A Look at 3 Weeks in August

On of the great things about forecasting the weather is being able to look at a wealth of information that allows me to peer a few weeks and months into the future.

July isn't quite over, yet I already have a pretty good idea what the first three weeks of August will be like.

The central part of the country is going to be hot with highs in the 90s to low 100s from Denver to Nashville and from Sioux Falls to Brownsville. The southern Great Plains will be drier than normal while the rest of the country holds with near-normal rainfall.  The monsoon will continue across the West with afternoon and evening flare-ups of thunderstorms.

Most of the country will have light winds which will allow a buildup of haze and smog.

There will be an increasing chance of a tropical storm. One area that looks prime is the eastern Caribbean Sea, the other is the Gulf of Mexico.  The threat picks up after August 8 as the general weather pattern weakens giving a tropical storm the chance to become a dominant force.

The Northeast and the Great Lakes will be getting occasional pushes of natural air-conditioning after a long, hot late spring and summer. The cool air is beginning to pool in northern Canada and will make occasional incursions into the northeast quarter of the U.S.

A Cool, Damp Autumn

A ribbon of warmer than normal water across the North Pacific may be setting the stage for a wetter than normal and cooler than normal fall for Canada and much of the northern U.S. The warmer than normal water

stretches from Japan to 50N 140W. Temperatures within the band are 2C to 4C above normal. To the north is a narrow band of cooler than normal temperatures. There are two potential implications for this pattern. The first is to allow the jetstream to dive south across North America, dragging cooler than normal air south from the Arctic. The second is a path for the remnants of typhoons which will migrate along or just south of the jet stream while continuing to feed off of the above normal sea surface temperatures.  It looks like it will be an interesting late summer and fall.

Severe Weather Outbreak
Central Minnesota, northern Wisconsin and Upper Michigan are under the gun today and tonight for tornadoes, torrential flooding rain, large hail and damaging wind. Some of the tornadoes may be large and a few areas will get more than 2 inches of rain (up to 5 inches).

Heavy rain will continue through Wednesday across east and central Texas. Flooding will continue to be a problem as another 2 to 5 inches of rain comes down in some areas.

The monsoon is well underway with scattered afternoon and evening thunderstorms across a large portion of the West. Days start out sunny, then thunderstorms flair up between noon and 2pm, dying out between midnight and 3am. The cycle will continue for a while.

Flooding in Texas and a Tropical Low in the Atlantic

Texas is going to get a deluge of rain through Wednesday. A tropical flow off the Gulf of Mexico will force moisture well inland. 3 to 8 inches of rain will be likely from Brownsville to Lake Charles, Louisiana and inland to Dallas, Laredo and the Big Bend area. Expect a lot of runoff and flooding in the Houston, Galveston, College Station, Brownsville, Laredo -- and many other areas.

Oklahoma and Kansas will be drying out over the next 2 weeks as temperatures continue in the 90s to near 100. The lack of rainfall and the persistent heat will stress crops.

The Midwest will also be a little drier but since moisture is at least adequate right now, there shouldn't be an immediate stress on crops despite high temperatures in the 90s. A bigger concern is the risk of an early frost / freeze from Pennsylvania and New York to Michigan, Ohio, Indiana and Wisconsin. That discussion is being handled right now in our 30 day outlook, here.

A tropical low will likely form southeast of South Carolina / east of Georgia August 7 to 10. The Gulf of Mexico will have quite a bit of thunderstorm activity through August 10, but there's no hint of tropical storm formation at this point. We're discussing the longer term tropics here.

Tropical Storm Bonnie Dies

At 3pm EDT TS Bonnie was a sorry sight. This is the radar for south Florida.

Winds around the low are well below tropical storm force, sustained at 20 to 30 mph at the most with a couple of weather stations reporting gusts to 39 mph.

Computer models wash this storm system out, bringing a weak low to near Biloxi and Mobile Saturday afternoon, and a cluster of thunderstorms into the Florida panhandle, southern Mississippi, southern Alabama and southeast Louisiana ahead of the low.

