baroclinic_instability Posted April 25, 2011 Share Posted April 25, 2011 The NAM shows the potential for separation between the northern stream upper low and the southern stream anomaly with vigorous low level WAA associated with the incoming anomaly nearly creating its "own" ridge and decent separation between the synoptic lows. Should such a scenario unfold it would undoubtedly be a historic tornado day verbatim NAM with locally backed wind fields in Tennessee and favorable low level moisture fields through almost the entire warm sector. Some of these wind fields progged by the guidance are just off the charts. Of course this would all be highly dependent on the strength of the dynamic tropopause--currently not something that will be well forecast--but the potential on the high end is something that I have never seen. Link to comment Share on other sites More sharing options...
blackjack123 Posted April 25, 2011 Share Posted April 25, 2011 SPC has listed a day 2 moderate risk and mentions a complex but potentially dangerous day. "POTENTIALLY DANGEROUS DAY!!!" I dont hear strong wording like that very often except maybe 4-10-08 which ended up being a bust compared to what could have happened. Can somebody explain this. Is SPC talking about like 5000-6000J/KG+ CAPE and other insane parameters. Link to comment Share on other sites More sharing options...
Hoosier Posted April 25, 2011 Share Posted April 25, 2011 Models slowing down the front a tad around here. Upcoming day 2 slight risk may have to be pulled a little west. Link to comment Share on other sites More sharing options...
cyclone77 Posted April 25, 2011 Share Posted April 25, 2011 All I can say is wow looking at some of the forecast soundings for Wednesday. There are some huge differences between the NAM and GFS. The NAM develops a secondary southern low, and really limits instability further north. The GFS paints a completely different scenario further north with much more instability, as it doesn't develop this southern low. Right now I'd lean towards the NAM, as I feel it handled today's setup considerably better than the GFS. Northeast Mississippi/northern Alabama and parts of Tennessee look pretty dangerous Wednesday afternoon. Link to comment Share on other sites More sharing options...
SmokeEater Posted April 25, 2011 Share Posted April 25, 2011 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT MON APR 25 2011 VALID 261200Z - 271200Z ...THERE IS A MDT RISK OF SVR TSTMS LATE TUE/TUE NIGHT ACROSS MUCH OF ARKANSAS...PARTS OF NORTHEAST TEXAS...NORTHERN LOUISIANA...NORTHERN MISSISSIPPI...NORTHWEST ALABAMA....WESTERN TENNESSEE...PARTS OF THE MISSOURI BOOTHEEL... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK AREA...FROM PARTS OF THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY THROUGH THE LOWER GREAT LAKES AND APPALACHIANS... ...SYNOPSIS... A COUPLE OF SIGNIFICANT SHORT WAVE IMPULSES EMBEDDED WITHIN A STRONG UPPER JET NOSING INLAND OFF THE PACIFIC WILL LIKELY CONTINUE TO CONTRIBUTE TO THE EVOLUTION OF A LARGE SCALE UPPER TROUGH OVER THE CENTRAL U.S. THROUGH THIS FORECAST PERIOD. ONE IMPULSE IS ALREADY DIGGING INTO THE SOUTHERN PLAINS...AND EXPECTED TO SUPPORT LOW/MID-LEVEL CYCLOGENESIS ACROSS THE LOWER AND MIDDLE MISSOURI VALLEY INTO THE UPPER MISSISSIPPI VALLEY LATE TONIGHT INTO EARLY TUESDAY. AS DOWNSTREAM RIDGING REMAINS STRONG OFF THE ATLANTIC SEABOARD...MODELS SUGGEST THAT THE INITIAL IMPULSE WILL PIVOT AROUND THE EASTERN AND NORTHERN PERIPHERY OF THE MID-LEVEL CYCLONIC CIRCULATION...WITH THE SURFACE CYCLONE OCCLUDING AND GRADUALLY WEAKENING LATER TUESDAY INTO EARLY WEDNESDAY. AT THE SAME TIME...A STRONGER UPSTREAM