Sept-Oct heavy rain and Flooding threat

[Hoosier]

Not used to seeing this wording in an afd.  DVN

Thursday and Friday...The 00z NAM is the most optimistic model with
respect to strength of upper MS RVR Valley ridge shunting most of
precip making processes to the south for a much needed rain reprieve
for most of Thu into the first part of Friday, while the remnants of
tropical system "Gordon" loom acrs the southeastern plains to lower
MS RVR Valley. The 00z GFS is in the middle and suggests overrunning
light to moderate showers acrs the southern to southeastern third
of the CWA until late Thu afternoon, then mainly dry CWA-wide until
approaching lift off the tropical wave induces more overrunning
showers in the south toward Friday morning. The 00z ECMWF is more
ominous with a heavy rain producing elevated storm cluster flaring
up acrs much of the southern 2/3`s of the CWA out of Wed night and
through Thu morning, before some decrease/decay noted into Thu
evening. For now, will side with the GFS with POP placement and QPF
potential and wish-cast away the ECMWF.

[janetjanet998]

DVN update

 

AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
1147 AM CDT TUE SEP 4 2018  
   
UPDATE  
  
ISSUED AT 1148 AM CDT TUE SEP 4 2018  
  
HAVE EXPANDED THE FLASH FLOOD WATCH TO INCLUDE MUCH OF THE CWA AND  
EXTENDED IT THROUGH AT LEAST WEDNESDAY EVENING.   
  
WHILE THE WEATHER WAS DRY IN THE DVN CWA TODAY, THE AXIS OF DEEP  
TROPICAL MOISTURE EXTENDED FROM EASTERN KS TO WESTERN IA AND INTO  
CENTRAL/SOUTHERN MN AND NORTHERN WI. UNFORTUNATELY, THE WET  
PATTERN QUICKLY RETURNS THIS EVENING AS A MID LEVEL SHORT WAVE AND  
SPEED MAX ARRIVES FROM THE SOUTHWEST. DEEP LAYER SHEAR INCREASES  
WITH THUNDERSTORMS PUSHING INTO OUR WESTERN CWA EARLY THIS EVENING.  
DAMAGING WINDS AND AN ISOLATED TORNADO OR TWO IS POSSIBLE,   
ESPECIALLY WHERE SPC HAS A SLIGHT RISK. THE HRRR/NAMNEST SUGGEST   
SEVERAL LINES OF STORMS FORMING OVERNIGHT OVER MUCH OF THE CWA   
(EXCEPT OUR FAR SE) WITH TRAINING OR REPEATING STORMS.  
  
IN THE MEANTIME, PWAT'S INCREASE TO OVER 2 INCHES ONCE AGAIN SO   
TORRENTIAL RAINFALL OF 1-2 INCHES PER HOUR RATES EXPECTED. 1 HR   
FFG VALUES ARE ONLY ABOUT AN INCH ESPECIALLY IN OUR NW HALF OF THE  
CWA SO THE THREAT OF FLASH FLOODING WILL INCREASE OVERNIGHT AND   
THROUGH WEDNESDAY EVENING, AS THE FRONTAL BOUNDARY SAGS INTO THE   
CWA AND STALLS. AT LEAST SEVERAL INCHES OF NEW RAINFALL IS   
EXPECTED IN SOME AREAS, ON TOP OF THE 4-9 INCHES THAT HAS ALREADY   
FALLEN IN THE PAST WEEK. ADDITIONAL ROUNDS OF STORMS PRODUCING   
TORRENTIAL RAIN AND FLASH FLOODING IS POSSIBLE THROUGH THE   
WEEKEND, AS THE REMNANTS OF TROPICAL SYSTEM "GORDON" NEARS THE   
AREA. THIS ALL MAKES THE RIVER FLOODING SITUATION EVEN WORSE AS   
TIME GOES ON.  

 

[CheeselandSkies]

Last week I remarked to a coworker that it seemed the difference between this and the June 2008 river flooding event was that one was upper Midwest-wide, whereas this year's was totally Wisconsin-centric. It would appear that is no longer the case.

[janetjanet998]

Euro shifted south-east some from 24 hours ago..but still looks like a hair NW of the GFS...and a little stronger

anyone have the QPF maps?

