Rainy pattern is here to stay - how long and how much?

7pm UPDATE

Flash Flood Warnings have been extended further east and now include areas near the Mississippi River on the TN/MS side (red boxes in the graphic below). A stationary front is oriented just east of where the Flash Flood Watches are in effect (green shaded counties) with the axis of heaviest rainfall just west of that front.

Models have insisted that the front would pull back to the west tonight, moving the heavy rain axis west of the metro with it. However, with all of the rain along the river, this "cooled" air is effectively keeping the front to our east. As long as it stays east, we'll remain under the conveyor with waves of heavy rain and thunderstorms.

The latest high-resolution model data (HRRR model) now thinks the front could move back to about Memphis by rush hour tomorrow. If that is correct, then periods of heavy rain will continue overnight. The HRRR model prints out overnight rainfall totals ranging up to 4-5" west of the river to less than an inch on the far eastern side of the metro (below).

Predicted rainfall totals for the overnight hours (through 6am Thursday) from the high-resolution HRRR model. Graphic courtesy WxBell.

If these totals are realized, significant flooding issues could result, especially in urban areas, and creeks and streams will overflow their banks. The Loosahatchie River is already predicted to crest above flood stage tomorrow. Additional rainfall will only exacerbate these types of issues.

FLASH FLOODING OVERNIGHT IS ESPECIALLY DANGEROUS. It is very hard to see how deep water is (or even see that you are about to drive through low-lying flooding or pooling on roadways). Nearly half of all flooding deaths occur in vehicles. Remember - turn around, don't drown!

UPDATE 7:20pm
The Flash Flood Watch has been extended east to include the rest of the metro (shaded green counties).

In addition, the NWS Weather Prediction Center is monitoring our area for flooding as the "warm conveyor belt" continues to affect the same areas. There is concern that it will move very little overnight in the metro.

ORIGINAL POST (1:30pm)

There's really no much more that needs to be said, but there's a lot that can be said. I'll try and split the difference.

Weather systems like this, in which fronts stall, low level jet streams are active, abundant moisture is shooting out of the tropics like a firehose, and waves of upper level energy pulse through the region, are very difficult to predict where the heaviest will fall. Last weekend, we warned of perhaps half a foot of rain, especially in east AR. Forecast totals in the metro dropped early in the week as it looked like the heaviest would remain west of the local area.

Within the past 24-36 hours, those forecast totals are starting to climb again. The rainfall forecast from the NWS Weather Prediction Center from 6am this morning through 6pm Saturday aare shown below with generally mentioned amounts of 3-5" possible for the metro. However, you'll need to add the inch and a half received overnight to that! So far this morning, the airport has received nearly an inch more.

NWS Weather Prediction Center rainfall forecast from 6am Wednesday through 6pm Saturday.

As of 1pm, a Flash Flood Watch has been issued for most of the metro, except Fayette and Marshall Counties, and all areas west of the river (green shaded counties below). Flash Flood Warnings are also in effect west of the river (red boxes in the graphic below). The lighter green irregular-shaped areas are river Flood Warnings, which includes the Loosahatchie River in the metro.

As of now, we're expecting another round of steady, occasionally heavy, rain and some thunderstorms later this afternoon through the evening hours. There are some indications that  the axis of heavy rain will shift from the Mississippi River area westward overnight. However, another wave of rain will move in tomorrow with thunderstorms again possible. Thursday is likely to be the heaviest rain with this system here in the metro. The area is outlooked within a moderate risk of rainfall exceeding flash flood guidance, meaning there is a 10-15% chance that more rain will fall than the ground can handle and flash flooding will ensue.

The Excessive Rainfall Outlook for Wednesday indicates a large area in the Lower Mississippi Valley  west into eastern TX that will be prone to flash flooding. A Moderate Risk exists from the Memphis area southwest into the MS Delta.

By Friday, the overall upper level pattern begins to shift as a low over deep south TX/northern Mexico - which is ultimately responsible for this pattern - moves towards the Mid-South and a front moves to our east. That will mean less very heavy and steady rain over the same areas, but continued elevated rain and thunderstorm chances into Friday and Saturday as the low moves into the region. Driven more by daytime heating, rain and thunder chances should be highest in the afternoon and evening time frame as we head into the weekend. One last round of potential thunderstorms arrives late Sunday as an upper level low moves overhead with dry and very warm weather expected to start next week.