IMPULSE IS PROGGED TO DIG ACROSS THE SOUTHERN ROCKIES AND PLAINS...THROUGH THE LOWER MISSISSIPPI VALLEY...CONTRIBUTING TO SURFACE CYCLOGENESIS ACROSS THE RED RIVER VALLEY AREA INTO THE OZARK PLATEAU. GIVEN FAVORABLE LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION... STRONG SHEAR...AND A MOIST RETURN FLOW OFF THE GULF OF MEXICO... ASSOCIATED WITH THE EVOLVING PATTERN...CONDITIONS MAY BECOME INCREASINGLY SUPPORTIVE FOR A MAJOR OUTBREAK OF SEVERE THUNDERSTORMS. THIS COULD POTENTIALLY IMPACT A RATHER BROAD AREA OF THE CENTRAL AND EASTERN U.S...WITH THE RISK FOR TORNADOES...LARGE HAIL AND DAMAGING WIND GUSTS. REMNANTS OF DAY 1 CONVECTION...WHICH COULD BE CONSIDERABLE NEAR EAST OF THE MID AND LOWER MISSISSIPPI VALLEY...POSE THE PRIMARY UNCERTAINTY WITH REGARD TO THE MAGNITUDE AND EXTENT OF THIS POTENTIAL. IT IS STILL UNCLEAR HOW MUCH IMPACT THAT THIS WILL HAVE ON SUBSEQUENT DESTABILIZATION...BUT THIS SHOULD MOSTLY AFFECT AREAS NORTH AND EAST OF THE LOWER MISSISSIPPI VALLEY...WHERE /MODERATE RISK/ PROBABILITIES HAVE BEEN MAINTAINED AND EXPANDED A BIT NORTHWARD AND EASTWARD. ...GREAT LAKES/OH AND TN VALLEYS INTO APPALACHIANS... GUIDANCE REMAINS STRONGLY SUGGESTIVE THAT OUTFLOW FROM REMNANTS OF OVERNIGHT CONVECTION MAY BE ADVANCING EASTWARD THROUGH PORTIONS OF CENTRAL KENTUCKY AND MIDDLE TENNESSEE...WHILE SLOWING AND STALLING ACROSS NORTHWESTERN ALABAMA AND NORTHERN MISSISSIPPI INTO THE VICINITY OF THE SURFACE COLD FRONT ACROSS THE ARKLATEX...AT 12Z TUESDAY. WHILE STRONGER FORCING ASSOCIATED WITH THE INITIAL UPPER IMPULSE TENDS TO LIFT NORTHWARD TOWARD THE GREAT LAKES REGION DURING THE DAY...AWAY FROM THE OUTFLOW...IT CURRENTLY APPEARS THAT INSOLATION AHEAD OF THE CONVECTIVE BOUNDARY WILL CONTRIBUTE TO WEAK TO MODERATE BOUNDARY LAYER DESTABILIZATION. THIS MAY BE ENOUGH TO CONTRIBUTE TO REDEVELOPMENT AND INTENSIFICATION OF STORMS AS THE BOUNDARY ADVANCES TOWARD THE UPPER OHIO VALLEY INTO THE WESTERN SLOPES OF THE APPALACHIANS. ALTHOUGH MODELS SUGGEST THAT THE PRE-COLD FRONTAL SOUTHERLY LOW-LEVEL JET WILL TEND TO WEAKEN ACROSS THIS REGION THROUGH THE DAY...VERTICAL SHEAR STILL SEEMS LIKELY TO REMAIN FAVORABLE FOR ORGANIZED STRONG/SEVERE STORM DEVELOPMENT...INCLUDING THE RISK FOR SUPERCELLS. DESTABILIZATION ALONG THE COLD FRONT...ACROSS PARTS OF LOWER MICHIGAN INTO THE LOWER OHIO VALLEY...IS MORE UNCERTAIN DO TO THE POSSIBILITY OF LINGERING CLOUD COVER/PRECIPITATION. BUT...IF IT OCCURS...ADDITIONAL STRONG/SEVERE STORM DEVELOPMENT IS POSSIBLE LATE TUESDAY AFTERNOON AND EVENING. ...SOUTHERN PLAINS/ARKLATEX INTO THE LOWER MISSISSIPPI VALLEY... STRENGTHENING MID-LEVEL FORCING FOR UPWARD VERTICAL AND FLOW FIELDS ASSOCIATED WITH THE APPROACHING IMPULSE MAY NOT IMPACT THE WARM SECTOR...AND THE PRE-FRONTAL ENVIRONMENT NORTH OF THE OUTFLOW...UNTIL THE 27/00-03Z TIME FRAME TUESDAY EVENING. HOWEVER...MODELS DO SUGGEST THAT INSOLATION ALONG AND NORTH OF THE RETREATING OUTFLOW WILL CONTRIBUTE TO MODERATE TO STRONG DESTABILIZATION BENEATH STEEP MID-LEVEL LAPSE RATES ACROSS CENTRAL AND SOUTHERN ARKANSAS...WHICH PROBABLY WILL NOT STABILIZE MUCH DURING THE EVENING. COUPLED WITH ENLARGING...CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS NEAR AND BENEATH A STRENGTHENING LOW-LEVEL JET /50-60+ KT AT 850 MB/...CONDITIONS APPEAR LIKELY TO BECOME CONDUCIVE TO THE DEVELOPMENT OF ORGANIZED SEVERE CONVECTIVE DEVELOPMENT...INCLUDING POTENTIALLY LONG-LIVED SUPERCELLS CAPABLE OF PRODUCING STRONG TORNADOES. THIS THREAT MAY PERSIST DEEP INTO THE EVENING...PERHAPS THROUGH THE OVERNIGHT HOURS...SPREADING EAST NORTHEASTWARD TOWARD THE TENNESSEE VALLEY. ..KERR.. 04/25/2011 Link to comment Share on other sites More sharing options...
