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> April 19-21 Plains/MW/OV/GL Severe Weather, Long range (6-10 days): Forecasts and Observations
ClicheVortex2014
post Apr 17 2017, 11:36 PM
Post #21




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I swear, 12z NAM better not disappoint.






This post has been edited by ClicheVortex2014: Apr 17 2017, 11:38 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)

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ClicheVortex2014
post Apr 18 2017, 12:51 AM
Post #22




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QUOTE
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1219 AM CDT TUE APR 18 2017

VALID 191200Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
PLAINS TO THE MID MISSISSIPPI VALLEY...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHERN
OKLAHOMA TO PORTIONS OF THE MIDWEST...

..SUMMARY

SEVERE THUNDERSTORMS CAPABLE OF LARGE HAIL, DAMAGING WINDS, AND A
COUPLE TORNADOES WILL BE POSSIBLE FROM THE CENTRAL PLAINS TO THE
MIDDLE MISSISSIPPI VALLEY WEDNESDAY INTO WEDNESDAY NIGHT.

..SYNOPSIS

A PROGRESSIVE MID-LEVEL PATTERN WILL EXIST ACROSS MUCH OF THE
CENTRAL/NORTHERN US ON WEDNESDAY, WITH SEVERAL LOW-AMPLITUDE
IMPULSES EMBEDDED IN WESTERLY FLOW. ONE OF THESE IMPULSES WILL
INITIALLY BE LOCATED OVER THE CENTRAL/NORTHERN HIGH PLAINS WEDNESDAY
MORNING AND WILL ADVANCE EAST/NORTHEAST, REACHING THE UPPER GREAT
LAKES BY THURSDAY MORNING. MEANWHILE, A MORE AMPLIFIED TROUGH WILL
MOVE ASHORE THE PACIFIC COAST OVERNIGHT.

..MID MISSOURI VALLEY TO THE MID MISSISSIPPI VALLEY

ON THE NOSE OF A SOUTH/SOUTHWESTERLY LOW-LEVEL JET, SHOWERS AND
THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS PORTIONS OF THE REGION
AT THE BEGINNING OF THE PERIOD. TO THE SOUTH OF THIS PRECIPITATION,
A WARM FRONT IS FORECAST FROM EAST-CENTRAL NEBRASKA EASTWARD TO
NORTHERN ILLINOIS. AS THE AFOREMENTIONED CENTRAL US IMPULSE PASSES
OVER THE REGION LATER IN THE DAY, A SURFACE LOW AND TRAILING COLD
FRONT WILL ADVANCE EASTWARD ACROSS THE MID MISSOURI VALLEY,
EVENTUALLY REACHING THE MISSISSIPPI VALLEY LATE IN THE PERIOD. ALONG
AND SOUTH OF THE WARM FRONT, MODEST DIURNAL HEATING, DEW POINTS IN
THE LOWER 60S, AND STEEPENING MID-LEVEL LAPSE RATES SHOULD
CONTRIBUTE TO MODERATE SURFACE-BASED BUOYANCY. ADDITIONALLY, AMPLE
EFFECTIVE SHEAR SHOULD OFFER THE POTENTIAL FOR MID-LEVEL ROTATION IN
STRONGER CELLS. WHILE A COUPLE TORNADOES MAY BE POSSIBLE NEAR THE
WARM FRONT, STORM MODES WILL MOST LIKELY BE CHARACTERIZED BY SMALL
BOWS/CLUSTERS, RESULTING IN DAMAGING WINDS AND LARGE HAIL BEING THE
PRIMARY THREATS.


--------------------
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 18 2017, 08:45 AM
Post #23




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Day 4 sounds promising. Can't post it now but it doesn't sound like it warrants only a slight risk. But I'm sure there'll be an enhanced risk soon enough


--------------------
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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JDStormsWx
post Apr 18 2017, 08:50 AM
Post #24




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QUOTE(ClicheVortex2014 @ Apr 18 2017, 08:45 AM) *
Day 4 sounds promising. Can't post it now but it doesn't sound like it warrants only a slight risk. But I'm sure there'll be an enhanced risk soon enough


Some differences between GFS/EURO only warranting a slight for the moment most likely. Geographic region similar on both, but progression of trough a little different for each leading to differing storm modes.
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ClicheVortex2014
post Apr 18 2017, 09:48 AM
Post #25




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NAM not as interesting as GFS....




--------------------
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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JDStormsWx
post Apr 18 2017, 09:58 AM
Post #26




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QUOTE(ClicheVortex2014 @ Apr 18 2017, 09:48 AM) *
NAM not as interesting as GFS....




Fairly sure some adjustments were made to the NAM. In it's long range it's has not been as volatile as it used to be. Plus, it's the 84hr NAM.. lol laugh.gif
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ClicheVortex2014
post Apr 18 2017, 10:07 AM
Post #27




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QUOTE(JDStormsWx @ Apr 18 2017, 10:58 AM) *
Fairly sure some adjustments were made to the NAM. In it's long range it's has not been as volatile as it used to be. Plus, it's the 84hr NAM.. lol laugh.gif

Yeah I'm just used to the craziness that was the hour 84 NAM. It's weird having the GFS be more aggressive than NAM.


