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> April 25-30 Plains/MW/OV/GL Severe Weather Outbreak Sequence, Long range (6-10 days): Forecasts and Observations
ClicheVortex2014
post Apr 20 2017, 05:39 PM
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GFS and Euro are showing some major severe weather potential associated with a large longwave trough that has numerous shortwaves rotating around it. Seasonably rich moisture (if not slightly unseasonal) will be present in the warm sector... looking at multiple rounds of severe weather.








This post has been edited by ClicheVortex2014: Apr 26 2017, 12:00 PM


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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ClicheVortex2014
post Apr 20 2017, 05:39 PM
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QUOTE(ClicheVortex2014 @ Apr 20 2017, 01:44 PM) *
Strongest day 10 severe weather signal on I've seen. Almost 80% of the analogs had at least 1 severe report in central AR.




--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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ClicheVortex2014
post Apr 21 2017, 12:52 AM
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GFS still coming in hot




Then this happens a few days later


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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snowlover2
post Apr 21 2017, 04:41 AM
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Day 8 area outlined.
Attached Image

QUOTE
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Fri Apr 21 2017

Valid 241200Z - 291200Z

...DISCUSSION...
...Monday/Day 4...
The medium-range models begin the Day 4 to 8 period with an
upper-level low over northern Georgia and move this feature to the
east coast on Monday/Day 4. Thunderstorm development will be
possible during the day across parts of the eastern Carolinas.

...Tuesday/Day 5...
Both the ECMWF and GFS advect moisture into eastern parts of the
Great Plains on Tuesday/Day 5 and move a relatively low-amplitude
upper-level trough across the region. Although a localized severe
threat would be possible across parts of the southern Plains Tuesday
afternoon and evening, any convective development should remain very
isolated.

...Wednesday/Day 6...
Both the ECMWF and GFS continue moisture advection across the
south-central U.S. as an upper-level trough moves into the Four
Corners region on Wednesday/Day 6. Both models place an axis of
instability by afternoon across east Texas extending north
northeastward into the Ozarks. If this pattern materializes, severe
thunderstorms will be possible along the northern part of the
instability corridor in the Ozarks and mid Mississippi Valley on
Wednesday afternoon and evening.

...Thursday/Day 7...
The ECMWF and GFS differ in their solutions on the shortwave trough
positions for Thursday/Day 7. The ECMWF develops a negatively tilted
shortwave trough over the central Plains while the GFS maintains
southwesterly flow across the central U.S. If the ECMWF were to
verify, a cluster of severe storms would be possible across eastern
parts of the central Plains eastward into the mid Mississippi
Valley. Predictability remains low due to differences in model
solutions concerning smaller-scale features.

...Friday/Day 8...
The ECMWF and GFS are in better agreement in the western U.S.,
developing a vigorous upper-level trough in the Four Corners region.
This coincides with strong moisture advection across the Great
Plains. The synoptic setup which the medium-range models have been
forecasting for a couple days, could result in a significant severe
weather event on Friday into Friday night across parts of the
southern and central Plains with tornadoes, large hail and wind
damage possible. Due to the potential for a higher-end event on
Friday, have added a 15 percent contour where model consensus places
the greatest chance of severe weather.

..Broyles.. 04/21/2017


--------------------
# of T-Storm Watches:5

# of T-Storm Warnings:10

# of Tornado Watches:2

# of Tornado Warnings:
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ClicheVortex2014
post Apr 21 2017, 12:35 PM
Post #5




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--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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ClicheVortex2014
post Apr 21 2017, 12:47 PM
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Unprecedented on MV's index



--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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StL weatherjunki...
post Apr 21 2017, 01:51 PM
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QUOTE(ClicheVortex2014 @ Apr 21 2017, 01:35 PM) *


Closer to my backyard, only 98% of the 48 hail analogs were significant ...
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--------------------
All model guidance is just that, guidance. It is the responsibility of the forecaster to take that information, make it better, and to appropriately communicate the forecast to the users.

