The SPC has issued a MODERATE RISK of Severe Thunderstorms for the Eastern Carolinas today. Moderate Risks are uncommon in the CASI area so this indicates that people should be on the alert today for Severe Thunderstorms. SPC says "WE EXPECT BOW ECHOES WITH DAMAGING WINDS TO BE PRIMARY SEVERE THREAT." In addition, a SLIGHT RISK of Severe Thunderstorms has been issued for the rest of the CASI area South of New York. Also a Mesoscale Discussion from this morning indicated the possibility of a Severe Thunderstorm Watch for the Central Atlantic: http://www.nssl.noaa.gov/~spc/products/meso/mcd0588.gif As always, for more information see http://www.nssl.noaa.gov/~spc/products/outlook/dy1.htm There also could be heavy rain with some of these thunderstorms in the NE US today ; a Flash Flood Watch is in effect for SE PA at this time. http://www.met.tamu.edu:80/personnel/students/mkay/warnings_pa.html --------- Wow! Those were some unbelievable humidity and heat combinations yesterday in the southeast and south central. Dewpoints were in the 70's over a good part of the nation yesterday from TX to PA, with a few spots going into the 80's, which is very rare. Some of the winners for Temp/Dewp I saw yesterday were: Texas: FTW 1pm 93/81 North Carolina: GSB 1pm 95/77 (Apparent Temp 112) Florida: SRQ 1pm 90/79 SRQ 8pm 88/81 Georgia: FTY 8pm 86/81 --------- The first Tropical Storm of the season in the East Pacific has formed; the Atlantic is still quiet. (And yes I plan to update the CASI Tropical Pages *finally* this weekend ;)). For more information on Tropical Storm Agatha you can see Member Michael Pitt's Tropical Pages at http://www.qisfl.net/home/hurricanemike/ --------- You may have heard the discussions of El Nino / La Nina on the Weather Channel on elsewhere. If you've wondered if the beautiful SST image they show on TWC to indicate the demise of El Nino and a possible La Nina is available online, the answer is, "where do you think they got it?". It sure is - at http://metoc-u1.fnmoc.navy.mil/otis/otis.html and other imagery including current SST and wave heights are available from http://metoc-u1.fnmoc.navy.mil/ocean.html For more information on El Nino / La Nina I bring you a quote from Member Larry Cosgrove (wxamerica{at}aol.com)'s Morning Weather Discussion for those of you who don't receive it: ============================================================= "Cosgrove's College Of Meteorological Knowledge "The El Nino/La Nina Controversy" As you may have heard on national news outlets, it appears that the strong, and long lasting El Nino/Southern Oscillation episode is now ending. A study of sea surface temperatures (SSTs) in the Pacific Ocean off of South America shows that the area of much warmer than normal water has shrunk considerably in the past month. The ENSO event reached its peak in December/January, and was still well-defined until last month. Now the area of relative warmth is limited to a section close to the Peruvian/Ecuadorian coastline. And just north of the Equator (west of the Galapagos Islands), SSTs have fallen far below normal. For this reason, some meteorologists and climatologists insist that a 'La Nina' SST anomaly is about to begin. It might help to sort out what the various terms mentioned so far mean, and what practical effect on national weather each might bring. Here is an outline of each phase: El Nino: Spanish Euphemism for "The Christ Child", literally "little boy", possibly because its effect on early Spanish America's weather was usually noticed between Christmas and Easter. El Nino SST anomaly is warmer than normal waters in the Pacific Ocean from the Marshall Islands to off of South America. Southern Oscillation or acronym 'ENSO' are other terms for El Nino. ENSO Effects on North America and surrounding areas include a defined split in the polar jet stream. A southern branch descends from west of HI to near Baja California, then continues eastward to TX and FL (sometimes as far south as Yucatan and Cuba), before continuing into open Atlantic Ocean. The northern branch, meanwhile, is usually the weaker of the two, and moves through central Canada in a Rex-block arrangement, thus preventing cA air from dropping out of the Northwest Territories. End result: southern states are colder than normal, above normal precipitation, while northern states stay milder than average and often (but not always) drier than usual. El Nino episodes usually occur every 4 years or so, with 'major' deviations (1982-83 and 1997-98 are examples) possible an average of every fifteen years. La Nina is a 'coined' term implying the climatological opposite of El Nino. Northern Oscillation is another phrase synonymous with La Nina. The inverse of an ENSO year sees cooler than normal SSTs in the tropical Pacific. La Nina is not as common as El Nino, and has virtually no regularity of occurrence. For instance, do NOT assume that if there is no El Nino, that La Nina will occur. The last major La Nina episode was 1995-1996. La Nina does NOT bring the direct climatological inverse of El Nino. For example, in northeast U.S. snowstorms, heavy snowfalls are more likely in an ENSO year, as arctic air in a dominant arctic/polar jet stream flow often prevents deep moisture advection for precipitative processes. Synoptic climatology of La Nina in North America: Polar jet stream is unified, but there is no predictable trend where troughs or ridges will set up. Some La Nina episodes feature cold and wet in the West, others locate the cA air masses in the eastern U.S. It should also be said that the southern U.S. may be dry in a Northern Oscillation winter, but temperature trends in that region are very ambiguous." ============================================================= That's all for today folks, keep an eye out and report your findings to the StormForm! -- ============================================================== Jesse Ferrell - Meteorologist/Web Dev. - j{at}weatherwatchers.org Central Atlantic Storm Investigators - www.weatherwatchers.org "And here a twister comes... here comes the twister." --Talking Heads || ICQ No. 136862 ||