--------------------
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 18 2017, 11:02 AM
Post #28




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GFS bit dry... characteristically so.




--------------------
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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JDStormsWx
post Apr 18 2017, 11:09 AM
Post #29




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QUOTE(ClicheVortex2014 @ Apr 18 2017, 11:02 AM) *
GFS bit dry... characteristically so.




Impressive at 21z SW of OKC area. Most likely early initiation in this case moving into a decent environment.
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ClicheVortex2014
post Apr 18 2017, 11:12 AM
Post #30




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Accuweather is the first 'professional' outlet to call this a possible severe weather outbreak. But signs (synoptically and with guidance) have been present for a week. My gut says tornadic supercell outbreak on Friday... squall overnight... possible discrete cells ahead of a re-developed squall on Saturday.

http://www.accuweather.com/en/weather-news...sunday/70001409

This post has been edited by ClicheVortex2014: Apr 18 2017, 11:14 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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ClicheVortex2014
post Apr 18 2017, 11:15 AM
Post #31




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Day 1/system 1... Wednesday



--------------------
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 18 2017, 11:28 AM
Post #32




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% of analogs with >1 severe report based on GFS



SPC outlook



--------------------
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 18 2017, 11:38 AM
Post #33




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From: Athens, Ohio
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This post has been edited by ClicheVortex2014: Apr 18 2017, 11:38 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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JDStormsWx
post Apr 18 2017, 01:41 PM
Post #34




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From: Stillwater, OK
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Tad difference in trough orientation/strength w/ latest euro run for friday.. *click on photo for gif*

This post has been edited by JDStormsWx: Apr 18 2017, 01:42 PM
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ClicheVortex2014
post Apr 18 2017, 02:12 PM
Post #35




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QUOTE(JDStormsWx @ Apr 18 2017, 02:41 PM) *
Tad difference in trough orientation/strength w/ latest euro run for friday.. *click on photo for gif*

Definitely a step toward GFS.

I was just looking at it on Weatherbell and was about to look how it changed from the last run. Verbatim, not as unstable as GFS... but it doesn't matter that much whether it's 3000 CAPE or 2000.


--------------------
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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JDStormsWx
post Apr 18 2017, 02:16 PM
Post #36




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QUOTE(ClicheVortex2014 @ Apr 18 2017, 02:12 PM) *
Definitely a step toward GFS.

I was just looking at it on Weatherbell and was about to look how it changed from the last run. Verbatim, not as unstable as GFS... but it doesn't matter that much whether it's 3000 CAPE or 2000.


Yep, especially w/ dynamics that may be in play. Someday we'll be able to see soundings from euro. *sighs*
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ClicheVortex2014
post Apr 18 2017, 02:26 PM
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QUOTE(JDStormsWx @ Apr 18 2017, 03:16 PM) *
Yep, especially w/ dynamics that may be in play. Someday we'll be able to see soundings from euro. *sighs*

Just from looking at low-level RH on GFS sounding text and comparing to Euro, doesn't look like it's any more moist than GFS. That could be a problem for a higher tornado threat.



This post has been edited by ClicheVortex2014: Apr 18 2017, 02:29 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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JDStormsWx
post Apr 18 2017, 02:33 PM
Post #38




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QUOTE(ClicheVortex2014 @ Apr 18 2017, 02:26 PM) *
Just from looking at low-level RH on GFS sounding text and comparing to Euro, doesn't look like it's any more moist than GFS. That could be a problem for a higher tornado threat.



That sounding down west of Dallas? Thinking best opportunity for tor threat is north of border given better shear and less capping, it would at least seem per GFS
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ClicheVortex2014
post Apr 18 2017, 02:37 PM
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QUOTE(JDStormsWx @ Apr 18 2017, 03:33 PM) *
That sounding down west of Dallas? Thinking best opportunity for tor threat is north of border given better shear and less capping, it would at least seem per GFS

Ooh, you're absolutely right. I didn't check up there. Yeah that was west of Dallas... these are south of OKC, both soundings in Oklahoma still. The second sounding is closer to OKC.




--------------------
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 18 2017, 08:35 PM
Post #40




Rank: F5 Superstorm
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DFW offers some early insight

QUOTE
Global models continue to exhibit good agreement regarding the
large-scale evolution of the next potent shortwave on Friday
night. At this time, it appears most of us should remain dry
during the day on Friday, thanks to a a stout capping inversion,
which will be continually re-supplied and strengthened by 35-45 kt
southwesterly flow at 800 mb. By late Friday evening, the brunt of
the forcing for ascent associated with the approaching shortwave
should be upon us, which will send a strong cold front through the
region. As parcels are forced to their LFCs, expect thunderstorms
to zipper down the front, but there may be a tendency for storms
to eventually be undercut by the rapidly progressing cold front.
Steep mid-level lapse rates of 7-8 C/km, and strong deep layer
shear (effective bulk shear values near 50 kts), will support
supercells capable of producing primarily large hail and damaging
wind gusts. The overall coverage of severe storms may ultimately
be limited by the overnight occurrence, along with signs that the
aforementioned inversion may not be fully lifted and eroded. At
this time, the primary area we`re focusing on for severe weather
is north of I-20, but the pertinent details will continue to be
refined over the next few days.


--------------------
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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