Sept-Oct heavy rain and Flooding threat

[janetjanet998]

new DVN long term

HE LONG RANGE OFFERS LITTLE HOPE FOR MORE THAN A SHORT REPRIEVE   
FROM THIS EXCEPTIONALLY WET PATTERN. THAT DAY IS TUESDAY, WHEN THE   
UPPER HIGH IS EXPECTED TO NUDGE A BIT FARTHER WEST, HELPING PUSH THE   
FOCUS FARTHER WEST FOR ORGANIZED STORMS.   
  
BEYOND THE DETAILS THIS IS WHAT IS IMPORTANT.  
  
HEAVY RAIN WILL IMPACT THE MIDWEST EVERY 24 HOUR PERIOD THIS WEEK.  
  
THE SYNOPTIC PATTERN SUGGESTS THE SAME DIURNAL INCREASE AND DECREASE   
IN CONVECTION IN THE RING OF FIRE PATTERN WILL CONTINUE THROUGH   
THURSDAY, AS THE UPPER HIGH SHIFTS SLIGHTLY EAST ALLOWING OUR AREA   
TO ONCE AGAIN BE THE MAIN FOCUS FOR HEAVY RAINFALL. THE PWAT VALUES   
ARE NOT EXPECTED TO LOWER AND THE DURATION OF THIS AIR MASS IS QUITE   
CONCERNING. CERTAINLY WE WILL CONTINUE TO HAVE WIDESPREAD RIVER   
FLOODING.  THE MOST CONCERNING POTENTIAL I SEE IN THE EXTENDED, AS   
IT WOULD SUGGEST A FAR MORE WIDESPREAD HIGH CONFIDENCE HEAVY RAIN   
EVENT, IS THE POSSIBLE PRE RAIN EVENT THURSDAY NIGHT THROUGH SATURDAY   
NIGHT. A PRE, OR PREDECESSOR RAINFALL EVENT, IS WITH LANDFALLING   
TROPICAL FEATURES MOISTURE PLUME AS IT INTERACTS WITH THE WESTERLY   
FLOW ALOFT NORTH OF THE TROPICAL HIGH, WHICH IS MORE OR LESS THE   
CURRENT RING OF FIRE PATTERN.   
  
RAINFALL IN THE WEEK AHEAD COULD ADD UP TO OVER 5 INCHES IN MANY   
LOCATIONS NORTH OF HIGHWAY 34.  STILL, MESOCALE DETAILS WILL   
DETERMINE STORM INITIATION EACH DAY, AND THOSE LOCATIONS WILL SEE   
THE HIGHEST IMPACTS. THAT UNFORTUNATELY IS BEYOND THE ABILITY TO BE   
FORECAST BEYOND A DAY, AND WILL RESULT IN THE THREAT FOR HEAVY RAIN   
TO BE FORECAST IN A MORE WIDESPREAD AREA THAN IS WILL VERIFY UNTIL   
THURSDAY.  AFTER THURSDAY, THE PRE EVENT COULD OFFER A LESS   
CONVECTIVE, BUT MORE WIDESPREAD HEAVY RAIN EVENT.   

[Chinook]

Considering the past several days of precip, some areas of IA/WI are already above 150% of normal for a 30-day time period (Aug 3- Sep 2). That generally gives indicators of where creeks and rivers are above normal or currently flooding. Some sections of Iowa, Missouri, and Kansas are in D1 - D4 drought, but many of those drought designations will change with the current and future heavy rains. Some areas of Michigan are in D0 - D2 drought. Maybe a few positive changes in Michigan are coming up.

[ChicagoNWburbs]

HRRR has been trending south for the last few runs with tonight’s activity, with the latest run targeting the northern tier of counties in IL.

