2015 Short Term Severe Weather Discussion

[snowlover2]

New day 2 has almost all of Iowa in an enhanced risk with most of IL and south in slight risk.

[Tim from Springfield (IL)]

The new Day 2 has scaled back the Enhanced threat in IA to the western/central parts of the state, but everything else for this subforum appears little changed:

 

http://www.spc.noaa.gov/products/outlook/day2otlk.html

[nwohweather]

Quite a few heavy storms in the Toledo area but their bark is worst than their bite

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[Gilbertfly]

18z 4k looks like it had 4 or 5 rounds of storms impacting LOT sunday through monday...different styles and different intensities...

[snowlover2]

New day 1 has enhanced risk for western Iowa with a slight risk for the rest of Iowa, much of IL and south to the gulf coast.

 

New day 2 has introduced an enhanced risk from just south of Indy to northern MS with a slight risk from covering SE MI south covering most of OH and IN and south to the gulf coast.

[snowlover2]

New day 2 dropped the enhanced area all together.

[Chinook]

Quite a few heavy storms in the Toledo area but their bark is worst than their bite

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Areas in SE Michigan might want to watch out for higher destabilization (1500 J/kg) tomorrow. The 4km NAM (12z and 6z) has some higher-reflectivity thunderstorms near the Thumb tomorrow.

[Powerball]

Areas in SE Michigan might want to watch out for higher destabilization (1500 J/kg) tomorrow. The 4km NAM (12z and 6z) has some higher-reflectivity thunderstorms near the Thumb tomorrow.

 

The issues, as always, will be:

 

1. Extent of morning convection/convective debris. Would like to see temps get into the 80s to feel comfortable about the t'storm/severe threat.

 

2. Where the trigger mechanisms set up. If the storms fire up along the pre-frontal trough, then the window for widespread strong/severe t'storms will be much shorter.

[snowlover2]

SPC hinting at another threat a week from now.

 

 

 

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0411 AM CDT SUN MAY 10 2015

VALID 131200Z - 181200Z

...DISCUSSION...
AN UPPER RIDGE IS EXPECTED TO BE ANCHORED FROM THE GULF OF MEXICO TO
THE BAHAMAS AND CARIBBEAN FOR THE EXTENDED OUTLOOK PERIOD /DAY
4...WED MAY 13...TO DAY 8...SUN MAY 17/...WITH HEIGHT RISES EXPECTED
ACROSS MUCH OF THE U.S. EAST OF THE ROCKIES THROUGH DAY 6 /FRI MAY
15/. GIVEN THE POSITION OF THE UPPER RIDGE...GREAT UNCERTAINTY
EXISTS WITH THE TIMING AND AMPLIFICATION OF A SERIES OF MIDLEVEL
IMPULSES EXPECTED TO TRACK NEWD ACROSS THE SRN/CENTRAL HIGH PLAINS
TO THE MID AND UPPER MS VALLEY...AND THEN ESEWD TO THE MIDDLE AND
NRN ATLANTIC STATES. GIVEN THESE REASONS...THE FORECAST FOR SEVERE
STORMS EAST OF THE ROCKIES IS TOO UNCERTAIN THROUGH DAY 6...AND THE
LACK OF FAVORABLE CAPE/SHEAR PARAMETER SPACE PRECLUDES THE INCLUSION
OF ANY 15 PERCENT AREAS.

00Z GFS/ECMWF/UKMET ARE IN REMARKABLE AGREEMENT WITH THE FORMATION
OF A LARGE-SCALE TROUGH OFF THE WEST COAST DAY 4/5...WITHIN A
SPLIT-FLOW REGIME ACROSS NORTH AMERICA. THIS PARENT TROUGH WITH A
LARGE BASAL CLOSED LOW IS EXPECTED TO MOVE INLAND ACROSS THE WRN
STATES DAY 6. SLY LOW-LEVEL FLOW DEVELOPING ACROSS THE PLAINS
STATES AND EVENTUALLY INTO THE LOWER MS TO OH VALLEYS PRIOR TO DAYS
7-8 /SAT MAY 16 AND SUN MAY 17/ WILL SUPPORT MOISTURE RETURN AHEAD
OF THE LARGE-SCALE WRN TROUGH. SOME TIMING AND TRACK DIFFERENCES
EXIST IN DAY 7 AND 8 WITH THE STRONGEST FORCING FOR ASCENT...SUCH
THAT THE INCLUSION OF SEVERE WEATHER THREAT AREAS IS NOT PREDICTABLE
THIS FAR OUT IN THE OUTLOOK. HOWEVER...PORTIONS OF THE PLAINS TO
THE MIDDLE TO UPPER MS VALLEY WILL NEED TO MONITORED FOR A SEVERE
WEATHER THREAT NEXT WEEKEND...AS DEEP-LAYER WINDS WILL BE
STRENGTHENING WITHIN AN ENVIRONMENT WITH STRONG TO VERY STRONG
INSTABILITY.

