David Reimer Posted December 28, 2010 Share Posted December 28, 2010 Since this upcoming system has the potential to bring a variety of impacts, both in winter and severe weather areas, I figured we might as well get a severe weather thread going in order to keep each specific topic clean. The 18Z GFS showed an ominous tornado outbreak over MS on New Years Eve. CAPE values over 1,000 j/kg with the wind patterns you would expect for a winter pattern. I'm definitely watching this system for a potential chase day. Link to comment Share on other sites More sharing options...
Indystorm Posted December 28, 2010 Share Posted December 28, 2010 And I would assume that with respect to general climatology that La Nina years might be more conducive to Dixie winter svr outbreaks? Current parameters do look scary for MS. AFD JAN does express concern for New Year's Eve. Link to comment Share on other sites More sharing options...
David Reimer Posted December 28, 2010 Author Share Posted December 28, 2010 The NAO goes to a neutral/positive phase just in time for this potential event. Seeing that raises my confidence that a event has a higher chance then normal to occur as this system passes through the area. Link to comment Share on other sites More sharing options...
Hoosier Posted December 28, 2010 Share Posted December 28, 2010 Looks like a conditional severe threat possible as far north as eastern Missouri over into southern/central IL on Friday. Not all that optimistic on any clearing and with mid level lapse rates progged to be fairly modest, it's going to be tough to realize much instability. But shear profiles are strong with decent turning noted in the low levels. Seems like a setup which may support isolated strong/severe wind gusts and possibly a tornado if any instability can be realized. Still some questions with how this setup evolves as model differences remain on exactly when and to what extent the surface low begins to rapidly deepen. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 28, 2010 Share Posted December 28, 2010 GFS showing the better conditional setup over the NAM with a stronger sfc low allowing it to pull mid 50 dews up into western IL with sfc temps reaching 66/67 allowing for a nice pocket of instability in that area under great amounts of shear. Link to comment Share on other sites More sharing options...
northpittweather Posted December 28, 2010 Share Posted December 28, 2010 Looks like not one huge event, but 3 or more small scale but significant events could happen over a region from the south to the lakes Link to comment Share on other sites More sharing options...
