thewxmann Posted April 8, 2012 Share Posted April 8, 2012 I remember they would issue extend period threats covering more than one day, although I'm pretty sure last year did not have a 7 day risk issued at all (or even a 6 day risk). I'm pressed to remember whether 2010 did either. I remember 2/5/08 had a 6 day risk area highlighted. 4/27 last year was 5 days. Ah found one, 5/31 of 2008 for June 6th. Good catch. Had to look back at the SPC archives to see what happened on that day. Link to comment Share on other sites More sharing options...
andyhb Posted April 8, 2012 Author Share Posted April 8, 2012 Was part of that crazy outbreak sequence that year from May 22nd through early June. Gotta say that some of the 00z GFS ensemble members just look like plain and simple nastiness next weekend (I.E. stronger upper level circulation, very deep SLP, check out member P005 if you want an idea at some of the more dangerous solutions). Although with that said, the OP is nothing to sneeze at either. Link to comment Share on other sites More sharing options...
andyhb Posted April 8, 2012 Author Share Posted April 8, 2012 12z GFS slows it down...and really intensifies the ridge in the east... Link to comment Share on other sites More sharing options...
jdrenken Posted April 8, 2012 Share Posted April 8, 2012 Has SPC ever issued a Day 7 area? January 22nd had a Day 7-8 disco, but not an actual highlighted zone. Link to comment Share on other sites More sharing options...
andyhb Posted April 8, 2012 Author Share Posted April 8, 2012 Although with that said, I find it a bit strange since the lead impulse is stronger and the ridge is weaker on Thursday/Friday on this run (compared to 00z/06z), but then it ends up with a stronger ridge by Saturday/Sunday... And now that I look at it, Friday looks to have similar potential to what the 00z GFS previously had on Saturday. Link to comment Share on other sites More sharing options...
Superstorm93 Posted April 8, 2012 Share Posted April 8, 2012 Something might eventually come out of this period, but the variance in the models is something that is really hard to look beyond for now. Link to comment Share on other sites More sharing options...
brettjrob Posted April 8, 2012 Share Posted April 8, 2012 Friday looks like the closest thing to a sure bet for higher-end potential at the moment... so long as the cap isn't a problem, which it could be. Not to sound like a broken record, since I preached this leading up to the big mid-March trough, but... climatology does not favor big multi-day Plains events this early in the season. The fact that this trough once again takes its time translating across the West Coast and Great Basin definitely makes me suspicious. I'd be more excited to see a faster and more consolidated ejection into the Rockies/Plains, but the pattern has not favored that this year so far. Taking each day at face value on the modeling, Thu-Sun all have significant potential. Those warm mid-levels in the earlier of those days might be tough to overcome with low-mid 60s dew points, as opposed to the upper 60s you might have with a similar setup in May (e.g., 4-5 May 2007). Speaking of which, I strongly suspect the GFS is overdoing low-level moisture, given less-than-favorable trajectories coming around the East Coast high. Overall, this feels like a case where the synoptic pattern looks a little out-of-whack (at least for April), but it's not like you can ignore the impressive setups the models have variously shown for each day in the Thu-Sun timeframe. Link to comment Share on other sites More sharing options...
SquatchinNY Posted April 8, 2012 Share Posted April 8, 2012 Link to my livestream channel http://www.justin.tv/svrwarn/ Mods, if I'm not allowed to post that here, please delete. Link to comment Share on other sites More sharing options...
andyhb Posted April 8, 2012 Author Share Posted April 8, 2012 Friday looks like the closest thing to a sure bet for higher-end potential at the moment... so long as the cap isn't a problem, which it could be. Not to sound like a broken record, since I preached this leading up to the big mid-March trough, but... climatology does not favor big multi-day Plains events this early in the season. The fact that this trough once again takes its time translating across the West Coast and Great Basin definitely makes me suspicious. I'd be more excited to see a faster and more consolidated ejection into the Rockies/Plains, but the pattern has not favored that this year so far. Taking each day at face value on the modeling, Thu-Sun all have significant potential. Those warm mid-levels in the earlier of those days might be tough to overcome with low-mid 60s dew points, as opposed to the upper 60s you might have with a similar setup in May (e.g., 4-5 May 2007). Speaking of which, I strongly suspect the GFS is overdoing low-level moisture, given less-than-favorable trajectories coming around the East Coast high. Overall, this feels like a case where the synoptic pattern looks a little out-of-whack (at least for April), but it's not like you can ignore the impressive setups the models have variously shown for each day in the Thu-Sun timeframe. Excellent post. Personally, I'm not sure I find this system nearly as questionable as the March 18th/19th system thanks to the much less meridional flow aloft, in addition to the fact that the upper/mid level jet overlaps the warm sector for virtually the entire period and the relatively fast moving surface lows/fronts (I.E. you don't get the stalling front/weak forcing problem, therefore problems breaking the cap like we had on 3/18 and 3/19). I do agree that the threat may have shifted east on Saturday towards the Ozarks and I do think Thursday is looking less impressive per the GFS, with possible capping problems as you mentioned. For the second point, I'm not sure about anyone else, but it looks to me like the moisture is being advected northwestward from the Caribbean/Western and Central Gulf all the way from Friday to Monday on the 12z GFS. The 850 mb flow especially, which would ensure good deep layer moisture as well. Link to comment Share on other sites More sharing options...
