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Central/Western Summer Medium/Long Range Discussions


Srain

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Another large 30% sig hatched area for the D3 across portions of the Northern Plains. I'm growing increasingly confident that at least one of these days is going to end up as a moderate risk, given the at least modest shear and plentiful instability, the weekend still may hold the greatest potential as the strongest flow aloft overlaps the warm sector, although the Euro is not in sync with much of the rest of guidance and kicks the dominant vort max northward.

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18z GFS continues to suggest a robust threat in the Eastern Dakotas through MN and IA perhaps into WI around the end of this weekend as a strong vort max and near 70 kt 500 mb jet streak kicks the ejecting s/w trough negatively tilted and rapidly enhances LLJ dynamics, leading to 0-3 km SRH of 250-400 m2/s2 in addition to already strong instability of 3000+ J/kg SBCAPE. Rather impressive looking setup.

You don't see dynamic troughs like that everyday this time of year...

Nevermimd the fact that it's June, that's somewhat rare for even April and May for strong/moderate instability to be overlapped by impressive SRH Values (even though it's only 0-3KM and not 0-1KM SRH), and a strong 500mb jet core. All those conditions would lead to some impressive tornado parameters as well. Haven't looked at anything, but how does the EML/CINH look? Given this is still 4 days out, if that GFS Solution were to verify, it definitely could be an active severe weather day. Tornado potential would probably depend on if storms could become surface-based, and what storm mode they take on.
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Quite a drastic change in today's 1630 to 2000Z Day 1 outlook, was in a 30% hail/wind area, now down to 5%.

http://www.spc.noaa.gov/products/outlook/archive/2013/day1otlk_20130624_1630.html

http://www.spc.noaa.gov/products/outlook/archive/2013/day1otlk_20130624_2000.html

Writeup seems to blame this on "northeastward advection of stronger capping elevated mixed layer air".

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Just getting over spring rush... pto finally available.  Will be out tomorrow chasing SW Minnesota CAPE bombs.  Great turning, need some more speed at all levels.  Maybe 4000mlCAPE will make up for it.  Actually reminds me a lot of the Austin day in 2009.  One could only dream...  WRF shows storms at least in the target area.  Beggars can't be choosers and this looks like "it" for quite some time with the massive western ridge setting up...

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TORNADO WARNING

NATIONAL WEATHER SERVICE PADUCAH KY

740 PM CDT WED JUN 26 2013

 

THE NATIONAL WEATHER SERVICE IN PADUCAH HAS ISSUED A

 

* TORNADO WARNING FOR...

  NORTHWESTERN CAPE GIRARDEAU COUNTY IN SOUTHEAST MISSOURI...

 

* UNTIL 815 PM CDT

 

* AT 737 PM CDT...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A

  TORNADO WAS LOCATED NEAR DAISY...AND MOVING SOUTH AT 40 MPH.

 CAPE COUNTY EMERGENCY MANAGER ALSO REPORTED A ROTATING WALL CLOUD 

ASSOCIATED WITH THIS STORM. 

 

  HAZARD...TORNADO AND PING PONG BALL SIZE HAIL.

 

  SOURCE...WEATHER SPOTTERS REPORTED FUNNEL CLOUD.

 

 

* LOCATIONS IMPACTED INCLUDE...

  BOLLINGER MILL STATE HISTORIC SITE...JACKSON...DAISY...

  MILLERSVILLE...BURFORDVILLE...GORDONVILLE AND OAK RIDGE.
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  • 4 weeks later...

A very wet and stormy pattern is developing across the Plains this week that is certainly different than the pattern seen the past two summers. The upper ridge that plagued the Plains lending to a big drought is becoming a distant memory with increasing rain chances and even some potential for flooding.

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  • 2 weeks later...
  • 2 weeks later...

I've been down here in Austin Texas since June 4. I'll be here til late September.

 

It's hot as Dante's Inferno. There is no rain. Everything just dries up and blows away in these incessant southeasterly winds.

 

I hate summer with all my heart.

 

It's so damned hot that a high of only 90 degrees feels like a late September Canadian front in Washington DC.

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GFS still  dropping a lot of rain along the AZ CA border. That area has a drought but 3-4 inches of rain is a lot in one day for the desert.

 

6Z GFS was a bit happier with the Ivo remnants, near 5 inches, but 3 inches of rain per 12Z GFS in the drainage basin of the hypersaline Salton Sea will do short term wonders for the ecosystem.

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  • 3 weeks later...