k*** Posted April 25, 2011 Share Posted April 25, 2011 anyone else having problems with the SPC website? Link to comment Share on other sites More sharing options...
SmokeEater Posted April 25, 2011 Share Posted April 25, 2011 anyone else having problems with the SPC website? Nah, loading right up for me. Link to comment Share on other sites More sharing options...
Calderon Posted April 25, 2011 Share Posted April 25, 2011 anyone else having problems with the SPC website? no, working fine for me. Link to comment Share on other sites More sharing options...
hannie Posted April 25, 2011 Share Posted April 25, 2011 I am hearing that this system may be pulled west for weds....do you think it will stay east of Louisville...or do I need to worry? Link to comment Share on other sites More sharing options...
B-Rent Posted April 25, 2011 Share Posted April 25, 2011 anyone else having problems with the SPC website? I've had intermittent issues with all weather.gov sites the last week. Sent from my HTC Thunderbolt using Tapatalk. Link to comment Share on other sites More sharing options...
CUmet Posted April 26, 2011 Author Share Posted April 26, 2011 A somewhat disturbing trend that I've noticed in following the last 24 hours worth of model runs is that the GFS, ECMWF, and UKMET have all trended stronger with the second low on Wednesday. The NAM has always had a strong second low. In this particular case, it will be important for the intensification of this low to materialize in order to back the surface winds. This seems pretty likely in this particular case given the progression of the second shortwave, but those who have more expertise with the synoptic aspect can probably comment further on this. Link to comment Share on other sites More sharing options...
TheWeatherPimp Posted April 26, 2011 Share Posted April 26, 2011 A somewhat disturbing trend that I've noticed in following the last 24 hours worth of model runs is that the GFS, ECMWF, and UKMET have all trended stronger with the second low on Wednesday. The NAM has always had a strong second low. In this particular case, it will be important for the intensification of this low to materialize in order to back the surface winds. This seems pretty likely in this particular case given the progression of the second shortwave, but those who have more expertise with the synoptic aspect can probably comment further on this. The other guidance - except the NAM, have all trended farther Northwest with the low as well. Link to comment Share on other sites More sharing options...
TheWeatherPimp Posted April 26, 2011 Share Posted April 26, 2011 Tomorrow is looking better and better with precip clearing out of Indiana by 12z with destabilization in progress across Eastern Illinois and all of Indiana by late morning per the rapid refresh. Link to comment Share on other sites More sharing options...
electronicmaji Posted April 26, 2011 Share Posted April 26, 2011 Tomorrow is looking better and better with precip clearing out of Indiana by 12z with destabilization in progress across Eastern Illinois and all of Indiana by late morning per the rapid refresh. No rain for NWA?? Link to comment Share on other sites More sharing options...
hm8 Posted April 26, 2011 Share Posted April 26, 2011 39 straight hours of 50 STI on the 15z SREF. Which is pretty ridiculous. Link to comment Share on other sites More sharing options...
hm8 Posted April 26, 2011 Share Posted April 26, 2011 I will be be occupied pretty much all day tomorrow and wont be able to get to a computer....but if anyone here could be so kind as to text me if it looks like anything noteworthy is happening in SEMI, I'd greatly appreciate it. I'm always on edge when I'm not updated on my weather.... PM me if you're willing Link to comment Share on other sites More sharing options...
janetjanet998 Posted April 26, 2011 Share Posted April 26, 2011 freak.. north system has 1000 CApE to work with..south 3000 Link to comment Share on other sites More sharing options...