..PETERS.. 05/10/2015

[Hoosier]

2. Where the trigger mechanisms set up. If the storms fire up along the pre-frontal trough, then the window for widespread strong/severe t'storms will be much shorter.

Unless I'm misunderstanding, wouldn't the opposite be true? You'd get multi rounds instead of waiting for the front.

[Powerball]

Unless I'm misunderstanding, wouldn't the opposite be true? You'd get multi rounds instead of waiting for the front.

 

Not necessarily. In some setups (and this has happened plenty of times locally), the subsidence/stabilization from storms with the pre-frontal trough can limit action with the actual front itself.

[Powerball]

The 00z NAM verbatim suggests an enhanced tornado threat across MI tomorrow, as it has the winds veering nicely late in the afternoon with the strengthening LLJ.

[nwohweather]

Not necessarily. In some setups (and this has happened plenty of times locally), the subsidence/stabilization from storms with the pre-frontal trough can limit action with the actual front itself.

You're talking about regular storms not severe before the front rolls through

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[geddyweather]

The 00z NAM verbatim suggests an enhanced tornado threat across MI tomorrow, as it has the winds veering nicely late in the afternoon with the strengthening LLJ.

Noticed this. Definetly worth watching...

I think the biggest thing that this event hinges on is if the sun comes out to play for a few hours tomorrow, even if its just in the morning (which I think we may have a shot at).

[andyhb]

Seeing some pretty nasty forecast soundings from the short term models tomorrow in IN, NW OH and Lower MI. We'll see where we are as far as junk convection/etc. tomorrow morning, could be a significant threat. This trough looks quite favorable just going by pattern recognition alone.

[Torchageddon]

My attention was captured when I saw I was under a Slight Risk and some higher probs. than normal for MBY for later today. I'm getting some vibes of May 12, 2000 which today is 1 day removed from the 15th anniversary of the worst thunderstorm I've ever experienced and the last time flash flooding, extremely strong winds, and tornado spin-ups were all together in unison in my neck of the woods. Not only the date, but even the shape and scope of the Slight Risk area is similar to how that day unfolded state-side too with very scattered tornado reports all the way down to Texas. Temperature high will be the same in addition, but the amount of rain or early storms could be the main difference as May 12 had lots of sun to destabilize. I'm going to be watching this because its fitting together a little too good to discount today paying homage to 15 years ago.

 

Addressing the amount of daytime heating, it may not prevent a strong thunderstorm from impacting me because I still think back to July 8, 2007 where all day long I was under thick overcast skies and I don't even remember seeing much sun at all...by late afternoon I got the worst hail storm I've ever seen and 25 minutes to my south they had baseball sized hail. A mid-grade Tornado then was sweeping beside HWY 9 near Mildmay ON. It was a strange supercell that came from the north and was heading due south and I find it interesting the only supercell that I know of to hit MBY occurred where the sun didn't peak that day. If I just get a few hours of sun today I think I may get smacked.

 

Areas in SE Michigan might want to watch out for higher destabilization (1500 J/kg) tomorrow. The 4km NAM (12z and 6z) has some higher-reflectivity thunderstorms near the Thumb tomorrow.

 

I'm curious how it will pan out in mid-western Ontario, I look to the Thumb to see what is down the pike.

[Stebo]

DTX is pretty bold on the potential later today. 

 

INTERESTING FORECAST SETTING UP FOR LATER TODAY AS STALLED FRONTAL
BOUNDARY OVER FAR SOUTHEAST LOWER MICHIGAN LIFTS GRADUALLY NORTH
THROUGH THE AREA...ALLOWING A WEDGE OF MODERATELY UNSTABLE AIR TO
WORK INTO THE AREA DURING THE LATE MORNING AND AFTERNOON. THIS
PROCESS WILL BEGIN DURING THE PRE-DAWN HOURS AS WEAK SHORTWAVE
CROSSES THE AREA...BUT MAIN MOVEMENT WILL OCCUR DURING THE COURSE OF
THE MORNING IN THIS AFTERNOON AS BOUNDARY LAYER MIXING...FROM
DIURNAL HEATING AND A STRENGTHENING SOUTHERLY COMPONENT TO THE FLOW
IN ADVANCE OF APPROACHING LOW PRESSURE FORCES THE FRONTAL BOUNDARY
STEADILY NORTHWARD THROUGH THE CWA.

