May 2013 Pattern and Discussion

[JoshM]

Hail in GA Monday? -27 at 500mb:

 

 

Screen Shot 2013-05-02 at 3.11.14 PM.png

 

Nice bowling ball... will be interesting to see the observed pressure in those areas, IF it happens like that.

[superjames1992]

Snow in the SE (Fayetteville, AR area) in May.  Yes.

 

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE TULSA OK
358 PM CDT THU MAY 2 2013

ARZ001-002-010-011-OKZ058-063-030500-
/O.NEW.KTSA.WW.Y.0011.130503T0600Z-130503T1800Z/
BENTON-CARROLL-WASHINGTON AR-MADISON-OTTAWA-DELAWARE-
358 PM CDT THU MAY 2 2013

...WINTER WEATHER ADVISORY IN EFFECT FROM 1 AM TO 1 PM CDT FRIDAY...

THE NATIONAL WEATHER SERVICE IN TULSA HAS ISSUED A WINTER WEATHER
ADVISORY FOR SNOW AND SLEET...WHICH IS IN EFFECT FROM 1 AM TO 1
PM CDT FRIDAY...

FOR THE FOLLOWING COUNTIES...
* IN OKLAHOMA...OTTAWA AND DELAWARE. IN ARKANSAS...BENTON...
WASHINGTON...CARROLL AND MADISON.

HAZARDOUS WEATHER...
* RAIN WILL MIX WITH OR CHANGE OVER TO SNOW THIS EVENING AND
TONIGHT ACROSS NORTHEAST OKLAHOMA AND NORTHWEST ARKANSAS AS AN
UNSEASONABLY COLD UPPER LOW DEEPENS OVER THE AREA. THIS SHOULD
ALLOW TEMPERATURES TO COOL OFF ENOUGH THROUGH THE EVENING FOR
SNOW TO DEVELOP WITHIN HEAVIER BANDS OF PRECIPITATION.

* LOCAL SNOW ACCUMULATIONS 1 TO 2 INCHES ARE POSSIBLE TONIGHT.
MOST IF NOT ALL ACCUMULATIONS WILL BE CONFINED TO GRASSY AND
ELEVATED SURFACES. IT IS ALSO LIKELY THAT ACCUMULATIONS WILL
VARY CONSIDERABLY OVER RELATIVELY SHORT DISTANCES.

IMPACTS...
* ACCUMULATING SNOW ON TREES THAT HAVE LEAFED OUT COULD BE ENOUGH
TO CAUSE LIMBS TO BE BROUGHT DOWN BY THE WEIGHT OF THE SNOW.
THIS CAN POTENTIALLY CAUSE POWER OUTAGES IN A FEW AREAS. A FEW
BRIDGES OR OVERPASSES MAY BECOME SLICK DURING HEAVIER PERIODS
OF SNOW...ESPECIALLY AT HIGHER ELEVATIONS IN NORTHWEST
ARKANSAS.

DEFINITION...
* A WINTER WEATHER ADVISORY MEANS THAT WINTERY PRECIPITATION MAY
ACCUMULATE ON ROADWAYS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...
* USE EXTRA CAUTION IF DRIVING.

* STAY TUNED TO NOAA WEATHER RADIO...COMMERCIAL RADIO OR
TELEVISION FOR THE LATEST INFORMATION CONCERNING THIS WEATHER
EVENT. ADDITIONAL WEATHER INFORMATION CAN ALSO BE FOUND AT:
WEATHER.GOV/TULSA.

&&

$

[Cheeznado]

This a impressive sounding for lapse rates and LL CAPE- 18Z Monday (from Wright Weather)

 

 

 

 

[GaWx]

Snow in the SE (Fayetteville, AR area) in May.  Yes.

 

URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE TULSA OK

358 PM CDT THU MAY 2 2013

ARZ001-002-010-011-OKZ058-063-030500-

/O.NEW.KTSA.WW.Y.0011.130503T0600Z-130503T1800Z/

BENTON-CARROLL-WASHINGTON AR-MADISON-OTTAWA-DELAWARE-

358 PM CDT THU MAY 2 2013

...WINTER WEATHER ADVISORY IN EFFECT FROM 1 AM TO 1 PM CDT FRIDAY...

