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July 11-14 Severe Weather Event


Powerball

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Location and coverage (as always) are in question, but there's a pretty good signal for a ROF setup in our region during the period noted in the title.

 

Even if shear isn't all that impressive, the decent low-level convergence being progged, a NE expansion of the EML (850mb temps of 20*C+) and the corresponding high instability values should aid in the setup.

 

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GFS has maintained some crazy parameters and I can't wait to see what happens when we get in range of the NAM.

 

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The thing that concerns me is that SPC is far from impressed with the setup.

 

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0350 AM CDT TUE JUL 07 2015

VALID 101200Z - 151200Z

...DISCUSSION...
THE LATEST MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST THAT A FAIRLY
PROMINENT SUBTROPICAL HIGH CENTER WILL REDEVELOP WEST NORTHWESTWARD
FROM THE SOUTHEASTERN U.S. INTO THE SOUTHERN PLAINS AND SOUTHERN
ROCKIES REGION LATE THIS WEEK THROUGH THE WEEKEND. AN AMPLIFIED
RIDGE APPEARS LIKELY TO BUILD ALONG AN AXIS NORTH OF THE HIGH CENTER
THROUGH THE PLAINS INTO PORTIONS OF THE CANADIAN PRAIRIES...FLANKED
BY TROUGHING NEAR THE PACIFIC COAST AND ACROSS THE EAST. THIS
REGIME MAY BE ACCOMPANIED BY THE DEVELOPMENT OF MODERATE TO STRONG
POTENTIAL INSTABILITY...PARTICULARLY ACROSS PARTS OF THE NORTHERN
PLAINS INTO THE MID MISSOURI VALLEY...ASSOCIATED WITH STEEPENING
MID-LEVEL LAPSE RATES AND THE RETURN OF SEASONABLY MOIST BOUNDARY
LAYER CONDITIONS. WITHIN THE WESTERLY/NORTHWESTERLY MID/UPPER FLOW
ON THE NORTHERN AND EASTERN PERIPHERY OF THE RIDGE...THE ENVIRONMENT
MAY BECOME INCREASINGLY CONDUCIVE TO THE DEVELOPMENT OF ORGANIZED
THUNDERSTORM CLUSTERS. HOWEVER...THE PREDICTABILITY OF A MORE
PRECISE LOCATION OF WHERE THESE CLUSTERS MAY FORM ON ANY GIVEN DAY
THIS WEEKEND INTO EARLY NEXT WEEK REMAINS LOW. AND...THERE REMAINS
LITTLE IN THE MODEL OUTPUT TO SUGGEST ANYTHING BEYOND RELATIVELY
MINOR OR MARGINAL /FOR THE SEASON/ SEVERE WEATHER POTENTIAL. AS A
RESULT...SEVERE WEATHER PROBABILITIES APPEAR TO REMAIN BELOW 15
PERCENT THROUGH THE PERIOD.

 

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Marginal risk on the day 3 outlook.  Given the amount of instability available to feed these complexes, you can't rule out one or more of them taking off and resulting in a better severe threat.  Barring some sort of MCV enhancement or something, the mid-level flow still looks a bit marginal, but it's not awful especially given the instability. 

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From LOT's AFD this morning. 

SATURDAY THROUGH WEDNESDAY...

WARM/MOIST PUSH APPEARS TO REALLY GET GOING SATURDAY THROUGH THE
REST OF THE WEEKEND...WITH MORE SUMMER LIKE CONDITIONS EXPECTED
THROUGH EARLY NEXT WEEK. MODELS DO VARY WITH REGARDS TO
THUNDERSTORM CHANCES...ALTHOUGH...THE PERIOD APPEARS TO CONTINUE
TO BE ACTIVE. THERE IS THUNDERSTORM CHANCES DURING THE DAY
SATURDAY BUT WILL BE PARTLY DRIVEN BY WHERE LIFTING WARM FRONT IS
SITUATED...WITH MODELS STRUGGLING WITH AT THIS TIME.
HOWEVER...GUIDANCE IS HINTING AT A BETTER POSSIBILITY FOR MORE
ORGANIZED DEVELOPMENT SATURDAY NIGHT INTO EARLY SUNDAY MORNING.
STILL UNCERTAINTY PRESENT...BUT A POSSIBLE SCENARIO WILL BE FOR
MCS DEVELOPMENT TO THE WEST/NORTHWEST SHIFTING ACROSS THE CWA
DURING THIS TIME. IF THIS WERE TO OCCUR... DAMAGING WINDS AND
HEAVY RAINFALL WOULD BE POSSIBLE. ONCE AGAIN...STILL SOME
UNCERTAINTY...BUT SYNOPTIC SETUP WITH INCREASING
MOISTURE/INSTABILITY WOULD SUPPORT THIS POSSIBILITY AT THIS TIME.