Mid/long range pattern on the 12z GFS/Euro appears highly suggestive of the potential for severe weather (possibly widespread) as we move towards the Autumnal Equinox/last two weeks of September. Both models appear to anchor a large upper trough in the West and rotate periodic vort-maxes through the flow (Euro being more extreme and ejecting a powerful impulse towards the end of the run).

 

There appears to be substantial ensemble support as well.

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BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND

324 PM CDT WED SEP 11 2013

 

THE NATIONAL WEATHER SERVICE IN GRAND FORKS HAS ISSUED A

 

* TORNADO WARNING FOR...

  CENTRAL LAKE OF THE WOODS COUNTY IN NORTH CENTRAL MINNESOTA...

 

* UNTIL 415 PM CDT

 

* AT 322 PM CDT...A CONFIRMED TORNADO WAS LOCATED 6 MILES NORTH OF

  GRACETON...AND MOVING SOUTHEAST AT 30 MPH.

  SOURCE...WEATHER SPOTTERS CONFIRMED TORNADO.

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Mid/long range pattern on the 12z GFS/Euro appears highly suggestive of the potential for severe weather (possibly widespread) as we move towards the Autumnal Equinox/last two weeks of September. Both models appear to anchor a large upper trough in the West and rotate periodic vort-maxes through the flow (Euro being more extreme and ejecting a powerful impulse towards the end of the run).

 

There appears to be substantial ensemble support as well.

 

Glad someone else saw this. GFS and Euro have been on this scenario for a few days now in the 1 week+ range. We'll have to watch out for any influences from TC's in the Gulf/Atlantic, and crappy lapse rates are always something to look out for in September, but this is the best looking H5 setup we've seen since May.

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Glad someone else saw this. GFS and Euro have been on this scenario for a few days now in the 1 week+ range. We'll have to watch out for any influences from TC's in the Gulf/Atlantic, and crappy lapse rates are always something to look out for in September, but this is the best looking H5 setup we've seen since May.

 

Speaking of that, the 18z GFS is quite simply a train of strong systems riding over the -PNA ridge and then ejecting out into the Central US.

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Glad someone else saw this. GFS and Euro have been on this scenario for a few days now in the 1 week+ range. We'll have to watch out for any influences from TC's in the Gulf/Atlantic, and crappy lapse rates are always something to look out for in September, but this is the best looking H5 setup we've seen since May.

 

This. I can't even count how many times over the past decade a promising fall pattern has coincided with tropical mischief that ruins everything with cirrus and mid-level warmth. Uncanny.

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This. I can't even count how many times over the past decade a promising fall pattern has coincided with tropical mischief that ruins everything with cirrus and mid-level warmth. Uncanny.

 

Hey now, let's just keep this thing on the board for the next few days (00z GFS did) before that comes into play.

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Models seem to be coming into further agreement regarding a potent s/w trough ejecting across the Central/Northern Plains in the 96-144 hr range, which will likely generate the first potential of svr weather in this upcoming western troughing regime.

 

That said, the bigger potential may exist with the series of strong jet streaks progressing from the Aleutians through the Pacific NW, which may eventually lead to the development of a larger scale system across the Western/Central CONUS .

 

tUHHOtx.gif

 

That said, the moisture trajectories from the Gulf may end up being less than stellar in both cases if the 12z Euro is on the right track.

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Getting more interested in the 9/25-9/27 period. Still significant uncertainty even on the broad scale, as evidenced by yesterday's (15/12z) Euro pumping a western CONUS death ridge during the same period. However, for today at least, the GFS and Euro are both leaning toward a favorable pattern.

 

post-972-0-55550700-1379367502_thumb.gif

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The pattern leading into this seems to be a fairly classic one proceeding long-wave trough evolution in the western/central CONUS. 12z GFS essentially has the same idea heading into truncation. The evolution will also be dependent on how the lead s/w trough (that ejects out around a week from now +/- a day) acts to "pave the way" so to speak for the second and stronger jet streak that eventually carves out the larger scale feature we're seeing on the various models.

 

Not sure how much severe potential will be with that lead trough though since it will be in a rather unfavorable flow regime in the wake of this week's system that traverses the Northern Plains.

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Starting to look like moisture will be a major limiting factor for next week, regardless of the exact evolution of the trough. We get wiped pretty good by the front this weekend.

 

Anyone seen this video from an outbreak on 1973-09-25? Stumbled across it on YT a few days ago, and it only served to kick my SDS and delusional fall chase hopes into high gear.

