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July 15-20 Severe Weather


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Man, if the NAM parameters for Monday evening hold and we get convection in northern IL or southern WI, then there's going to be hell to pay.

Yeah, I'll be honest, even as a non-met, I know enough to know that 4 to 5 K joules of cape and 40 knot bulk shear is plenty for a decent outbreak given the right timing. I feel like this potential is coming out of nowhere. I'm interested to see what SPC does for the next couple days.

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It has odors of a couple infamous NW flow scenarios of yore...not strong odors but odors nonetheless...

which ones? there was a big one a few years ago that was almost moving due south but I forgot the date.

I'll be out on the boat tomorrow up on the chain so hoping storms hold off which I think they should.

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which ones? there was a big one a few years ago that was almost moving due south but I forgot the date.

I'll be out on the boat tomorrow up on the chain so hoping storms hold off which I think they should.

Oh I'm thinking of two very specific, unforgettable ones...

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I was reading another (old) thread from a different weather board on NW flow. Is one of them the Plainfield, IL tornado?

Well, with upper-70 dews, 30-45kt of bulk shear, and what will likely be, depending on clearing from anything in the morning, extreme instability (likely being lowballed on the models right now barring major insolation disruption), and not-sucky-for-July hodos, yeah, that's one...

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Roanoke July '04?

Though, I know that event featured a nice trough pushing through the Lakes, down the backside of the ridge out west.

Yeah, Roanoke was definitely a stronger trough. But you gotta worry if you have any forcing for convection with huge instability and curved hodos in place. Gotta be worried.

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DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1235 AM CDT SUN JUL 17 2011

VALID 171200Z - 181200Z

..THERE IS A SLGT RISK OF SVR TSTMS FROM NRN MT

EWD INTO THE

CNTRL GREAT LAKES...

..MT TO THE UPPER GREAT LAKES

WEAK HEIGHT RISES WILL ENCOMPASS MUCH OF THE CONUS SUNDAY AS A

DOMINANT UPPER HIGH BUILDS OVER THE CNTRL PLAINS. DESPITE THIS

EVOLUTION IT APPEARS THERE WILL BE A RISK OF SEVERE TSTMS ALONG A

CORRIDOR FROM THE NRN ROCKIES...EWD INTO THE UPPER GREAT LAKES.

ISOLATED SEVERE STORMS...SOME SUPERCELLULAR IN NATURE...DEVELOPED

ACROSS THE NRN PLAINS SATURDAY IN SPITE OF NONDESCRIPT MID-UPPER

LEVEL FLOW REGIME WITH NO IDENTIFIABLE SHORT WAVE TROUGHS. STRONG

HEATING AND WEAK WARM ADVECTION MOST LIKELY WERE RESPONSIBLE FOR

THIS ACTIVITY AND THESE PROCESSES WILL LIKELY BE THE DRIVING

MECHANISMS FOR TSTM DEVELOPMENT ALONG/NORTH OF A FRONT THAT WILL BE

DRAPED FROM CNTRL MT...ESEWD ACROSS NRN SD INTO WI.

EPISODIC BOUTS OF WARM ADVECTION MAY INDUCE CONVECTION ATOP THE

COOLER BOUNDARY LAYER...POSSIBLY ACROSS MT/WRN ND EARLY IN THE

PERIOD. THIS ACTIVITY COULD THEN SPREAD/DEVELOP EWD ACROSS THE

DAKOTAS INTO THE UPPER MS VALLEY BY MID DAY AS REMNANT LLJ VEERS

INTO THIS PORTION OF THE SLGT RISK REGION. IT/S NOT ENTIRELY CLEAR

WHETHER STORMS WILL EVOLVE INTO THE WARM SECTOR AS STRONG CAPPING

WILL LIKELY INHIBIT DEEPER UPDRAFTS. FOR THIS REASON WILL OPT TO

INCLUDE AREAS PRIMARILY NORTH OF THE WIND SHIFT WHERE WARM ADVECTION

WILL BE MAXIMIZED. IF AN MCS CAN EVOLVE OVER THE UPPER MS VALLEY

THEN A COLD POOL WILL PROVE INSTRUMENTAL IN SUBSEQUENT MOVEMENT

TOWARD THE GREAT LAKES...POSSIBLY AS FAR SE AS CHI METRO AREA LATE

IN THE PERIOD.