 


RODRIGUEZ

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Pretty surprised this thread isn't getting very much attention. I'd be extremely surprised if we don't end up seeing a couple of wind driven enhanced if not moderate risk areas on Sunday and Monday. Yeah, shear is only around 40kts, but CAPE is also 4000-6000 J/kg. That's insane without any shear. The NAM shows an explicit MCS Sunday within a very favorable thermodynamic environment. The GFS then absolutely blows up cells on Monday in northern Indiana/Ohio. Looking forward to see how this actually plays out...in my experience this year, the better an event looks far out, the worse it plays out...I hate the models.

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Pretty surprised this thread isn't getting very much attention. I'd be extremely surprised if we don't end up seeing a couple of wind driven enhanced if not moderate risk areas on Sunday and Monday. Yeah, shear is only around 40kts, but CAPE is also 4000-6000 J/kg. That's insane without any shear. The NAM shows an explicit MCS Sunday within a very favorable thermodynamic environment. The GFS then absolutely blows up cells on Monday in northern Indiana/Ohio. Looking forward to see how this actually plays out...in my experience this year, the better an event looks far out, the worse it plays out...I hate the models.

"shear is only around 40 knots" that's easily favorable for MCS development/maintenance. The June 29 derecho thrived with less shear than that (mostly 35 knots).

 

The instability being shown by GFS and NAM is absolutely amazing... this is what we should see in July. Not something like ILX's crappy sounding last night, 60 degrees/60 dew point. 

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Insane cape continues to be advertised by all models late this weekend/early next week.  NAM forecast soundings show in excess of 8000j/kg cape (lol) in parts of Iowa late Sunday.  Sunday night there could actually be a pretty decent severe weather event with a fairly powerful upper jet plowing in right over the insane instability pool.  Decent LLJ support as well.  With the seasonally strong upper jet combined with decent shear profiles, and potential extreme instability there could be some derecho potential me thinks.  Gonna be very interesting to see how this plays out.  

 

Iowa sounding from 18z NAM..

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Several notable matches showing up in the sharppy soundings for some areas, such as 7/13/04, 8/28/90 and 8/6/62 for Topeka. Overall setup is a pretty good match synoptically to some of these huge cape/modest shear setups with the wild card of that enhanced upper level jet.

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I know the whole TORCON thing is rather controversial in the Meteorology world... but since Dr. Forbes is one hell of a Meteorologist, here's his thoughts

 

SATURDAY
Isolated severe thunderstorms in northwest, central, and east ND, 
east SD, northwest, central, and south MN, IA, west WI, northwest 
and west-central IL, north MO. TORCON - 3 northwest IL, east IA, 

south MN; 2 rest of area

 

https://scontent-ord1-1.xx.fbcdn.net/hphotos-xaf1/t31.0-8/11411944_10152997021418201_7491500277508803952_o.jpg

 

SUNDAY

Isolated severe thunderstorms along and north of a warm front in 
east ND, northwest, central and south MN, WI, central and south MI, OH, north and central IL, north-central and east IA, north, 

central, and southeast IN, northeast SD. TORCON - 2 to 3 for now; could be higher in some locations if a low pressure center forms on the front - but models disagree on where that could occur

 

https://scontent-ord1-1.xx.fbcdn.net/hphotos-xpt1/t31.0-8/11143373_10152997077198201_2790698790353582065_o.jpg

 

MONDAY

Computer models disagree on the weather pattern, reducing confidence in the details of the forecast. Isolated severe thunderstorm in parts of the area including northeast MN, WI, MI, northeast IL, IN, OH, NY, PA, WV, east KY, east TN, NJ. TORCON - 2 to 3 for now

 

It's weird to go from this crappy November-like weather to full-on mid-summer MCS/derecho season with extreme CAPE within a week.

