Archive for August, 2009

Wildfires
August 31, 2009

Hot, dry conditions have made conditions conducive to the development of wildfires in the southwest U.S.

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The image above is from late in the day Sunday (Pacific time). At the bottom of the image, the red dot just north of Los Angeles indicates the fire near Mt Wilson. The heavy smoke is drifting into Nevada. Other Fires are in the Sierra Nevada Mountains of California and in southwest Utah.

MtWilsonje

The black and white image above is from the Naval Research Laboratory and was taken at 4pm eastern time (1pm pacific) this afternoon. The highlighted area includes the the white dot near Mt Wilson where the smoke and fire are most intense plus a faint smoke plume drifting to the northeast. As the sun gets lower in the sky this evening, shadows will make the smoke plume more visible in satellite images.

Mt Wilson sits north of the Los Angeles Basin and is the site of numerous radio and TV transmission towers as well as other communications facilities. Also, the famed Mt Wilson Observatory is nearby.

John Collins

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Active Monday
August 31, 2009

There is quite a bit of weather to look at today.

Cooler, less humid air has filtered into a portion of the Mid Atlantic region. A frontal boundary has stalled to the southeast of Maryland and Monday morning temperatures have been in the 60s. A disturbance is moving along that boundary and has pushed clouds over much of Maryland. Rain shower activity associated with the disturbance has remained south and east of the Baltimore-Washington area. With high pressure moving in from the Great Lakes, the rain area is expected to be held to the south and east of the metro areas. The high pressure will eventually win out and dry, pleasant weather is expected most of the week.

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The satellite image above shows the clouds associated with the weather disturbance over the east coast.

Two areas have been highlighted in the image above.

In the Atlantic, a tropical wave is showing increasing signs of organization and may very well become a tropical depression and perhaps eventually a named storm. The next name for Atlantic storms is Erika.

In the Pacific, powerful Hurricane Jimena continues to spin off the Mexican coast with category 4 winds of 145 mph. Jimena is headed for Baja, California.

Added at 12:30pm……..

I want to include this image from the Naval Research Laboratories in Monterey, CA.

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The satellite image combines the sea level surface pressure isobars with the combined IR/visible satellite image from 5:00am Monday morning. Notice the large area of high pressure over the Atlantic Ocean. It is under the southern margin of this “Bermuda High” that the latest tropical wave is showing signs of organizing into another tropical depression or storm. When these large scale Atlantic ridges extend westward into the southeast and Mid Atlantic states, warm and muggy tropical conditions develop similar to the conditions the region experienced last week.

Another ridge of high pressure is centered over Iowa, Illinois and Wisconsin and extends eastward to the Atlantic coast. This is the air mass that has brought cooler, less humid conditions to Maryland. The “trough” of low pressure that is wedged between the Atlantic and Midwest ridges is the cloudy, unsettled weather that runs along the U.S. coastline. The dry air has moved far enough east that the rain associated with the “trough” has been confined to areas east and south of the Baltimore-Washington metro region.

By the way, the yellow “dots” in the cloud free areas of the U.S. on the satellite image are the city lights of metropolitan areas. The satellite image was taken before sunrise in the U.S.

John Collins

Danny, A Close Brush
August 29, 2009

Danny is still on track to be a nmear miss.

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The forecast map for Saturday afternoon shows Danny as a weak tropical storm off the New Jersey coast, headed toward Cape Cod.

Danny is really just a part of the “tropical environment” running out ahead of frontal boundaries coming out of the Midwest. Danny’s biggest impact will be the rough seas and dangerous rip currents along the coast. The storm should also enhance rain chances on the DELMARVA Peninsula through at least midday Saturday. After that, any showers and thunderstorms should become more scattered but will remain as at least a slight risk in the forecast for the remainder of the weekend for areas east of the Bay, including the Maryland beaches.

John Collins

Danny Protection
August 27, 2009

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An area of low pressure in the mid levels of the atmosphere is forecast to slide south from Canada into the great lakes region Friday and Saturday.  The low will play a major role in steering tropical storm Danny as it approaches the mid Atlantic coast this weekend.  Winds coming around the base of the low pressure trough are expected to sweep off the Carolina coast and catch Danny before it gets too close to the eastern United States.  If the forecast holds, Danny will be pushed northeast along the coast, but well east of Ocean City.  For areas that extend farther east, however, like Cape Cod, the upper level winds may steer Danny dangerously close to shore.

Tom Tasselmyer

Danny Slow To Strengthen
August 27, 2009

Tropical Storm Danny is having a tough time developing into a more powerful system.