TheWeatherPimp Posted April 26, 2011 Share Posted April 26, 2011 The backed wind potential on Wednesday is insane Link to comment Share on other sites More sharing options...
cyclone77 Posted April 26, 2011 Share Posted April 26, 2011 The forecast soundings from northern Alabama into Kentucky are pretty scary Wednesday afternoon. So much potential. Sure hope people in those areas are aware of what's coming. Link to comment Share on other sites More sharing options...
cyclone77 Posted April 26, 2011 Share Posted April 26, 2011 Very impressive theta-e feeding due north underneath the very powerful west-southwesterly 100kt+ H5 jet. Just wow. Link to comment Share on other sites More sharing options...
Chrisrotary12 Posted April 26, 2011 Share Posted April 26, 2011 I feel like southern Arkansas will be under the gun tomorrow. I like the Clarke, Dallas, Nevada, and Ouachita county section of the state.......but overall the next two days should be incredible from a meteorological standpoint. Link to comment Share on other sites More sharing options...
Stebo Posted April 26, 2011 Share Posted April 26, 2011 I'd certainly argue there is a growing potential further North on Wednesday per the latest model runs, SREF showing higher numbers much further North than previous runs too. Link to comment Share on other sites More sharing options...
TheWeatherPimp Posted April 26, 2011 Share Posted April 26, 2011 00z GFS is ugly for portions of Eastern Indiana/Ohio Link to comment Share on other sites More sharing options...
baroclinic_instability Posted April 26, 2011 Share Posted April 26, 2011 GFS just bombed this run with the northern stream upper low displaced farther W allowing for more growth of the secondary main impulse Wednesday. Main result is even stronger mid level mass response and a slightly larger occlusion/dry slot, as expected. The hodos are almost unrealistic. Link to comment Share on other sites More sharing options...
Hoosier Posted April 26, 2011 Share Posted April 26, 2011 Tomorrow is looking better and better with precip clearing out of Indiana by 12z with destabilization in progress across Eastern Illinois and all of Indiana by late morning per the rapid refresh. I like the speed shear tomorrow but the directional shear isn't that good in the area. Not sure how great the tornado threat will be but overall severe parameters look decent for whatever is around. Link to comment Share on other sites More sharing options...
cyclone77 Posted April 26, 2011 Share Posted April 26, 2011 Pretty sick forecast soundings coming out of far southeast Oklahoma/northeast Texas tomorrow evening. This event won't be as widespread as what will happen Wednesday, but some strong tornadoes look quite possible over some of the same areas that were impacted today. 00z NAM forecast sounding over far southeast Oklahoma tomorrow evening... Link to comment Share on other sites More sharing options...
Stebo Posted April 26, 2011 Share Posted April 26, 2011 GFS just bombed this run with the northern stream upper low displaced farther W allowing for more growth of the secondary main impulse Wednesday. Main result is even stronger mid level mass response and a slightly larger occlusion/dry slot, as expected. The hodos are almost unrealistic. Yeah Wednesday is starting to get that scary potential to it. Especially with the models uniformly trending left each run. Link to comment Share on other sites More sharing options...
weathergy Posted April 26, 2011 Share Posted April 26, 2011 Impressive night folks. Let's hope that total fatalities, and damage remains to a minimal from this system. That Vilonia tornado was certainly impressive. Link to comment Share on other sites More sharing options...
Stebo Posted April 26, 2011 Share Posted April 26, 2011 Pretty sick forecast soundings coming out of far southeast Oklahoma/northeast Texas tomorrow evening. This event won't be as widespread as what will happen Wednesday, but some strong tornadoes look quite possible over some of the same areas that were impacted today. 00z NAM forecast sounding over far southeast Oklahoma tomorrow evening... Wow not often do you see such amazing shear coinciding with large instability like this. Link to comment Share on other sites More sharing options...
weathergy Posted April 26, 2011 Share Posted April 26, 2011 Yeah Wednesday is starting to get that scary potential to it. Especially with the models uniformly trending left each run. Certainly. Each model is trending SEMI more, and more into the warm sector. Link to comment Share on other sites More sharing options...
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