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July 22-27 Severe Potential


hm8

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The overnight severe and convection was quite interesting from the standpoint of the numerous intersecting outflow boundaries, at least three of them at different times. The final outflow emanating from the storms as they plowed through S Wisconsin and N Illinois looked ominous until it fell apart just before the lake. Bow and I were a bit concerned about serious damage from our places through about Geos' location, given the outflow was starting to bow outward just east of Rockford.

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PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

1003 AM CDT THU JUL 26 2012

.TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON

.DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.

..REMARKS..

0139 AM TSTM WND DMG OHARE AIRPORT 41.98N 87.90W

07/26/2012 COOK IL BROADCAST MEDIA

HANGER WALL COLLAPSED

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TORNADO WARNING

OHC007-155-PAC039-261745-

/O.NEW.KCLE.TO.W.0008.120726T1721Z-120726T1745Z/

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE CLEVELAND OH

121 PM EDT THU JUL 26 2012

THE NATIONAL WEATHER SERVICE IN CLEVELAND HAS ISSUED A

* TORNADO WARNING FOR...

SOUTHEASTERN ASHTABULA COUNTY IN NORTHEAST OHIO...

NORTHEASTERN TRUMBULL COUNTY IN NORTHEAST OHIO...

SOUTHERN CRAWFORD COUNTY IN NORTHWEST PENNSYLVANIA...

* UNTIL 145 PM EDT

* AT 118 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS

STORM WAS LOCATED 6 MILES NORTHWEST OF KINSMAN...OR 16 MILES SOUTH

OF JEFFERSON...AND MOVING EAST AT 45 MPH.

* LOCATIONS IMPACTED INCLUDE...

MEADVILLE...KINSMAN...ANDOVER...HARTSTOWN...GENEVA...CONNEAUT LAKE

AND COCHRANTON.

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The overnight severe and convection was quite interesting from the standpoint of the numerous intersecting outflow boundaries, at least three of them at different times. The final outflow emanating from the storms as they plowed through S Wisconsin and N Illinois looked ominous until it fell apart just before the lake. Bow and I were a bit concerned about serious damage from our plaes through about Geos' location, given the outflow was starting to bow outward just east of Rockford.

No damage to report here. Storm woke me up, but that was it.

Cumulus building up nicely this afternoon. Hoping the NAM is right about convection today.

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No damage to report here. Storm woke me up, but that was it.

Cumulus building up nicely this afternoon. Hoping the NAM is right about convection today.

It looks like East Central Wisconsin is in line for another round of perhaps borderline severe storms. It is backbuilding to the south and west a bit, so we'll see if it affects cities further south like Madison, Milwaukee and Chicago.

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AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