So, for the next few days, we strongly recommend avoiding driving into or through areas known to hold water or flood in heavy rain; if you come across these areas, avoid them - turn around don't drown; and be sure your street gutters and other areas where water flows around your home are free of debris. If you are typically affected in some way by rising water during heavy rain, expect those problems again and prepare now.

Follow our social channels for the latest information and be sure to get the MWN mobile app for current radar loop, forecast, and Flash Flood Warnings delivered via StormWatch+!

Erik Proseus
MWN Meteorologist

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More rain in the forecast in the days ahead

After Sunday night’s severe weather event (we’ll have a recap soon here on the MWN Blog), the weather in the metro area has turned much quieter over the last 48 hours. However, our next weather maker is beginning to organize to our southwest, and will begin making its impact felt tonight.

As an upper level disturbance approaches the area, with moisture levels increasing from the Gulf of Mexico, light rain will move into the area late tonight, most likely after Midnight. Rainfall will continue into at least Wednesday morning, meaning residents should expect a wet morning commute. Overall rain amounts should remain light, no greater than a half inch, and thunderstorms are not expected either as the Mid-South will stay on the “cool” side of a warm front to our south across Louisiana and Central Mississippi.

While we may see a brief break in rainfall during the afternoon hours Wednesday, surface low pressure organizing over South Texas will begin slowly pushing northeast toward the area by Wednesday night. Additionally, the warm front to our south will begin advancing northward closer to the area. As this occurs, more rainfall will break out, that will persist into much of the day Thursday. Rainfall amounts during this wave will likely be more significant, up to an inch. With the warm front pushing as close as North Mississippi during this time, a few thunderstorms may develop, but any threat for strong storms should remain south of the metro with the warm front not expected to pass through, unlike this past Sunday.

NWS forecast rainfall amounts through Thursday evening, with up to an inch and a half possible in the metro.

By Thursday evening, with the system pushing off to our southeast, rain will begin tapering off, with decreasing clouds expected by Friday along with slightly cooler temperatures. Between tonight and Thursday evening, total rainfall amounts upwards of an inch and a half are possible (see above image).

--Kevin Terry, MemphisWeather.Net

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Tropical Storm Lee drops copious rainfall across the southeast

The map below shows the 7-day total precipitation encompassing the first week of September through this morning at 7am.  As you can see Tropical Storm Lee and it's remnants brought remarkable amounts of precipitation to the Gulf Coast states and Tennessee Valley, thanks in large part to it's very slow motion.  

While Memphis locations generally received under a half-inch, parts of northeast Mississippi received over 6" of rain!  Many locations in a swath across LA, MS, the FL panhandle, north AL, and east TN received 8"+. Below the map are selected rainfall totals for the storm, as reported to the NWS.

RAINFALL TOTALS

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(SELECTED STORM TOTAL RAINFALL IN INCHES THROUGH TUESDAY, 9/6/11, 4 PM CDT)

...ALABAMA...

TILLMANS CORNER 4.3 WNW             11.74

GRAND BAY 0.6 NW                    11.32

MOBILE                              10.92

ORANGE BEACH 3.0 ENE                10.50

FOLEY 2.0 SSW                       10.39

SPRINGVILLE 5.3 WNW                 10.36

THEODORE 3.7 WNW                    10.31

ENSLEY                               9.54

GUNTERSVILLE                         8.95

ALBERTVILLE 4.8 WNW                  8.94

BIRMINGHAM                           8.13

PINSON                               7.94

TUSCALOOSA 5 NE                      7.70

WILMER 7.9 SE                        7.55

GADSDEN                              7.18

MUSCLE SHOALS                        6.04

HUNTSVILLE/MADISON CO ARPT           5.52

...FLORIDA...

