wisconsinwx Posted September 6, 2014 Share Posted September 6, 2014 looking forward to my heavy rain MCS It's probably going to feel run of the mill given the frequency of them in your neck of the woods recently, unless you end up with say 3-4"+ of rain. Link to comment Share on other sites More sharing options...
hm8 Posted September 7, 2014 Share Posted September 7, 2014 Agreeing with Tony here that the Norbert-orgins mid-levels here is gonna make CAPE on the definite low side. Models do sometimes underestimate instability at this range, but it's logical in this case. Link to comment Share on other sites More sharing options...
cyclone77 Posted September 7, 2014 Share Posted September 7, 2014 looking forward to my heavy rain MCS Feeling about the same for here. Timing for severe isn't the best this far west the way it's looking. Still looks like some decent rains though with the tropical connection the other peeps mentioned. Gonna be fun to watch how the whole thing evolves over the coming days. Link to comment Share on other sites More sharing options...
bdgwx Posted September 7, 2014 Share Posted September 7, 2014 The 18Z DGEX run looks interesting for southern MI and northern IN. 344+ theta-e is widespread with a backed surface flow and 925mb winds ripping at 40 kts. Link to comment Share on other sites More sharing options...
Hoosier Posted September 7, 2014 Share Posted September 7, 2014 It's real when the DGEX gets mentioned in a severe thread. Link to comment Share on other sites More sharing options...
bdgwx Posted September 7, 2014 Share Posted September 7, 2014 It's real when the DGEX gets mentioned in a severe thread. I couldn't help myself. I was unimpressed with the CAPE values on the GFS run so I just had to see what the DGEX was showing. It's like a black hole...it sucks you in sometimes Link to comment Share on other sites More sharing options...
Hoosier Posted September 7, 2014 Share Posted September 7, 2014 I couldn't help myself. I was unimpressed with the CAPE values on the GFS run so I just had to see what the DGEX was showing. It's like a black hole...it sucks you in sometimes I thought the GFS was decent with SBCAPE. This is the 18z run valid 21z Wed. Struggles to get much instability into Michigan but pretty good farther south/west given the available shear. Link to comment Share on other sites More sharing options...
andyhb Posted September 7, 2014 Author Share Posted September 7, 2014 The 18Z DGEX run looks interesting for southern MI and northern IN. 344+ theta-e is widespread with a backed surface flow and 925mb winds ripping at 40 kts. High theta-e at the surface might not mean much if the mid level lapse rates are near saturated adiabatic. 00z GFS appears to have come in significantly faster/less amplified than the 12z run. Link to comment Share on other sites More sharing options...
Hoosier Posted September 7, 2014 Share Posted September 7, 2014 High theta-e at the surface might not mean much if the mid level lapse rates are near saturated adiabatic. 00z GFS appears to have come in significantly faster/less amplified than the 12z run. I thought that Halloween 2013 case that you mentioned earlier was worth talking about for a minute as it serves as an example of unimpressive mid level lapse rates being overcome and resulting in a fairly prolific severe weather episode. Per mesoanalysis archive, mid level lapse rates for that event are roughly on par with what's being shown for this one and CAPE was even less. However, that system was more impressive dynamically and had a surface low that was more or less bombing out. Not sure we will have that kind of deepening in this case. Link to comment Share on other sites More sharing options...
andyhb Posted September 7, 2014 Author Share Posted September 7, 2014 I thought that Halloween 2013 case that you mentioned earlier was worth talking about for a minute as it serves as an example of unimpressive mid level lapse rates being overcome and resulting in a fairly prolific severe weather episode. Per mesoanalysis archive, mid level lapse rates for that event are roughly on par with what's being shown for this one and CAPE was even less. However, that system was more impressive dynamically and had a surface low that was more or less bombing out. Not sure we will have that kind of deepening in this case. That trough was nearly as strong as the 11/17 one, although the surface low didn't deepen as much as that one on the day of the event. It was really maturing when it moved north of the border on 11/1 deepening below 976 mb. There was E Pacific tropical activity affecting that one as well (Sonia/Raymond). Link to comment Share on other sites More sharing options...
tornadotony Posted September 7, 2014 Share Posted September 7, 2014 Just not feeling this. 00z Euro is a good bit weaker than the 12z run was (990mb vs. 984 mb at 00z Thu). And you're gonna need hella dynamics to overcome how warm it's gonna be aloft. Link to comment Share on other sites More sharing options...
