June 20-21 and June 24-27 Heavy Rain/Severe Threats

[Chargers09]

Ew

[hawkeye_wx]

The NAM continues to show the Saturday morning MCS holding together enough to sweep down through eastern Iowa through midday, contaminating the afternoon potential somewhat.  The Euro, on the other hand, holds the storms in northern Iowa until afternoon when they dive south and blow up.  DVN is thinking any morning convection on the models may be overdone.

[A-L-E-K]

The NAM continues to show the Saturday morning MCS holding together enough to sweep down through eastern Iowa through midday, contaminating the afternoon potential somewhat.  The Euro, on the other hand, holds the storms in northern Iowa until afternoon when they dive south and blow up.  DVN is thinking any morning convection on the models may be overdone.

 

 

you look golden, enjoy the hot streak 

 

12z GFS loving the same old corridor for more action

[Hoosier]

I'd have to think at least one of these days will end up being a bigger event given the mid level flow alone. Those kinds of winds aloft can drive strong MCSs/derechos. Maybe some chances for tornadic setups too especially in regions with more backing in the low levels since there almost certainly will be good speed shear.

I agree entirely. 50-60+ kt mid level flow at times with that strong instability bodes well for getting something pretty good.

[Hoosier]

Enhanced risk area added in IA/IL for tomorrow.

[Gilbertfly]

12Z GFS is the only model that had the ongoing convection in s dakota...i did not look at the euro though, so not sure if it had it...fwiw

[Natester]

our eastern IA  posters are having a good run

 

Yeah.  Been nearly a year since I've had any severe weather.  The last time we've had a really bad storm was on June 30, 2014, the day of the derecho and the worst storm in Cedar Rapids since July 20, 2003.

[snowlover2]

ILN thoughts for Sunday and beyond.

 

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
348 PM EDT FRI JUN 19 2015


.LONG TERM /SUNDAY THROUGH FRIDAY/...
ON SUNDAY THE REMNANTS OF TROPICAL STORM BILL WILL BE EXITING THE
AREA ALLOWING FOR DRIER MID-LEVEL AIR TO WORK INTO THE AREA. A
SHORTWAVE FROM THE WEST WILL THEN MOVE EAST AND PUSH OVER MICHIGAN
DURING THE AFTERNOON. THIS SHORTWAVE WILL ALSO MOVE A COOL FRONT
INTO THE AREA SUNDAY EVENING. 850 TEMPERATURES WILL ALSO QUICKLY
WARM SUNDAY MORNING AND RISE ABOVE 20 DEGREES C IN SOME AREAS. THIS
WILL HELP STEEPEN LAPSE RATES ABOVE THE INVERSION. LOW LEVEL LAPSE
RATES ON BOTH THE NAM AND GFS ARE AROUND 7 TO 7.5 DEGREES C/KM. WITH
SLIGHTLY DRIER MID-LEVEL AIR MOVING IN THAT WILL ALSO HELP TO
INCREASE DCAPE AND ABSOLUTE SURFACE DELTA THETA-E VALUES. BOTH THE
GFS AND NAM ARE SHOWING SFC DELTA THETA-E VALUES BELOW -30 SUNDAY
AFTERNOON. DCAPE VALUES ARE ALSO FORECASTED TO BE AROUND 1500 J/KG.
CAPE VALUES ON BOTH THE GFS AND NAM ARE ALSO IN THE 2500 TO 3500
J/KG RANGE. EFFECTIVE BULK SHEAR VALUES ARE NOT TERRIBLY IMPRESSIVE
BUT ARE SUFFICIENT WITH 40 KTS FORECASTED. GIVEN THE ABOVE SOME
STORMS ARE EXPECTED BE STRONG TO SEVERE WITH DAMAGING WINDS BEING
THE MAIN THREAT. AS OF CURRENT THE GENERAL THINKING IS THAT THERE
WILL BE SOME DISCRETE CELLS AHEAD OF AN MCS THAT FORMS TOWARDS OUR
WEST. THE TIMING AND PLACEMENT STILL REMAINS UNCERTAIN.