David Reimer Posted December 28, 2010 Author Share Posted December 28, 2010 Holy ****... AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 304 PM CST TUE DEC 28 2010 ...SEVERE WEATHER EVENT POSSIBLE NEW YEARS EVE... .DISCUSSION... THE FIRST SECTION OF THIS DISCUSSION WILL COVER THE SEVERE WEATHER EVENT POTENTIAL FOR LATE WEEK...AND WILL BE FOLLOWED BY A DISCUSSION COVERING THE REMAINDER OF THE FORECAST PERIOD. NEW YEARS EVE... SYNOPTIC OVERVIEW: LATER THIS WEEK...A LARGE...DEEP-LAYER CYCLONE WILL BE BARRELING EAST OF THE ROCKIES AS A DEEP-LAYER RIDGE AMPLIFIES OVER THE EAST COAST AND WRN ATLC. THE TROUGH WILL HAVE GAINED CONSIDERABLE AMPLIFICATION ON THURSDAY FROM STRONG UPPER-LEVEL JET ENERGY DIVING INTO THE BACKSIDE OF THE TROUGH. A SW-NE-ORIENTED JET MAX / 115 KT AT H2 / WILL BE PUSHING THROUGH THE TROUGH AXIS OVER THE SOUTHERN PLAINS ON FRIDAY. THIS WILL OCCUR AS A MID-LEVEL CYCLONE CUTS OFF IN THE BASE OF THE TROUGH AND RACES NORTH-NORTHEASTWARD OVER THE CENTRAL PLAINS...DEEPENING TO A NEAR-518-DECAMETER H5 LOW BY 00Z ON JANUARY 1 2011. THE MOST INTENSE MID/UPPER-LEVEL FORCING AND DEEP- LAYER Q-VECTOR CONVERGENCE ASSOCIATED WITH THESE FEATURES IS FORECAST TO REMAIN NW OF THE CWA AS THE UPPER TROUGH LIFTS NEWD. HOWEVER... TRAILING MID/UPPER-ASCENT EMBEDDED WITHIN A LONG FETCH OF DIFFERENTIAL POSITIVE VORTICITY ADVECTION IN SOUTHWESTERLY FLOW ALOFT IS FORECAST TO SUPPORT THE INITIATION OF CONVECTION ON FRIDAY...PARTICULARLY AFTER NOON...COMPLEMENTED BY LOW-LEVEL CONVERGENCE INVOF A POWERFUL COLD FRONT PROGGED TO CROSS THE REGION NEW YEARS EVE. MOISTURE OVERVIEW: AN ELONGATED SYNOPTIC FRONT OVER THE WRN AND CNTRL ATLC CURRENTLY EXTENDS FROM NEAR NOVA SCOTIA TO NEAR 30N53W TO JUST EAST OF PUERTO RICO. THE FRONT EXTENDS FURTHER SWWD ACROSS THE CNTRL CARIBBEAN SEA TO THE COAST OF COLOMBIA AS A STATIONARY FRONT. A PLUME OF DEEP TROPICAL MOISTURE HAS BEEN STEADILY BUILDING DURING THE LAST FEW DAYS INVOF THE FRONT AND SURFACE LOW NEAR THE COAST OF COLOMBIA AS A SERIES OF WEAK TROPICAL IMPULSES HAVE DRIFTED WWD AND BECOME ABSORBED INTO THE FRONT. AMSU/SSMI TOTAL PRECIPITABLE WATER PRODUCT DEPICTS A NEARLY 180-MILE WIDE ZONE OF 2.0-2.2-INCH PWAT VALUES POOLING INVOF THE FRONT OVER THE CARIBBEAN...MARKING THE DEEP MOISTURE BREWING WELL TO THE SOUTH...DESPITE THE COLD/DRY AIRMASS ENTRENCHED ACROSS THE ARKLAMISS. THIS MOISTURE WILL BE A KEY PLAYER IN THE EVENTUAL EVOLUTION OF SEVERE CONVECTION POSSIBLE LATER THIS WEEK. THIS WILL OCCUR AS A DEEP-LAYER RIDGE TRANSLATES FROM THE SERN CONUS AND GULF OF MEXICO INTO THE SW NORTH ATLC. SRLY RETURN FLOW WEST OF RIDGE AXIS IS FORECAST TO PUMP COPIOUS AMOUNTS OF MOISTURE...WITH TROPICAL ORIGINS...INTO THE CWA FOLLOWING THE INITIAL MID-WEEK MOISTURE SURGE. MULTI-MODEL CONSENSUS IS FOR SURFACE DEWPOINTS TO CLIMB INTO THE MIDDLE 60S ACROSS THE FORECAST AREA ON FRIDAY AHEAD OF A POWERFUL COLD FRONT PROGGED TO CROSS THE REGION FRIDAY EVENING INTO FRIDAY NIGHT...WITH DEWPOINTS IN THE 64-66F RANGE NOSING UP TO THE INTERSTATE 20 CORRIDOR. PREFRONTAL PWAT VALUES OF 1.30-1.35 INCHES ARE PROGGED TO BE RUNNING UP TO 200 PERCENT OF NORMAL...WITH H85 THETA-E VALUES REACHING THE 325-327K RANGE IN RESPONSE TO STRONG AND PROLONGED LLVL SOUTHERLY MOISTURE TRANSPORT AT 30-40 KT DURING THE PRECEDING COUPLE OF DAYS. THESE MOISTURE PARAMETERS ARE WELL ABOVE NORMAL THIS DEEP INTO THE COLD SEASON. MESOSCALE PARAMETERS: NWP CONSENSUS SUGGESTS THAT THE COMBINATION OF THE AFOREMENTIONED MOISTURE PARAMETERS AND MID-LEVEL LAPSE RATES OF 6.3-6.5 C/KM WILL