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April 12th/13th and 15-16th Severe Weather Thread


andyhb

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While many convective parameters are very favourable for a significant tornado outbreak including long track, violent tornadoes.(40-50 sig tors on the sref) Precip models like the WRF and NAM hold off on almost all convection in the southern high risk. Although the 00utc nam shows some convection in KS/OK firing around 00utc. I wonder how the SPC will handle this in the 0600z update. It seems like convective coverage may be very limited but convection that does form will have enhanced strong tornado risk. Will 30% or 45% tornado be warranted? I guess we have to wait and see.

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While many convective parameters are very favourable for a significant tornado outbreak including long track, violent tornadoes.(40-50 sig tors on the sref) Precip models like the WRF and NAM hold off on almost all convection in the southern high risk. I wonder how the SPC will handle this in the 0600z update. It seems like convective coverage may be very limited but convection that does form will have enhanced strong tornado risk. Will 30% or 45% tornado be warranted? I guess we have to wait and see.

I'm not to worried about tomorrow, especially with less forcing today and things breaking out early. I think we'll see sups develop along the dryline across Northern OK and South/Central KS by 21-23z.

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I'm not to worried about tomorrow, especially with less forcing today and things breaking out early. I think we'll see sups develop along the dryline across Northern OK and South/Central KS by 21-23z.

Also we have decided (at least we think) to target the Southern area, likely the South Central Kansas area. We are about an hour away from Kansas City right now and we'll be staying there tonight and hitting the road early tomorrow. We figure by staying there, we can go either direction, but we'll likely head Southwest.

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I'm not to worried about tomorrow, especially with less forcing today and things breaking out early. I think we'll see sups develop along the dryline across Northern OK and South/Central KS by 21-23z.

I certainly didn't expect the amount of convection today that we ended up seeing...

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clipped from the evening discussion up here in the 612-651. i guess we're not out of the woods here in the twin cities.

THIS INCREASE IN CLOUDINESS IS AHEAD OF A LOW PRESSURE STORM

SYSTEM OVER COLORADO THAT WILL BE MOVING NORTHEAST ON SATURDAY

AND PASS ACROSS THE FA ON SUNDAY. THE LOW AND A STRONG WARM FRONT

EXTENDING TO THE EAST WILL BE THE FOCUS FOR SEVERE WEATHER

SATURDAY AFTERNOON ACROSS EASTERN NE AND IA. SOME SHOWERS AND

THUNDERSTORMS WILL LIKELY PUSH INTO SOUTHERN MN DURING THE LATE

AFTERNOON HOURS. AS THE WARM FRONT MOVES INTO THE CWA SATURDAY

NIGHT...SHOWERS AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD.

THERE SEEMS TO BE A CREDIBLE THREAT FOR SEVERE STORMS DURING THE

NIGHT FROM THE TWIN CITIES ON WEST AND SOUTH...WITH HIGH EMPHASIS

ACROSS SOUTHWEST AND SOUTH CENTRAL MN. THE AMOUNT OF LOW LEVEL

SHEAR INCREASES DURING THE EVENING WITH 0-1KM BULK SHEAR AT OR

ABOVE 40 KNOTS ON SEVERAL SOLUTIONS FOR SOUTHWEST AND SOUTH

CENTRAL MN. SEVERE WEATHER PARAMETERS ARE SUCH THAT TORNADOES

WOULD BE POSSIBLE ALONG THE WARM FRONT IN SOUTHERN MN. RECENT

RESEARCH DONE HERE BY DEVINNY AND HULTQUIST SHOW THAT THIS TYPE

OF UPPER PATTERN (SOUTHWEST FLOW ARCHETYPE) WAS THE ONLY ONE THAT

HAD STRONG NIGHTTIME TORNADOES IN OUR FORECAST AREA. MORE

DISTRESSING IS WATCHING THE CIPS WARM SEASON ANALOGS. YESTERDAY

THE NUMBER 5 ANALOG WAS MARCH 29 1998. TODAY THIS ANALOG HAS MOVED

TO NUMBER 3. HENCE...SATURDAY NIGHT IS AN INTENSE PERIOD OF

INTEREST.

IN ADDITION...A DIFFLUENT 850-300MB THICKNESS PATTERN SPREADS

INTO SOUTHWEST AND SOUTH CENTRAL MN BY 15/06Z ALONG WITH A LARGE

INCREASE IN THE DIFFERENTIAL TEMPERATURE ADVECTION. THIS PUSHES

THROUGH THE TWIN CITIES BY SUNDAY MORNING. THE 850-500MB WIND

CROSSOVER IS RATHER SIGNIFICANT EARLY IN THE EVENING AND THEN

BECOMES UNIDIRECTIONAL OVERNIGHT. AS THIS OCCURS MID LEVEL WINDS

INCREASE TO BETWEEN 80 AND 100 KNOTS BY SUNDAY MORNING. ONE

CONCERN IS THAT THE CONVECTION MAY BEGIN TO BOW DURING THE

OVERNIGHT HOURS AS IT RACES NORTHEAST TOWARDS THE TWIN CITIES. YOU

DEFINITELY GET A FEEL FOR THIS LOOKING AT THE ARW WRF.

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I'm not to worried about tomorrow, especially with less forcing today and things breaking out early. I think we'll see sups develop along the dryline across Northern OK and South/Central KS by 21-23z.

Thats somewhat like what the latest 00utc NAM shows. Maybe the models dont have a good hold on precip potential. But man when you see those sig tors on the SREF, they are pretty crazy. Whats your prediction on the northern high risk in Nebraska?

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While many convective parameters are very favourable for a significant tornado outbreak including long track, violent tornadoes.(40-50 sig tors on the sref) Precip models like the WRF and NAM hold off on almost all convection in the southern high risk. Although the 00utc nam shows some convection in KS/OK firing around 00utc. I wonder how the SPC will handle this in the 0600z update. It seems like convective coverage may be very limited but convection that does form will have enhanced strong tornado risk. Will 30% or 45% tornado be warranted? I guess we have to wait and see.

In this setup they will stay with a high risk. You can look at a date like 5/29/04 in an amazing setup where the cap held pretty strong in OK and S KS yet 2 monster lone supecells, one in OK and another in S KS dropped numerous tornadoes ultimately verifying the high risk anyway.

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In this setup they will stay with a high risk. You can look at a date like 5/29/04 in an amazing setup where the cap held pretty strong in OK and S KS yet 2 monster lone supecells, one in OK and another in S KS dropped numerous tornadoes ultimately verifying the high risk anyway.

True, limited storm coverage may enhance the strong tornado risk for the storms that do form with un obstructed flow of moisture and access to many favourable parameters without being limit by surrounding storms.

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