Fervent supporter of the idea to make GFS output beyond hour 168 proprietary! Anyone wanting to post/share/tweet/etc GFS output beyond day 7 should have 1) a limited set of graphics available with the option to 2) contribute a nominal fee to get a full suite of products while improving future GFS output. #EURObusinessfor-the-win
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ClicheVortex2014
post Apr 21 2017, 02:53 PM
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QUOTE(StL weatherjunkie @ Apr 21 2017, 02:51 PM) *
Closer to my backyard, only 98% of the 48 hail analogs were significant ...

Can you say 'statistically insignificant'? laugh.gif


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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ClicheVortex2014
post Apr 22 2017, 01:30 AM
Post #9




Rank: F5 Superstorm
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Posts: 20,769
Joined: 21-April 14
From: Athens, Ohio
Member No.: 29,453





Never seen anything like this in the 4 years I've been doing this




--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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ClicheVortex2014
post Apr 22 2017, 09:35 AM
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Member No.: 29,453





Long lead time + very early mentions of a significant event = eastern Oklahoma is about to get flooded with chasers. Hotels in Tulsa are probably wondering what the heck is going on.


QUOTE
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CDT Sat Apr 22 2017

Valid 251200Z - 301200Z

...DISCUSSION...
...Tuesday/Day 4...
The ECMWF and GFS solutions move an upper-level trough eastward into
the Great Plains on Tuesday/Day 4. Both solutions forecast a
corridor of moderate instability in the southern Plains by late
afternoon. A severe threat will be possible along parts of this
instability corridor in the southern Plains during the late
afternoon and evening. Will hold off on adding an area due to
spatial uncertainties.

...Wednesday/Day 5...
The ECMWF and GFS solutions move the upper-level trough into the mid
Mississippi Valley on Wednesday/Day 5 as a cold front advances
across the region. Ahead of the cold front, an axis of moderate
instability is forecast by both models suggesting a severe threat
will again be possible along parts of the instability corridor in
the late afternoon and evening. Again, spatial uncertainties
preclude adding an area at this time.

...Thursday/Day 6...
As with previous runs, the ECMWF ejects a lead shortwave trough
across the central Plains on Thursday/Day 6 while the GFS maintains
an upper-level trough further west in the Four Corners region. Both
solutions surge a moist high-quality airmass northward into the
southern Plains and develop a well-formed dryline by late afternoon.
In spite of the differences at 500 mb, both solutions move a
mid-level jet over the moist sector as a low-level jet strengthens
during the early evening. This setup suggests a higher-end severe
weather event will be possible in the southern and central Plains
during the late afternoon and evening with a potential for
tornadoes, large hail and wind damage.

...Friday/Day 7...
The ECMWF and GFS solutions continue to develop an upper-level
trough in the Four Corners region on Friday/Day 7 as a mid-level jet
ejects out of the base of the trough into the southern and central
Plains. The GFS maintains a high-quality moist sector over the
southern Plains Friday afternoon and evening while the ECMWF waits
until the overnight period to surge moisture northward across the
Southern Plains. Both of these solutions would be favorable for a
severe weather event in parts of the southern and central Plains
Friday or Friday night. A higher-end severe weather event will be
possible with supercells and a potential for tornadoes, large hail
and wind damage.

...Saturday/Day 8...
The ECMWF and GFS solutions move an upper-level trough across the
Four Corners region and southern Rockies on Saturday/Day 8 as
southwest mid-level flow remains over the central U.S. Both
solutions suggest a cold front will advance eastward across the mid
Mississippi Valley by late Saturday afternoon. A severe threat would
be possible along the front but uncertainty is substantial at this
range in the forecast period.


This post has been edited by ClicheVortex2014: Apr 22 2017, 09:36 AM


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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StormChazer
post Apr 22 2017, 11:02 AM
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QUOTE(ClicheVortex2014 @ Apr 22 2017, 09:35 AM) *
Long lead time + very early mentions of a significant event = eastern Oklahoma is about to get flooded with chasers. Hotels in Tulsa are probably wondering what the heck is going on.



Lucky for me, I live in Tulsa. This is looking to be a very good setup this far out.
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StormChazer
post Apr 22 2017, 11:27 AM
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Thursday is beginning to look like a good setup day as well.
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ClicheVortex2014
post Apr 22 2017, 11:33 AM
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22.4 EHI. Keep in mind, in the most simplistic way, EHI greater than 4 is generally favorable for strong tornadoes.