ON MONDAY ANOTHER POTENT SHORTWAVE WILL APPROACH THE AREA FROM THE
NORTHWEST. THE FRONT THAT IS SUPPOSED TO STALL AND WASHOUT SUNDAY
NIGHT WILL LIFT NORTH MONDAY ALLOWING 70 DEWPOINTS TO SPREAD OVER
MUCH OF THE AREA. FORECAST SOUNDINGS FOR MONDAY AGAIN SHOW HIGH
INSTABILITY VALUES ON BOTH THE GFS AND NAM. EFFECTIVE BULK SHEAR
VALUES ALSO INCREASE SLIGHTLY MONDAY AFTERNOON COMPARED TO SUNDAY
AFTERNOON. SFC DELTA THETA-E AND DCAPE VALUES ALSO STILL LOOK
IMPRESSIVE. THIS MEANS ANOTHER DAY OF POSSIBLE STRONG TO SEVERE
THUNDERSTORMS LOOKS ON TAP FOR MONDAY.

AN UPPER LEVEL RIDGE OVER THE MIDWEST TUESDAY WILL START TO ROTATE
SOUTHEAST TUESDAY AFTERNOON WHILE ANOTHER COLD FRONT APPROACHES THE
AREA FROM THE NORTH AND STALLS. THE EXACT DETAILS OF THE MESOSCALE
REMAINS CLOUDED FOR THE EXTENDED BUT THE OVERALL SYNOPTIC PATTERN
SEEMS TO BECOMING SLIGHTLY MORE CLEAR. IT APPEARS THAT TUESDAY
THROUGH THURSDAY THE UPPER LEVEL RIDGE WILL REMAIN JUST FAR ENOUGH
SOUTH TO KEEP THE CWA WEATHER ACTIVE WITH A CHANCE OF RAIN IN THE
FORECAST EVERYDAY.

[Chicago Storm]

maybe decaying garbage sunday morning

i like from the QC area running back WSW towards northern MO.

progged instability pool and llj nose say hard right turn saturday evening.

I'll bet against that.

We'll be MCS'ed.

[cyclone77]

4km NAM smokes Hawkeye tomorrow evening.  The eastern half of Iowa, northeast MO, and northern/central IL looking prime for a pretty sweet MCS tomorrow evening.  

[Gilbertfly]

01z hrrr not a fan of the hard right turn through 16z tomorrow...looks like it ignores a warm wing though in south central minnesota and doesn't turn hard

[hawkeye_wx]

4km NAM smokes Hawkeye tomorrow evening.  The eastern half of Iowa, northeast MO, and northern/central IL looking prime for a pretty sweet MCS tomorrow evening.  

 

Yeah, the 00z NAM has backed off bringing morning convection through the area, so there's more powder to blow in the evening.  On the other hand, one of my local mets just showed a model that brings a weakening line through in the morning and never blows up anything else in the evening except perhaps far southern Iowa.  I was just checking the hrrr and it still has some stuff making it here mid morning, although each run seems to be backing off a bit.

[Gilbertfly]

4km NAM smokes Hawkeye tomorrow evening. The eastern half of Iowa, northeast MO, and northern/central IL looking prime for a pretty sweet MCS tomorrow evening.

8+ county polygon still on my 2015 severe bucket list...so you're telling me there's a chance

[cyclone77]

Yeah, the 00z NAM has backed off bringing morning convection through the area, so there's more powder to blow in the evening.  On the other hand, one of my local mets just showed a model that brings a weakening line through in the morning and never blows up anything else in the evening except perhaps far southern Iowa.  I was just checking the hrrr and it still has some stuff making it here mid morning, although each run seems to be backing off a bit.

 

HRRR already loading up big time cape over the western half of Iowa by noon behind the retreating MCS.  

[cyclone77]

4km NAM showing nearly due southerly winds ahead of that southeastward moving linear MCS over Iowa tomorrow late afternoon/eve.  850s 45-55kts out of the southwest.  Should be enough to at least kink up the line a bit for a brief tornado threat at times along the line.  More than likely it will probably mainly help develop some mesos along the line to enhance wind damage potential.  

 

A few images from 4km NAM

 

[snowlover2]

New day 2 is out and no real change from the previous day 3. Text sounds interesting.

 

 

 

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1229 AM CDT SAT JUN 20 2015  
 
VALID 211200Z - 221200Z  
 
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID MS  
VALLEY AND NRN OH VALLEY...  
 
...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL AND  
NRN PLAINS...LOWER TO MID MO VALLEY...MID MS VALLEY...OH  
VALLEY...CNTRL APPALACHIAN MTNS AND WRN NEW ENGLAND...  
   