SUPPORT A RELATIVELY WIDE ZONE OF UPWARDLY BUOYANT PARCELS...WITH AN AXIS OF SBCAPE/MLCAPE VALUES OF 600-1100 J/KG AHEAD OF THE FRONT. WITH SREF MEDIAN EFFECTIVE BULK SHEAR MAGNITUDES OF 40-50 KT...THE JUXTAPOSITION OF THE AFOREMENTIONED INSTABILITY AND MODERATE/STRONG DEEP-LAYER SHEAR WILL SUPPORT ORGANIZED CONVECTION. THE CURRENT THINKING IS THAT MULTIPLE CONVECTIVE MORPHOLOGIES COULD BE SUPPORTED. GIVEN THE ANTICIPATED DISPLACEMENT OF THE STRONGEST DEEP ASCENT NORTHWEST OF THE CWA...THERE WILL BE THE POTENTIAL FOR DISCRETE SUPERCELLS TO EVOLVE AHEAD OF THE FRONT. STRONG LINEAR FORCING ALONG THE FRONT COULD ALLOW FOR CONVECTION TO EVOLVE TOWARD A MORE QUASILINEAR CONVECTIVE SYSTEM MODE LATER IN THE EVENT AS THE FRONT CROSSES THE REGION. ULTIMATELY...IT IS TOO EARLY TO PIN DOWN THE EXACT DETAILS ON CONVECTIVE MORPHOLOGY...THOUGH ORGANIZED CONVECTION IS LOOKING INCREASINGLY LIKELY. CONVECTIVE HAZARDS: VERY STRONG LOW-LEVEL FLOW / SOUTHWESTERLY H85 WINDS OF 40-45 KT / WILL CERTAINLY RESULT IN STRONG LLVL SHEAR. WHERE SURFACE WINDS ARE RELATIVELY BACKED AHEAD OF THE FRONT... STRONG DIRECTIONAL SHEAR ASSOCIATED WITH STRONGLY CURVED LLVL HODOGRAPHS WILL SUPPORT 0-1 KM STORM RELATIVE HELICITY VALUES OF 150-300 M2/S2...RESULTING IN THE POTENTIAL FOR TORNADOES. THE QUANTITY OF LLVL MOISTURE AND LLVL BUOYANCY WILL FURTHER ENHANCE THE POTENTIAL FOR TORNADOES. MODELS PROJECT THE SIGNIFICANT TORNADO PARAMETER TO REACH 2-5 UNITS RANGE ACROSS A LARGE PART OF THE CWA...WHICH STUDIES SUGGEST COULD BE SUPPORTIVE OF SIGNIFICANT TORNADOES. AN ANALOG TO THIS EVENT...THE 26 NOVEMBER 1988 EVENT...WITH SIMILAR SYNOPTIC AND MOISTURE GEOMETRIES...SUPPORTED MULTIPLE TORNADOES INCLUDING STRONG TORNADOES ACROSS PORTIONS OF THE REGION. THE UPCOMING NEW YEARS EVENT IS FORECAST TO FEATURE A MORE INTENSE CYCLONE OVER THE UPPER MIDWEST WITH MINIMUM SURFACE PRESSURES DOWN TO NEAR 990 MB...SUGGESTING THE POTENTIAL FOR GREATER MOISTURE TRANSPORT INTO THE CWA. DAMAGING WINDS WILL ALSO BE A CONCERN WITH THE CONVECTION...WITH THE POTENTIAL FOR A WIDESPREAD... SIGNIFICANT DAMAGING WIND EVENT IF A QLCS EVOLVES. GIVEN THE DEGREE OF INSTABILITY AND DEEP-LAYER SHEAR...WITH H5 TEMPS FALLING TO THE -13 TO -15C RANGE...LARGE HAIL WILL ALSO BE A CONCERN. HEAVY RAINFALL COULD ALSO BECOME A CONCERN...ESPECIALLY IF THE SYSTEM SLOWS DOWN AS EARLIER RUNS OF THE ECMWF HAVE SHOWN. FORECAST CHANGES: GIVEN THE POTENTIAL FOR A HIGHER-END SEVERE WEATHER THREAT...ALONG WITH THE POTENTIAL IMPACTS GIVEN ITS OCCURRENCE ON NEW YEARS EVE...THE NATIONAL WEATHER SERVICE WILL BE RAMPING UP THE SEVERE POTENTIAL IN OFFICIAL PRODUCTS. A SPECIAL WEATHER STATEMENT IS BEING ISSUED HIGHLIGHTING THE POTENTIAL FOR A SEVERE WEATHER EVENT ON NEW YEARS EVE...AND ESPECIALLY THE CONCERN FOR TORNADOES. THIS SYSTEM WILL HAVE THE POTENTIAL TO HAVE A SIGNIFICANT IMPACT ON THE ARKLAMISS REGION...AND EVERYONE SHOULD CLOSELY MONITOR FUTURE FORECASTS AND OUTLOOKS ISSUED BY THE NATIONAL WEATHER SERVICE IN JACKSON FOR UPDATES ON THIS SITUATION. /COHEN/ Link to comment Share on other sites More sharing options...