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Insane cape continues to be advertised by all models late this weekend/early next week.  NAM forecast soundings show in excess of 8000j/kg cape (lol) in parts of Iowa late Sunday.  Sunday night there could actually be a pretty decent severe weather event with a fairly powerful upper jet plowing in right over the insane instability pool.  Decent LLJ support as well.  With the seasonally strong upper jet combined with decent shear profiles, and potential extreme instability there could be some derecho potential me thinks.  Gonna be very interesting to see how this plays out.  

 

Iowa sounding from 18z NAM..

 

00z 1 up'd that

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3 days out but 00z NAM looks pretty good across a fairly large area of the Upper Midwest on Monday afternoon/evening, particularly through the Upper MS Valley into N IL.

 

Should be decent ascent for initiation especially with the left exit region of the upper jet punching right over the warm sector.

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Pretty much over my house Sunday evening off the 0z NAM

 

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Some interesting conditional setups on the way to be sure.  With differential heating/old outflow boundaries lying around, remnant MCVs, and who knows what else, it could be an interesting weekend/early week with this upcoming ROF event.

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Most interesting AFD in weeks

.LONG TERM...(SATURDAY THROUGH THURSDAY)

ISSUED AT 403 AM EDT FRI JUL 10 2015

WET AND ACTIVE WEATHER IN STORE FOR THE AREA EARLY NEXT WEEK AS

"RING OF FIRE" PATTERN DEVELOPS ON NORTHEAST FRINGE OF BUILDING

CENTRAL CONUS RIDGE. NUMEROUS SHORTWAVES WILL CASCADE DOWN THE

RIDGE INTO OUR REGION AND CAPITALIZE ON MOIST AND UNSTABLE AIRMASS

AS THETA-E PLUME FOLDS EAST. UNFORTUNATELY...MESOSCALE (AND

ASSOCIATED SENSIBLE WEATHER) DETAILS REMAIN HIGHLY UNCERTAIN AT

THIS POINT WITH POTENTIAL FOR CONVECTION TO MODULATE THE

TIMING/STRENGTH/PLACEMENT OF INDIVIDUAL WAVES.

SATURDAY STILL LOOKING DRY THOUGH WITH STRONG SHORTWAVE RIDGING

BETWEEN BOOKEND TROUGHS. HIGH DEGREE OF SUBSIDENCE AND DRY LOWER

LEVELS WILL LEAD TO A FAIRLY PLEASANT DAY...THOUGH MID/HIGH CLOUDS

WILL BE STEADILY INCREASING. STILL...FILTERED INSOLATION AND SOME

WEAK WAA LATE IN THE DAY SHOULD ALLOW HIGH TEMPS TO AT LEAST MOVE

SLIGHTLY CLOSER TO SEASONAL AVERAGES WITH LOW 80S EXPECTED.

REMOVED ANY MENTION OF PRECIP PRIOR TO 00Z WITH NEARLY ALL

GUIDANCE KEEPING OUR CWA DRY THROUGH THAT TIME. PRECIP CHANCES

WILL INCREASE FROM WEST TO EAST OVERNIGHT THOUGH AS WAA WING OF

NEXT SHORTWAVE PUSHES THROUGH OUR AREA. MODELS SHOW A HEALTHY

SWATH OF 305K ISENTROPIC ASCENT AND GOOD MOISTURE ADVECTION IN OUR

WESTERN CWA ON THE NOSE OF NOCTURNAL 40 KT LLJ. BUMPED UP POPS BUT

STOPPED JUST SHY OF CATEGORICAL FOR NOW. ISENTROPIC ASCENT IS

WEAKER DURING THE DAY SUNDAY BUT DOES SHIFT EAST AND WILL HAVE THE

ADDED BENEFIT OF SOME DIURNAL DESTABILIZATION. A FEW SEVERE STORMS

MAY BE POSSIBLE GIVEN VERY WARM/MOIST AIRMASS BEHIND FRONT

(SURFACE DEWPOINTS LOW TO MID 70S) AND DEEP LAYER SHEAR 25-30 KTS

BUT MORNING PRECIP/CLOUD COVER MAKES DEGREE OF INSTABILITY

UNCERTAIN. HEAVY RAIN/FLOODING ALSO A CONCERN GIVEN RETURN OF 2+

INCH PW VALUES AND DEEP WARM CLOUD LAYERS.

