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July 21-? Severe Weather


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If that cap goes though (which I realize is a rather large "if" considering the cap problems that nearly every system lately has encountered), it looks to have a potentially dangerous powder keg waiting to go off underneath it.

Although, the MCS does appear to be weakening a bit and fragmenting towards the tail end...

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If that cap goes though (which I realize is a rather large "if" considering the cap problems that nearly every system lately has encountered), it looks to have a potentially dangerous powder keg waiting to go off underneath it.

Although, the MCS does appear to be weakening a bit and fragmenting towards the tail end...

A lot of "ifs" tomorrow, even should the MCS pass through central MN into Wisconsin by late morning, there is still the possibility the boundary layer overcomes this by late day. It seems any way we cut it it will be close.

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Looks like a potential derecho may be developing out of that QLCS in Minnesota if we can get the clouds/storms to clear out ahead of it.

Fortunately the MCS activity ahead of it has largely diminished, so that's a plus. And it has a pretty strong MCV to help it along too.

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12z SPC-WRF radically different from the 00z, with a major severe weather outbreak for MN/IA. I don't know that I totally buy it as it has not performed well recently in subtly/weakly forced environments.

Today is a tough call. There may be enough subsidence behind the MCS. Also always wary of that much shear and instability juxtaposed this time of year, because oftentimes that WAA that causes such strong shear also efficiently caps the atmosphere. We'll see.

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12z SPC-WRF radically different from the 00z, with a major severe weather outbreak for MN/IA. I don't know that I totally buy it as it has not performed well recently in subtly/weakly forced environments.

Today is a tough call. There may be enough subsidence behind the MCS. Also always wary of that much shear and instability juxtaposed this time of year, because oftentimes that WAA that causes such strong shear also efficiently caps the atmosphere. We'll see.

Not to mention it initialized amazingly poor with the ongoing MCS. Amazing how poor all guidance initialized (NAM/GFS/4 KM SPC WRF which initializes from the GFS). It will be an interesting event...HRRR which finally did catch a clue to the ongoing MCS has backed off...possibly owing to subsidence behind the MCS as well as a shunted warm front/low dew points. Right now the area of interest across central MN only in the mid to upper 70s with dew points in the upper 60s.

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Here we go:

mcd1708.gif

MESOSCALE DISCUSSION 1708

NWS STORM PREDICTION CENTER NORMAN OK

0152 PM CDT SAT JUL 23 2011

AREAS AFFECTED...FAR ERN SD...MUCH OF CENTRAL AND SRN MN AND FAR NRN

IA.

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 231852Z - 232015Z

STORMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY ACROSS

PORTIONS OF CENTRAL/SRN MN THROUGH THE AFTERNOON...AND ALSO POSSIBLY

DEVELOPING WWD INTO ERN SD AND SWD INTO NRN IA. A WW LIKELY WILL BE

NEEDED IN THE NEXT HOUR OR SO FOR PORTIONS OF THIS AREA.

ELEVATED STORMS HAD RECENTLY DEVELOPED IN AN E-W BAND ACROSS WEST

CENTRAL MN...NORTH OF A STC-VVV LINE. THESE STORMS WERE LOCATED

AHEAD OF THE SEWD MOVING SYNOPTIC FRONT...THAT EXTENDED FROM NWRN MN

SEWD INTO ERN SD. SUFFICIENT DEEP LAYER SHEAR AND INSTABILITY EXISTS

FOR MARGINALLY SEVERE HAIL WITH THESE STORMS THE NEXT HOUR OR TWO.

HOWEVER...WITH ADDITIONAL HEATING/BOUNDARY LAYER DESTABILIZATION AND

STRONGER LARGE SCALE FORCING SPREADING IN FROM THE WEST... MORE

STORMS ARE FORECAST TO DEVELOP AND BECOME SURFACE BASED. ONCE THIS

HAPPENS...EFFECTIVE SHEAR AT 40-50 KT AND MODERATE INSTABILITY WILL

BE FAVORABLE FOR SUPERCELLS. WHILE SEVERE HAIL/WINDS SHOULD BE THE

PRIMARY THREATS...THE VERY MOIST BOUNDARY LAYER AND THE FORECAST OF

STRONGLY VEERING LOW LEVEL WIND PROFILES WOULD SUPPORT A TORNADO OR

TWO. BY LATE AFTERNOON...HIGH RESOLUTION AND OPERATIONAL MODELS ARE

IN AGREEMENT OF STORMS CONGEALING INTO A SEWD MOVING LINEAR MCS...

WITH WIND DAMAGE BECOMING THE PRIMARY THREAT AT THAT TIME.

..IMY.. 07/23/2011

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WRF-NMM blows up a line of storms and moves it through here late this afternoon and early this evening, which is plausible along the outflow boundary from the MCS as it heads into the increasingly unstable atmosphere. Of course t doesn't even have a clue about the ongoing/weakening MCS in Wisconsin or the storms developing in IN/OH.

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A little old--------

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

159 PM CDT SAT JUL 23 2011

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

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

..REMARKS..

0139 PM TORNADO 2 N KENTLAND 40.80N 87.45W

07/23/2011 NEWTON IN LAW ENFORCEMENT

BRIEF TORNADO 1300 S NEAR RT 41 REPORTED BY SHERIFF

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A little old--------

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

159 PM CDT SAT JUL 23 2011

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

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

..REMARKS..

