Valid Monday August 03, 2015 to Friday August 14, 2015
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EDT July 31 2015Synopsis
: A cold front is predicted to propagate
southeastward from the northern tier of the lower 48 states at the beginning of
the period and evolve into a stationary front, stretching from the central
Plains to the Mid-Atlantic by Thursday. A series of cold fronts are anticipated
to enter the Pacific Northwest and northern California during the 3-7 day
period. Much of Alaska is expected to have a relatively mild weather pattern
during days 3 to 7, with potential warming across the southern half of Alaska
and the central-southern panhandle during week-2. Hazards
For Monday August 03 - Friday August 07:
- Heavy rain for parts of the Central Plains, and the Middle Mississippi
and Ohio Valleys, Wed, Aug 5.
- Excessive heat for parts of the Southeast, Tue-Fri, Aug 4-7.
- Flooding is ongoing or likely for parts of the Middle and Lower Mississippi
- Severe drought for parts of the western third of the CONUS, southern
Georgia, southern Florida, North Carolina and Hawaii.
- Slight chance of much above normal temperatures across parts of the Central
and Southern Plains, Lower Mississippi Valley, and Southeast, Sat-Fri, Aug 8-14.
- Slight chance of much above normal temperatures across parts of the
southern half of mainland Alaska and central-southern Alaska Panhandle,
Sat-Fri, Aug 8-14.
A cold front is expected to sink
southward from the northern tier at the beginning of the period, developing
into a stationary front stretching from the Central Plains to Mid-Atlantic by
Thursday. This front may bring heavy rain to parts of the Central Plains,
Middle Mississippi, and Ohio Valleys on Wednesday. There is significant
uncertainty regarding the specific locations expected to receive heavy rain and
rainfall totals. Localized areas may receive anywhere from an inch to three
inches of rainfall in a 24-hour period. Additionally, atmospheric conditions
may be conducive to severe weather associated with this front, initially for
parts of the Northeast and Ohio Valley on Monday and Tuesday, followed by the
Central and Northern Plains on Tuesday and Wednesday. At this time, the Storm
Prediction Center has not highlighted any areas of risk yet, but updated
forecasts should be monitored at www.spc.noaa.gov, as well as local forecasts
The subtropical ridge is anticipated to extend into the southeastern CONUS,
promoting strong, onshore flow off the Gulf of Mexico. This pattern may lead to
excessive heat across parts of the Southeast Tuesday to Friday, and heavy
rainfall across central and eastern Gulf Coast areas Thursday and Friday.
However, an associated heavy rainfall area is not designated at this time due
to significant model uncertainty. Daily maximum heat index values may reach
greater than 105 deg F over these areas.
There is a potential for localized heavy rainfall across parts of the Four
Corners region on Monday, associated with the Southwest monsoon. Warm, moist
flow associated with a surface low over the Southern Plains, in conjunction
with the persistent low over Baja California, has the potential to reinvigorate
chances for heavy rain to localized areas of the Four Corners region, Central
Plains, and Middle Mississippi Valley by late next week into next weekend.
Significant model uncertainty precludes a specific area from being highlighted
at this time. Interests in these areas should take caution, since heavy rains
may lead to flash flooding and dangerous conditions, especially in low-laying
areas between canyons and arroyos.
As of Friday, July 31 2pm, Hurricane Guillermo has the potential to have a
track approaching Hawaii, most likely reaching Hawaii around Wednesday. This
tropical disturbance may bring heavy rain, high winds, and significant wave
heights to parts of Hawaii on Wednesday and Thursday. Updated information
regarding this storm should be monitored using the National Hurricane Center
website (http://www.nhc.noaa.gov). For Saturday August 08 - Friday
There is relatively good model agreement indicating the
building of an amplified upper-level ridge across the southern tier and
south-central CONUS during week-2. This pattern is expected to persist for the
duration of week-2, favoring a slight risk of much above normal temperatures
across parts of the Central and Southern Plains, Lower Mississippi Valley, and
Southeast. The GEFS Reforecast Tool shows the possibility of parts of
South-Central CONUS experiencing temperatures greater than 100 deg F.
The majority of models indicate the possible development of an amplified
ridge over parts of mainland Alaska and the Alaska Panhandle. This pattern
supports a slight risk of much above normal temperatures for parts of the
southern half of mainland Alaska and central-southern Alaska Panhandle during
the week-2 period. Some models indicate the potential of an upper-level
shortwave propagating across southern, mainland Alaska, which would decrease
the likelihood for much above normal temperatures as well as the duration of
the event. The GEFS Reforecast Tool shows a 20% chance of temperatures in these
highlighted areas reaching greater than the 85th percentile, compared to
Forecaster: Melissa Ou
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.