 

 

What an impressive autumn setup for the Plains; arguably high risk material. The Salina tornado shown in the video had a 170-mile path into SE NE.

 

http://bangladeshtornadoes.org/UScases/092573/09267300zh5.gif

http://bangladeshtornadoes.org/UScases/092573/09257321zsf.gif

http://bangladeshtornadoes.org/UScases/092573/092573pth.gif

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From about late Sep into early Nov, if you get a legit MJO wave, intimately tied with the AAM cycle, that orbits 7-8-1, usually synoptic features place favorably for tornado outbreaks. The issues with tropical system's clouds and enough moisture return are valid. This year could prove productive with what I'm seeing in the W Pac.

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DAY 2 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1256 AM CDT THU SEP 26 2013

   VALID 271200Z - 281200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE SRN HIGH
   PLAINS...

   ...SYNOPSIS...
   AMPLIFIED UPPER-LEVEL TROUGH OVER THE WEST WILL EJECT ONTO THE
   NRN/CNTRL PLAINS BY 12Z/SAT...AS A PROMINENT RIDGE REMAINS FROM THE
   WRN GULF TO THE GREAT LAKES. SURFACE COLD FRONT FROM THE UPPER
   MIDWEST TO THE CNTRL HIGH PLAINS WILL ACCELERATE BY THE LAST HALF OF
   THE PERIOD...LIKELY AUGMENTED BY CONVECTIVE OUTFLOW...AND SHOULD
   REACH THE UPPER MS VALLEY TO SRN HIGH PLAINS. THIS BOUNDARY WILL
   OVERTAKE A LEE TROUGH ANCHORED ACROSS THE SRN HIGH PLAINS.

   ...SRN/CNTRL HIGH PLAINS...
   AFTERNOON CONVECTION WILL FORM ALONG THE LEE OF THE SRN ROCKIES
   AND BECOME WIDESPREAD FRI EVENING/NIGHT WITHIN A FAVORABLY COUPLED
   RIGHT-ENTRANCE REGION OF A VIGOROUS ULJ AND A STRENGTHENING SLY LLJ.
   THE LATTER WILL YIELD AN INFLUX OF RICHER WRN GULF MOISTURE AND
   SHOULD RESULT IN A PLUME OF WEAK TO MODERATE BUOYANCY DEVELOPING
   FROM WRN TX INTO SWRN KS BY EARLY EVENING. ALTHOUGH HIGH-LEVEL LAPSE
   RATES WILL BE MODEST...STEEP LOWER-LEVEL LAPSE RATES ALONG WITH
   STRONG DEEP-LAYER SHEAR WILL YIELD INITIAL HAZARDS OF SEVERE
   HAIL/WIND. THIS SHOULD TRANSITION TO A RISK FOR ISOLATED SEVERE WIND
   AND PERHAPS A COUPLE OF TORNADOES FRI EVENING.

   ...MN..
   ISOLATED TO WIDELY SCATTERED ELEVATED CONVECTION SHOULD BE ONGOING
   AT 12Z/FRI WITHIN THE EXIT REGION OF A STRONG LLJ OVER THE CNTRL
   PLAINS TO UPPER MIDWEST. GUIDANCE IS FAIRLY CONSISTENT THAT THIS
   WILL BE ACCOMPANIED BY A PLUME OF STEEP MID-LEVEL LAPSE RATES AND A
   RISK FOR MARGINALLY SEVERE HAIL MAY PERSIST INTO EARLY D2. IN THE
   WAKE OF THIS ACTIVITY...A CAPPING INVERSION SHOULD INHIBIT
   SURFACE-BASED WARM SECTOR DEVELOPMENT. BUT WITH NEAR RECORD-WARM
   TEMPERATURES...INHIBITION MAY SUFFICIENTLY DIMINISH FOR ISOLATED
   STORMS FORMING ALONG THE FRONT BY LATE AFTERNOON. WEAK BUOYANCY
   SHOULD REMAIN A LIMITING FACTOR GIVEN A MODIFIED CP AIR MASS...BUT
   AMPLE DEEP-LAYER SHEAR COULD YIELD A RISK OF ORGANIZED SEVERE. WITH
   THIS EXPECTED TO BE OVER A NARROW CORRIDOR...AND GIVEN SUBSTANTIAL
   DIFFERENCES WITH GUIDANCE OVER THE DEGREE OF FRONTAL ACCELERATION
   DURING PEAK DIURNAL HEATING...WILL DEFER ON POSSIBLE SLIGHT RISK
   ISSUANCE.

   ..GRAMS.. 09/26/2013

 

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