FSD – CTC signature just east of CWA at 1930z

Watching convection developing just past the FSD CWA line in Des Moines area as Cloud Top Cooling is showing a steady decrease in cloud top cooling rates from -8 degrees C/15 minutes over Pocahontas County IA at 1915z to -19 degrees C/15  minutes over Palo Alto County IA at 1932z.

Here is the KFSD reflectivity and enhanced echo top. Echo top was up to 37 kft on the storm in Pocahontas County IA at 1950z.

Update…this appears to be a false alarm as cell has continued to weaken and no cloud to ground lightning was indicated. Echo top reached 39kft before collapsing.

Tim/Steve

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MPX: Severe Warning dieux.

Thunderstorms are beginning to increase in coverage over the southwest portion of the MPX CWA. Modest increases in updraft strength and upper divergence coincided well 50 dbz reaching over 33kft. 60 dbz exceeded 22 kft. Felt hail was a certainty with the storm, as it rode near the warm front.

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MPX: 1st warning of the day

Line of storms over Dakota and Rice County has intensified with MESH increasing to 1.73 inches at 1925Z. At 1900Z, composite updraft increased to 17 while we saw an increase of upper divergence. Expect large hail although this storm is right along the instability gradient so we could start to see some wind problems soon as 1km 3dvar wind shows 25+ m/s. MRD/TY

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OUTLOOK: 14 June 2012

Today, were are focused on the Upper Mississippi Valley for severe convective development.  A potent, negatively-tilted shortwave trough is moving quickly across the north-central U.S.   Strong deep-layer shear associated with the trough should combine with moderate (to strong) instability and deep moisture to produce severe convection, including supercells.  It is uncertain, however, whether sufficient heating can occur in the wake of a late-morning mesoscale convective system across eastern Minnesota and western Wisconsin.  If destabilization can occur in the vicinity of the residual outflow boundary, tornadoes will be possible.

A secondary area of interest is in south-central Nebraska, where the surface front curves to the southwest.  In this area, the moisture is both deep and quality; the instability , strong to extreme; and the winds at the surface should back, augmenting — to some extent — the marginal wind shear.  That said, severe hail and winds should be the primary threats.

We will start operations in the Minneapolis (MN), Sioux Falls (SD), and Hastings (NE) county warning areas, with an eye toward the  Duluth (MN) CWA — should destabilization occur.

-G. Garfield, Week 5 Coordinator

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EWP STATUS FOR 14 JUNE 2012: 1-9 p.m. SHIFT

EWP STATUS FOR 14 JUNE 2012: 1-9 p.m. SHIFT

On Thursday, we will begin our shift at 1 p.m.  The operational models depict a strong, negatively-tilted shortwave trough entering the Upper Midwest by early afternoon.  The associated strong deep-layer shear and moderate instability will support supercells/organized convection in Minnesota and Wisconsin during the afternoon/evening hours.   Given moderate low-level shear and low LCLs, a tornado threat may emerge as well.  However, this may be tempered by a relatively quick transition to the linear convective mode, owing to the strong forcing associated with the ejecting upper trough.  Current thinking is that the Duluth, Minneapolis, and LaCrosse county warning areas are the most likely candidates for severe operations.

– G. Garfield, Week 5 Coordinator

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MAF Update at 00Z…A Few Warnings SW of Midland

Watching 2 main cells that are giving some of the higher terrain areas the business.  Generally seeing an increase in the coverage of storms east of the Davis Mountains now and that is what the OUNWRF has been advertising starting late afternoon/early evening.  Expect areas around and south of Midland to see increase in thunderstorm activity through the early evening hours.

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FSD – CIRA WRF Simulated imagery off on location but good on timing

After seeing the CIRA sim imagery do very well in ABQ, we switched to FSD where the sim imagery indicated deep convection developing between 2100-2200z, but the location of the convection was about 130mi ese of where convection developed in Tripp and Lyman counties in central SD.

CIRA WRF Simulated IR 10.4 valid at 13 Jun 2100z:

GOES IR 2100z:

GOES IR 2130z:

CTC 2132z in Tripp and Lyman Co:

GOES IR 2144z:

CTC 2144z in Tripp and Lyman Co:

CIRA WRF Simulated IR 10.4 valid at 13 Jun 2200z:

GOES IR 2200z:

GOES IR 2230z:

CIRA WRF Simulated IR 10.4 valid at 13 Jun 2300z:

GOES IR 2300z:

CIRA WRF Simulated IR 10.4 valid at 14 Jun 0000z:

GOES IR 14 June 0014z:

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FSD: Bad day for MESH in SD

Ended up getting some very large hail reports (at least 2.5 inches in Beadle County and Tea Cup Sized in Brule County). However, the MESH never got to 2 inches. The old school algorithm did not do much better – with largest of 2.25 in Brule County.

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