[janetjanet998]

WPC still has 5-7 inches 7 day totals over IA area...hints of SE push and pattern change days 6-7

A little out of our sub forum but same event 

MESOSCALE PRECIPITATION DISCUSSION 0746  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
501 PM EDT SUN SEP 02 2018  
  
AREAS AFFECTED...CENTRAL KS/SOUTHEAST NE/NORTHWEST MO/SOUTHERN IA  
  
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY  
  
VALID 022055Z - 030255Z  
  
SUMMARY...AN INCREASING COVERAGE OF THUNDERSTORMS IS EXPECTED  
THROUGH 00Z AND 03Z ACROSS CENTRAL KS INTO SOUTHEASTERN NE,  
SOUTHERN IA AND NORTHERN MO. 3-5 INCHES OF RAIN IS EXPECTED  
THROUGH 03Z, SOME OF WHICH WILL OVERLAP WITH RECENT HEAVY RAINFALL  
ACROSS THE REGION POSING AN INCREASED THREAT FOR FLASH FLOODING.  
  
DISCUSSION...2030Z VISIBLE SATELLITE IMAGERY AND SURFACE  
OBSERVATIONS PLACED A SURFACE TROUGH, ENHANCED BY DIFFERENTIAL  
HEATING, FROM WEST-CENTRAL KS INTO NORTHWEST MO. RADAR IMAGERY  
ALREADY SHOWED SCATTERED THUNDERSTORMS ACROSS CENTRAL KS,  
INCREASING IN COVERAGE OUT AHEAD OF A STRUNG OUT LOW-MID LEVEL  
TROUGH AXIS WITH A COUPLE OF VORTICITY CENTERS STRETCHING ACROSS  
THE CENTRAL HIGH PLAINS. THE 20Z SPC MESOANALYSIS SHOWED 1500-2500  
J/KG MLCAPE ACROSS KS INTO MO AND SOUTHERN IA WITH ERODING CIN  
CONFIRMED BY THE RECENT INCREASE IN THUNDERSTORM DEVELOPMENT  
ACROSS KS. EAST OF 100W, GPS SITES AND THE 18Z LMN SOUNDING SHOWED  
PRECIPITABLE WATER VALUES OF 1.5 TO 1.8 INCHES ACROSS KS/NE/IA/MO.  
  
INCREASED FORCING FOR ASCENT OVER THE CENTRAL PLAINS AND MIDWEST  
IS EXPECTED THROUGH 00Z AS SUBTLE EASTWARD MOVEMENT OF THE  
MID-LEVEL TROUGH AXIS OCCURS. THE RAP HAS BEEN TRENDING STRONGER  
WITH A FORECAST 70-90 KT UPPER LEVEL JET FORECAST TO LIE FROM  
NORTHWEST IA TO LAKE SUPERIOR, PLACING THE RIGHT ENTRANCE REGION  
AND ADDED UPPER LEVEL DIVERGENCE OVER CENTRAL KS/NE BETWEEN  
00-03Z. MEANWHILE, CLOSER TO THE SURFACE, 850 MB WIND SPEEDS  
SHOULD INCREASE FROM THE SOUTH INTO THE 20-30 KT RANGE ACROSS KS  
BEYOND 00Z WITH OVERRUNNING OF THE AFOREMENTIONED SURFACE TROUGH  
AND ANY NEWLY DEVELOPED CONVECTIVE OUTFLOW BOUNDARIES WITH NEARLY  
UNIDIRECTIONAL FLOW ABOVE THE LFC SUPPORTING TRAINING/REPEATING OF  
CELLS FROM SOUTHWEST TO NORTHEAST. 3-5 INCHES OF RAIN THROUGH 03Z  
IS EXPECTED IN A FEW LOCATIONS, SOME OF WHICH IS EXPECTED TO  
OVERLAP WITH RECENT HEAVY RAINFALL AND LOWERED FLASH FLOOD  
GUIDANCE, SUPPORTING FLASH FLOODING IN A FEW LOCATIONS.  
  

