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HOME> Expert Assessments>Hazards Outlook

U.S. Hazards Outlook - Made July 01, 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 Saturday July 04, 2015 to Wednesday July 15, 2015

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 01 2015

Synopsis: A series of cold fronts are forecast to impact the central and eastern part of the Lower 48, while upper-level high pressure is expected to impact regions from the Southwest U.S. to mainland Alaska. Low pressure is expected to bring active weather to the Aleutians and far western Alaska during the period.

Hazards Detailed Summary

For Saturday July 04 - Wednesday July 08: At the beginning of this period, an 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 for this entire period. Some of these areas may experience temperature anomalies approaching 20 degrees F or greater above climatology, especially early in the period. 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 still 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 stalled frontal boundary at the beginning of the period is expected to focus locally heavy rainfall over parts of the Tennessee Valley. The threat for heavy rain is greatest on Friday and Saturday where the hazard is depicted, with increased uncertainty beyond that, as the frontal zone is forecast to slowly move north as a warm front ahead of the next shortwave trough and associated surface low. Within the depicted hazard, some areas could receive over 2 inches of rain during the period.

To the southeast of the front, hot and humid conditions are likely, though the latest guidance suggests that heat index values will not warrant a depicted hazard at this time.

As a forecast upper-level trough swings through southern Canada during the period, surface low pressure and an associated cold front are expected to impact the northern Plains, upper Midwest, and Great Lakes, resulting in cooler-than-normal temperatures and increased rain chances by late in the period. Currently there is insufficient model support for a heavy rain hazard.

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. Active weather is possible over the Aleutians during the period, though no additional hazard depiction is warranted.

For Thursday July 09 - Wednesday July 15: 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. However, the forecast pattern looks potentially less amplified than that for the early part of 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


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.