Friday, July 15, 2011
The above animation is of the SST (Sea Surface Temperature) in the ENSO regions. ENSO regions are the regions monitored to declare a La Nina or El Nino.
Using the above image and the animation at the top of the base, we see the eastern regions of the ENSO areas are beginning a cool down trend that has been evident for at least a month, and noticeable for 2 weeks.
This would be defined as an 'East-Based La Nina'.
An East-Based La Nina would create extremely cold temperatures in the Northern US and around normal precipitation. However, remember that colder temperatures bring about more dry snow. Thus, chances for above normal snowfall would increase.
The big question is if this situation will pan out. We will continue monitoring this closely, so keep up to date on all the information on the right sidebar by clicking on the link named '2011-2012 Winter Forecast'.
Related: 2011-2012 Winter Forecast
The colors we see on the upper border are of the jet stream. Since the jet stream is used to being farther south instead of what its current position is with the ridge in place, the jet stream naturally increases in speed in response to the pressure.
That said, any storms that occur in the higher speed of the jet stream will have at least a slightly higher chance of tornadoes.
STRONG-SEVERE ELEVATED TSTMS ARE IN PROGRESS THIS MORNING ACROSS PORTIONS OF WRN/CNTRL MN WHERE LOW-LEVEL WAA/ISENTROPIC ASCENT IS BEING ENHANCED BY VEERING NOCTURNAL LLJ. 12Z ABR SOUNDING SHOWS THAT THIS ACTIVITY IS BEING FUELED BY A THERMODYNAMIC ENVIRONMENT CHARACTERIZED BY VERY MOIST BOUNDARY LAYER AND STEEP MIDLEVEL LAPSE RATES WITH MUCAPE OF 3000-3500+ J/KG. THOUGH THE LLJ WILL DIMINISH THROUGH THE REMAINDER OF THE MORNING...WEAK WAA WILL PERSIST...LIKELY SUSTAINING ONGOING ACTIVITY WITH A CONTINUED THREAT FOR MAINLY LARGE HAIL. BY AFTERNOON...CONSIDERABLE UNCERTAINTY EXISTS WITH REGARD TO SEVERE WEATHER POTENTIAL DUE TO THE TENDENCY FOR MIDLEVEL HEIGHT RISES IN THE WAKE OF SHORT WAVE TROUGH CURRENTLY LIFTING NEWD THROUGH ND...AND THE LINGERING EFFECTS OF ONGOING STORMS ACROSS MN. ONE AREA OF ENHANCED TSTM POTENTIAL WILL LIKELY BE ALONG THE LEADING EDGE OF CLOUD SHIELD ASSOCIATED WITH A CONVECTIVELY INDUCED VORTICITY MAXIMUM OVER CNTRL NEB WHICH WILL CONTINUE NEWD THROUGH THE MID MO VALLEY TODAY. HERE...DAYTIME HEATING COMBINED WITH BOUNDARY LAYER DEWPOINTS IN THE 70S WILL YIELD A STRONGLY UNSTABLE AIR MASS WITH MLCAPE APPROACHING 3000-3500 J/KG. STRONGER DEEP-LAYER SHEAR WILL REMAIN FARTHER TO THE N/NW OF MCV TRACK WITH ENVIRONMENT SUPPORTIVE OF MULTICELL AND MARGINAL SUPERCELL STORM MODES. HAIL AND LOCALLY DAMAGING WINDS WILL BE THE MAIN THREATS. ELSEWHERE...ISOLATED TO WIDELY SCATTERED SEVERE TSTMS WILL BE POSSIBLE ALONG SURFACE FRONT WHICH WILL STALL THIS AFTERNOON FROM THE RED RIVER VALLEY INTO CNTRL NEB. LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE WITH THE GREATEST POTENTIAL FOR A TORNADO OR TWO EXISTING ALONG OUTFLOW-REINFORCED WARM FRONT LIFTING NWD/NEWD THROUGH FAR ERN ND AND NWRN MN. ...NRN HIGH PLAINS... MIDLEVEL HEIGHT GRADIENT WILL TIGHTEN TODAY BETWEEN STRONG VORTICITY MAXIMUM TRANSLATING ACROSS CNTRL SASKATCHEWAN AND BUILDING RIDGE AXIS OVER THE NRN PLAINS INTO UPPER MS VALLEY. AND WHILE LARGE-SCALE FORCING WILL REMAIN NEGLIGIBLE THROUGH THE DIURNAL HEATING CYCLE...CONVERGENCE ALONG WEAK SURFACE FRONT AND OROGRAPHIC INFLUENCES WILL LIKELY FOSTER WIDELY SCATTERED TSTM DEVELOPMENT THIS AFTERNOON INTO EVENING. RESIDUAL BOUNDARY LAYER DEWPOINTS IN THE 50S BENEATH STEEP MIDLEVEL LAPSE RATES WILL YIELD MODERATE INSTABILITY LATER TODAY WITH MLCAPE OF 1000-1500 J/KG. WHEN COUPLED WITH VERTICALLY VEERING WIND PROFILES AND 35-50 KT OF DEEP-LAYER SHEAR...SETUP WILL FAVOR SUPERCELL STORM MODES WITH THE PRIMARY HAZARDS BEING LARGE HAIL AND DAMAGING WIND GUSTS. ...GULF COAST STATES... FORCING ASSOCIATED WITH QUASI-STATIONARY MIDLEVEL VORTICITY MAXIMUM AND RESIDUAL SYNOPTIC- AND MESO-SCALE BOUNDARIES WILL SERVE AS THE FOCI FOR WIDESPREAD TSTM ACTIVITY THROUGH THE DIURNAL HEATING CYCLE. GIVEN THE PRESENCE OF A VERY MOIST AIR MASS /I.E. PW VALUES IN EXCESS OF TWO INCHES/ AND STEEPENING LOW-LEVEL LAPSE RATES...ENVIRONMENT WILL BECOME SUPPORTIVE OF STRONG WET MICROBURSTS CAPABLE OF LOCALLY DAMAGING WIND GUSTS.