Hoosier Posted December 28, 2010 Share Posted December 28, 2010 GFS showing the better conditional setup over the NAM with a stronger sfc low allowing it to pull mid 50 dews up into western IL with sfc temps reaching 66/67 allowing for a nice pocket of instability in that area under great amounts of shear. Is that a typo? I didn't see the GFS showing that verbatim. Link to comment Share on other sites More sharing options...
northpittweather Posted December 28, 2010 Share Posted December 28, 2010 Looks like it could get bad with a fairly dangerous set up in the south, and even up north in the OV Valley where pockets of very low cape forms, or even where no cape is present, could be a threat of wind damage and tornadoes Link to comment Share on other sites More sharing options...
Chicago WX Posted December 28, 2010 Share Posted December 28, 2010 Is that a typo? I didn't see the GFS showing that verbatim. 60-65º maybe? Link to comment Share on other sites More sharing options...
tornadotony Posted December 28, 2010 Share Posted December 28, 2010 60-65º maybe? We all know those are too low...even in full cloud cover that will be at least a few degrees too low...models cannot handle WAA like this right after a cold snap...hell they struggle with most WAA at all in the winter... Link to comment Share on other sites More sharing options...
Hoosier Posted December 28, 2010 Share Posted December 28, 2010 We all know those are too low...even in full cloud cover that will be at least a few degrees too low...models cannot handle WAA like this right after a cold snap...hell they struggle with most WAA at all in the winter... Probably right...I just wanted to know if that's what the model was actually showing or just what he was thinking. Link to comment Share on other sites More sharing options...
TheWeatherPimp Posted December 28, 2010 Share Posted December 28, 2010 Like I said earlier this week in the other thread, I fully believe we'll see 60's into Illinois and portions of Indiana. Timing will be crucial with where the severe weather threat sets up, as it would appear a faster fropa is possible. Link to comment Share on other sites More sharing options...
Srain Posted December 28, 2010 Share Posted December 28, 2010 College Station was 66 day under clouds. Keep an eye on TX tomorrow. I suspect we will have an interesting beginning to the chance of any severe weather event that may be ahead. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 28, 2010 Share Posted December 28, 2010 Probably right...I just wanted to know if that's what the model was actually showing or just what he was thinking. 66 max near near STL Link to comment Share on other sites More sharing options...
tornadotony Posted December 29, 2010 Share Posted December 29, 2010 May be a hiccup, but the 18z GFS has a pocket of CAPE >750J/kg in ern MO at 18z Friday... Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 29, 2010 Share Posted December 29, 2010 May be a hiccup, but the 18z GFS has a pocket of CAPE >750J/kg in ern MO at 18z Friday... alittle more than the 12z run showed. Link to comment Share on other sites More sharing options...
David Reimer Posted December 29, 2010 Author Share Posted December 29, 2010 Anyone else seeing some similarities to the April 24, 2010 outbreak? Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 29, 2010 Share Posted December 29, 2010 also a 20 at 21z a tad east Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 29, 2010 Share Posted December 29, 2010 also something to note is the differences in the models on how strong the sfc low gets as its in the area of IA/MO/IL we all know the key is going to be how much sunshine we can get, a descent amount would go a long way in the instability department, its not going to take much. Link to comment Share on other sites More sharing options...
Indystorm Posted December 29, 2010 Share Posted December 29, 2010 Anyone else seeing some similarities to the April 24, 2010 outbreak? New Year's Eve is a long way from April. Are dews/temps/shear and other parameters really that similar for this event? Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 29, 2010 Share Posted December 29, 2010 New Year's Eve is a long way from April. Are dews/temps/shear and other parameters really that similar for this event? Ya I dont see any model throwing out 3000 CAPE for new years eve..like 4/24 along with other differences Link to comment Share on other sites More sharing options...
L.B. LaForce Posted December 29, 2010 Share Posted December 29, 2010 holy crap, didnt even see this thread, ive still been posting in the other..lol Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 29, 2010 Share Posted December 29, 2010 21z SREF Link to comment Share on other sites More sharing options...
Derek30 Posted December 29, 2010 Share Posted December 29, 2010 Will be interesting to see how many folks decide to chase MS during the event. These events really worry me, especially with the threat of nocturnal tornadoes in the Deep South. Seem to always get nocturnals in the Deep South during outbreaks. Would be like sleeping on needles down there. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 29, 2010 Share Posted December 29, 2010 Link to comment Share on other sites More sharing options...
L.B. LaForce Posted December 29, 2010 Share Posted December 29, 2010 nice gradient, looks like a fricken dryline...lol Link to comment Share on other sites More sharing options...