TIMING OF THE EARLY MORNING SHORTWAVE SUGGESTS MUCH/ALL OF SCATTERED
SHOWER ACTIVITY ASSOCIATED WITH IT WILL SHIFT NORTH OF THE AREA BY
AROUND DAWN...LEAVING A WINDOW INTO EARLY THIS AFTERNOON WHERE MID
AND UPPER LEVEL CLOUD COVER WILL BE REDUCED. THIS SHOULD ALLOW THE
LOWER STRATUS DECK...THE SOUTHERN EDGE OF WHICH NOW LIES ROUGHLY
ALONG I-94...TO MIX OUT AND ALLOW FOR AT LEAST SOME SUNSHINE OVER
THE AREA. THIS WILL BE THE MOST IMPORTANT PART OF THE FORECAST AS
THE DEGREE OF DESTABILIZATION WILL HINGE DIRECTLY ON HOW QUICKLY THIS
PROCESS OCCURS THIS MORNING. WHILE NOT A PERFECT SETUP FOR STRONG
HEATING...TIMING (AND LOCATION OF CURRENT STRATUS) SUGGESTS THAT
GUIDANCE VALUES OF 80F OR SLIGHTLY MORE OVER THE SOUTHERN CWA WILL
BE REASONABLE FOR AFTERNOON HIGH TEMPERATURES. WITH DEWPOINTS IN THE
LOWER 60S...THIS SHOULD YIELD SBCAPES AROUND 1500 J/KG.

AS LOW PRESSURE RIPPLES INTO AREA ALONG AN APPROACHING COLD
FRONT...EXPECT THE COVERAGE AND INTENSITY OF SHOWERS AND STORMS TO
INCREASE DURING THE MID AFTERNOON. TIMING OF THE FEATURE DURING THE
DIURNAL TEMPERATURE/INSTABILITY MAXIMUM IS CERTAINLY SUPPORTIVE OF
VIGOROUS CONVECTION. OVERALL DEEP LAYER SHEAR WILL INCREASE NOTABLY
AS THE ATMOSPHERIC WIND FIELD STRENGTHENS...AND BACKING WINDS IN THE
LOWEST 5-10KFT...AS LOW PRESSURE LIFTS INTO THE AREA...WILL BE VERY
FAVORABLE TO ROTATING THUNDERSTORMS. ASSUMING PARTS OF THE AREA CAN
ACHIEVE THE FORECAST INSTABILITY...SUCH AN ENVIRONMENT WILL BE
CONDUCIVE TO THE FORMATION OF A FEW TORNADOES. IN ADDITION...THERE
WILL BE A BROADER THREAT OF DAMAGING WINDS AS THE MID LEVEL FLOW
INCREASES TO 60 KNOTS OR BETTER BY LATE AFTERNOON. WHILE SOME HAIL
WILL ALSO BE POSSIBLE...MLCAPES SHOULD LAG SBCAPES SUBSTANTIALLY AS
DEPTH OF THE UNSTABLE AIRMASS REMAINS RATHER SHALLOW. THIS WILL
LIMIT THE POTENTIAL FOR STRONG...SUSTAINED UPDRAFTS IN ALL BUT THE
STRONGEST STORMS.

[geddyweather]

Nice morning here, blue sky and few clouds. Noticed some remnants of the TX supersoaker heading this way. Hoping that doesn't get in the way of anything.

[Harry Perry]

Thinking areas east of 127 and especially near Flint stand the best chance at severe weather this afternoon.

We had one solid hour of sunshine before the stratus moved back in from the approaching rain, not enough to even raise our temps. This sunshine however will be beneficial to areas on the east side of the state, as they will have several hours of it thus plenty of time to destabilize.

[nwohweather]

Very sunny and muggy here south of Toledo. Gassed the car up and ready to go for this afternoon

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[Powerball]

Not the best looking satellite image, but it'll have to due. I've seen setups with far worse cloud debris.

[Harry Perry]

Latest IR shows lots of breaks starting to show up, so it's better than nothing.

[dmc76]

Not the best looking satellite image, but it'll have to due. I've seen setups with far worse cloud debris.

Clouds are staring to lift around our area.

[dmc76]

Just like that near full sun. Let the destabilization begin.

[Powerball]

Clouds are staring to lift around our area.

Check the visible satellite...

[Harry Perry]

Started raining here, temps have already dropped to 65°.

Grand Rapids meso update hitting hard on severe weather here later on today, but with stabilization of the atmosphere, being at the entrance region of the jet is just going to keep developing showers overhead rather than storms. All eyes should be peeled on the east side of the state, some of the latest convective models show quite the storm(s) over there.

[hm8]

Latest HRRR has a notable UH track through MI

[andyhb]

Storm comes very close to both Lansing and Flint on that track.

[hm8]

Also this

[geddyweather]

Single cells starting to form in Srn IN. Might have to watch those for development as they move NE into the 5% TOR area.