At this point, Bonnie is a tropical low and the prospect for it to regain strength is minimal.

Is Tropical Storm Bonnie A Tropical Storm?

The cluster of thunderstorms... dubiously dubbed Tropical Storm Bonnie by the National Hurricane Center.. is moving to the northwest at about 30 mph as of 6am EDT. The center of Bonnie is at 25.5N 79W.

Bonnie is acting like a small cluster of thunderstorms, not a tropical storm and speculation as to why it is a tropical storm is that (A) we're short on hurricanes this year or (B) the NHC is under pressure to forecast for the Gulf oil clean up. Either way it looks like bad science.

Hurricane Hunter aircraft report a 2 knot drop in flight level winds, down to 41 kts. The central pressure has risen to 1009mb. As it passed over Nassau the wind gusted to about 20 kts. A few buoys continue to show gusts of 23 to 26 kts, only about 3 to 5 kts higher than the diurnal swing noted Thursday. Doppler velocities are around 45 kts at 5000 to 7000ft above mean sea level.

Bonnie is tracking along the plume of mid-level moisture which is not normal for a tropical system. Tropical storms tend to track toward mid-level dry areas.

This system will lash south Florida today as a cluster of thunderstorms, probably producing a few tornadoes.

After that, Bonnie should fizzle southwest of Fort Myers and the thunderstorms will track into the Florida Panhandle, south Alabama and south Mississippi Saturday and Sunday.

You can get the latest on the 5-day forecast when you get our daily briefing.

The bottom line is that TS Bonnie does not look like a tropical storm.

Wishing for a Hurricane?

Here's something I have been Tweeting and Facebooking about: In the tropics forecasters are itching for a hurricane. Tropical Depression 3 is over the Bahamas.

Tropical Depression 3 over the Bahamas Thursday.

The clouds are spinning, there are showers and thunderstorms forming squalls, but winds are barely 25 mph. Nonetheless, the National Hurricane Center has posted tropical storm warnings for the Bahamas and the Florida Keys.  On the satellite images I've watched this afternoon the area where the wind might be approaching tropical storm strength is about 10 miles across. The computer models wash this system out by the time it passes the Keys.  The National Hurricane Center thinks it will hit Louisiana Sunday night which seems far-fetched.

There's also a tropical low near Tampico, Mexico that actually looks more interesting but it is so close to the coast it may reach tropical storm strength for only a couple of hours. It will soak northeast Mexico with a solid 5 to 10 inches of rain through the weekend, causing widespread flooding. It is also going to be a big boost for the summer monsoon from the Desert Southwest into the Great Basin and east across the mountains of Colorado.

Severe Storms and a Yukon Heatwave

Yesterday, thunderstorms dumped hail, blasted wind and poured torrential rain across a swath from Montana to the Ohio Valley. There were 8 tornadoes.

We have a threat of large hail and damaging wind again today but it doesn't look like it will be as widespread as Monday's damage.  The greatest risk will be across the mid-Mississippi Valley and Ohio Valley.

There are only a few wildfires over the West today.  You will find a little smoke in the air if you are heading to Yellowstone or Cody, Wyoming, and across a large portion of eastern Canada, especially around Hudson Bay.

This map produced by NOAA shows that the hot spot for wildfires is Kansas.
A weak tropical low will move across the Bahamas on Thursday and Friday. There will be a few 45 mph squalls, but that should be it. The low will move across Florida over the weekend.

The Yukon is in for a big heatwave July 29 through August 4. Temperatures will be in the 80s, even across eastern Alaska.

The Summer Monsoon

The summer monsoon season is here with scattered showers and thunderstorms across eastern Arizona, New Mexico, Colorado and parts of Utah. The moisture is a great thing, but it also increases the threat of wildfires. 

Lightning caused wildfires are natural and necessary. As a weather forecaster, however, it plays havoc with predicting afternoon high temperatures. The smoke blots out the sun (or at least dims the sun) and can lop a solid 5 degrees off of what the temperature could reach under clear to partly cloudy skies.