Powerball Posted September 7, 2014 Share Posted September 7, 2014 It is the NAM of course, but it generates about 1000 to 2000 J/KG of SBCAPE in the warm sector of this system Wednesday... Link to comment Share on other sites More sharing options...
Hoosier Posted September 7, 2014 Share Posted September 7, 2014 It is the NAM of course, but it generates about 1000 to 2000 J/KG of SBCAPE in the warm sector of this system Wednesday... Was just going to post that. Generally don't trust the NAM in the 72-84 hour range but I was interested to see what kind of instability values it was generating. It's doing that with temps that aren't extraordinarily high and dews generally under 75. Day 3 outlook hinted at higher probs and a possible upgrade to moderate risk. Day 4 risk area is unchanged. Link to comment Share on other sites More sharing options...
Hoosier Posted September 7, 2014 Share Posted September 7, 2014 Absolutely atrocious mid-level lapse rates on the NAM at the sites I'm clicking around on for Wednesday. Talking about 700-500 of 5C or less. Link to comment Share on other sites More sharing options...
Quincy Posted September 7, 2014 Share Posted September 7, 2014 Potential is there, but key instability ingredients will probably be lacking, especially on Wednesday. (as mentioned, mid-level lapse rates are lousy looking) While it may be on the western fringe of (mostly west of) this sub-forum, Tuesday seems to have the higher ceiling at this point. Even there it's not a lock yet, especially if convective debris wins out and further mitigates the threat. Link to comment Share on other sites More sharing options...
Powerball Posted September 7, 2014 Share Posted September 7, 2014 Even with the poor mid-level lapse rates, we can still have a setup where much of the convection is simply low-topped and produces minimal lightning... Link to comment Share on other sites More sharing options...
andyhb Posted September 7, 2014 Author Share Posted September 7, 2014 At this point, I'm more impressed with Tuesday further west (once again targeting E Nebraska and W IA). Link to comment Share on other sites More sharing options...
Gilbertfly Posted September 8, 2014 Share Posted September 8, 2014 D3 QPF... and I should add....D2 has a half inch or more for most of the eastern half of iowa Link to comment Share on other sites More sharing options...
Hoosier Posted September 8, 2014 Share Posted September 8, 2014 Plenty of questions with this setup and certainly will be interesting/educational to watch it play out. A bit tough to pin down the best area for Wednesday but at this point it seems to me like the best ingredients may line up over Indiana (trying not to be a homer lol). I'm skeptical about the threat once you get north of southern Michigan. Link to comment Share on other sites More sharing options...
Jackstraw Posted September 8, 2014 Share Posted September 8, 2014 ^^^ I hope it cranks up it these parts. I'm 50 miles due East of you and feel like we've been sucked into the LAF screw hole void the last couple months! Link to comment Share on other sites More sharing options...
bdgwx Posted September 8, 2014 Share Posted September 8, 2014 I think I'm going to have to agree with the central Indiana area as well. The NAM is still a bit more bullish with the theta-e advection into Michigan, but I'm not convinced that'll verify. Plus, like andyhb said the lapse rates are very unimpressive up there so it might not matter anyway. The shear/instability alignment from the 00Z GFS valid at 21Z on Wednesday was about 40 kts 0-6km and 1800 j/kg of SBCAPE near Indianapolis so that's respectable. The NE/IA border area seems to be in the hotzone for nearly every outbreak this summer it seems. Link to comment Share on other sites More sharing options...