..SUMMARY  
 
STRONG TO SEVERE THUNDERSTORMS MAY OCCUR ON SUNDAY FROM THE MID  
MISSISSIPPI VALLEY EASTWARD ACROSS THE NORTHERN OHIO VALLEY WHERE  
DAMAGING WIND GUSTS AND HAIL WILL BE POSSIBLE. OTHER MARGINALLY  
SEVERE THUNDERSTORMS WITH WIND DAMAGE AND HAIL POTENTIAL MAY OCCUR  
ACROSS PARTS OF THE NORTHEASTERN STATES. MARGINALLY SEVERE STORMS  
WITH HAIL AND STRONG WIND GUSTS WILL ALSO BE POSSIBLE IN PARTS OF  
THE CENTRAL AND NORTHERN PLAINS...LOWER TO MID MISSOURI VALLEY AND  
IN THE CENTRAL APPALACHIAN MOUNTAINS ON SUNDAY.  
   
..MID MS AND NRN OH VALLEYS  
 
AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD ACROSS THE GREAT LAKES  
REGION ON SUNDAY AS A 50 TO 65 KT MID-LEVEL JET MAX MOVES THROUGH  
NRN PARTS OF THE OH VALLEY STATES. AT THE SFC...A SLOW MOVING COLD  
FRONT IS FORECAST TO MOVE SWD INTO THE MID MS VALLEY AND OH VALLEY  
SUNDAY AFTERNOON WITH A VERY MOIST AIRMASS LOCATED NEAR AND TO THE  
SOUTH OF THE FRONT. SFC DEWPOINTS IN THE LOWER 70S F SHOULD  
CONTRIBUTE TO THE DEVELOPMENT OF MODERATE TO STRONG INSTABILITY  
ACROSS MO...IL...INDIANA AND OH. THUNDERSTORMS APPEAR MOST LIKELY TO  
INITIATE ACROSS INDIANA AND OH BY LATE AFTERNOON JUST AHEAD OF THE  
UPPER-LEVEL TROUGH AND JUST TO THE SOUTH OF THE MID-LEVEL JET. IN  
ADDITION TO STRONG INSTABILITY...FORECAST SOUNDINGS AT INDIANAPOLIS  
AND COLUMBUS OH FOR 00Z/MONDAY SHOW 40 TO 50 KT OF 0-6 KM SHEAR  
SUGGESTING THAT THE ENVIRONMENT WILL BE FAVORABLE FOR SEVERE STORMS.  
SUPERCELLS WITH LARGE HAIL AND ISOLATED WIND DAMAGE WILL BE POSSIBLE  
WITH CELLS THAT REMAIN DISCRETE. HOWEVER...IT SEEMS EQUALLY LIKELY  
THAT A SEVERE WIND PRODUCING LINEAR MCS COULD ORGANIZE AND MOVE  
QUICKLY EWD ACROSS THE OH VALLEY. THE LATTER WOULD LIKELY BE DRIVEN  
BY MESOSCALE FACTORS. ALTHOUGH THE ERN PART OF THE SLIGHT RISK AREA  
APPEARS TO HAVE THE GREATEST POTENTIAL FOR SCATTERED SEVERE  
STORMS...A CONDITIONAL THREAT FOR DAMAGING WIND GUSTS MAY DEVELOP AS  
FAR WEST AS NERN MO WHERE STRONG INSTABILITY AND MODERATE DEEP-LAYER  
SHEAR SHOULD SUPPORT ISOLATED SEVERE THUNDERSTORM DEVELOPMENT.

[snowlover2]

New day 1 maintains enhanced area for eastern half of IA into nw IL.

 

 

 

...UPPER MS VALLEY...

EARLY THIS MORNING...MATURING MCS IS PROGRESSING ESEWD ACROSS CNTRL
SD WITH SUBSTANTIAL/EXPANDING PRECIP SHIELD STRETCHING FROM SCNTRL
ND TO NEAR THE NEBRASKA BORDER. THIS ACTIVITY IS PROGRESSING AT
ROUGHLY 35KT AND SHOULD MIGRATE INTO NWRN IA BY SUNRISE. WHILE THIS
ACTIVITY COULD BE SEVERE AT 12Z IT/S NOT CLEAR WHETHER THIS ACTIVITY
WILL DISSIPATE BEFORE DIURNAL HEATING CONTRIBUTES TO
REINTENSIFICATION DURING THE AFTERNOON HOURS. WEAK HEIGHT FALLS
WILL AFFECT THIS REGION DURING THE DAY WITH LEADING EDGE OF PRIMARY
COLD FRONTAL SURGE EXPECTED TO EXTEND FROM WRN MN...SWWD INTO ERN
NEB AT 18Z...THEN INTO CNTRL IA BY EARLY EVENING.