0139 PM TORNADO 2 N KENTLAND 40.80N 87.45W

07/23/2011 NEWTON IN LAW ENFORCEMENT

BRIEF TORNADO 1300 S NEAR RT 41 REPORTED BY SHERIFF

Bizarre.

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can see the towers up to my north. up to 74dbz with those cells west of st. cloud. wouldn't surprise me to see one of those warned soon.

they may clip the north metro but the better stuff is obviously yet to come.

Eh, with the high freezing levels, prolly won't get a warning based on the non-supercellular nature of the storms.

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A little old--------

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

159 PM CDT SAT JUL 23 2011

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

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

..REMARKS..

0139 PM TORNADO 2 N KENTLAND 40.80N 87.45W

07/23/2011 NEWTON IN LAW ENFORCEMENT

BRIEF TORNADO 1300 S NEAR RT 41 REPORTED BY SHERIFF

Wow...my old stomping ground and I never saw a tor there....but some good flat prairie to watch storms, however. Looks like SPC seems to think the storms in IL/IN/OH will only produce a few wet downbursts and no extensive svr. Maybe it was a gustnado since there certainly were no supercells in the area at the time.

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Eh, with the high freezing levels, prolly won't get a warning based on the non-supercellular nature of the storms.

maybe not, but mpx is already getting storm reports of 1" hail from stearns co.

0245 PM HAIL 1 S RICHMOND 45.44N 94.52W

07/23/2011 M1.00 INCH STEARNS MN EMERGENCY MNGR

0243 PM HAIL 1 E COLD SPRING 45.46N 94.41W

07/23/2011 M0.88 INCH STEARNS MN TRAINED SPOTTER

0237 PM HAIL ST CLOUD 45.55N 94.17W

07/23/2011 M0.75 INCH STEARNS MN TRAINED SPOTTER

0229 PM HAIL 1 ESE ST JOSEPH 45.56N 94.30W

07/23/2011 M0.75 INCH STEARNS MN TRAINED SPOTTER

edit:

0251 PM HAIL COLD SPRING 45.46N 94.43W

07/23/2011 M1.25 INCH STEARNS MN TRAINED SPOTTER

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maybe not, but mpx is already getting storm reports of 1" hail from stearns co.

0245 PM HAIL 1 S RICHMOND 45.44N 94.52W

07/23/2011 M1.00 INCH STEARNS MN EMERGENCY MNGR

0243 PM HAIL 1 E COLD SPRING 45.46N 94.41W

07/23/2011 M0.88 INCH STEARNS MN TRAINED SPOTTER

0237 PM HAIL ST CLOUD 45.55N 94.17W

07/23/2011 M0.75 INCH STEARNS MN TRAINED SPOTTER

0229 PM HAIL 1 ESE ST JOSEPH 45.56N 94.30W

07/23/2011 M0.75 INCH STEARNS MN TRAINED SPOTTER

edit:

0251 PM HAIL COLD SPRING 45.46N 94.43W

07/23/2011 M1.25 INCH STEARNS MN TRAINED SPOTTER

That is a little surprising.

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MESOSCALE DISCUSSION 1711

NWS STORM PREDICTION CENTER NORMAN OK

0457 PM CDT SAT JUL 23 2011

AREAS AFFECTED...SE NEB...SRN IA...NRN MO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 232157Z - 232330Z

IT IS NOT CERTAIN THAT A WW WILL BE NEEDED...BUT TRENDS WILL BE

MONITORED FOR THE POSSIBILITY OF AN INCREASING SEVERE THREAT.

A SMALL CLUSTER OF STORMS NOW ADVANCING SOUTH THROUGH EAST OF

LINCOLN NEB MAY BE ASSOCIATED WITH A WEAK IMPULSE EMBEDDED WITHIN A

MID/UPPER MOISTURE PLUME EMANATING FROM THE SOUTHERN PLATEAU. WHILE

DEEP LAYER MEAN WESTERLY FLOW FIELDS ON THE NORTHERN PERIPHERY OF

THE SUBTROPICAL RIDGE ARE ONLY ON THE ORDER OF 15-20 KTS...THE SMALL

CONVECTIVE SYSTEM IS SHOWING SOME SIGNS OF ORGANIZATION. ACTIVITY

APPEARS LIKELY TO DEVELOP NORTHEASTWARD THEN EASTWARD ALONG AN OLD

OUTFLOW BOUNDARY ACROSS SOUTHERN IOWA...WHERE A CORRIDOR OF HIGH

MOISTURE CONTENT /CHARACTERIZED BY UPPER 70S SURFACE DEW POINTS AND

PRECIPITABLE WATER AROUND 2 INCHES/ IS CONTRIBUTING TO LARGE CAPE.

FURTHER UPSCALE CONVECTIVE GROWTH APPEARS POSSIBLE THROUGH THE

00-02Z TIME FRAME...GENERALLY SOUTH OF THE INTERSTATE 80 CORRIDOR

ACROSS SOUTHWEST AND SOUTH CENTRAL IOWA. HEAVY PRECIPITATION

LOADING COULD EVENTUALLY CONTRIBUTE TO LOCALIZED STRONG

DOWNBURSTS...AND LOW-LEVEL THERMAL PROFILES MAY BE UNSATURATED

ENOUGH FOR THE EVOLUTION OF A SIGNIFICANT COLD POOL CAPABLE OF

PRODUCING A BROADER SCALE SWATH OF WINDS THAT COULD AT LEAST

APPROACH SEVERE LIMITS.

..KERR.. 07/23/2011

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