snowlover2 Posted September 8, 2014 Share Posted September 8, 2014 New day 2 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1232 AM CDT MON SEP 08 2014 VALID 091200Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS LATE TUESDAY AFTERNOON INTO TUESDAY NIGHT ACROSS PARTS OF THE CENTRAL PLAINS/MID MISSOURI VALLEY REGION INTO THE UPPER MIDWEST... ..SUMMARY SEVERE STORMS ARE EXPECTED LATE TUESDAY AFTERNOON INTO TUESDAY NIGHT ACROSS PARTS OF THE CENTRAL PLAINS AND MID MISSOURI VALLEY REGION...NORTHEASTWARD INTO THE UPPER MIDWEST. THESE STORMS WILL BE ACCOMPANIED BY THE RISK FOR SWATHS OF DAMAGING WIND GUSTS...A FEW TORNADOES...AND PERHAPS LARGE HAIL. ..SYNOPSIS IT STILL APPEARS THAT THE STRONGER POLAR WESTERLIES WILL REMAIN NEAR OR NORTH OF THE CANADIAN/U.S. BORDER AREA THROUGH MUCH OF THIS FORECAST PERIOD. HOWEVER...AS ONE SIGNIFICANT EMBEDDED CYCLONIC CIRCULATION ACCELERATES EAST OF HUDSON BAY...MODELS INDICATE THAT ANOTHER WILL BEGIN TO EVOLVE WITHIN BROADER-SCALE UPPER TROUGHING DIGGING SLOWLY ACROSS THE WESTERN CANADIAN PROVINCES AND INTERNATIONAL BORDER AREA. AT THE SAME TIME...TO THE SOUTHEAST OF THIS LATTER FEATURE...A SIGNIFICANT UPPER JET... EMERGING FROM THE PACIFIC...IS FORECAST TO CONTINUE PROPAGATING EAST NORTHEASTWARD AROUND THE NORTHERN PERIPHERY OF REMNANT SUBTROPICAL RIDGING CENTERED OVER THE SOUTHERN TIER STATES. WITHIN THE STRONGER SUBTROPICAL STREAM...ONE SIGNIFICANT IMPULSE IS EXPECTED TO PROGRESS ACROSS THE NORTH CENTRAL PLAINS AND MIDDLE MISSOURI VALLEY BY EARLY TUESDAY EVENING...THEN INTO THE UPPER MIDWEST OVERNIGHT...AS AN UPSTREAM IMPULSE SHIFTS ACROSS THE GREAT BASIN AND CENTRAL ROCKIES. AT LEAST PARTLY IN RESPONSE TO FORCING ASSOCIATED WITH THESE PERTURBATIONS...MODELS CONTINUE TO SUGGEST THAT SIGNIFICANT CYCLOGENESIS WILL OCCUR ALONG A SOUTHWARD ADVANCING COLD FRONT. AT THE SURFACE...IT STILL APPEARS MOST PROBABLE THAT THIS WILL COMMENCE IN THE VICINITY OF THE MID MISSOURI VALLEY DURING THE EVENING...BEFORE PROCEEDING NORTHEASTWARD TOWARD THE UPPER GREAT LAKES REGION OVERNIGHT. THIS SHOULD BE ACCOMPANIED BY CONSIDERABLE STRENGTHENING OF LOWER/MID TROPOSPHERIC WIND FIELDS AND VERTICAL SHEAR WITHIN THE WARM SECTOR OF THE LOW...WHERE MOISTURE CONTENT IS ALSO EXPECTED TO INCREASE TO SEASONABLY HIGH VALUES. GIVEN THE INCREASING LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION AND DESTABILIZATION...A SUBSTANTIAL INCREASE IN CONVECTIVE POTENTIAL IS EXPECTED ACROSS THE MID MISSOURI VALLEY THROUGH THE UPPER MIDWEST TUESDAY INTO TUESDAY NIGHT...INCLUDING THE RISK FOR SEVERE STORMS. OTHERWISE...THE RISK FOR THUNDERSTORM ACTIVITY WILL BEGIN TO LOWER ACROSS SOUTHWESTERN DESERTS INTO THE CENTRAL AND SOUTHERN ROCKIES...THOUGH WIDELY SCATTERED DIURNAL THUNDERSTORM ACTIVITY REMAINS POSSIBLE. THE RISK FOR THUNDERSTORM ACTIVITY MAY ALSO LINGER ACROSS PARTS OF THE SOUTHEAST...MAINLY NEAR OR