Same exact location, just 12 hours earlier. The transformation is amazing


This post has been edited by ClicheVortex2014: Apr 22 2017, 11:43 AM


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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StL weatherjunki...
post Apr 22 2017, 12:50 PM
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From: Morgantown, WV
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Looks to be a serious flooding potential here too, GFS indicating 4 day totals around 10"
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--------------------
All model guidance is just that, guidance. It is the responsibility of the forecaster to take that information, make it better, and to appropriately communicate the forecast to the users.

Fervent supporter of the idea to make GFS output beyond hour 168 proprietary! Anyone wanting to post/share/tweet/etc GFS output beyond day 7 should have 1) a limited set of graphics available with the option to 2) contribute a nominal fee to get a full suite of products while improving future GFS output. #EURObusinessfor-the-win
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ClicheVortex2014
post Apr 22 2017, 12:52 PM
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QUOTE(StL weatherjunkie @ Apr 22 2017, 01:50 PM) *
Looks to be a serious flooding potential here too, GFS indicating 4 day totals around 10"

Doesn't surprise me given the quasi-stationary jet/stationary front.


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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StL weatherjunki...
post Apr 22 2017, 01:01 PM
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QUOTE(ClicheVortex2014 @ Apr 22 2017, 01:52 PM) *
Doesn't surprise me given the quasi-stationary jet/stationary front.

Yea, just a bit of anomalous moisture too

This post has been edited by StL weatherjunkie: Apr 22 2017, 01:02 PM
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--------------------
All model guidance is just that, guidance. It is the responsibility of the forecaster to take that information, make it better, and to appropriately communicate the forecast to the users.

Fervent supporter of the idea to make GFS output beyond hour 168 proprietary! Anyone wanting to post/share/tweet/etc GFS output beyond day 7 should have 1) a limited set of graphics available with the option to 2) contribute a nominal fee to get a full suite of products while improving future GFS output. #EURObusinessfor-the-win
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JDStormsWx
post Apr 22 2017, 01:18 PM
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Would also keep an eye on Tuesday.. both EURO/GFS initiate in central/east OK/KS in pretty decent environment.
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ClicheVortex2014
post Apr 22 2017, 01:57 PM
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QUOTE(JDStormsWx @ Apr 22 2017, 02:18 PM) *
Would also keep an eye on Tuesday.. both EURO/GFS initiate in central/east OK/KS in pretty decent environment.

Looks a bit dry and capped. Nonetheless worth watching though.


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 6 (Last: 7/7/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
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StL weatherjunki...
post Apr 22 2017, 01:57 PM
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From: Morgantown, WV
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QUOTE(ClicheVortex2014 @ Apr 22 2017, 12:33 PM) *


22.4 EHI. Keep in mind, in the most simplistic way, EHI greater than 4 is generally favorable for strong tornadoes.

Same exact location, just 12 hours earlier. The transformation is amazing

These are wild soundings. Goes to show how potent the warm front will be and also indicates that the warm front will be the feature to watch early in the event for tornadoes. Enhanced backing along the warm front boosts SRH relative to the cold front/dry line and it doesn't appear that surface convergence will be an issue.

Edit, capping along the cold front/dry line appears to be an issue

This post has been edited by StL weatherjunkie: Apr 22 2017, 01:59 PM


--------------------
All model guidance is just that, guidance. It is the responsibility of the forecaster to take that information, make it better, and to appropriately communicate the forecast to the users.

Fervent supporter of the idea to make GFS output beyond hour 168 proprietary! Anyone wanting to post/share/tweet/etc GFS output beyond day 7 should have 1) a limited set of graphics available with the option to 2) contribute a nominal fee to get a full suite of products while improving future GFS output. #EURObusinessfor-the-win
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JDStormsWx
post Apr 22 2017, 02:00 PM
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QUOTE(ClicheVortex2014 @ Apr 22 2017, 01:57 PM) *
Looks a bit dry and capped. Nonetheless worth watching though.


Wouldn't be widespread given cap, but both initiate along dryline.

This post has been edited by JDStormsWx: Apr 22 2017, 02:01 PM
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