There's a semi-interesting looking tropical wave along 68W between 20-25N this morning but it is very disorganized. The next interesting one is along 30W between 15-30N.  The computer models don't even hint at a low pressure center in the central Atlantic until the first week of August.  It the central Atlantic doesn't get active in August, this could be a hug bust of a hurricane season.

The Great Lakes and Upper Mississippi Valley, which has been pounded by severe weather this summer, will start to get a break from at least the big severe thunderstorms - although rainy weather will likely continue - as the jet stream weakens a lot in the next few days.

Wamer Than Normal But The Ice Grows

The 15 June 2010 report from NOAA concludes that the first six months of the year were the warmest on record around the globe. Temperatures were the warmest across Canada, North Africa and the Middle East. Western Asia, Norway and a small area from Florida to the central U.S. experienced cooler then normal temperatures.

The Southern Ocean and a sizeable portion the East Pacific had cooler then normal temperatures. El Nino conditions switched to La Nina during the first six months of 2010. La Nina is in the process of strengthening and colder than normal water is already pushing past the point halfway between Peru and Indonesia, reaching 160E longitude this week.

NOAA reports that the Arctic sea ice was at its lowest point on record for June, 10.6% below the 20 year average. Meanwhile, Antarctic sea ice has increased 8.3%, the largest extent ever. Just two years ago Antarctic sea ice was melting at a quick pace.

The sea ice data needs to be placed in the context that the data set is limited, only going back to 1979. Nonetheless, it presents a problem for weather forecasters and climatologists because the Antarctic sea ice coverage indicates a cooling of ocean temperatures and a reversal in the climate trend.

Large portions of the South Pacific and South Atlantic reflect this reversal, too, as sea surface temperatures dip below normal.

It won't be known until November if the cooling trend will also begin in the Northern Hemisphere.

Severe Storms and Heat

Minnesota, Wisconsin and Upper Michigan look like the place not to be today - if you don't want to experience severe weather.

Thunderstorms are already rolling across the northern part of Minnesota and the whole mess is expected to expand late this morning and through the night. Ugly is the word for it.

The heatwave is building across the South and up the mid-Atlantic states. Temperatures around 100 will be of interest to the network newscasts into the weekend.

Much of the mountain west will be continuing to heat up, too. Highs will be in the 90s and 100s for the next 2 weeks which means the fire danger is just going to rocket up. There shouldn't be a problem for afternoon readings in the 4-Corners area to hit 115F Friday through Sunday - maybe even 120.

Pockets of Severe Weather

It is going to be a busy day for thunderstorms across the southern U.S. and up the Appalachian Mountains.
Arkansas, Georgia and South Carolina will have the greatest rainfall and the highest threat of severe thunderstorms. Tomorrow, the threat of severe thunderstorms will be over northern and central Minnesota, northern Wisconsin and Upper Michigan.

The Southwest is going to be hot with widespread 105 to 115 temperatures.

By the weekend the jet stream will be running across the northern tier of states with a very warm atmosphere to the south of the jet.

August in July

Significantly cooler air is pouring into the East Coast - much needed relief from the heat and humidity. Well, the humidity will still be up there today thanks to showers and thunderstorms associated with the front.

Severe thunderstorms will be a problems across the Plains this afternoon and tonight. There is a threat of large hail and damaging wind, as well as a small threat of tornadoes. The storms won't be well organized, but the greatest threat of severe is in the area bounded by the red.

Cold air coming through Canada early next week will drop snow levels across the Canadian Rockies down to 8000 feet... pretty low for mid-July.

This continues to look like a very long August weather pattern... which will probably last well into August.

A Tropical Depression and a Cold Front

The tropical depression had a lowest pressure early this morning of 1006mb with estimated winds of 35 mph, although those are isolated speeds. Satellite estimated winds are on the order of 30 mph and there does not appear to be a closed circulation at this point. The forecast calls for the area of lowest pressure to make it onshore around 1pm CDT.