[janetjanet998]

ESOSCALE PRECIPITATION DISCUSSION 0747...CORRECTED  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
601 PM EDT SUN SEP 02 2018  
  
CORRECTED FOR NEEDED RECREATION OF MPD GRAPHIC  
  
AREAS AFFECTED...EASTERN IA/SOUTHERN WI/NORTHERN IL  
  
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE  
  
VALID 022138Z - 030325Z  
  
SUMMARY...TRAINING AND REPEATING ROUNDS OF HEAVY RAIN WILL CAUSE A  
THREAT FOR FLASH FLOODING FROM EASTERN IA INTO SOUTHERN  
WI/NORTHERN IL THROUGH 03Z. 2-4 INCHES OF ADDITIONAL RAINFALL ARE  
POSSIBLE.  
  
DISCUSSION...LOCAL RADAR IMAGERY AT 21Z SHOWED TWO MCVS OVER IA,  
ONE ALONG THE WESTERN IA/MO BORDER AND THE OTHER ALONG THE IA/WI  
BORDER, BOTH MOVING TOWARD THE NORTHEAST. EACH MCV WAS CONNECTED  
TO CLUSTERS OF HEAVY RAINFALL WITH DUAL-POL ESTIMATED RAIN RATES  
OF 1-2 IN/HR WITHIN THE HEAVIER CORES. TRENDS OVER THE PAST HOUR  
HAVE SHOWN CONVECTION FILLING IN BETWEEN THE TWO MCVS OVER CENTRAL  
IA. THE SPC MESOANALYSIS AT 21Z DEPICTED A SIZABLE AREA OF 2000+  
J/KG MLCAPE JUST SOUTH OF THESE MCVS.  
  
WHILE RECENT RUNS OF THE HRRR HAVE STRUGGLED TO CAPTURE THE  
MAGNITUDE OF RAINFALL OCCURRING OVER IA AND WI, THE IDEA OF FUTURE  
EVOLUTION IS HINTED AT IN ITS SIMULATED REFLECTIVITY OUTPUT. BOTH  
MCVS ARE EXPECTED TO CONTINUE A TRACK OFF TOWARD THE  
EAST-NORTHEAST WHILE 25-30 KT 850 MB FLOW FROM THE SOUTHWEST  
OVERRUNS A REMNANT OUTFLOW BOUNDARY ENHANCED BY DIFFERENTIAL  
HEATING. GIVEN THE 850-300 MB MEAN WIND IS ROUGHLY 20-30 KT (A  
ROUGH PROXY FOR STORM MOTIONS), SOME TRAINING/REPEATING OF HEAVY  
RAIN CORES IE EXPECTED. IN ADDITION, DIFFLUENT FLOW ALOFT IS  
EXPECTED TO ENHANCE AS AN UPPER LEVEL JET TO THE NORTH STRENGTHENS  
THROUGH 03Z AS FORECAST BY THE RAP. FLASH FLOOD GUIDANCE IS RATHER  
LOW OVER THE REGION (1.5 TO 2.5 INCHES IN 3 HOURS) HELPING SUPPORT  
THE THREAT FOR FLASH FLOODING WITH 2-4 INCHES OF ADDITIONAL  
RAINFALL POSSIBLE THROUGH 03Z.  
  

[Hoosier]

Looks like there's a good chance for a named system eventually (would be Gordon).  Of course where it goes and the timing after landfall remains to be seen.

 

[Jim Martin]

From the National Weather Service in Cleveland in their Area Forecast Discussion this evening...

The frontal boundary may slow down or try to stall somewhere in
the region by the end of the week. We will have to watch 
closely what is going on down near Florida currently with a 
potential tropical system developing. Models show this area of 
tropical moisture and system coming around the ridge of high 
pressure into the Midwest and Great Lakes Region by Friday and 
Saturday. If that is the case and we have a stalled out front in
the region, we will potentially have a very wet and stormy 
weather pattern. It is way to early to get specific but 
definitely something to be weather aware.
 

