWF ensemble means feature an amplified
ridge near the West Coast. The amplified upper-level ridge continues to support
a slight risk of much above-normal temperatures across much of the western U.S.
from July 30 through August 1. A moderate risk of much-above normal
temperatures is posted across parts of California, the Great Basin, and Pacific
Northwest where the 6Z GFS ensemble mean indicates temperatures averaging more
than 8 degrees F above-normal on July 30 and 31. Based on guidance from the
GEFS reforecast tool, a slight risk of much above-normal temperatures is posted
for parts of the mid-Atlantic and Southeast from July 30 to August 1.
According to the U.S. Drought Monitor (USDM), released on July 21, severe,
or greater intensity, drought covers 5.68 percent of the U.S. Drought Monitor
areas (including Alaska, Hawaii, and Puerto Rico), an increase of a half
percent since the previous week. This increase is due to an expansion of
short-term severe drought east of the Rockies.
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.