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Here's the new day 2:

day2probotlk_0600_any.gif

SPC AC 170554

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1254 AM CDT SUN JUL 17 2011

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NERN STATES WWD TO THE

MIDWEST...

...SYNOPSIS...

LITTLE CHANGE IN OVERALL UPR PATTERN EXPECTED MONDAY WITH SPRAWLING

UPR HIGH COVERING MOST OF THE COUNTRY. THIS WILL KEEP THE UPR

TROUGH ALONG THE W COAST AT BAY WITH ASSOCIATED WLYS ARCING ACROSS

SRN CANADA TO NEW ENGLAND.

...NERN STATES...

CLUSTERS OF TSTMS MAY ALREADY BE ONGOING ALONG THE QC/ON BORDER AT

12Z MONDAY AS A LEAD MID-LEVEL WAVE GRAZES ACROSS THE REGION. DEBRIS

CLOUDS/PCPN WILL BE KEY TO WHERE STRONGEST INSTABILITY EVOLVES

MONDAY AFTN. WNWLY TROPOSPHERIC FLOW WILL TRANSPORT BOTH STEEP

MID-LVL LAPSE RATES AND MOIST BOUNDARY LAYER AIR MASS EWD DURING THE

NEXT COUPLE OF DAYS. ATTM...IT APPEARS THAT THE STRONGEST HEATING

AND POTENTIAL THERMAL BUOYANCY SHOULD BECOME ESTABLISHED ACROSS SRN

NEW ENGLAND WWD TO ALONG THE NY/PA BORDER.

AS AIR MASS HEATS AND EXIT REGION OF A 100+ KT H25 JET APPROACHES

THE REGION...TSTMS SHOULD DEVELOP AS CAP IS ERASED. ACTIVITY WILL

FAVOR RESIDUAL BOUNDARIES LEFT-OVER FROM SUNDAY NIGHT STORMS AND

ALONG THE LEE TROUGH. FCST HODOGRAPHS SUGGEST THAT BOTH SUPERCELLS

AND FAST-MOVING BOW ECHOES WILL BE LIKELY WITH VERTICAL SHEAR IN

EXCESS OF 35 KTS AND DEEP UNIDIRECTIONAL WNW FLOW. DAMAGING WINDS

AND LARGE HAIL WILL BE LIKELY. STORMS WILL LIKELY WEAKEN DURING THE

EVENING AND WITH SOUTH EXTENT...ROUGHLY THE MASON-DIXON LINE.

...MIDWEST/UPR MS VLY REGION...

CONDITIONAL SLGT RISK WILL BE PAINTED FROM OH/MI WWD INTO THE UPR MS

VLY ON MONDAY AS PRECEDING DAY MCS ROBUSTNESS/PLACEMENT WILL BE IN

QUESTION. 00Z GFS AND LATEST ECMWF SUGGEST THAT SOME SEMBLANCE OF A

NOCTURNAL MCS OR TWO WILL EXIST EARLY IN THE DAY 2 PERIOD ACROSS THE

UPR MS VLY...POSSIBLY AS FAR S AS CHICAGOLAND. THE REGION WILL

REMAIN ALONG SWRN FRINGE OF 45-50 KTS OF NW MID-LEVEL FLOW AND

WITHIN A VERY UNSTABLE DOWNSTREAM ENVIRONMENT. THUS...IT IS

POSSIBLE THAT THE MORNING MCS MAY CONTINUE DOWNSTREAM INTO PARTS OF

THE MIDWEST THROUGH THE DAY. ANOTHER POSSIBILITY IS FOR STORMS TO

DEVELOP ALONG RESIDUAL OUTFLOW BOUNDARIES AS HEATING PEAKS.