JUST EAST OF SOUTHERN MID ATLANTIC COASTAL AREAS. ..CNTRL PLAINS/MID MO VALLEY INTO THE UPPER MIDWEST WHILE CONFIDENCE IN THE DEVELOPMENT OF SEVERE THUNDERSTORM ACTIVITY IS INCREASING FOR LATE TUESDAY INTO TUESDAY NIGHT...A NUMBER OF UNCERTAINTIES LINGER WHICH WILL TEMPER THE PROBABILISTIC FORECAST...AND PRECLUDE A HIGHER CATEGORICAL OUTLOOK AND THE INCLUSION OF 10 PERCENT SIGNIFICANT SEVERE PROBABILITIES...AT LEAST FOR NOW. DIFFERENCES AMONG THE MODELS CONTINUE CONCERNING THE TIMING OF MORE RAPID DEEPENING OF THE SURFACE LOW AND ITS TRACK...WHICH COULD HAVE AN APPRECIABLE IMPACT ON THE SEVERE WEATHER POTENTIAL. FURTHERMORE...MODELS CONTINUE TO SUGGEST THAT CONSIDERABLE HIGH-LEVEL CLOUD COVER/CONVECTION ASSOCIATED WITH THE LEAD UPPER IMPULSE WILL OVERSPREAD MUCH OF THE REGION DURING THE DAY. WHILE LOWER/MID TROPOSPHERIC LAPSE RATES MAY BE INITIALLY FAIRLY STEEP ACROSS THE DEVELOPING WARM SECTOR...MODEL FORECAST SOUNDINGS INDICATE MOISTENING AND SATURATION FROM UPPER INTO MID-LEVELS PRIOR TO THE ONSET OF EXPECTED VIGOROUS STORM DEVELOPMENT. AND IT REMAINS UNCLEAR WHAT...IF ANY...IMPACT THIS WILL HAVE. STILL...WITH SURFACE DEW POINTS LIKELY TO INCREASE TO AROUND 70F /ALONG WITH PRECIPITABLE WATER INCREASING UP TO AROUND 2 INCHES/...BENEATH REMNANT STEEP LOWER/MID TROPOSPHERIC LAPSE RATES...SIZABLE MIXED-LAYER CAPE ON THE ORDER OF 2000-3000 J/KG IS FORECAST TO DEVELOP BY TUESDAY AFTERNOON. AS THIS OCCURS AND LARGE-SCALE ASCENT BEGINS TO INCREASE ACROSS THE MID MISSOURI VALLEY...TOWARD THE UPPER MIDWEST...BOUNDARY LAYER BASED STORM DEVELOPMENT MAY BEGIN AS EARLY AS THE 20-22Z TIME FRAME. VERTICAL SHEAR IS EXPECTED TO ALREADY BE CONDUCIVE TO THE DEVELOPMENT OF SUPERCELLS BY THE TIME THIS OCCURS...BEFORE SOUTHERLY LOW-LEVEL JET STRENGTHENING /TO AT LEAST 40-50 KT AT 850 MB/ CONTRIBUTES TO THE EVOLUTION OF SIZABLE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS SOMETIME LATE TUESDAY AFTERNOON OR EVENING. AT THE SAME TIME...LIFT ASSOCIATED WITH STRENGTHENING LOW-LEVEL WARM ADVECTION PROBABLY WILL SUPPORT A CONSIDERABLE INCREASE IN STORMS...AND THE UPSCALE CONVECTIVE GROWTH OF AN ORGANIZING CONVECTIVE SYSTEM...INITIALLY ACROSS PARTS OF EASTERN NEBRASKA INTO IOWA...BEFORE SPREADING NORTHEASTWARD. HOW QUICKLY THIS OCCURS MAY IMPACT THE TORNADO POTENTIAL...WHICH SHOULD BE PRESENT GIVEN THE SIZE OF THE LOW-LEVEL HODOGRAPHS IN THE PRESENT OF HIGH BOUNDARY-LAYER MOISTURE CONTENT/HUMIDITY. A STRONG TORNADO OR TWO MAY NOT BE OUT OF THE QUESTION...PARTICULARLY WITH ANY LINGERING DISCRETE STORMS EARLY TUESDAY EVENING. HOWEVER...IT SEEMS THAT POTENTIALLY DAMAGING WIND GUSTS WILL BECOME THE MORE PREDOMINANT SEVERE THREAT...AS HEAVY PRECIPITATION LOADING AND THE DOWNWARD TRANSPORT OF MOMENTUM INCREASE WITH THE DEVELOPING MESOSCALE CONVECTIVE SYSTEM. ..KERR.. 09/08/2014 Link to comment Share on other sites More sharing options...