 

new WPC maps thru day 3 seems to favor a more NW path..NAM like with 3-4 inches center on SE IA..with Gordon still yet to come

[Hoosier]

30 minutes ago, janetjanet998 said:

Euro shifted south-east some from 24 hours ago..but still looks like a hair NW of the GFS...and a little stronger

anyone have the QPF maps?

 

new WPC maps thru day 3 seems to favor a more NW path..NAM like with 3-4 inches center on SE IA..with Gordon still yet to come

[hawkeye_wx]

None of that Iowa precip is from Gordon.  However, the euro is still trying to stall a band of heavy rain from southern Iowa to the Quad Cities area Wednesday into Thursday.

[janetjanet998]

7 minutes ago, hawkeye_wx said:

None of that Iowa precip is from Gordon.  However, the euro is still trying to stall a band of heavy rain from southern Iowa to the Quad Cities area Wednesday into Thursday.

following tropical system for years I have seen tropical system really crank out some huge amounts along and north of a stalled front..models often under forecast amounts in those set ups. I assume DVN will soon discuss this 

 

 

[bdgwx]

The Euro QPF map looks similar to what COAMPS has been showing.

[janetjanet998]

WPC day 4/5 maps in...if you add the days 1-3 on top of that

5 day totals look to be 4-7 inches along a line 50 miles north and south from Ottamu IA to kankakee IL...1-5 day totals not out yet

in other words I'm in the bullseye

[janetjanet998]

round 5

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
250 PM EDT Tue Sep 04 2018
 
Day 1
Valid 1741Z Tue Sep 04 2018 - 12Z Wed Sep 05 2018 

1800 UTC update

Upper Mississippi Valley into the Upper Great Lakes

The previous Excessive Rainfall outlook was upgraded to add a high 
risk from far north central IA...southeast MN into north central 
WI into a small portion of the southwest U.P. There is very good 
agreement in the latest 1200 utc hi res guidance and hi res 
ensemble means for an axis of very heavy and likely excessive 
rainfall amounts across the moderate to high risk area.  There is 
very good run to run continuity in the hi res arw and nmmb...which 
often can show large run to run variability...leading to above 
average confidence.  Probabilities from the href mean/hrrr are 
showing 60-90% probabilities for 5"+ amounts through 1200 utc 
Wednesday across the high risk areas...30 to 40% probabilities for 
8"+ across southeast MN into west central WI.  Very favorable 
conditions will continue to heavy rainfall this afternoon into 
tonight across these regions.  Very favorable right entrance 
region jet dynamics will move across a region with pw anomalies 
2.5-3+ standard deviations above the mean.  A period of training 
of cells in a west southwest to east northeasterly direction 
expected late afternoon into the overnight hours---supporting 
1-2"+ hourly rainfall amounts and totals in the 3-6"+ range across 
these areas.

[Hoosier]

With a slowed/stalled front and rich tropical airmass, I would personally lean on the higher modeled amounts.  The exact placement of those higher end amounts probably won't be correct at this point though.  

[bdgwx]

I agree. This is not atypical of global models. They often play catch up in regards to rainfall amounts when a tropical system phases with a slow moving front. There's probably going to be a stripe of 4-6" with locally higher amounts somewhere in the midwest when it's all said and done. We just don't know exactly where yet.

[hlcater]

Oh I forgot to mention literally every creek around here is in major floodstage. When I chased yesterday I had to turn around on multiple occasions due to flooded/impassable bridges. Many farm fields have turned to lakes.

[snowlover2]

Wow looking like a soaker for IL/IN/OH.

[Hoosier]

Curiously the HWRF has been consistently running left with the track of remnant Gordon... with the most recent run tracking through Iowa into Wisconsin.  I think the "hurricane models" are mostly GFS based which could explain the farther southeast clustering of those.

[Hoosier]

00z NAM seems quick with things... looks like the remnant Gordon is already in IL on Saturday morning.

[Hoosier]

Besides the heavy rain potential with Gordon, it looks pretty raw on the northern side too, cool and a bit breezy... a lot different than the weather of late.  