VERTICAL SHEAR WILL NOT BE PARTICULARLY STRONG...UNLESS AN MCV CAN

BECOME ESTABLISHED. HOWEVER...HOT/MOIST LLVL ENVIRONMENT AND

FAVORED WNW FLOW ALOFT MAY YIELD AT LEAST ISOLD FAST MOVING LINE

SEGMENTS. ACTIVITY WILL LIKELY BACKBUILD DURING THE EVENING INTO

THE UPR MS VLY AND PERHAPS AS FAR NW AS ND WITH AN ISOLD SVR THREAT.

..RACY.. 07/17/2011

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Chase/tornado vid from a friend of mine in ND today.

Very nice footage and tornado. B)

Also, we have a 4-8 day severe threat:

day48prob.gif

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0338 AM CDT SUN JUL 17 2011

VALID 201200Z - 251200Z

...DISCUSSION...

UPR HIGH WILL CONTINUE TO ELONGATE ACROSS THE SRN TWO-THIRDS OF THE

NATION FROM WED INTO NEXT WEEKEND...EVENTUALLY WITH DUAL

CENTERS...ONE OVER THE SERN STATES AND ANOTHER SHIFTING TOWARD THE

CNTRL ROCKIES. PAC UPR TROUGH EXPECTED TO EJECT TO THE NRN

INTERMOUNTAIN W ON TUE /DAY 3/ WILL CONTINUE ENE INTO THE NRN PLAINS

ON WED /DAY 4/. AT LEAST 60 METER HEIGHT FALLS ASSOCIATED WITH THE

TROUGH WILL SPREAD ATOP A ROBUST INSTABILITY AXIS IN THE CNTRL

DAKOTAS ON WED. CAP WILL LIKELY BE TEMPERED AS THIS IMPULSE SKIRTS

THE REGION AND ORGANIZED SVR STORMS WILL BE PSBL WED AFTN/EVE.

ACTIVITY WILL THEN SPREAD DOWNSTREAM INTO NWRN/NCNTRL MN BY EARLY

THURSDAY.

THEREAFTER...AS THE PRIMARY HIGH CELL SHIFTS WWD...HEIGHTS WILL FALL

ACROSS SERN CANADA AND THE NERN STATES AND COULD BRING A ROUND OF

SVR WEATHER LATE IN THE WEEK TO NEW ENGLAND. HOWEVER...A LOT

DEPENDS ON UPSTREAM DEVELOPMENT DURING THE MID-WEEK PERIOD AND

TIMING/LOCATION OF ANY ORGANIZED TSTM POTENTIAL IS UNCERTAIN ATTM.

LIKEWISE...LEADING EDGE OF FRESH CP AIRMASS...FOLLOWING THE IMPULSE

MOVING TOWARD THE NERN STATES LATE IN THE WEEK...WILL STALL ACROSS

THE UPR MS VLY AND NRN PLAINS. THIS REGION COULD BE THE FOCUS FOR

EPISODIC SVR WEATHER EVENTS THAT ARE DIFFICULT TO TIME.

..RACY.. 07/17/2011

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Get ready for an epic light show with the next couple night's MCS parade, complexes rounding massive heat domes always deliver the electrical goods.

Feel pretty confident that there will be a complex in or around Chicago for tomorrow mornings trek to work. This really is classic mid summer stuff, although the shear numbers seem rather high as well, so things might really get funky.

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Get ready for an epic light show with the next couple night's MCS parade, complexes rounding massive heat domes always deliver the electrical goods.

Feel pretty confident that there will be a complex in or around Chicago for tomorrow mornings trek to work. This really is classic mid summer stuff, although the shear numbers seem rather high as well, so things might really get funky.

What do you mean by "funky"?

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