MILTON 1.4 NNE                      10.03

NICEVILLE 4.5 SE                     7.35

PENSACOLA 3.8 N                      6.57

WEST PENSACOLA 10.9 SW               6.35

DESTIN ARPT                          6.29

ENSLEY 2.1 ENE                       6.10

PACE 2.4 N                           6.06

NAVARRE 2.3 NNW                      6.02

DESTIN AIRPORT                       5.93

PENSACOLA RGNL ARPT                  5.81

VALPARAISO/EGLIN AFB                 5.71

GONZALEZ 2.1 E                       5.68

APALACHICOLA MUNI ARPT               5.49

EGLIN AFB 5.6 NE                     5.33

HURLBURT FIELD AWS                   5.30

...GEORGIA...

LA FAYETTE 2.9 NE                   10.00

RINGGOLD 5 W                         8.95

LAFAYETTE 5 SW                       8.71

TRENTON 5.8 S                        8.55

NAOMI 2 E                            7.88

NEW ENGLAND 2 SE                     7.84

LYERLY 4.8 SSE                       7.65

CURRYVILLE 3 W                       6.81

ROME/RUSSELL FIELD                   6.00

...KENTUCKY...

CRANKS CREEK RESERVOIR               5.49

CUMBERLAND                           4.75

WHITESBURG                           4.00

FLATWOODS 0.5 WNW                    3.67

BOWLING GREEN                        3.24

PLUM SPRINGS 0.8 NNW                 3.10

LEXINTGON/BLUE GRASS FIELD           2.74

...LOUISIANA...

HOLDEN                              15.43

N.O. CAROLLTON                      14.32

MAUREPAS                            13.63

PONCHATOULA 4 SE                    13.22

CONVENT 2 S                         13.04

RESERVE 0.5 SSE                     12.43

GRAY 0.5 ENE                        12.15

MARRERO 1.9 E                       11.21

NEW ORLEANS/MOISANT                 11.00

MONTICELLO 3.0 ENE                  10.91

PONCHATOULA 11.8 E                  10.59

MERAUX 0.8 WNW                      10.10

ZACHARY 3.5 WNW                      9.04

BOOTHVILLE                           8.83

BATON ROUGE/RYAN MUNI ARPT           8.20

...MISSISSIPPI...

WAVELAND 1.1 NW                     14.11

FLORENCE 0.9 E                      13.45

SAUCIER 6.4 ESE                     11.75

GULFPORT 2.0 NE                     11.71

LONG BEACH 0.7 S                    11.59

PASS CHRISTIAN 5.0 N                11.31

RICHLAND 0.3 WSW                    11.25

PHILADELPHIA 5.4 E                  11.18

JACKSON                             11.15

PEARL 3.4 ESE                       11.14

GULFPORT-BILOXI                     11.14

JACKSON WFO                         11.13

PASCAGOULA                          10.95

KILN 6.6 N                          10.90

...NORTH CAROLINA...

BLOWING ROCK 2.8 ENE                 7.18

BOONE                                6.56

LAUREL SPRINGS 3 WSW                 5.34

LENOIR                               5.28

FRANKLIN 7.5 SW                      4.93

...TENNESSEE...

CLEVELAND 3 ESE                     12.22

CHARLESTON                          11.50

APISON 2.7 SW                        9.59

CLEVELAND                            9.58

RICEVILLE 3.7 WSW                    9.50

GEORGETOWN                           9.48

OOLTEWAH 6.7 NNW                     8.58

OAK RIDGE                            8.34

KNOXVILLE MUNI ARPT                  7.03

CLARKSVILLE 10.2 WSW                 5.53

CUMBERLAND CITY 1.2 ESE              5.41

OAK RIDGE 6.9 NNE                    5.09

CROSSVILLE MEMORIAL ARPT             4.98

LAWRENCEBURG 8.8 SE                  4.95

COOKEVILLE 4.6 WNW                   4.23

CHRISTIANA 6.5 E                     4.22

NASHVILLE METRO ARPT                 3.53

CHATTANOOGA-LOVELL FIELD             3.04

...VIRGINIA...