[janetjanet998]

0Z Nam aggressive with the front cleaning IA by Weds evening

 

 

[Hoosier]

00z GEM... oof

[Hoosier]

One thing I am noticing on the models with the tropical remnant is a tendency for some baroclinic enhancement as it moves toward the Lakes... so not only is there potential for significant rain, but maybe a deepening surface low too.  00z Euro that just came in depicts that nicely.

[janetjanet998]

the mesoscale chaos throws a monkey wrench into smaller river forecast but its easier to focus on the main stems..

The Missouri river above Kansas city is already in flood(tempered by the low volume Kansas river(so far) from MCI downstream)  

also IMO the Mississippi river above STL could  have issues (tempered by rather low inflow from the MO river(so far) from STL downstream)

  
HYDROLOGY  
  
ISSUED AT 330 AM CDT MON SEP 3 2018  
  
MAINLY MINOR TO MODERATE FLOODING CONTINUES OR REMAINS FORECASTED  
OVER THE NEXT 7-10 DAYS ON MANY TRIBUTARY RIVERS, WITH MINOR   
FLOODING FORECASTED ON THE SOUTHERN MAINSTEM MISSISSIPPI. HOWEVER,  
RIVER LEVELS AND FORECASTS COULD POTENTIALLY GO HIGHER IN THE NEXT  
5-7+ DAYS AS WE ADD ADDITIONAL RAINFALL.   
  
HEAVY RAINFALL SUNDAY AFTERNOON AND NIGHT YIELDED ANOTHER ROUND OF   
1 TO 4 INCH RAIN AMOUNTS, HOWEVER THESE OCCURRED IN FAIRLY NARROW   
SWATHS LARGELY JUST CLIPPING PORTIONS OF SEVERAL TRIBUTARY RIVER  
BASINS MOST NOTABLY THE PECATONICA. HAVING LARGELY SPARED THE TRIBS  
WITH THIS ADDITIONAL RAINFALL FORECASTS ARE LARGELY UNCHANGED OR  
COMING IN A BIT LOWER, AND SEEING A FEW SITES (KALONA, SIGOURNEY  
AND DEWITT) CREST OR RECEDE WITH LOWER LEVELS AS RUNOFF ABATES.  
HOWEVER, ADDITIONAL SECONDARY RISES AT THESE SITES ARE EXPECTED   
THROUGH ROUTED FLOW AND/OR ADDITIONAL FORECASTED RAINFALL.   
  
AS FOR THE NEXT 24 HOURS WILL SEE ANOTHER ROUND OF SHOWERS AND STORMS  
TODAY. DO NOT ANTICIPATE WIDESPREAD HEAVY RAIN RATHER MORE SWATHS OR  
NARROW CORRIDORS OF 1-4 INCH RAINFALL TOTALS. THUS, A GOOD CHANCE   
THIS RAIN WON'T HAVE A LOT OF IMPACT ON RIVER LEVELS UNLESS IT OCCURS  
DIRECTLY OVER A BASIN IN WHICH CASE COULD RESULT IN ADDITIONAL AND   
RAPID RISES AND HIGHER STAGES.   
  
ENCOURAGING DRIER SIGNAL IS PRESENT FOR TONIGHT THROUGH TUESDAY NIGHT  
WITH ONLY SPOTTY PRECIPITATION, AS DRIER AIR ADVECTS IN FROM HIGH   
PRESSURE OVER THE MID ATLANTIC. THE SURFACE BOUNDARY AND MOIST   
CONVEYOR WILL REFOCUS THE MORE ORGANIZED WIDESPREAD HEAVY RAIN POTENTIAL  
TO OUR NORTH AND WEST.   
  
CONCERN BEYOND IS FOR ADDITIONAL ROUNDS OF HEAVY RAIN TAKING AIM YET  
AGAIN ON THE REGION OVER THE LATTER HALF OF THE WEEK AND THROUGH THE  
UPCOMING WEEKEND WITH BOUNDARY STALLED NEARBY AND POTENTIAL FOR TROPICAL  
REMNANTS LIFTING NORTHWARD AND INTERACTING WITH THE FRONT. SHOULD THIS  
OCCUR THEN WE COULD POTENTIALLY BE LOOKING AT AN INCREASED RISK OF   
SIGNIFICANT FLASH FLOODING AND MAJOR RIVER FLOODING. SOMETHING THAT WILL  
BE MONITORED VERY CLOSELY IN THE COMING DAYS.  

