Philippines brace for Typhoon Mirinae; big snowstorm wallops Colorado

Category 2 Typhoon Mirinae continues to trek westward towards the Philippine Islands, but has not intensified and may be weaker than advertised. Latest infrared satellite loops show no eye, and little change to the areal extent, organization, and temperature of the cloud tops over the past six hours. Satellite estimates of Mirinae's intensity declined over the past twelve hours, and support a Category 1 typhoon. Microwave imagery shows no eyewall, and it appears wind shear has managed to disrupt the inner core. Wind shear remains a moderate 15 knots, and the ocean temperatures are very warm, 29°C. With environmental conditions forecast not forecast to undergo any major changes over the next two days, Mirinae should be somewhere between a Category 1 and Category 3 typhoon when it makes landfall on Friday afternoon (EDT). The main threat from the storm will be heavy rains, and Mirinae is currently producing maximum rains of about eight inches per day along its track (Figure 1). The mountains of Luzon Island will cause additional uplift and lead to higher rain amounts as the typhoon passes over, and rain amounts in excess of twelve inches near Mirinae's core will cause serious flooding and dangerous mudslides. The ground is still flooded and the dams brimming full from the previous two typhoons to hit the Philippines over the past five weeks, so Mirinae will probably cause much heavier damage than is usual for a typhoon of its intensity. The typhoon is forecast to pass within 200 miles of the capital of Manila, where flood water from the September 26 deluge of Typhoon Ketsana is still standing in the streets of some suburban areas. More than one million people are living in flooded districts near Manila.


Figure 1. Rainfall forecast for Typhoon Mirinae for the 24-hour period ending at 06 UTC Friday October 30, 2009. Mirinae is expected to dump 8+ inches of rain along a narrow swath near its core. Image credit: NOAA/NESDIS.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss, and the the Caribbean is dominated by dry air and high wind shear. However, a non-tropical low pressure system is expected to develop in the middle-Atlantic on Monday, and may spend enough time over water to acquire some tropical characteristics and become Subtropical Storm Ida. Wunderblogger Weather456 has a nice discussion of the meteorology of this storm, which may bring high winds to Bermuda next week. Elsewhere in the Atlantic, none of the computer models is calling for tropical storm development over the next seven days. Several models are calling for a tropical storm to form off the Pacific coast of Mexico by the middle of next week.

Major snowstorm wallops Colorado
The season's first major snowstorm is walloping Colorado, Wyoming, and western Nebraska and South Dakota today. In the mountain regions just west of Denver, up to 38 inches of snow has fallen, with another 4 - 12 inches possible today. It was the biggest October snowstorm in the Denver region since 1997.

Portlight's Paul Timmons on the Barometer Bob Show Tonight
Portlight's Paul Timmons will be appearing live tonight (Thursday) at 8pm EDT on the Barometer Bob Show, an Internet radio show that I have appeared on several times in the past. Be sure to catch his discussion of how Portlight got started, where they're going, and what's new!

Jeff Masters