snowlover2 Posted September 8, 2014 Share Posted September 8, 2014 New day 3 DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0230 AM CDT MON SEP 08 2014 VALID 101200Z - 111200Z ...THERE IS A SLGT RISK OF SVR TSTMS WEDNESDAY AFTERNOON AND EVENING ACROSS SOUTHERN PORTIONS OF THE GREAT LAKES REGION INTO THE MIDDLE MISSISSIPPI AND LOWER OHIO VALLEYS... ..SUMMARY SEVERE STORMS ARE POSSIBLE WEDNESDAY ACROSS SOUTHERN PORTIONS OF THE GREAT LAKES REGION INTO PARTS OF THE MIDDLE MISSISSIPPI AND LOWER OHIO VALLEYS. THIS WILL BE ACCOMPANIED BY THE RISK FOR DAMAGING WIND GUSTS...POSSIBLY A COUPLE OF TORNADOES...AND COULD IMPACT THE CHICAGO...DETROIT...INDIANAPOLIS AND CLEVELAND METROPOLITAN AREAS. ..SYNOPSIS MODELS CONTINUE TO INDICATE A SOUTHWARD SHIFT OF THE POLAR WESTERLIES THROUGH THIS FORECAST PERIOD. STRENGTHENING OF CYCLONIC MID/UPPER FLOW IS EXPECTED ACROSS THE NORTHERN ROCKIES AND NORTHERN PLAINS...AROUND THE SOUTHERN PERIPHERY OF AN ELONGATED CLOSED LOW/POSITIVELY TILTED TROUGH ADVANCING ACROSS THE INTERNATIONAL BORDER AREA. THIS WILL BE PRECEDED BY A SOUTHWESTERLY SUBTROPICAL JET...WHICH IS FORECAST TO CONTINUE PROPAGATING NORTHEASTWARD THROUGH THE GREAT LAKES REGION WEDNESDAY AND WEDNESDAY NIGHT. ASSOCIATED WITH THESE DEVELOPMENTS...A FAIRLY DEEP SURFACE CYCLONE SHOULD CONTINUE TO MIGRATE NORTHEAST OF THE UPPER MISSISSIPPI VALLEY...THROUGH PORTIONS OF EASTERN ONTARIO/WESTERN QUEBEC BY THE END OF THE PERIOD. IN ITS WAKE...A SIGNIFICANT COLD FRONT WILL CONTINUE TO SURGE SOUTHEASTWARD...REACHING THE LOWER OHIO VALLEY/OZARK PLATEAU AND SOUTHERN PLAINS BY 12Z THURSDAY. THESE FEATURES ARE EXPECTED TO PROVIDE THE FOCUS FOR THE HIGHEST THUNDERSTORM PROBABILITIES ON WEDNESDAY...INCLUDING THE RISK FOR SEVERE STORMS ACROSS SOUTHERN PORTIONS OF THE GREAT LAKES REGION SOUTHWESTWARD AT LEAST THROUGH THE MID MISSISSIPPI VALLEY. ..SRN GREAT LAKES REGION INTO MID MS/LOWER OHIO VALLEYS SIMILAR POINTS OF UNCERTAINTY CONCERNING THE SEVERE WEATHER POTENTIAL ON TUESDAY CONTINUE INTO WEDNESDAY WITH THE EVOLVING SYSTEM OVER THE UPPER MIDWEST/GREAT LAKES REGION. IT CURRENTLY SEEMS MOST PROBABLE THAT A WEAKENING AREA OF CONVECTION ASSOCIATED WITH THE STRONGEST FORCING FOR UPWARD VERTICAL MOTION...AND THE CORE OF THE STRONGER DEEP-LAYER WIND FIELDS...WILL SPREAD AHEAD OF THE CYCLONE...ACROSS PARTS OF LOWER MICHIGAN AND ADJACENT PORTIONS OF THE GREAT LAKES EARLY WEDNESDAY. HOWEVER...ON THE TRAILING SOUTHERN FLANK OF AN ASSOCIATED OUTFLOW BOUNDARY...WARM ADVECTION MAY SUPPORT ANOTHER DEVELOPING CLUSTER OF STORMS ACROSS PARTS OF NORTHERN ILLINOIS AND INDIANA BY MID DAY. IT APPEARS THAT THIS WILL COINCIDE WITH THE EASTWARD/NORTHWARD ADVECTION OF SEASONABLY HIGH MOISTURE CONTENT...WITH SURFACE DEW POINTS INCREASING TO NEAR 70F EXPECTED AS FAR NORTH AS SOUTHERN LOWER MICHIGAN /AND PRECIPITABLE WATER INCREASING TO 1.75 TO 2 INCHES/. AND IT APPEARS THAT THIS WILL OCCUR IN THE PRESENCE OF AT LEAST 40-50 KT MEAN WEST SOUTHWESTERLY LOWER/MID TROPOSPHERIC FLOW. WITHIN THIS ENVIRONMENT...INCREASING