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HOME> Expert Assessments>Hazards Outlook

U.S. Hazards Outlook - Made June 30, 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 Friday July 03, 2015 to Tuesday July 14, 2015

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT June 30 2015

Synopsis: A frontal boundary is expected to be the focal point for unsettled weather across the central and eastern U.S. during the first several days of the period. Upper-level high pressure is forecast to dominate over the northwestern U.S. early in the period, expanding northwestward toward mainland Alaska later in the period. Periodic unsettled weather is expected over parts of the Southwest extending into the central Rockies, increasing in frequency heading toward the middle of the period.

Hazards Detailed Summary

For Friday July 03 - Tuesday July 07: At the beginning of this period, an amplified upper-level ridge is forecast over the western third of the CONUS with a trough downstream centered near the Great Lakes. This pattern favors much above-normal temperatures across parts of the Northwest, including northern California for this entire period. Some of these areas may experience temperature anomalies of 24 degrees F or greater above climatology, with temperatures reaching the triple digits. Because of the long duration of these anomalously warm temperatures, people outdoors or without air conditioning should take precautions.

Over the southwestern CONUS, a combination of remnant cold fronts and increased monsoonal flow out of the south is likely to lead to periods of locally heavy rain, spreading northward later in the period. While there is not sufficient confidence to warrant a specific hazard depiction, updated local forecasts should be monitored for the increasing potential of localized heavy rain and flooding over the next one to two weeks.

Over the central and eastern CONUS, a frontal boundary is expected to focus locally heavy rainfall extending from parts of eastern Oklahoma eastward through the Tennessee Vally into the Mid-Atlantic. The threat for heavy rain is greatest on Thursday and Friday where the hazard is depicted, with increased uncertainty beyond that, as the frontal zone is forecast to slowly move north. This increases odds for locally heavy rain over parts of the Midwest and Great Lakes by the end of the period.

To the southeast of the front, hot and humid conditions are likely, especially during the middle and latter parts of the period when the upper-level trough weakens and the frontal zone retreats northward. The excessive heat hazard is depicted as such due to the greatest likelihood of maximum heat index values exceeding 105F for multiple days.

Warm and dry conditions are anticipated across much of mainland Alaska, increasing chances for wildfire risk across parts of this area during this period as well as Week-2. An upper-low is forecast to impact the Alaskan panhandle at the beginning of the period, and some active weather is possible over the Aleutians late in the period, though neither currently warrants any additional hazards being specified.

For Wednesday July 08 - Tuesday July 14: During Week-2 the forecast circulation is dominated by positive 500-hPa height anomalies centered over the Gulf of Alaska with downstream troughing centered over the Great Lakes. The ensemble means indicate that the ridging over the northeastern Pacific and Alaska is part of a rex block at least early in the period, with an anomalous trough forecast to the south, just off the coast of California. Such a pattern favors increased rainfall associated with multiple cold fronts extending from the central Plains to the Northeast. A combination of stalled cold fronts and anomalous southerly flow will lead to increased chances of locally heavy rain and flooding for parts of the Southwest and Great Basin.

Anomalous ridging over Alaska increases the chances of dangerous fire weather, and so the hazard depicted in the 3-7 day period continues into Week-2.

With persistent ridging forecast just off the Northwest Coast, a slight risk of much above-normal temperatures continues through Week-2. Within that region the threat of much above-normal temperatures is moderate for the first three days of the period over the interior Pacific Northwest. However, the forecast pattern looks potentially less amplified than that for the 3-7 day period, as the height pattern exhibits some retrogression and undercutting is possible late in Week-2.

The most recent U.S. Drought Monitor, valid on June 23, indicates a small increase (from 13.62 to 14.31) in the percentage of the CONUS in severe to exceptional drought (D2-D4).

Forecaster: Stephen Baxter


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Please consult local NWS Forecast Offices for short range forecasts and region-specific information.