136 PM CDT THU JUL 26 2012

MESOSCALE DISCUSSION

130 PM CDT

AN CLOSED UPPER LEVEL LOW CONTINUES TO SPIN SOUTHEASTWARD ACROSS

NORTHERN MINNESOTA. SURFACE LOW PRESSURE OVER CENTRAL WISCONSIN

POSITIONED JUST NW OF OSHKOSH AT 18Z CONTINUES TO MOVE

SOUTHEASTWARD. ATTENDANT COOL FRONTAL/DRY BOUNDARY TRAILS IT TO

THE WEST AND SOUTHWEST WITH THE WARM FRONTAL BOUNDARY EXTENDING

EASTWARD ACROSS CENTRAL LAKE MICHIGAN. RADAR MOSAIC CONTINUES TO

SHOW A BAND OF SHRA/TSRA FROM NEAR GREEN BAY SOUTHWEST ACROSS THE

DELLS. VISIBLE SATELLITE IMAGERY SHOWS CUMULUS DEVELOPMENT NOW

EXPANDING SOUTHWEST FROM THE CURRENT STORMS BACK ACROSS DUBUQUE

AND ARCHING BACK TO CEDAR RAPIDS AND DES MOINES. A FEW CELLS HAVE

DEVELOPED WITH IN THIS AREA OF CU IN THE LAST HALF HOUR OR SO. RAP

MESOANALYSIS INDICATES A CORRIDOR OF BETTER INSTABILITY EXTENDING

FROM NORTHERN MISSOURI ACROSS EASTERN IOWA INTO EASTERN WISCONSIN

WHERE THE CURRENT STORMS ARE WITH CAPE VALUES INCREASING ACROSS

THE NORTHWEST CWA. ABUNDANT MID LEVEL CLOUD COVER CONTINUES ACROSS

THE SOUTHEASTERN HALF OR SO OF THE AREA MUTING INSTABILITY BUT A

MESOVORTEX CONTINUES EAST-NORTHEASTWARD APPROACHING THE SOUTHERN

CWA NOW. EXPECT THAT DEVELOPMENT WILL CONTINUE SOUTHWESTWARD FROM

THE CURRENT ACTIVITY IN WI WITH A FAIRLY SOLID BUT NARROW LINE

QUITE POSSIBLE IN THE NEXT 1-2 HOURS. BASED ON RADAR TRENDS

ARRIVAL IN THE NORTHWEST CWA WOULD BE DURING THE 19Z HOUR WITH

ARRIVAL IN THE NORTHWEST CHICAGO METRO SOMETIME IN THE 21Z HOUR. A

SEVERE THREAT DOES EXIST WITH WITH CAPE VALUES IN THE 1000-1500

J/KG RANGE AND A CORRIDOR OF STRONG DCAPE VALUES SPREADING

SOUTHEAST AHEAD OF THE FRONT...COMBINED WITH DEEP LAYER SHEAR

VALUES IN THE 30-40 KT RANGE. FORECAST SOUNDINGS SHOW LIMITED MID

LEVEL LAPSE RATES BUT A GOOD DEGREE OF CAPE FOCUSED ABOVE THE

FREEZING LEVEL. IT APPEARS THAT THE DAMAGING WIND THREAT MAY BE

JUST A BIT GREATER THAN THE LARGE HAIL THREAT. OVERALL THREAT FOR

STORMS TO REACH/EXCEED SEVERE LEVELS DOES APPEAR MARGINAL/ISOLATED BUT

POSSIBLE...WHEREAS THE THREAT FOR NUMEROUS STRONG SUB-SEVERE

STORMS IS MUCH GREATER. NEAR-TERM DEVELOPMENT OVER THE

SOUTHEASTERN CWA LOOKS UNLIKELY BEYOND SOME SHOWER ACTIVITY GIVEN

THE ABUNDANT CLOUD COVER AND MINIMAL INSTABILITY WITH NEW

DEVELOPMENT LOOKING TO OCCUR TO THE SOUTH.

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Not really, MAYBE a tenth of an inch or so at the most. Just enough to wet the pavement.

That's a bummer. We got a little over an inch here. Maybe you'll get some more out of that storm to the north of Detroit... it's heading south, so keep your fingers crossed.

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One last chance for something...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE MIDWEST/OH VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE EAST

COAST...SOUTHEAST...AND SOUTH...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL/NRN

HIGH PLAINS...

...SYNOPSIS...

MODESTLY AMPLIFIED MID/UPPER FLOW CONTINUES ACROSS THE CONUS TODAY

WITH COMPLEX TROUGHS ALONG THE WEST COAST AND OVER THE MIDWEST

SEPARATED BY A BROAD SUMMERTIME RIDGE AXIS OVER THE INTERMOUNTAIN

WEST/ROCKIES. IN THE EAST...THE FORECAST TODAY IS COMPLICATED AFTER

SUBSTANTIAL AND WIDESPREAD CONVECTION AMIDST ENHANCED FLOW FIELDS

AND ABUNDANT INSTABILITY AHEAD OF THE AMPLIFYING MIDWEST TROUGH

YESTERDAY. THE LARGER SCALE TROUGH IS COMPRISED OF SEVERAL SMALLER

SCALE VORTICITY CENTERS...THE STRONGEST OF WHICH IS CURRENTLY

CROSSING WI/LAKE MI. OTHER DISTURBANCES...SOME CONVECTIVELY

INDUCED/SUSTAINED...EXIST WITHIN THE BELT OF 25-50KT WSWLY MID LEVEL

FLOW FROM THE ARKLATEX TO OH VALLEY AND NORTHEAST. THE PRIMARY

SYNOPTIC BOUNDARY ACROSS THE MIDWEST WILL SERVE TO FOCUS THE

DEVELOPMENT OF A WEAK SURFACE LOW THAT IS FORECAST TO TRACK ESEWD

FROM LAKE MI TO OH TODAY. MEANWHILE...CONVECTIVE AND DIFFERENTIAL

HEATING BOUNDARIES AND SURFACE TROUGHING WILL PERSIST BENEATH THE

MODEST CYCLONIC FLOW ALOFT...FROM SRN NEW ENGLAND AND SERN NY SWWD

TO THE CAROLINAS AND INTO THE DEEP SOUTH/TN VALLEY.