INFLOW OF WEAK TO MODERATE MIXED-LAYER CAPE SHOULD SUPPORT FURTHER CONVECTIVE INTENSIFICATION...WITH THE UPSCALE GROWTH INTO AN ORGANIZING CONVECTIVE SYSTEM POSSIBLE. AS THIS OCCURS...HEAVY PRECIPITATION LOADING AND THE DOWNWARD TRANSPORT OF MOMENTUM ARE EXPECTED TO CONTRIBUTE TO SWATHS OF DAMAGING WIND GUSTS AS CONVECTION SPREADS TOWARD THE LOWER GREAT LAKES REGION THROUGH EARLY EVENING. ADDITIONAL STORM DEVELOPMENT IS EXPECTED ALONG AND AHEAD OF THE SOUTHWARD ADVANCING FRONT...INTO A PROGRESSIVELY WEAKER FLOW REGIME ACROSS THE SOUTHERN PLAINS. ..KERR.. 09/08/2014 Link to comment Share on other sites More sharing options...
A-L-E-K Posted September 8, 2014 Share Posted September 8, 2014 should see a great MCS over IA tues night and a decent but weakening system into Chicago by mid morning wed Link to comment Share on other sites More sharing options...
Indystorm Posted September 8, 2014 Share Posted September 8, 2014 The expected "southward shift of the polar westerlies" is the key ingredient in the discussion for me which gives a heads up to those of us in the forum in the central IN area. Link to comment Share on other sites More sharing options...
Hoosier Posted September 8, 2014 Share Posted September 8, 2014 12z NAM gets the surface low down to around 987 mb and is still suggesting decent instability. Question is how trustworthy is it at this range. Link to comment Share on other sites More sharing options...
IWXwx Posted September 8, 2014 Share Posted September 8, 2014 12z NAM gets the surface low down to around 987 mb and is still suggesting decent instability. Question is how trustworthy is it at this range. I know that I'm not trusting the NAM...yet. It's been kinda on it's own so far. Link to comment Share on other sites More sharing options...
Hoosier Posted September 8, 2014 Share Posted September 8, 2014 I know that I'm not trusting the NAM...yet. It's been kinda on it's own so far. We're going to need as much surface heating as possible, especially with the very poor mid level lapse rates. If lapse rates aloft were steep then it would be easier to get away with less than ideal heating, but it gets harder in a case like this. NAM is suggesting temps AOA 80 for about the southern 2/3 of the state. With 850 mb temps around 18-20C, any short period/breaks of sun should allow that to occur. Link to comment Share on other sites More sharing options...
bdgwx Posted September 8, 2014 Share Posted September 8, 2014 12z NAM gets the surface low down to around 987 mb and is still suggesting decent instability. Question is how trustworthy is it at this range. That's a -22mb pressure deficit from the outer-most closed isobar. Impressive for September... Link to comment Share on other sites More sharing options...
Hoosier Posted September 8, 2014 Share Posted September 8, 2014 NAM is considerably deeper than the GFS at the surface and aloft. Link to comment Share on other sites More sharing options...
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