FANCY GAP                            6.77

HILLSVILLE 8.9 SE                    6.34

SHIPMAN 1.8 NW                       6.30

BEDFORD 1.1 N                        6.08

ROCKFISH                             5.58

ROANOKE                              5.20

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Fall weather on the way

The rainy pattern of the past 2 weeks has finally shifted east today. Weak high pressure takes over this weekend before another cold front moves through Monday. However, this front will be dry. Thus, the MWN forecast reflects dry and warm weather this weekend, followed by cooler and much less humid weather behind the front for much of next week. In fact, dewpoint temperatures - a measure of humidity in the air - will be their lowest since spring. These low dewpoints will allow overnight temperatures to drop as well, with some locations in outlying areas near 50 by Tuesday and Wednesday mornings! We'll be watching for another front late in the week that could bring our next chance of rain.

Interesting fact of the day: Though there was much more accumulating rain the week before last than this past week (at least in the metro area), the manual rain gauge co-located with the WXLIVE! rain gauge recorded 13 straight days of measurable precipitation. That string will come to an end today, and it's about time! To learn more about the CoCoRaHS program, a network of volunteer precipitation observers, click here.

In the tropics, Tropical Depression #8 formed in the Atlantic a couple of days ago, but as of 3pm has deterioriated into an open wave, meaning it no longer has a closed circulation and cannot be classified as a depression.

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Impressive rainfall statistics for this week

A low pressure system over the south-central U.S. that lingered throughout the week has brought impressive rainfall totals to the greater Memphis area. Flash Flood Watches have been in effect for several days and Flash Flood Warnings have been posted as heavier rains encompass the area. Yesterday's downpours caused flash flooding in the city and some water rescues, including evacuation of a large daycare center. (See the article by The Commercial Appeal.)

Here is a sampling of totals since last Sunday (9-13-09), aggregated from a number of sources including official data, CoCoRaHS precipitation observers, and personal weather station owners. As you can see there are widespread totals of 4-6" across the board.

Official observations:
MEMPHIS INTL AIRPORT: 4.92"
NWS-MEMPHIS/GERMANTOWN, TN: 4.63"
GERMANTOWN CO-OP: 4.35" (since 9-15)

CoCoRaHS observers:
Bartlett 3.6 N: 4.91" (this is at the MemphisWeather.net site)
Bartlett 1.0 WNW: 6.02"
Bartlett 0.9 NE: 4.71" (not incl. 9-19)
Memphis 5.5 ENE: 5.45" (not incl. 9-19)
Memphis 3.2 NW: 7.18"
Atoka 1.9 S: 4.73"
Atoka 3.2 ESE: 3.45" (not incl. 9-19)
Hickory Withe 3.0 SSE: 4.69"
Oakland 1.3 NE: 4.30"
Southaven 4.8 SE: 3.46"

Area Personal Weather Stations:
Village of Arlington, TN: 5.03"
Appling Lake, Bartlett: 4.60"
Sutton Place Subdivision, Cordova: 3.38"
Eads, TN: 3.94"
Plantation Lakes, Olive Branch, MS: 5.38"
Brentwood Farms, Southaven, MS: 3/23"

Here is a map showing Doppler radar rainfall estimates for the Mid-South. Quite impressive totals! Red colors are 5"+ totals, while pinks highlight areas that have received 10"+!

Unfortunately, the MemphisWeather.net Forecast calls for more of the same this weekend, though we may get a bit of a break on Monday before another system moves in towards the middle of next week and, possibly, stalls out, bringing more rain chances. And September is typically a dry month in the Mid-South!

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Gullywasher yesterday... and what about the snow?

Two weather topics on everyone's mind today... the rainfall totals from yesterday and the snow potential for tonight.


#1. Wow, what a rain! Check out the map below for a look at 24-hour precipitation reports from this morning for the eastern U.S. Note the 1.5-5"+ totals across the Mid-South, Tennessee Valley, and lower Mississippi Valley. These reports come from the CoCoRaHS network of trained precipitation observers. Reports from inside Shelby County are all between 3.50-3.75" while totals to our east are generally about 0.50-1.00" higher! At WXLIVE in Bartlett, the automated weather equipment recorded 2.85", while the manual "official" rain gauge right next to it reported 3.59" for the event. The difference is larger than I usually see between them (usually the automated gauge is ~10% under, depending on the wind). That's still the most rain recorded in one calendar day since WXLIVE was installed in June 2005. The 3.48" recorded at the airport on the 10th was also a record for the date. Wow!!