 

[hawkeye_wx]

I'm hoping Gordon's remnants can get up to Iowa.  We obviously don't need the rain, but it's a rare occurrence for this area.  They almost always veer east before reaching Iowa.

[janetjanet998]

49 minutes ago, hawkeye_wx said:

I'm hoping Gordon's remnants can get up to Iowa.  We obviously don't need the rain, but it's a rare occurrence for this area.  They almost always veer east before reaching Iowa.

he seems to be getting his act together rather fast

not sure if a stronger system would mean a more east track?

 

seems to be on the east side of the thin cone now too

[Hoosier]

4 hours ago, hawkeye_wx said:

I'm hoping Gordon's remnants can get up to Iowa.  We obviously don't need the rain, but it's a rare occurrence for this area.  They almost always veer east before reaching Iowa.

You are correct about the tendency to curve east.  Here's a map from LOT showing systems that have passed in/near the cwa... it's pretty well up to date as you can see Alberto on there from earlier this year.  That being said, sometimes a remnant low pressure area persisted beyond what this map shows (an example would be Alicia 1983, which tracked into Iowa but is not pictured) so the actual occurrence of systems tracking into Iowa is a little underdone here, but it's pretty rare any way you cut it.  Of course this is just the track of the surface low, and a system could track somewhat east of Iowa and still bring rain there.

[Hoosier]

12z Euro is pound town.  The Gordon remnant brings quite a bit of rain too with continued suggestion of reinvigoration as it moves toward the Lakes.  

[janetjanet998]

latest DVN Hydro..

HYDROLOGY  
  
ISSUED AT 146 PM CDT MON SEP 3 2018  
  
SINCE 6 AM TODAY, ADDITIONAL HEAVY RAIN HAS FALLEN OVER THE  
AREAS GENERALLY NORTH OF HIGHWAY 30 IN IOWA AND ILLINOIS THIS  
MORNING. THE AFTERNOON ACTIVITY THUS FAR IS EITHER NEAR AND WEST  
OF WATERLOO, AND OVER OUR ILLINOIS COUNTIES. STORMS ARE SMALL IN  
SIZE, QUICK MOVING AROUND 30 TO 35 MPH, AND ARE PRODUCING  
TORRENTIAL RAINFALL RATES. THIS CONTINUES TO OFFER A FLASH FLOOD  
POTENTIAL.   
  
THE RAIN WHICH FELL IN NARROW SWATHS OVERNIGHT, FELL IN WIDE  
SWATHS THIS MORNING, AND NARROW AFTERNOON SWATHS IS ENOUGH TO HAVE  
MORE OR LESS INCREASED THE WIDESPREAD NATURE OF THE RIVER  
FLOODING. MINOR TO MODERATE FLOODING IS NOW EXPECTED ON MOST  
TRIBUTARIES IN IOWA AND ON THE ROCK AND PECATONICA IN ILLINOIS.   
  
ON THE LOWER STRETCHES OF THE IOWA, SKUNK, WAPSI, AND ROCK,  
SIGNIFICANT MODERATE FLOODING IS FORECAST, AND IN SOME CASES,  
LEVELS JUST UNDER MAJOR. THESE ARE IN PARTICULAR NEED OF CLOSE  
MONITORING, AS THEY COULD POSSIBLY EXCEED MAJOR IN THE WEEK AHEAD,  
MAINLY IF WE GET HEAVY RAINS JUST AHEAD OF THE CRESTS.   
  