IF CONVECTIVE DEBRIS IS NOT TOO SIGNIFICANT IT APPEARS BOUNDARY
LAYER HEATING SHOULD CONTRIBUTE TO SUBSTANTIAL DESTABILIZATION WITH
MUCAPE APPROACHING 4000 J/KG JUST SOUTH OF REMNANT MCS CLOUD SHIELD.
AFTERNOON CONVECTION THAT EVOLVES AHEAD OF COLD FRONT SHOULD BE
SUFFICIENTLY SHEARED FOR SUPERCELL STRUCTURES AND VERY LARGE HAIL IS
EXPECTED...IN ADDITION TO DAMAGING WINDS. FORECAST SOUNDINGS ALSO
SUGGEST ISOLATED TORNADOES MAY EVOLVE...ESPECIALLY IF CONVECTIVE
MODE REMAINS FAVORABLY DISCRETE. TSTMS THAT EVOLVE OVER IA SHOULD
PROPAGATE TOWARD NRN IL AS LLJ VEERS INTO THIS REGION AFTER DARK.

[snowlover2]

ILN mentions supercells possible on Sunday.
 

 

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
442 AM EDT SAT JUN 20 2015

.SYNOPSIS...
THE REMNANTS OF TROPICAL STORM BILL WILL MOVE THROUGH THE REGION
TODAY...PRODUCING SHOWERS AND THUNDERSTORMS WITH HEAVY RAINFALL.
AFTER A BRIEF RESPITE TONIGHT...THUNDERSTORMS...SOME OF WHICH MAY
BE STRONG TO SEVERE...ARE FORECAST FOR SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CENTER OF WHAT IS LEFT OF T.S. BILL WAS LOCATED W OF SDF. MODELS
ARE IN GOOD AGREEMENT IN MOVING THE LOW ALONG THE OHIO RIVER TODAY
AND INTO THE APPALACHIANS BY THIS EVENING. PRECIPITABLE WATER
VALUES WILL INCREASE TO OVER 2 INCHES TODAY AS THE SYSTEM PASSES
BY.

WILL CONTINUE THE FLASH FLOOD WATCH OVER THE SRN HALF OF THE
FA...NEAR THE PATH OF THE LOW. ONE TO TWO INCHES OF RAINFALL WILL
BE POSSIBLE. WENT 100 POP ACROSS THE SRN HALF OF THE FA...WITH
LIKELY POPS ACROSS THE NRN TIER.

LOOKS LIKE THE BEST CHANCE OF SEVERE WILL E OF HERE...IN THE
APPALACHIANS. WHILE AN ISOLATED STRONG STORM CAN`T BE RULED OUT...THE
BETTER SHEAR WILL BE E OF THE FA...ALONG WITH THE FACT THE THE
SYSTEM WILL BE EXITING THE REGION DURING THE PEAK OF THE DAY.

ONE PIECE OF GOOD NEWS IS THAT THE MODELS HAVE
CONTINUED THE TREND OF MOVING THE SYSTEM THROUGH QUICKLY WITH
MUCH OF THE REGION DRY BY 00Z. THEREFORE HAVE SPED UP THE BACK EDGE
OF THE PCPN.

TEMPS WILL BE HELD DOWN AGAIN TODAY DUE TO THE RAIN AND PCPN.
HIGHS WILL BE IN THE MID 70S TO THE UPPER 70S IN THE SOUTH. UP IN
THE NORTH HIGHS WILL MAKE THE UPPER 70S TO LOWER 80S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
FA WILL BE BETWEEN SYSTEM FOR MUCH OF TONIGHT. PCPN ASSOCIATED
WITH BILL SHOULD BE IN THE APPALACHIANS AT THE BEGINNING OF THE
PERIOD. AN H5 S/W DROPPING THROUGH THE GREAT LAKES TONIGHT WILL
REACH THE NW PORTIONS OF THE FA LATE IN THE PERIOD. KEPT SOME
CHANCE POPS ACROSS THE NW PART OF THE FA...BUT KEPT THE SE DRY.