Ellinwood Posted April 8, 2012 Share Posted April 8, 2012 Link to my livestream channel http://www.justin.tv/svrwarn/ Mods, if I'm not allowed to post that here, please delete. protip: 13 year-olds shouldn't have livestream channels. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted April 8, 2012 Share Posted April 8, 2012 Based on the 12z GFS alone, the trajectories in the Gulf become more favorable for Sat/Sun. Link to comment Share on other sites More sharing options...
Chinook Posted April 8, 2012 Share Posted April 8, 2012 Looks like the Euro breaks out heavy precip first on Thursday (03z Friday) near Salina and Topeka. Link to comment Share on other sites More sharing options...
thewxmann Posted April 8, 2012 Share Posted April 8, 2012 A large part of the Fri-Sat setup still depends on how of the longwave trough over the EPAC ejects. The trough might not eject all coherently one piece (remember the phasing issues during the March 2 system?), which again will probably not be resolved till the system comes onshore. The 12Z ECMWF indicates this and is close to shearing the system apart. The good news is, we have greater agreement on the evolution of the Thursday system. There will likely be severe thunderstorms, but south of I-70 looks to be capped, and north of I-70 moisture does not appear to be sufficient for widespread tornadoes. Link to comment Share on other sites More sharing options...
andyhb Posted April 8, 2012 Author Share Posted April 8, 2012 Keep in mind the Euro has a bias of holding back UL energy in the SW too long. I actually think the Euro looks a bit more impressive than the 12z GFS for Saturday, H5 jet is punching directly into the warm sector at 12z on Saturday, awaiting the Wundermap update for what it looks like in between Saturday morning and Sunday morning. Link to comment Share on other sites More sharing options...
jdrenken Posted April 8, 2012 Share Posted April 8, 2012 Here is our early next week storm of interest... Link to comment Share on other sites More sharing options...
andyhb Posted April 8, 2012 Author Share Posted April 8, 2012 Anytime you see a system like that about to come on shore in April, the eyebrows begin to raise. Latest AFD snippets: ICT: THURSDAY-SUNDAY...MODELS CONTINUE TO SUGGEST PERIODIC BOUTS OFSEVERE WEATHER WILL BE POSSIBLE LATE WEEK AND THROUGH THE WEEKEND...AS PERIODIC SHORTWAVES EJECT NORTHEAST OUT OF WESTERN CONUS LONGWAVE TROUGH...INTERACTING WITH A MOIST/UNSTABLE WARM SECTOR ACROSS THE CENTRAL/SOUTHERN PLAINS. SPECIFICS REGARDING TIMING AND PLACEMENT OF SYNOPTIC FEATURES AND ASSOCIATED COVERAGE...PLACEMENT AND MAGNITUDE OF RESULTANT THUNDERSTORMS HAVE YET TO BE PINNED DOWN GIVEN CONTINUED POOR MODEL AGREEMENT. VARIOUS GFS AND ECMWF SOLUTIONS OVER THE PAST FEW DAYS WOULD SUGGEST THERE IS A THREAT DURING THE LATE AFTERNOON-OVERNIGHT HOURS ANYTIME FROM THURSDAY-SUNDAY. DESPITE THIS DISPARITY...THE DEGREE OF FORECASTED INSTABILITY AND WIND SHEAR SUGGESTS THE POTENTIAL EXISTS FOR HIGHER-END SEVERE WEATHER THIS PERIOD. STAY TUNED FOR LATER FORECASTS...AS SPECIFICS WILL BECOME CLEARER THE NEXT FEW DAYS. TSA: UPPER RIDGE BEGINS TO BREAKDOWN/SHIFT EAST AROUND MID WEEK WITHDEEPER MOISTURE SURGING INTO THE CENTRAL PLAINS THURSDAY INTO FRIDAY. MULTIPLE UPPER WAVES WILL MOVE ACROSS DURING THIS TIME INTO THE WEEKEND BEFORE MAIN UPPER LOW MOVES OUT OF THE DESERT SOUTHWEST AROUND SUNDAY. THE BOTTOM LINE IS...AN ACTIVE WEATHER PATTERN WILL PERSIST THROUGH THE UPCOMING WEEK WITH MULTIPLE CHANCES FOR STORMS...INCLUDING SEVERE WEATHER. EXACT TIMING AND OVERALL SEVERE THREATS WILL CONTINUE TO BE REFINED THROUGHOUT THE WEEK. Link to comment Share on other sites More sharing options...
Superstorm93 Posted April 9, 2012 Share Posted April 9, 2012 HPC for Saturday Link to comment Share on other sites More sharing options...
andyhb Posted April 9, 2012 Author Share Posted April 9, 2012 That high off the east coast is in a great position for moisture advection... Link to comment Share on other sites More sharing options...