Hoosier Posted December 29, 2010 Share Posted December 29, 2010 I hate how narrow that tongue of better moisture is. It's been showing up like that run after run. Check out the NAM valid almost at the same time. lol Link to comment Share on other sites More sharing options...
tornadotony Posted December 29, 2010 Share Posted December 29, 2010 This honestly is looking like a really dangerous outbreak potential down in the delta and westward toward E TX. I mean seriously, 65F dews on New Year's Eve? Seriously? Factor in good lapse rates (by winter standards) and typical strong wintertime shear profiles and you've honestly got a recipe for disaster. JAN's AFD, HWO, and SPS are well within reason. As for up here, it will depend on how warm we get. This is not a typical synoptic pattern for wintertime tornadoes, but I think we can definitely eek out a good wind damage threat if we get warmer than anticipated. GFS would lean more favorably than the NAM to any severe threat this far north. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 29, 2010 Share Posted December 29, 2010 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1258 AM CST WED DEC 29 2010 VALID 301200Z - 311200Z ..NO SVR TSTM AREAS FORECAST ..SYNOPSIS A DEEP WESTERN STATES TROUGH WILL CONTINUE TO ADVANCE TOWARD THE PLAINS ON THURSDAY...WITH THE LEAD BRUNT OF THIS TROUGH/EXIT REGION OF A STRONG POLAR JET EJECTING NORTHEASTWARD OVER THE CENTRAL/SOUTHERN PLAINS THURSDAY NIGHT. THIS SCENARIO WILL LEAD TO INCREASING PROSPECTS FOR DEEP CONVECTION/SEVERE POTENTIAL ACROSS THE SOUTH CENTRAL CONUS FROM THURSDAY NIGHT INTO EARLY FRIDAY. ..EASTERN OK/ARKLATEX THURSDAY NIGHT AS THE PARENT UPPER SYSTEM EJECTS/TAKES ON A MORE NEUTRAL TO SLIGHTLY NEGATIVE TILT...DUAL ROUNDS OF PLAINS SURFACE CYCLOGENESIS ARE EXPECTED DURING THE PERIOD WITH AN ATTENDANT LEE TROUGH/COLD FRONT GRADUALLY DEVELOPING EASTWARD ACROSS THE SOUTH-CENTRAL PLAINS. AT THE SAME TIME...A MODIFIED GULF AIRMASS WILL GRADUALLY RETREAT NORTHWARD AS A RELATIVELY MOIST AIRMASS/WARM SECTOR BECOMES INCREASINGLY ESTABLISHED THURSDAY NIGHT INTO FRIDAY. CURRENT EXPECTATIONS ARE FOR DEEP CONVECTION/TSTMS TO BECOME INCREASINGLY PROBABLE/PREVALENT ESPECIALLY LATE THURSDAY NIGHT /MAINLY AFTER 03Z/ ACROSS THE ARKLATEX/PORTIONS OF EASTERN OK. AS THE LEADING EDGE OF HEIGHT FALLS/FORCING ALOFT GRAZE THE WARM SECTOR...SUCH DEVELOPMENT WILL OCCUR BOTH IN A WARM ADVECTION/MOISTURE TRANSPORT CONVEYOR ACROSS THE ARKLATEX/OZARKS...AS WELL AS TOWARD THE END OF THE PERIOD NEAR A SHARPENING TRIPLE POINT ACROSS OK/NORTH TX/SOUTHERN KS. THE COMBINATION OF WEAK BUT ADEQUATE BUOYANCY /UPWARDS OF 500 J PER KG MLCAPE/ AMID UPPER 50S/NEAR 60F SURFACE DEWPOINTS...COUPLED WITH STRONG SOUTHWESTERLY FLOW ALOFT AND AMPLE LOW LEVEL SHEAR /AIDED BY A 45-50 KT SOUTHERLY LOW LEVEL JET/...WILL SUPPORT AT LEAST A CONDITIONAL POTENTIAL FOR SOME SUPERCELLS/ORGANIZED LINE SEGMENTS CAPABLE OF A TORNADO AND/OR DAMAGING WIND RISK THURSDAY NIGHT/EARLY FRIDAY. UNCERTAINTIES REGARDING THE SPECIFIC EXTENT OF WARM SECTOR MOISTENING/DESTABILIZATION...AS WELL AS THE NOCTURNAL/LATE NIGHT TIMING OF THE PERCEIVED PRIMARY SEVERE POTENTIAL...PRECLUDE A CATEGORICAL SLIGHT RISK AT THIS TIME. ..GUYER.. 12/29/2010 Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.