Jul 20, 2014

Derecho expected for the Northern Plains and Western Great Lakes

This upcoming week will feature some significant and widespread heat and humidity from the east facing slopes of the Rockies to the East Coast. The weather setup for this week  features a sprawling high pressure area surface and aloft , acting like a heat pump, extending from the Southwest States to the Great Lakes.

The image to the left is the 500 hPa level (approximately 18,000 feet above the surface of the earth) from Sunday morning 20 July 2014  8AM EDT. An upper air chart such as this is called a constant pressure chart; on the chart the pressure is 500 hPa but the 500 hPa pressure is "located" at a different "height" above ground.) Think of upper-air maps as a topographic map of the atmosphere. The solid black lines are the actual heights of the 500 hPa and also can serve or approximate the the direction of the the winds aloft at near 18,000 feet. The distance between these contours can also approximate the wind speed -in general the closer the distance between any two contours, the stronger the winds and the greater the distance between the contours then the lighter the winds. The center of the "heat" producing high is located over southwest New Mexico with an elongated axis of higher heights extending to western South Dakota. From the Pac Northwest States to northern Wisconsin, a flow of air bringing some Pacific moisture prevails along with embedded disturbances that will cause ascent or lift.

The combination of all of these above features is expected to cause a significant severe weather outbreak across the Northern Plains to Wisconsin during Monday into Tuesday morning (July 21-22). Here is the severe weather outlook from SPC for Monday 21 July. The severe weather will initially start over the the border region of North and South Dakota with Montana as scattered but intense supercells during Monday afternoon, capable of producing severe hazards of damaging winds, large hail and a few tornadoes. These supercells are then expected to merge into a strong progressive derecho over the eastern parts of the Dakotas and then move rapidly east across and towards Minnesota to Wisconsin by late Monday night into Tuesday morning.

This derecho is expected to cause extremely strong winds of hurricane force (75 mph) or more in places along its path. The remnants of this system may also  redevelop and perhaps affect our area during Tuesday night, though probably not as intense. Often times these derecho are "episodic" in nature, that is they tend to develop on consecutive days and may even form over the same geographic region or move across the same region as the predecessor derecho did. Progressive derechos during the summer tend to form and become quite intense during extreme heat and or heat waves. The pattern for the development of these derechos is often referred to as "ridge-rollers and the ring-of-fire"

Jun 28, 2014

Potential for Tropical system off the Southeast US Coast

An area of disturbed weather off the the Southeast U.S. coast has been designated (disturbance) 91L by the National Hurricane Center. While not a true warm core system - yet - it will develop a warm core over time. Pic 1 is the location of the low and the convection associated with it.
Pic 1
 As you can see the the area of lowest atmospheric pressure is removed from the area of strongest convection. This is a satellite signature of unfavorable wind shear aloft which leads to a very disorganized system.

Pic 2

The model tracks for this nascent system are displayed in (Pic 2). There is a lot of "scatter" (basically in two clusters):  one group/cluster tracking the system toward the SW, while the other is on a track toward the SE. So a forecast S-SE motion is forecast. likely.

Since the motion is toward the south -  and south moving tropical systems tend not develop much or only very gradually (in the northern hemisphere) - only a slight or low probability (Pic 3) for development of this system is expected over the next 48 hours. 

Pic 3

If the system should intensify and attain sustained wind speeds of 40 mph or more then it will be "christened" with the name Arthur.

Jun 24, 2014

Northeast LIVE streaming radar and current temperatures.

Polygon key: RED = Severe Thunderstorm Warning PURPLE = Tornado Warnings BLUE = Special Marine Warning GREEN = Flash Flood Warning

May 1, 2014

April Weather Summary - BELOW normal again !

Here in Albany, April was another month of BELOW normal temperatures. The monthly summary indicates a slightly below normal month on both precipitation and temperatures.
The monthly average temperature was 47.4° or 0.4° BELOW normal This is now the 6th consecutive month where the average temperature for Albany has been BELOW normal. The last time Albany recorded six straight months of below normal temperatures was during the period of September 1993 through March 1994! (The monthly summary for Albany is to the left).

The April summary for some other locations: Bennington, VT - Average monthly temperature 45.3° or - 0.2°; precipitation 2.46" or .81" BELOW normal.  Glens Falls, NY - Average monthly temp was 46.6° or 2° ABOVE normal. This above normal month for Glens Falls was the first one since October of 2013. precip was 2.82" or -.18" BELOW normal. For Pittsfield, MA the average monthly temperature was 43.7° or a half degree BELOW normal. This the 4th consecutive month of BELOW normal temperatures for this location.

May Preview for Albany: 

   30-YEAR AVERAGE FOR MAY (1981 - 2010)          
                                                     HI      LO     AVG   PRECIP   SNOW
                                                     69.4°   47.1°   58.3°   3.61"        0.1"
Albany extremes for May  WARMEST    COLDEST      WETTEST       DRIEST     MOST SNOW
                                       67.0° 1826    50.4° 1967     8.96" 1953     0.15" 1903       5.4" 1945 
The warmest temperature observed in May: 97° on the 22nd in 1911. The coldest: 26° in 1968 on the 6th. Also the highest peak wind gust ever observed in Albany occurred in May on the 31st in 1998 during a severe weather outbreak (which included a tornado at the airport when this peak wind was recorded as well as the Mechanicville F3 tornado). Yes severe weather season starts here in the Capital Region in May. Best to be ready for it now!