[janetjanet998]

another south tick.......now bullseye on Quincy IL with a 7 inch bullseye area instead of SE IA

 

this reminds me of tracking a moderate winter storm and each model run...but  we are talking inches of rain instead of snow

 

DVN

WEEKEND GORDON REMNANTS CONCERNS...STILL MANY QUESTIONS AND   
UNCERTAINTIES TO BE WORKED OUT BY LATER MODEL RUNS OVER THE NEXT 48   
HRS, BUT TRENDS ON THE LATEST MEDIUM RANGE GUIDANCE AND ESPECIALLY   
THE ECMWF/GFS, SUGGEST THAT INCREASING MID LEVEL WAVE PROGRESSION   
WITH SOME DIGGING ACRS THE NORTHERN ROCKIES AND PLAINS TO HAVE AN   
EARLIER "KICKER" EFFECT EASTWARD ON THE TROPICAL WAVE. THIS COMBINED   
WITH THE EXTENT OF GROWING GRT LKS MID LEVEL RIDGING MAY ACT AS A   
DEFLECTOR SHIELD, SHUNTING THE BRUNT OF GORDON JUST TO THE SOUTH AND   
EAST OF THE DVN CWA MAINLY FROM CENTRAL MO, CENTRAL INTO   
NORTHEASTERN IL AND EVENTUALLY IN/MI FROM SATURDAY THROUGH SUNDAY.   
THIS MORE OF A CLASSIC PATH FOR AN INLAND STRIVING TROPICAL SYSTEM   
THAT COMES ASHORE IN THE GULF ACRS AL/LA. ALTHOUGH THIS TRACK WOULD   
STILL PRODUCE ADDITIONAL RAINS OF 1 TO 3 INCHES ACRS THE FAR SOUTHERN   
AND SOUTHEASTERN CWA SATURDAY INTO SUNDAY WHICH COULD STILL PRODUCE   
SOME FLOODING AND FLASH-FLOODING, THE BRUNT OF THE CWA AND IT'S   
SWOLLEN RIVERS WOULD BE SPARED. SO THESE ARE OPTIMISTIC TRENDS FOR   
THE "HOME TEAM", BUT CAN'T LET THE GUARD DOWN JUST YET AND WILL HAVE   
TO WATCH FOR LATE WEEK MID CONUS PHASING BETWEEN UPPER TROF'S AND   
RELATED UPPER JET TRENDS FOR BETTER DEFINING THE PATH THAT THE   
GORDON REMNANTS WILL TAKE. AND AS MENTIONED BEFORE, THE GRT LKS   
RIDGING COMPLEX TO BE A BIG PLAYER AS WELL. STAY TUNED! 

 

 

[janetjanet998]

THe 06z models including the GEFS mean shifted once again SE now STL area east into OH

[janetjanet998]

12z NAM shifted back north from 06z some

hits SE IA wetsern IL good with first round but then BARLEY misses that area ot the SE by like 75 miles with max amounts from Gordon..

No over lap ..but still 3-5 inches SE IA area..then 7-10 with gordan for areas SE

[Hoosier]

3 minutes ago, janetjanet998 said:

12z NAM shifted back north from 06z some

hits SE IA wetsern IL good with first round but then BARLEY misses that area ot the SE by like 75 miles with max amounts from Gordon..

No over lap ..but still 3-5 inches SE IA area..then 7-10 with gordan for areas SE

It kinda shows what type of amounts we could be talking about if the same areas were to get hit over and over.

[Hoosier]

Daytime 50s on the north side? 

[janetjanet998]

12z GFS about 50 miles southeast of the 12 NAM with max amounts

CMC is much more SE with the actual low but much faster..looks goofy

[janetjanet998]

The 12z GEFS mean come in  a little north the O6z and more wet..

This is is do to a couple of them dumping around a foot of rain 

I think I am seeing a small slow moving disturbance in the models at 850mb over SE IA overnight..this could be what is causing huge amounts there before gordon.. 15z RAP very bullish with stationary heavy rain

I haven't been paying attention but could this be the tropical thing that moved into LA/TX 2 days ago?

[janetjanet998]

Euro now south too...in line with GFS  at HR 96..