MID LEVEL IMPULSES EMANATING FROM THE WEST COAST UPPER TROUGH WILL

TRAVEL NEWD AND THEN EWD TO CREST THE UPPER RIDGE OVER THE GREAT

BASIN AND ROCKIES. LIFT ASSOCIATED WITH THESE IMPULSES WILL COINCIDE

WITH THE PEAK IN THE DIURNAL HEATING CYCLE ACROSS THE NRN ROCKIES

AND ADJACENT HIGH PLAINS AND ACT TO STRENGTHEN LEE TROUGH OVER MT TO

WY LATER TODAY...AND PROMOTE WARM FRONTAL DEVELOPMENT ACROSS THE WRN

DAKOTAS TONIGHT.

...MIDWEST/OH VALLEY...

HAVE INCREASED DAMAGING TSTM WIND PROBABILITY FOR PARTS OF THIS AREA

WITH THIS UPDATE. ISOLATED TSTMS HAVE ALREADY FORMED AHEAD OF THE

STRONGER SHORT WAVE TROUGH DEVELOPING SEWD FROM WI/LAKE MI EARLY

TODAY. SATELLITE IMAGERY ALSO INDICATES THAT ABUNDANT SURFACE

HEATING AND SUBSEQUENT DESTABILIZATION SHOULD OCCUR AHEAD OF THE

ONGOING CONVECTION FROM IND INTO OH. GENERALLY UNIDIRECTIONAL SHEAR

ON THE ORDER OF 30-40KT...IN CONCERT WITH MODEST INSTABILITY AND A

WELL HEATED BOUNDARY LAYER...SHOULD RESULT IN AN INCREASING CHANCE

FOR RELATIVELY FAST-MOVING ORGANIZED STORMS POSING A THREAT OF

DAMAGING WINDS AND PERHAPS SOME HAIL. STORMS MAY EVOLVE INTO ONE OR

TWO LARGER BOWING CONVECTIVE SYSTEMS WHILE CROSSING THE OH RIVER

LATER TODAY IN PARTS OF THIS AREA. POTENTIAL FOR ENHANCED LOW LEVEL

SHEAR NEAR A WEAK SURFACE LOW/WAVE COINCIDENT WITH POCKETS OF

LOCALLY STRONGER LOW LEVEL CAPE SUGGEST A BRIEF/WEAK TORNADO CANNOT

BE COMPLETELY RULED OUT.

...ERN SEABOARD...

WEAK HEIGHT FALLS SHOULD MAINTAIN BACKGROUND ASCENT ACROSS THE

REGION AMIDST ANOMALOUSLY MOIST AIRMASS WITH PW VALUES AROUND 2

INCHES. OVERTURNING YESTERDAY AND RESIDUAL CONVECTIVE DEBRIS WILL

PROBABLY LIMIT THE POTENTIAL FOR GREATER DESTABILIZATION TODAY.

HOWEVER...EVEN A COUPLE OF HOURS OF SUNSHINE WILL BOOST INSTABILITY

SUFFICIENTLY FOR AN INCREASE IN AFTERNOON AND EVENING CONVECTIVE

VIGOR. EXPECT STORMS TO BE MOST PREVALENT WITHIN LEE TROUGH AND

AHEAD OF A LEADING LOW AMPLITUDE SHORT WAVE TROUGH CURRENTLY MOVING

EAST FROM THE OH VALLEY. SURFACE TROUGH ALONG THE EAST COAST FROM

DELMARVA TO NYC MAY PROVIDE A FOCUS FOR WEAK SURFACE LOW/WAVE

DEVELOPMENT ESPECIALLY LATER TODAY AS THE STRONGER IMPULSE NOW OVER

WI/LAKE MI BEGINS TO ENHANCE LARGE SCALE ASCENT ACROSS THE EAST.

CLOUD-BEARING SHEAR VALUES WILL BE IN THE RANGE OF 30-40KT FROM NRN

VA TO SRN NEW ENGLAND WITH THE HIGHER MAGNITUDES LIKELY NORTH AND

OFFSET FROM THE GREATER POTENTIAL INSTABILITY. NONETHELESS...STORMS

DEVELOPING IN THIS REGIME COULD ORGANIZE INTO SHORT LINE SEGMENTS

WITH WIND DAMAGE POSSIBLE. A SUPERCELL OR TWO CANNOT BE RULED OUT

AND LOCALLY STRONGER LOW LEVEL SHEAR AND LOW LFC/HIGH BOUNDARY LAYER

RH NEAR ANY WEAK SURFACE LOWS COULD SUPPORT A WEAK BRIEF TORNADO.

...INTERIOR NW/ROCKIES TO HIGH PLAINS...

