By Chris Hubbard

As a mid level trough builds into the Pacific NW, the threat for some critical fire weather is heightened for Four Corners and the surrounding regions. An area already effected by an extended drought, this region will see extremely low relative humidities and strong winds, both of which are fire weather triggers.

500mb Winds and RH levels for Wednesday(SimuAWIPS)

As seen in the image above, the strong, negatively-tilting trough that is heading into the NW is also bringing some strong, warm currents into the SW regions. Mixing together the aforementioned winds and low RH with an area already being hit with a drought and with downslope effects warming this air even further, the threat for fire is appropriately critical.

The threat continues into Thursday as well as these conditions continue.

500mb Winds and RH levels for Thursday (SimuAWIPS)

As the week continues, a dome of high pressure anomalies will begin build across the west central region of the Plains. This will allow an extended period of warm and dry conditions to build across the interior Rockies.

6-10 Day Temperature Outlook (CPC)

6-10 Day Precipitation Forecast (CPC)

As for portions of the eastern US, a surge of warm and humid (tropical like) air masses will invade the region begin this weekend. Let summer begin!

by Mark Sperduti

]]> http://zoomradar.com/blog/?feed=rss2&p=3437 0 http://zoomradar.com/blog/?p=3415 http://zoomradar.com/blog/?p=3415#comments Mon, 17 Jun 2013 16:09:10 +0000 admin http://zoomradar.com/blog/?p=3415 Posted by Tyler Castillo

Today, the Storm Prediction Center has issued a slight risk for areas just south of Casper, Wyoming extending as far south as Midland, Texas.

The tornado threat is low today, although damaging winds are possible. Hail will be the biggest threat today. The storms should initiate later in the afternoon as MLCAPE values approach 3000 J/kg as a result of intense daytime heating.

Storms that develop today will most likely be supercellular as sfc-500mb bulk shear will be maintained around 35-40 knots.

Here is the current map of the U.S., as you can see there are chances for some storms across many parts of the country. These areas include the southeast, northeast, Great Lakes region, and northwest. The only severe areas will be the  region outlined above.

by Chris Hubbard

An area of disorganized thunderstorms and clouds has formed in the NW Caribbean Sea. Although there has been no major development over the past day, there is still a chance for this storm to develop in the next 48 hours. The NHC states that it has a 30% chance of developing into a tropical system. This area of clouds is expected to move inland onto the Yucatan Peninsula and bring heavy rains and strong winds to the peninsula.

Other than this storm there are no other areas of interest in either the Atlantic nor the Eastern Pacific and no systems are expected to form in the near future.

Over the past several days, the Ohio Valley and mid-Atlantic states have been slammed by severe storms as a result of a progressive shortwave trough accompanied by a surface low pressure.

On Wednesday, June 12, most of the 409 storms reports can be found within the Ohio Valley. This includes 30 tornado reports, 257 wind reports, and 122 hail reports. Not all of these reports can be associated to the Ohio Valley region as there were a couple reports made out west.

Yesterday’s severe events were mainly confined to the mid-Atlantic states. The system produced a total of 798 storm reports, which included 9 tornado reports, 80 hail reports, and 709 wind reports.

A mid level trough is headed to the DelMarVa region and will reach the area tonight. This system will be cause of some potentially serious weather effecting places from Richmond to Philadelphia. A strong low pressure (~992mb) is one of the main proponents of the severity of the weather.

Some strong vertical wind shear is also going to be in play, elevating CAPE levels (seen in the upper left hand picture). A strong pocket of PVA is associated with this front (bottom left), which is what will cause the heights to fall so low. A low pressure system with this low of a level almost looks like a winter Nor’easter and is not very common for June when we are so close to solstice. Tornado watches will most likely be issued for the DelMarVa region as well as for SE PA. Strong thunderstorm warnings will be far more extensive, reaching down into the Carolinas as the derecho stretches further south.