The strongest wind is north of the low and the onshore flow will increase tides. Heavy rains of 4 to 8 inches are likely across south Texas.

It is highly questionable whether this tropical system is worthy of an upgrade to a tropical storm. Data as of 6:55 CDT does not support an upgrade.

The leading edge of cooler, drier air is working across the Great Lakes today. The band of clouds associated with it show up in the morning satellite image.

The front will make it to the East Coast tomorrow. The northwest third of the country has some very quiet weather today.

A Tropical Storm or No?

The tropical disturbance has rolled off the Yucatan Peninsula and into the southwest Gulf of Mexico. There's quite a lot of thunderstorm activity clustered around it and shearing off to the north toward Houston, Texas.

The question is: What will it do now? It looks like it will strengthen a little overnight but probably not beyond tropical depression status. Winds will be strongest on the east side of the system (south-southeast at 15 to 30 knots with gusts to 45 knots). The center will form off the coast of Corpus Christi overnight and then move to the north-northwest before crossing the coast Thursday morning.


The big impact is going to be rain. 4 to 8 inches of rain will be likely in the Houston area, northward to near Dallas-Ft. Worth and southwest to near College Station and Corpus Christi.

This is one computer model's prediction for just after sunrise Thursday. Expect a lot of flooding. The heaviest concentration of rain will eventually press northeastward across Arkansas Friday and Saturday and will likely cause flooding there.

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A Brief Break For The East Coast

The East Coast is going to get a break from the heat this weekend. In the meantime, temperatures will be in the 90s to just over 100 and the humidity will be high. A cold front will plow from the Great Lakes across the East Coast Saturday, chopping a solid 15 degrees off the temperature - and smack the area with some severe weather. But the break will be short-lived as the extreme heat returns by Wednesday, July 14.

Heavy rain will be problem over the lower Mississippi River Valley today through early Thursday. Louisiana and south Arkansas may wind up having the biggest issues with flooding.

The western U.S. will heat up and the risk of wildfires will increase through the next couple of weeks. The heat will spread eastward across the Plains by next Tuesday and then reach the East Coast 24 to 48 hours later - Wednesday and Thursday. Temperatures will be in the 90s, slopping over to the low 100s over most of the country, except for the Pacific Northwest and the northern Rockies where it will be considerably cooler.

The 3rd week of July is typically the hottest of the year and this year will be no exception.

A Quiet Weather Pattern

The weather across the USA today is unusually tranquil. The large mass of clouds in a horseshoe shape over the central part of the country is not all that active. There will some strong thunderstorms over southeast Nebraska, Missouri, eastern Kansas, Illinois, eastern Oklahoma and Arkansas mid afternoon until midnight.

The area of clouds east of North Carolina and Virginia will drift westward over the next couple of days, increasing the threat of showers and thunderstorms from the mid-Atlantic coast to New England. The showers and thunderstorms over Florida and the Gulf of Mexico will drift to the northwest, spreading rain across the lower Mississippi Valley and much of Alabama and Georgia as we go the the week.

So.. no hurricanes on the horizon, it will be getting hotter over the western U.S. and most of the severe thunderstorm activity will be over the central Great Plains and the mid/lower Mississippi Valley.

Another Tropical Storm is Brewing

At first glance there's not much going on today. The morning satellite image shows some thunderstorms in south central Canada and clouds/rain associated with the remnants of Alex still lingering over TX and NM (what's left of Alex is over Mexico).

An upper level weather system behind a cool front will continue to bring showers and thunderstorms to Montana - with the activity spreading across Wyoming, North Dakota and South Dakota today and tonight. Showers and thunderstorms will be widespread across Florida and develop westward today across the Gulf of Mexico.

The next storm system of concern is a tropical wave over the Caribbean Sea. It looks like it will track pretty close to Alex's path, reaching the Yucatan Peninsula Tuesday or early Wednesday.

Right now it looks like maximum winds will be around 45 knots on Tuesday. Oddly, the Tropical Prediction Center seems none too concerned.