DEWPOINTS IN THE UPPER 40S TO LOW 50S WILL RESIDE IN THIS REGION

BENEATH PLUME OF STEEP MID LEVEL LAPSE RATES RESULTING IN 800-1200

MLCAPE WITH DAYTIME HEATING. IMPULSES CRESTING THE UPPER RIDGE WILL

LIKELY PROMOTE STORM DEVELOPMENT OVER THE HIGHER TERRAIN OF WY...MT

AND WRN SD. ACTIVITY WILL SUBSEQUENTLY MOVE NEWD INTO THE HIGH

PLAINS. GIVEN SOMEWHAT LIMITED LOW LEVEL MOISTURE...STORMS WILL BE

HIGH BASED. HOWEVER...EFFECTIVE SHEAR EAST OF THE LEE TROUGH AND

ALONG DEVELOPING WARM FRONT WILL BE SUFFICIENT FOR SUPERCELL STORM

STRUCTURE WITH SOME LARGE HAIL AND ISOLATED DAMAGING WIND EVOLVING

FROM THIS CONVECTION THROUGH THE EARLY EVENING. ACTIVITY MAY THEN

CONSOLIDATE INTO A SMALL MCS BUT OVERALL SEVERE WEATHER THREAT WILL

REMAIN MARGINAL DUE TO LIMITED INSTABILITY AND LACK OF STRONGER

FORCING.

...SOUTHEAST/SOUTH...

AREAS OF STRONG INSTABILITY WILL DEVELOP ACROSS MUCH OF THE SOUTH

FROM THE SRN APPALACHIANS WWD ACROSS THE MS VALLEY TO THE SRN

PLAINS. WHILE ALL OF THIS REGION WILL REMAIN REMOVED FROM THE

STRONGER MID LEVEL FLOW ASSOCIATED WITH THE MIDWEST/ERN U.S. UPPER

TROUGH...THE GLANCING INFLUENCE OF THE LARGER SCALE TROUGH...WHEN

COMBINED WITH THE AVAILABLE INSTABILITY...WILL LIKELY RESULT IN

SCATTERED STRONGER STORMS WITH SOME POTENTIAL FOR A FEW WET

MICROBURSTS.

OUTFLOW AND DIFFERENTIAL HEATING ASSOCIATED WITH THE LOOSELY

ORGANIZED MCS ACROSS ARKLATEX THIS MORNING MAY PROVIDE A FOCUS FOR

MORE CONCENTRATED/STRONGER STORM ACTIVITY ACROSS PARTS OF NERN TX

LATER TODAY AS AIRMASS BECOMES STRONGLY UNSTABLE. HOWEVER...LARGE

SCALE SUPPORT AND WEAK SHEAR SHOULD LIMIT MORE WIDESPREAD SEVERE

WEATHER THREAT.

..CARBIN/LEITMAN.. 07/27/2012

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Some pretty good instability and moisture out there now. stratocumulus clouds has mixed out into a low SCT-BKN CU deck now.

0-3km CAPE is above 100 J/KG, so there should be some good wind with whatever storms develop.

There's a few cells popped up around Jackson, and a cell that was headed toward Flint seems to have decided to cruise southeast now.

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Some pretty good instability and moisture out there now. stratocumulus clouds has mixed out into a low SCT-BKN CU deck now.

0-3km CAPE is above 100 J/KG, so there should be some good wind with whatever storms develop.

I'm up in Goodrich MI today (just SE of town). That monster cell is headed directly at me. Sky is black and the thunder can be heard.

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Decent CAPE, Delta-T's of 10C+ and LL lapse rates of 6C+...

1028 AM WATER SPOUT 12 E SOUTH MILWAUKEE 42.91N 87.63W

07/27/2012 LMZ673 WI TRAINED SPOTTER

WELL DEFINED WATERSPOUT LASTED ABOUT 10 MINUTES. TIME

ESTIMATED BASED ON STRONGEST LOW LEVEL ROTATION ON TMKE

TDWR. 30 KNOT OUTBOUND 18 KNOT INBOUND AT THAT TIME. WEAK

CIRCULATION EVIDENT FROM ABOUT 1025 TO 1034 AM.

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Not really, MAYBE a tenth of an inch or so at the most. Just enough to wet the pavement.

Interesting.

Got some pretty heavy rain around 7AM-8AM yesterday morning, along with some loud cracks of thunder on my side of town.

Visibilities were easily less than a mile.

As far as severe weather, meh, got some pretty good wind with the outflow boundary around 2 AM, and I did get some thunder and lightning from a non-severe t'storm that popped up, then eventually non-stop lightning from other storms in the vicinity (though no thunder).

It doesn't matter though, I'm still more than satisfied after July 4th.

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