THE MISSISSIPPI RIVER IS NOW EXPECTED TO REACH MODERATE FLOOD  
LEVELS AT NEW BOSTON, KEITHSBURG, GLADSTONE LD/18, AND BURLINGTON.  
GREGORY LANDING HAS MINOR FLOODING EXPECTED.  
  
THE FORECAST REMAINS WET FOR WELL INTO THE EXTENDED, EVEN AFTER A  
BIT OF A BREAK IN THE NEXT 24 HOURS. THUS, THERE IS WATER YET TO  
FALL THAT IS NOT ACCOUNTED FOR IN THESE FORECASTS. THEREFORE,  
CHANGE IN CREST AND TIMING ARE LIKELY IN THE WEEK AHEAD.  
  
ERVIN  

 

[janetjanet998]

after this evening activity...it looks like round 4 is setting up over NE into MN and WI

you can tell the flow is pushing west by the new cells in Kansas moving NNW

 

WPC still has 5 inch amounts beat focused a little more S into  MO and IL

 

18z NAM continues with the push of the cold front through IA weds-thursday....

 

[hawkeye_wx]

8 minutes ago, janetjanet998 said:

after this evening activity...it looks like round 4 is setting up over NE into MN and WI

you can tell the flow is pushing west by the new cells in Kansas moving NNW

 

WPC still has 5 inch amounts beat focused a little more S into  MO and IL

 

18z NAM continues with the push of the cold front through IA weds-thursday....

 

Yeah, the trend has been to sag the mid to late-week heavy rain south, with less heavy stuff here.

[Hoosier]

Fyi, the severe posts were moved to the severe thread.

[Hoosier]

There's water inside of O'Hare.

[Stebo]

Just with the rain today and yesterday we are up to 1.40" on the month with much much more coming this week and into the weekend.

[hawkeye_wx]

Tonight's GFS shifted south again with Gordon's remnants and the Canadian shifted well south.

[Hoosier]

2 minutes ago, hawkeye_wx said:

Tonight's GFS shifted south again with Gordon's remnants and the Canadian shifted well south.

It's not easy for a system that landfalls as far east as this one to bring rain to your area.  We saw that type of solution on multiple runs though... whether this is a blip or the start of a trend is tough to say.  

[janetjanet998]

11 minutes ago, hawkeye_wx said:

Tonight's GFS shifted south again with Gordon's remnants and the Canadian shifted well south.

even after it passes it still remains rather active....

 

...but check out the pattern again around day 10 LOL.... ring of fire again sets up..actually west of here....

This might be a very long thread if that ridge stays in place out east this month and what looks be tropical systems moving around it

[cyclone77]

Picked up 1.23" of rain last night and today.  About a half inch of that fell in about 6-7 minutes last night as a very heavy cell went through.  You can definitely see how some areas have picked up excessive amounts after seeing rainfall rates like that.  One of the cells that went over today (which eventually went on to drop the birdfart nader near Rockford) exhibited supercell characteristics as it passed just to the northwest.  

Regarding Gordon's remnants later this week I've been pretty much expecting models to start shifting southeast with the track of it, as it's very unusual to see remnants this far northwest.  Looks like the trends have already started.  Although with as weird as this year's weather has been it still wouldn't be all too surprising to see such a northwest track like the Euro and GEM had been showing.

[Hoosier]

00z Euro still has a more northerly track of Gordon.  It actually looks like it ends up a little north of 12z.

[janetjanet998]

Waterloo IA 7.08 inches so far in September

[janetjanet998]

Gordon:

NAM north..dumps on central and northern IL..and SE IA ..I-80 area hit

GFS trended south with central IL to IND I-72 area hit

CMC further south still with the low..but has some decent rains more NW with the front

but all 3 have the heaviest rains falling mostly south of hard hit central IA area

[hawkeye_wx]

The upper midwest/great lakes ridging keeps strengthening on the models and is squashing the tropical remants... disappointing.  It appears whatever we can get from Wednesday's frontal passage may be it for the week.... a major change from a few days ago.

[Hoosier]

NHC track is still fairly far north

We'll see what happens