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The midday visible satellite imagery shows that most of the significant thunderstorm activity associated with Danny is east of the storm’s center. Upper winds have interfered to some degree with Danny’s organization and strengthening. Those winds are expected to become less of a factor and Danny is expected to become a marginal hurricane by Friday or Saturday.

The present forecast track keeps Danny out over the Atlantic but the storm will pass closer to the U.S. East Coast than Bill.

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The forecast map above is for Saturday morning. Current estimates are that there is a less than 50% chance that tropical storm force winds could lash the Mid Atlantic coast. But, with the storm spinning just off shore and a front approaching from the west, rain chances are fairly high for the region. And, again this weekend, high surf and dangerous rip currents are forecast for the Mid Atlantic coastal areas.

John  Collins

Danny Taking Shape
August 26, 2009

What, yesterday, was a tropical wave north of Puerto Rico is now Tropical Storm Danny.

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The early afternoon visible satellite image of the storm shows a developing circulation pattern in the lower cloud deck with most of the significant thunderstorm activity in the east half of the storm.

Danny is expected to follow a general track similar to Bill, but farther west. The official forecast keeps the storm off shore but some computer models have Danny making landfall in the Carolinas so the “cone” of track possibilities does include the DELMARVA Peninsula. Forecasters do think that Danny will reach marginal hurricane strength for a period of time either Friday or Saturday as the storm skirts the Carolina and Mid Atlantic coastline. Because of this, Danny could become more than a minor inconvenience. It goes without saying that anyone with interests east of the Bay should keep an eye on this storm by the weekend.

John Collins

More Tropical Weather
August 25, 2009

A tropical wave in the Atlantic appears to be becoming more organized and may reach tropical depression or storm strength.

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The wave is north of Puerto Rico and the Virgin Islands. Computer models show the storm becoming better organized and following a path similar to the one Bill took last week. The next name in the list for tropical storms is “Danny”.

Two tropical storms are churning in the Pacific.

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Ignacio is the eastern most storm at about 120 degrees west. Hilda is a more compact storm southeast of Hawaii at about 149 degrees west. Hilda is expected to reach hurricane strength and head toward a position south of the Hawaiian Islands over the next five days.

John Collins

Saturday Rain Progress
August 22, 2009

Significant rains and potential flooding have been threatening all day Saturday. As of early evening, the heaviest rains have skipped around the Baltimore area … for the most part. radsattotjThe map above shows the radar rain estimate for Friday and Saturday from the Dover AFB Weather Radar. Most of the significant rain today has been south of Baltimore. On Friday, one storm cell laid down a band of 4-5 inch rains in parts of Frederick, Montgomery, Howard and Carroll counties. That particular cell also showed tornadic wind rotation up in the cloud but no tornado damage was confirmed on the ground. Hurricane Bill is starting to turn to a more north to northeast trajectory and as the storm pulls away, a couple of cool fronts in the region will be able to move through and allow drier air to filter in.

sfcsat7pjNOAA/National Weather Service 5:00PM EDT 8/21/09

John Collins

Saturday Rain Progress
August 22, 2009

Significant rains and potential flooding have been threatening all day Saturday. As of early evening, the heaviest rains have skipped around the Baltimore area … for the most part.

radsattotjThe map above shows the radar rain estimate for Friday and Saturday from the Dover AFB Weather Radar. Most of the significant rain today has been south of Baltimore. On Friday, one storm cell laid down a band of 4-5 inch rains in parts of Frederick, Montgomery, Howard and Carroll counties. That particular cell also showed tornadic wind rotation up in the cloud but no tornado damage was confirmed on the ground.

Hurricane Bill is starting to turn to a more north to northeast trajectory and as the storm pulls away, a couple of cool fronts in the region will be able to move through and allow drier air to filter in.

sfcsat7pjNOAA/National Weather Service 5:00PM EDT 8/21/09

John Collins

Saturday Tropics
August 22, 2009

Hurricane Bill continues its’ track off the U.S. coast.GOESsatBill is several hundred miles off the Maryland coast with winds clocked at 100mph, a category two storm. Not much strengthening is expected from this point on and the storm should weaken an bit as it approaches the Canadian Maritime Provinces. The black speck at the lower right in the picture is Bermuda. The far outer rain bands of Bill hit the island yesterday.

The churning action of the storm over the Atlantic waters will produce high surf and dangerous rip currents along the Mid Atlantic and northeast coast of the U.S.

The satellite image shows considerable cloudiness over the east coast of the U.S. A couple of surface boundaries (cold fronts) are progressing slowly eastward.

namussfcwbgAs Bill moves farther to the northeast these fronts will eventually move through and the threat of rain will end. The air mass is extremely tropical in nature and heavy rains and some flooding are possible until the frontal passage. Much less humid air will start to filter into the region Sunday.

John Collins