#2. As cold air filters in today, holding temps in the upper 30s in the metro area, a developing low pressure system over the northern Gulf of Mexico will strengthen and move northeast tonight. The Mid-South will be on the back (cold) side of the low and precip will wrap around the low overnight as it moves northeast. Anything more than a tenth of an inch should remain east and south of the city and there is potential for some accumulating snow in northeast MS and eastern areas of west TN (nearer the TN River). However, in the metro area, expect mainly light drizzle or a light shower with temps in the mid 30s. Some snowflakes could mix in between 3am-10am but no accumulation is expected. Sorry school kids!


What do you have to say about yesterday's rain? How about the chance of snow? Leave me a comment!

Today's balmy weather to end this evening

Taking a look at StormView radar at 4:00pm, isolated light showers are beginning to pop up in northeast AR ahead of a strong winter cold front. Along the front, stretching from north-central to west-central AR, Little Rock NEXRAD is detecting a narrow band of rain, with some embedded heavy downpours. These showers will increase in intensity and coverage over the next several hours as the front sweeps east. Look for the front to pass through the metro region between 9-11pm this evening, with some showers ahead of it, moderate to heavy rain right along the front, and continuous light to moderate rainfall for a couple of hours after the front passes. Rain totals of 0.75"-1.00" are possible tonight.

In addition, the passage of the front will signal an end to today's "balmy" 60+ degree weather, with temps dropping up to 15 degrees in the hour or two after the front passes and bottoming out in the morning in the mid to upper 30s! Very little recovery will take place tomorrow with highs in the 40-45 degree range.

Scattered t'storms today, but a dry weekend

Wow, what a week it's been. Work has been incredibly busy this week and other stuff has taken up my free time, so that's why it's been nearly a week since blogging.

A hefty change in the forecast from yesterday morning to today and the result is rain and t'storms around the area a day earlier (today) and a pretty nice weekend on tap! It had looked like today would be dry and the weekend wetter, but that apparently won't pan out. Scattered storms around the area this afternoon will continue through the evening hours. Most people have a decent chance of getting at least a little rain. A few showers could linger overnighe, but with only a 20% chance or less of rain tomorrow and a dry day Sunday, it should be nice as temps top out in the upper 80s and humidity is a non-factor. Can't ask for much better for mid-August!

In the tropics, the Hurricane Center has yet to jump onboard with the low pressure east of Puerto Rico. Expect this could become a tropical storm without too much difficulty, though it's path looks to take it over a fair amount of terrain in Hispaniola and Cuba. If it can survive, there is potential for the storm to really gear up as it moves into the Florida Straits or the Gulf Stream. Long-range models are all over the place with it's eventual track, from moving it into the Gulf of Mexico, to striking south or eastern FL, to turning it north and moving it towards North Carolina! We'll have to keep our eye on eventual T.S. Fay.

On a side note, anybody but me enjoying watching the Olympic coverage on NBC or cable? It is fun to watch for a change. Talk about reality TV!

Crazy 8's!

Really off how things sometimes work out.. call it what you will, I just think it's coincidence.

Yesterday was 8/8/08 as you all know. The High Temp at the official recording station in Memphis (MEM INT'L) was 88. The high on MY weather station - WXLIVE! - was 88.8! 88 also happened to be the warmest it got anywhere in the Mid-South yesterday, which when combined with the low humidity and sunny skies meant it was just a perfect, almost early fall-like day! One more today before the rain chances re-appear tomorrow, which I don't think anyone will complain about. A drenching system is forecast to move southeast through AR and into MS. Memphis should be right around the edge of that precipitation shield, so chances are better for President's Island than they are for Arlington, but hopefully everybody will get more rain. Thunderstorm chances are actually fairly slim with this system. The map below shows the forecast precip amounts from 6am Sunday through 6am Monday.