National Situation Update: Tuesday, April 17, 2007
Homeland Security Threat Level: YELLOW (ELEVATED).
National Weather
Northeast: The Nor'easter just off the East Coast is forecast to move to the northeast resulting in decreasing winds and improving weather. Most areas will see less than one inch of precipitation today but many rivers are already at or above flood stage. Flood Warnings and Watches are in effect from the mid-Atlantic to New England. Interior areas of Pennsylvania and New York will receive one to two inches of wet snow. High Wind Watches are up for much of the Mid-Atlantic until midday with winds of 20 to 35 mph and gusts to 60 mph. Coastal Flood Warnings and Watches are in effect for New England where the combination of strong northeast winds and large waves will cause water to pile up along the coast. These conditions along with high astronomical tides (approximately noon and midnight) may produce coastal flooding near the time of high tide. High temperatures are still well below seasonal norms ranging from the 30s to the 60s.
South: High pressure will result in sunny, seasonably warm weather over much of the region. A frontal system over the Texas Panhandle, eastern Texas and Oklahoma will result in up to an inch of rain in some areas causing localized flooding. In north-central and east Texas the thunderstorms may produce hail, gusty winds and tornados. During the evening, the showers and storms will move into Arkansas and Louisiana. High temperatures will range from the 50s in parts of Oklahoma to the 80s in along the Gulf Coast.
West: A cold front moving in off the Pacific will produce showers and mountain snow over western Washington, western Oregon, Idaho, western Montana, and the northern reaches of California and Nevada. Behind the cold front gusty winds are forecast over California and Nevada. High temperatures will range from the 40s in parts of the Rockies, the Sierra Nevada and Pacific Northwest to the 90s in the lower Colorado River Valley.
Midwest: An upper-air low is moving eastward over the southern Plains will produce showers and thundershowers over Missouri, Nebraska and Kansas. A weak cold front will produce a few showers over Wisconsin, Minnesota and the western Great Lakes before it croaks completely. High temperatures will range from the 40s in Michigan's Upper Peninsula to the 70s in the mid-Mississippi Valley. (NOAA, National Weather Service, Media Sources)
Storm-Based Warnings will be implemented on October 1, 2007
NOAA's National Weather Service (NWS) will introduce this fall storm-based warnings for tornadoes, severe thunderstorms, flash floods, and marine hazards that are more geographically specific for these short-duration weather events. Currently, such warnings are issued county wide.
Storm-Based Warnings (threat-based polygon warnings), are essential to effectively warn for severe weather. Storm-Based Warnings show the specific meteorological or hydrological threat area and are not restricted to geopolitical boundaries. By focusing on the true threat area, warning polygons will improve NWS warning accuracy and quality. Storm-Based Warnings will promote improved graphical warning displays, and in partnership with the private sector, support a wider warning distribution through cell phone alerts, pagers, web-enabled Personal Data Assistants (PDA), etc. When issuing a warning, the NWS will specify areas within a county and refer to commonly known landmarks such as highways or rivers. (NOAA)
Avalanche Danger for Juneau Alaska
The Southeast Alaska Avalanche Center was reporting the Avalanche danger for urban paths on the Gastineau Channel side of Mt. Juneau yesterday as SERIOUS and the 24 hour trend as SAME DANGER. (The Southeast Alaska Avalanche Center www.avalanche.org/~seaac/index.html )
Avalanche Danger Scale
LOW (green)
MODERATE (yellow)
- Natural avalanches unlikely, potentially destructive avalanches unlikely to reach lower elevations from high starting zones. Human triggered avalanches possible.
- Unstable slabs possible on steep terrain.
- Use caution in or under steeper terrain.
SERIOUS (orange)
- Natural avalanches possible, potentially destructive avalanches may reach lower elevations from high starting zones. Human triggered avalanches probable.
- Unstable slabs probable on steep terrain.
- Be increasingly cautious in or under steeper terrain.
HIGH (red)
- Potentially destructive natural avalanches likely to reach lower elevations, human-triggered avalanches likely.
- Unstable slabs likely on a variety of aspects and slope angle.
- Being in avalanche terrain or runout zones is not recommended. Safest places are windward sides of ridges or lower angle slopes without steeper terrain above.
We do not normally use the fifth point of the U. S. scale, but on those rare occasions when avalanche danger is so high that is essentially off the scale and widespread large natural avalanches are probable, the designator is EXTREME (black). Being anywhere near avalanche terrain or runout zones is not recommended.
Tropical Weather Outlook
No new activity (FEMA HQ)
Earthquake Activity
No significant activity in the United States during the last 24 hours.
Monday, April 16, 2007, 9:20 AM EDT, an earthquake (magnitude 6.2) was detected 1,400 miles south of Melbourne, Victoria, Australia, at a depth of 6.2 miles. No reports of injuries or damage.(NOAA, USGS, Earthquake Hazards Program, Alaska Earthquake Information Center, Pacific Tsunami Warning Center, and West Coast/Alaska Tsunami Warning Centers)
Preliminary Damage Assessments
Joint PDAs for West Virginia are anticipated to begin on Wednesday, April 18, 2007.(FEMA HQ)
Wildfire Update
National Preparedness Level 1 (lowest on a scale from 1 to 5)
On Monday, a wildfire threatened a school and homes in Ware County, Georgia. The fire burned 700 acres. Red Flag Warnings are in effect for parts of Texas, New Mexico, Alabama, Florida, and South Carolina. (FEMA Region IV, NIFC, media sources)
Disaster Declaration Activity
No new activity (FEMA HQ)
Last Modified: Tuesday, 17-Apr-2007 08:07:29 EDT