Superstorm93 Posted April 9, 2012 Share Posted April 9, 2012 That high off the east coast is in a great position for moisture advection... Starting to wonder if the SPC may drop their D7 outlook on their next update due to today's inconsistency... Link to comment Share on other sites More sharing options...
andyhb Posted April 9, 2012 Author Share Posted April 9, 2012 Starting to wonder if the SPC may drop their D7 outlook on their next update due to today's inconsistency... Euro probably has its main threat on Sunday, although Saturday, if you look at the initial SLP's position in relation to the ejecting H5 jet, looks good too from a relative synoptic point of view. The main ULL is actually significantly stronger on the Euro compared to the GFS (with an embedded ~540 dm height contour at 144 hrs, compared to the GFS which has the depth at 546 at the same time and less defined, although 18z trended more towards the stronger Euro solution). If you look at the Day 4 map jdrenken posted, that is a very strong and large upper/mid level circulation off the coast at 96 hrs. GFS essentially has maintained a somewhat similar verbatim to the 00z run last night, perhaps shifting the main threat slightly further east. I think the 00z runs will be more telling on the topic of if/when/where the Day 4-8 outlooks will be placed. Link to comment Share on other sites More sharing options...
Amped Posted April 9, 2012 Share Posted April 9, 2012 Threat looks decent because there's a low in the middle of the country and it's mid April. Any halfway decent storm in the middle of the country will b ring together the ingredients for at least some Tornados. Link to comment Share on other sites More sharing options...
andyhb Posted April 9, 2012 Author Share Posted April 9, 2012 Saturday in the Eastern Plains/Lower MO Valley/Ozarks on the 00z GFS...holy moly. 90-100+ kt southwesterly H5 jet showing up at 138 to 144 hrs along with a 50+ kt south-southwesterly/southerly LLJ right out of the Caribbean/Western Gulf and a west-southwesterly H3 jet max in excess of 120 kts... This all juxtaposed with plentiful moisture with an excellent deep layer component as well (thanks to the aforementioned LLJ). Link to comment Share on other sites More sharing options...
nwburbschaser Posted April 9, 2012 Share Posted April 9, 2012 I was just looking at a map the other day which showed the tracks for lows which caused tornado outbreaks in Illinois during April, and this one fits right into that area. The forecast track seems to even resemble the track of the system that caused the 1965 Palm Sunday outbreak. Not saying that it will be anything like that system in intensity though. The action looks to be further west if anything happens this weekend. Link to comment Share on other sites More sharing options...
MnWeatherman Posted April 9, 2012 Share Posted April 9, 2012 Thursday might have capping issues, according to the 00Z GFS run. Narrow axis of moisture into Kansas and lack of forcing along the dryline is starting to make me think Thursday won't be much at all. Saturday appears to have the highest chance for widespread severe thunderstorms. Link to comment Share on other sites More sharing options...
andyhb Posted April 9, 2012 Author Share Posted April 9, 2012 Thursday might have capping issues, according to the 00Z GFS run. Narrow axis of moisture into Kansas and lack of forcing along the dryline is starting to make me think Thursday won't be much at all. Saturday appears to have the highest chance for widespread severe thunderstorms. Agreed, at least with the GFS' latest verbatim. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted April 9, 2012 Share Posted April 9, 2012 it will be interesting to watch the models come in this week to see how they handle the Sat threat, right know it looks rather interesting for eastern/ne IA, Far southern MN and WI and possibly northern IL. The 08/12z ECMWF showed NE IA, SO WI, and Northern IL. With possible development further north on Sun. Link to comment Share on other sites More sharing options...
andyhb Posted April 9, 2012 Author Share Posted April 9, 2012 Euro is a bit slower, although it still looks to have a potentially substantial threat on Saturday considering the wind fields and then possibly Sunday as well. Link to comment Share on other sites More sharing options...
brettjrob Posted April 9, 2012 Share Posted April 9, 2012 Euro is a bit slower, although it still looks to have a potentially substantial threat on Saturday considering the wind fields and then possibly Sunday as well. It looks a little faster to me compared to last night, and certainly higher-amplitude as the trough comes onshore. The SLP placement and low-level flow look a lot better along the dryline Thu-Fri, too, though I'm sure there will be some capping issues. Still, given a well-timed shortwave, I think either of those days could be explosive roughly along the 100th meridian per this run verbatim. Link to comment Share on other sites More sharing options...
blackjack123 Posted April 9, 2012 Share Posted April 9, 2012 Has SPC ever issued a Day 7 area? Here is a 7-8 day outlook highlighted October 11, 2007. http://www.spc.noaa.gov/exper/day4-820071011.html. I believe it shifted further east although. I think it was the day of the Nappanee, Indiana tornado on October 18, 2007. Link to comment Share on other sites More sharing options...
blackjack123 Posted April 9, 2012 Share Posted April 9, 2012 Here is a 7-8 day outlook highlighted October 11, 2007. http://www.spc.noaa....-820071011.html. I believe it shifted further east although. I think it was the day of the Nappanee, Indiana tornado on October 18, 2007. Sorry I made an error on the web address. It is under October 11, 2007 on the SPC day 4-8 outlook though. Link to comment Share on other sites More sharing options...
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