Although I am slightly joking this may provide to be actually educational for us in the future as we may learn more about these features.
The definition of an Upper Level Defined by the American Meteorological Association ( http://amsglossary.allenpress.com/glossary )
upper-level trough—(Also called upper trough, upper-air trough, high-level trough, trough aloft.) A pressure trough existing in the upper air.
This term is sometimes restricted to those troughs that are much more pronounced aloft than near the earth's surface. These troughs are often described as either short-wave or long-wave features.
upper-level cyclone—(Also called upper-level low, upper cyclone, upper low, high-level cyclone, low aloft.) A cyclonic circulation existing in the upper air; specifically as seen on an upper-level constant-pressure chart.
This term is often restricted to such cyclones associated with relatively little cyclonic circulation in the lower atmosphere.
METEOROLOGIST JEFF HABY @
The http://www.theweatherprediction.com
Upper level lows are important to forecasting and can dramatically alter one's forecast. Upper level lows can occur in association with a mid-latitude cyclone or may begin without the aid of a mid-latitude cyclone. Upper level lows without the aid of a surface low can develop when air flows over a mountain range, in association with an upper level short wave, or in association with a jet streak.
When analyzing a strong mid-latitude cyclone, some common patterns can be noticed. One is that the trough associated with a mid-latitude cyclone tilts toward the cold air (generally tilts to the northwest with height). Therefore, the upper level low pressure (trough) in association with a mid-latitude cyclone may be several 100 kilometers displaced from the surface low toward the west or northwest. Since the forecast models have a more difficult time initializing an upper level low than a surface low, upper level lows can result in a busted forecast. The forecast models have a better vertical resolution of the low levels of the troposphere as compared to the upper levels. In some mid-latitude cyclones, the tilt of the mid-latitude cyclone will be enough to allow the upper level low to displace from the surface low.
What causes an upper level low? An upper level low is a region of positive vorticity. This positive vorticity can be caused by counterclockwise curvature around the upper level trough and counterclockwise shear associated with the speed shear of a jet streak. The circulation around an upper level low can build to the surface over time. In these cases, two areas of low pressure will be noticed on the surface chart. These are sometimes referred to as double-barrel low-pressure systems. Upper level lows can also decrease in intensity through time.
A huge forecasting problem is determining whether an upper level low will strengthen or weaken with time. When nowcasting, they are best viewed on satellite imagery. Image by image they should be monitored for intensity. When the clouds brighten (become whiter) in association with the upper level low, that is an indication the upper level low is strengthening.
If an upper level low does show on the analysis or forecast models it is best seen at the 500 millibar level or 700 millibar level. Upper level lows have been responsible for bringing unexpected heavy snows in the winter. The spin-up of vorticity in an upper level low causes the air to rise and cool. Since the upper level low is tilted over the cold air, cold surface temperatures and upper level lifting combine to produce wintry precipitation well behind (to the west or northwest) or the surface cold front. When a mid-latitude cyclone begins to mature, watch for the development of the upper level low.
The 500-mb RUC model image below shows an upper level low over the south-central United States:
http://www.theweatherprediction.com/habyhints/2/
Currently Boca and I are focusing our attention on an Upper Level Low to the Northeast of PR, as evident in the 500mb Vorticity @ CIMSS.
http://cimss.ssec.wisc.edu/tropic/real- ... 8vor2.html
A good example of a Satelite Picture of an Upper Level low is depicted in the Water Vapor Graphic Below.
I would expect this upper level low to remain in place or moving northward around the upper ridge in the Atlantic. In the next few days... but, probably moving Northward. Mind you I don't know much about these features so I'll be learning as time goes on.
ATLANTIC OCEAN...
A 1029 MB HIGH OVER THE ATLANTIC NEAR 36N46W IS PRODUCING MAINLY
ELY SURFACE FLOW WITH FAIR WEATHER FROM 20N-30N BETWEEN
20W-50W. IN THE UPPER LEVELS...A RIDGE IS OVER THE W ATLANTIC N
OF 24N AND W OF 70W. A LOW IS FURTHER E NEAR 26N61W. CYCLONIC
FLOW IS FROM 18N-30N BETWEEN 50W-70W. DIFFLUENCE E OF THE
CENTER IS PRODUCING SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS ALSO FROM 21N-25N BETWEEN 54W-57W. A LARGE HIGH
IS OVER THE E ATLANTIC NEAR 19N27W. ANTICYCLONIC FLOW IS N OF
10N AND E OF 40W.
$$
FORMOSA
http://moe.met.fsu.edu/cgi-bin/gfstc2.c ... =Animation
Please feel free to input on this discussion.