There is also a chance for thunderstorms throughout Wednesday night as the warm front associated with the low passes through. Some late night thunderstorm warnings may be issued, an not so common occurrence. Once the warm front passes through, a plume of warm, moist air will enter the region, leading up to the events on Thursday.

Model simulations from SimuAWIPS.

The risk of severe weather will be aided by a strong upper level low working its way into the northern plains this evening.

Convective Outlook (SPC)

As for tonight, the ingredients needed for the formation of a mesoscale convective system (MCS) is highly possible.

MCSs

• May start from one cell or from a group of convective cells
• May initiate as a line along a cold front, dryline, or other mesoscale boundary
• Occur worldwide and year round
• Are generally stronger and more organized in a sheared and highly unstable environment
• Are strongest and live longest when strengths of the cold pool and low-level vertical wind shear remain in balance

MCS Types

• Squall line
• Bow echo
• Mesoscale convective complex (MCC)

MCS Weather Threats

• Damaging winds
• Severe turbulence and wind shear
• Intense lightning
• Large hail
• Heavy rain and flooding
• Tornadoes

Courtesy of the COMET Program.

Around midnight EST…

A nocturnally unstable atmosphere of over 2000 J/kg of CAPE.

Most Unstable CAPE (Courtesy of COD Meteorology)

And the existence of a 70 mph low level jet (LLJ) is looking to aid in the organization of a MCS which could track from Rapid City to as far as Chicago.

850mb Wind Speeds (Courtesy of COD Meteorology)

NAM Forecast Radar Reflectivity (Courtesy of PSU e-wall)

by Mark Sperduti

For today, the Storm Prediction Center has issued slight risks for two regions. These include central Tennessee and a much larger region stretching from South Carolina to southern Pennsylvania.

Day 1 Outlook

The current convective watches line up perfectly with the slight risks. These watches include the following:

Severe thunderstorm watch until 11 p.m. ET extending from southern Tennessee up to central Kentucky. The main threats include large hail and damaging winds.

Tornado watch until 10 p.m. ET for most of central Tennessee. Storms have already started to form across this area with stronger storms expected to develop as a result of daytime heating. Large hail and several tornadoes can be expected throughout the day if conditions continue to become more favorable.

Tornado watch for North and South Carolina until 10 p.m. ET. As with the tornado watch for Tennessee these storms are expected to increase in number and strength as daytime heating takes place.

The last tornado watch issued as of right now includes Virginia to south Pennsylvania. The watch will be effective until 10 p.m. ET. Storms are expected to continue developing and strengthening throughout the evening.

As for tomorrow, we can expect to see storms develop around the central and northern plains and into the Midwest as a result of strong mid level flow.

Record heat in the Southwest and another wet week for the Eastern seaboard are the two main topics in this weeks weather. An upper level trough is currently heading towards the Mississippi Valley, causing a strong influx of moist Gulf air ahead of it. This will be cause to some wet weather for the Southeast for the end of the weekend. As the week progresses, this moisture will move up the coast, hitting most of the Atlantic coastline.

Meanwhile, high pressure has built into the deserts of the SW, causing temperatures to climb into the triple digits. These conditions should die off by Monday however as a low pressure system comes into the region.

After making landfall in Florida, Andrea has now been given the title of a Post-Tropical Cyclone. The storm currently has sustained winds around 45 mph with a central pressure of 996mb. The system is tracking eastward at about 28 mph. Andrea is still capable of producing widespread flooding, damaging winds, and an isolated tornado. The post-tropical system is projected to move along the east coast.

The 120 hour rainfall forecast centers the heaviest rain in the northeastern states, with amounts ranging anywhere from 1 to 2 inches for areas along the coast.

Below is a map of the areas to be affected by tropical storm force winds.

Here is the current visible satellite imagery as the storm continues to progress towards the northeast.

The image below shows the moisture inflow into the system at the 700mb level with the wind direction and dew point depression indicated by the coloring. As evident by the image, Andrea is a widespread storm and is still pulling moisture out of the Gulf.