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July 5-8 Severe/Heavy Rain Possibilities


Hoosier

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Looking at DTX's radar, it's interesting to see the outflow boundaries from the storms move NW. You can sort of see the effects of this with the cell on the lower east side of the city, as it's been pouring in that area for nearly 45 minutes now as it keeps backbuilding.

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Looking at DTX's radar, it's interesting to see the outflow boundaries from the storms move NW. You can sort of see the effects of this with the cell on the lower east side of the city, as it's been pouring in that area for nearly 45 minutes now as it keeps backbuilding.

Looks like 15 mins of downpour at my house, must have just missed that leaving for work.

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From the way DTX is talking, the SPC Day 2 for Friday is going to look drastically different, seeing how there only in General Thunder right now

 

The late arrival of this forcing will allow ample time for diurnal
heating to build moderate instability across portions of the
forecast area. The sfc front, expected to bisect the forecast area
Thurs morning, will attempt to shift north of the I-69 corridor,
although northeast flow off Lake Huron will inhibit it from lifting
north of the forecast area. Southerly flow south of the boundary and
daytime heating will likely drive max temps over 90, with sfc
dewpoints making a run at 70. This would support 0-1KM ML Cape on
the order of 2000-2500 J/kg south of the sfc front. With some
enhancement to the mid level flow expected in the vicinity of the
MCV, there is a chance for strong to severe tstms late in the day.
Excellent moisture transport ahead of the MCV is expected to cause
some moisture pooling along/north of the low level baroclinic
zone/sfc front across srn and cntrl lower Mi. With precip water
forecast to exceed 2 in, precipitation efficiency will be quite good
and suggests a risk for some high intensity rainfall. Convective
trends later into Thus evening/night carries a good deal of
uncertainty. There is the potential for additional convective
development, especially if an e-w low level boundary is maintained,
as there will be an increase in low level southwest flow during the
night. So there is actually a chance that some locals may see over
an inch of convective rainfall.

Amplification of a mid level trough axis forecast to cross the
northern Great Lakes Friday continues to be shown with good
consistency among the 12Z model suite. The associated mid level
height falls and strengthening low level sw flow will act to drive
remnant outflow boundaries from Thurs night convection back
northward into Se Mi on Friday. The extent of convection Thurs night
will be key in how far south the remnant outflow is positioned by
Fri morning, which in turn will be key in how far north into the
forecast area the warm sector will be located by peak Fri heating.
The 12Z model suite all suggest that the instability axis will be
driven northward into Se Mi. The potential instability, and very
good cape density per model soundings, combined with an increase in
deep layer shear to 40 to 50 knots, will pose a formidable severe
weather risk late Friday.

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DVN mentioning big-time wind potential tomorrow night if we can destabilize tomorrow after the morning stuff moves out.  

 

Bit of their AFD...

 

All severe wx modes possible Thu evening, but damaging
straight line winds and flooding rain/intense rainfall rates will be
primary concerns. With the projected shear and thermodynamics, a
bowing storm segment with llvl cold pool mechanics could produce
downward wind bursts of 70 to 80 mph. Again, much will depend on
afternoon recovery/CAPE build up.

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17z HRRRx which only went out to 12hrs also had it running right along the MN/IA border 

 

 

Latest run takes it farther north, skirting by the LOT cwa.  We'll see.

 

Sorry for the extreme board slowness guys.  Hopefully it gets better soon.

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Twin Cities doubleheader tomorrow? The 18z 4k NAM and the latest runs of the HRRR are inching the morning MCS further north. Not convinced on either just yet, but several ingredients appear to be in place for a partial repeat of yesterday. Instability gonna pop if the morning line moves as planned. Tomorrow should be a fun day for many of us.

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NAM and other CAMs look pretty messy regarding tomorrow.  All over the place with instability, convective evolution, and also screwy with the sub H8 wind fields.  New GFS continues to look very potent, although it's totally underdoing the ongoing convection this evening, and basically leaves the instability axis untouched through tomorrow afternoon.  Really shows how potent this setup would be if we didn't have all this ongoing/festering convection and associated cloudiness to deal with.  

 

The overall synoptic setup for tomorrow is really good, but with so much ongoing convective crap it may take a big bite out of the potential.  Gonna have to wait till tomorrow morning to see what we have to work with regarding ongoing convection.

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SPC just took an axe to the Iowa potential today due to the big MCS down south clearing the region, although there's still a chance.  It would certainly help if the Missouri convection vanished by noon.

 

WHILE BAND OF

STG-SVR TSTMS STILL APPEARS PROBABLE ACROSS PARTS OF UPPER MIDWEST
TODAY...ITS INTENSITY...LONGEVITY AND SRN EXTENT ARE MORE IN DOUBT
NOW THAN IN PREVIOUS OUTLOOK PACKAGE. GIVEN THESE UNCERTAINTIES...
HAVE DIALED BACK TO 15%/SLGT UNCONDITIONAL RISK ACROSS THIS
REGION...ACKNOWLEDGING THAT LOCALIZED CONCENTRATION OR CORRIDOR OF
DAMAGING-GUST RISK MAY STILL DEVELOP SOMEWHERE WITHIN MN OR NRN IA
LATE THIS AFTN OR EVENING.
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Yeah today is an absolute mess. Things may still happen here later today, but that is highly dependent on how much sun we get. Skies are finally clearing now. Let's see if we get the heating before the wave in the Dakotas gets here. The latest HRRR looks decent but the 4k NAM shows a dying line

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