CONFIDENCE IN FORECAST DETAILS DROPS SIGNIFICANTLY FOR MONDAY AND

TUESDAY WITH MULTIPLE SHORTWAVES PUSHING THROUGH THE REGION IN A

MOIST AND POTENTIALLY VERY UNSTABLE ENVIRONMENT. SEVERE WEATHER

AND FLOODING MAY BE POSSIBLE BOTH DAYS DEPENDING ON THE EXACT

TIMING AND PLACEMENT OF INDIVIDUAL SHORTWAVES AND POTENTIAL MCS'S.

NOT SURPRISINGLY...GFS AND ECMWF MODELS OFFER VERY DIFFERENT

SOLUTIONS AND UNFORTUNATELY AT THIS POINT CAN DO NOTHING BUT

BLANKET MID-HIGH CHANCE POPS UNTIL DETAILS COME BETTER INTO FOCUS.

LOOKS LIKE WE COULD SEE A BREAK WEDNESDAY AND THURSDAY BUT

AGAIN...MAY DEPEND ON EARLY WEEK CONVECTION. VERY WARM THERMAL

PROFILES FOR EARLY NEXT WEEK SUGGEST GOING FORECAST COULD

POTENTIALLY BE MUCH TOO COOL. 90F EASILY POSSIBLE WITH SOME GOOD

AFTERNOON SUN/MIXING BUT CONFIDENCE IN CLOUD/PRECIP TRENDS TOO LOW

FOR ANYTHING MORE THAN MID 80S AT THIS POINT.

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SPC's day 4 outlook sounds excellent. I'm a bit nervous because, just like winter events, if you're in or near the bullseye 4 days out, you're probably gonna get screwed.

 

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DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0336 AM CDT FRI JUL 10 2015

VALID 131200Z - 181200Z

...DISCUSSION...
ON MON/D4...AN UPPER RIDGE WILL REMAIN SITUATED ACROSS THE CNTRL AND
SRN PLAINS...WITH A BAND OF RELATIVELY STRONG NWLY FLOW ALOFT ACROSS
THE MID MS AND LOWER OH VALLEYS. IN THE SAME GENERAL VICINITY...AN
ONGOING MCS IS EXPECTED WITH PERHAPS A THREAT OF DAMAGING WINDS.

OTHER CLUSTERS OF STORMS MAY BE ONGOING AS WELL FARTHER E ACROSS
OH...KY AND WV IN A ZONE OF WARM ADVECTION ON THE NOSE OF A WLY
LOW-LEVEL JET.

LATER IN THE DAY...EXTREME INSTABILITY IS FORECAST TO REDEVELOP
ACROSS MUCH OF THE MIDWEST
...BENEATH THIS FAVORABLE NW FLOW ALOFT.
ALTHOUGH THE EXACT CORRIDOR IS DIFFICULT TO PREDICT AT THIS TIME DUE
TO COMPLEXITIES ASSOCIATED WITH OUTFLOW BOUNDARIES...NEW STORM
DEVELOPMENT IS AGAIN LIKELY MONDAY EVENING NEAR THE MS RIVER OR
ACROSS CNTRL IL...AND EXTENDING SEWD ACROSS KY AND TN. DAMAGING
WINDS WILL AGAIN BE THE MAIN THREAT WITH ANY FORWARD PROPAGATING
SEVERE MCS. ALTHOUGH HIGHER-END WIND DAMAGE POTENTIAL MAY
EXIST...PREDICTABILITY ISSUES CURRENTLY PRECLUDE ANY HIGHER SEVERE
WEATHER PROBABILITIES.

 

 

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