AS THE H5 TROF MOVES ACROSS THE GREAT LAKES...A 50-65KT JET MOVES
IN. AT THE SFC...A CDFNT IS FORECAST TO MOVE SWD BY AFTERNOON. A
VERY MOIST AIRMASS...WITH DEWPOINTS IN THE LOWER 70S SHOULD
CONTRIBUTE TO THE DEVELOPMENT OF MODERATE TO STRONG INSTABILITY.
THUNDERSTORMS SHOULD INITIATE DURING THE AFTERNOON. 40-50 KT OF
0-6 KM SHEAR SUGGEST SEVERE STORMS WILL BE POSSIBLE. SUPERCELLS
WITH LARGE HAIL AND ISOLATED WIND DAMAGE COULD BE POSSIBLE.

THE THUNDERSTORMS WILL HAVE PUSHED THROUGH THE REGION BY EARLY
SUNDAY NIGHT...LEAVING ANOTHER DRY NIGHT FOR THE REGION. THE FRONT
STALLS IN KENTUCKY AND ACTS A FOCUS FOR SOME SCATTERED CONVECTION
ACROSS THE WESTERN COUNTIES ON MONDAY.

TEMPERATURES WILL REMAIN WARM TONIGHT WILL LOWS IN THE LOWER 60S
TO LOWER 70S. ON SUNDAY...HIGHS WILL BE VERY WARM IN THE SOUTH
REACHING TO AROUND 90. UP IN WEST CENTRAL OHIO HIGHS ARE EXPECTED
TO MAKE THE MID 80S.

AFTER A COOLER NIGHT SUNDAY NIGHT AS TEMPERATURES FALL TO
65-70...HIGHS MONDAY WILL BE THE MID TO UPPER 80S.

[A-L-E-K]

one of the best things about this type of pattern is that the subtle but frequent ripples in the flow cause the forecast to become super mesoscale dependent, so it's hard to get too into monday at this point but it looks explosive.

 

well defined MCS tracking across southern MN, southern flank still being fed by elevated instability and llj with the northern edge entering diurnally unfavorable decline period..however MCV looks well defined and it should probably survive to re-flare later this afternoon. Airmass to the south of the line over IA, MO and western IL should reload and do well. Further east towards MBY remains relatively cool and stable with NE flow on the backside of the tropical remnants...should keep heating and instability below guidance, but we'll see.

 

plume of relatively dry/stable air visible nicely here, this is why the models are driving a hard right turn later this evening.

 

 

 

[Powerball]

Looking good for wisconsinwx.

[A-L-E-K]

Haha

Edit. LOT already dialing back pops for tonight.

[wisconsinwx]

Haha

Edit. LOT already dialing back pops for tonight.

 

Tonight hasn't been looking good for either of us, but with models progging best convection just north on Monday, at least we have some wiggle room there.  Surprised to see enhanced risk, but shear seems to be great for once, and instability may be there as well.

[daddylonglegs]

Had a band move through this morning...  very brief heavy rain and some thunder...  done now. 

[hawkeye_wx]

The morning MCS has made it south into central Iowa and is still holding together a bit.  It remains to be seen what effect this will have on late afternoon storms.  Obviously, the sooner this stuff can die out, the better.  It is currently fairly dark and cool here.

[kystormspotter]

HRRR nearly has boundary to illinois. I would not be surprised if main tornado threat today is in nw illinois

[A-L-E-K]

still 68 on the bank clock, i think today is officially over in MBY

 

on to monday

[Powerball]

still 68 on the bank clock, i think today is officially over in MBY

 

on to monday

 

Today ever had a chance with Billy ****ing things up (both with the upper level heights and the subsidence in its wake).

[hawkeye_wx]

Robust storms are hanging around over here on the tail end of the MCS.  It appears they will largely pass north of me, but it continues to be gloomy and very cool.  There is some clearing trying to take place behind the storms.  They just need to get out of here while there is still time to heat up.

[Hoosier]

12z GFS still bringing a nice complex toward Chicagoland later.  Model battle continues.

[Gilbertfly]

Airmass change ongoing at my local...cool dry to warm and humider...matter of minutes. We'll see what shakes out from it later...but nice to feel the warmth.

In hinsdale currently...not in Bbrook

Fwiw