WPC still has bullseye of 6  inches around Quincy IL days 1-3

[Hoosier]

12z Euro

[janetjanet998]

18z RAP still has that overnight/morning event near Burlington ... interesting 

 

the storm total Precip out of ILX radar might be interesting .. it was reset this morning 

[janetjanet998]

ESOSCALE PRECIPITATION DISCUSSION 0774  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
233 PM EDT WED SEP 05 2018  
  
AREAS AFFECTED...SOUTHEAST IOWA, NORTHWEST ILLINOIS, NORTHERN  
MISSOURI  
  
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE  
  
VALID 051832Z - 052245Z  
  
SUMMARY...SCATTERED BANDS OF HEAVY RAIN AND EMBEDDED THUNDERSTORMS  
SHOULD CONTINUE AFFECTING PARTS OF SOUTHEAST IOWA, NORTHWEST  
ILLINOIS, AND NORTHERN MISSOURI ALONG AND AHEAD OF A SURFACE FRONT  
THIS AFTERNOON. RAIN RATES OF 1-2 IN/HR ARE EXPECTED, WHICH COULD  
CAUSE FLASH FLOODING GIVEN RELATIVELY HIGH SOIL MOISTURE LEVELS  
ACROSS THE REGION.  
  
DISCUSSION...REGIONAL RADAR MOSAIC SHOWS A RIBBON OF RAIN  
STRETCHING FROM THE SOUTHERN PLAINS INTO THE UPPER MIDWEST EARLY  
THIS AFTERNOON, WITH EMBEDDED CONVECTIVE CLUSTERS. IN GENERAL,  
THERE WAS NOT MUCH LIGHTNING, BUT THE SHALLOW CONVECTION WAS  
PRODUCING HEAVY RAINFALL DUE TO EFFICIENT WARM RAIN PROCESSES. THE  
ENVIRONMENT IS CHARACTERIZED BY DEEP MOISTURE WITH PRECIPITABLE  
WATER VALUES IN EXCESS OF 2 INCHES (GPS-PW OBSERVATIONS FROM  
WESTERN MISSOURI INTO NORTHWEST ILLINOIS ARE AROUND 2.1 INCHES),  
AND TALL, SKINNY CAPE PROFILES. THE CONVECTION WAS SOMEWHAT  
DISORGANIZED, HOWEVER, WITH A LACK OF STRONG FOCUSED CONVERGENCE  
IN THE LOWEST LEVELS OF THE TROPOSPHERE. RECENT RAP FORECASTS DO  
SHOW AN INCREASE IN LOW-LEVEL FRONTOGENESIS AND CONVERGENCE  
THROUGH THE AFTERNOON HOURS IN SOUTHEAST IOWA AND SURROUNDING  
AREAS, AND THE 17Z ANALYSIS DID SHOW THE POSSIBLE BEGINNING OF AN  
INCREASE IN 1000-925MB FRONTOGENESIS IN FAR NORTHEAST MISSOURI.  
THIS MAY AID IN GREATER CONVECTIVE ORGANIZATION WITH TIME. IF  
CONVECTIVE BANDS CAN BECOME ORIENTED IN A SW-NE FASHION (PARALLEL  
TO THE DEEP LAYER MEAN WIND), THAT WOULD LIKELY INCREASE THE FLASH  
FLOOD POTENTIAL.  
  
DESPITE THE LIMITED ORGANIZATION OF CONVECTIVE CLUSTERS, THE  
RAINFALL EFFICIENCY AND RELATIVELY HIGH SOIL MOISTURE LEVELS (WITH  
REGIONAL PRECIP ABOUT 250-500 PERCENT OF AVERAGE IN THE PAST TWO  
WEEKS) ARE COMPENSATING TO PRODUCE LOCALIZED FLASH FLOODING  
ALREADY, AND THIS MAY CONTINUE THROUGH THE REMAINDER OF THE  
AFTERNOON. IF A FRONTALLY-FORCED BAND OF CONVECTION DEVELOPS, A  
GREATER THREAT OF FLASH FLOODING COULD DEVELOP, AND THIS APPEARS  
MOST LIKELY FROM FAR NORTHEAST MISSOURI INTO THE GREATER QUAD  
CITIES AREA.  
  

[janetjanet998]

18z NAM is in and to has some over lapping of the two events....and as a result there is a bullseye of 15 inches near UIN

dry air from the NE eats away at Gordon saving north central IL from those amounts

 

[hawkeye_wx]

I picked up 1.36" today.  A band through Iowa City received 3+".  The Quad Cities area ended up in the dry hole this time.

My rainfall total since Saturday is 4.82".  I think that'll be enough for a while.