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HOME> Expert Assessments>Hazards Outlook

U.S. Hazards Outlook - Made July 31, 2015

 Days 3-7Days 8-14Prob. Days 8-14
Precipitation No HazardsNot Available
TemperatureNo Hazards
SoilsNot Available

Categorical OutlooksDay 3-7Day 8-14
8-14 Day Probabilistic OutlooksTemperature HazardsPrecipitation Hazards

Valid Monday August 03, 2015 to Friday August 14, 2015

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 31 2015

Synopsis: 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 Detailed Summary

For Monday August 03 - Friday August 07: 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 at www.weather.gov.

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 August 14: 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 climatology.

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.