THE NATIONAL WEATHER SERVICE IN TULSA HAS ISSUED A WINTER WEATHER

ADVISORY FOR SNOW AND SLEET...WHICH IS IN EFFECT FROM 1 AM TO 1

PM CDT FRIDAY...

FOR THE FOLLOWING COUNTIES...

* IN OKLAHOMA...OTTAWA AND DELAWARE. IN ARKANSAS...BENTON...

WASHINGTON...CARROLL AND MADISON.

$

 

 

According to the NWS in Little Rock:

"If this happens, it would be the latest snow on record in the state. According to official observations, the current record is a trace of snow at Fayetteville (Washington County), Gravette (Benton County) and Harrison (Boone County) on April 30, 1903."

 

Must be due to global warming!

[dwagner88]

ya i've already had right at 45 inches of rain for the year and if roberts rainfall totals verify it could get bad with flooding.

That is downright impressive. I'm closing in on 30" here. Annually MBY averages around 55-57 based on extrapolation from KCHA data and annual radar indicated totals.

[WilkesboroDude]

NC Mountains/Foothills upped to 5" from the HPC. 

[franklin NCwx]

ya i've already had right at 45 inches of rain for the year and if roberts rainfall totals verify it could get bad with flooding.

we are making a run at 100 inches this year

[DCMetroWinston]

While the snow was amazing and almost unprecedented, the lack of tornadoes is just as amazing. We are now 40% of normal the number of tornadoes to date.

[metalicwx366]

Here are radar estimates of this event down here. Lol I'm not going to complain because some areas saw nothing. But look at the jacksonville area which is why there are flash flood warnings down there and its still raining and they could see up to 5 more inches!

[CoastalWx]

Interesting meso low near Cape Canaveral. Winds E29G45.

[metalicwx366]

Interesting meso low near Cape Canaveral. Winds E29G45.

That feature continues to look better and better on satellite despite the high shear in the area.

[mackerel_sky]

The next few days could bring the entire normal monthly rainfall totals for May , for much of our region!

[WNCwx]

The old saying "upper level low causes weatherman’s woe" is gonna play true for some people in the next few days. I wouldn't bet the farm on the extreme forecasts. 

 

Regarding the WxSouth alert, I've seen it a dozen times on Fakebook™, and only attributed to him once.

[metalicwx366]

NWS JAX

SATELLITE AND RADAR

SHOW A DEVELOPING LOW OFF THE CENTRAL FL COAST. MODELS ARE

PERFORMING POORLY WITH THE EVOLUTION OF THIS LOW...AND SLIGHT

DEVIATION IN THE PATH WOULD CHANGE LOCATION OF RAIN BANDS AND WILL

MONITOR CLOSELY. STRONG AND GUSTY WINDS ACCOMPANY THE RAIN BANDS

WITH SUSTAINED SPEEDS OF 20-30 MPH AND GUSTS OF 35-40 MPH NEAR THE

COAST.

[Jon]

NWS JAX

SATELLITE AND RADAR

SHOW A DEVELOPING LOW OFF THE CENTRAL FL COAST. MODELS ARE

PERFORMING POORLY WITH THE EVOLUTION OF THIS LOW...AND SLIGHT

DEVIATION IN THE PATH WOULD CHANGE LOCATION OF RAIN BANDS AND WILL

MONITOR CLOSELY. STRONG AND GUSTY WINDS ACCOMPANY THE RAIN BANDS

WITH SUSTAINED SPEEDS OF 20-30 MPH AND GUSTS OF 35-40 MPH NEAR THE

COAST.

Wrong thread. That's better suited for the OBS thread, no?

[metalicwx366]

Wrong thread. That's better suited for the OBS thread, no?

No, unless the forecast discussion on the previous page and winter weather advisory also get moved there.

[WilkesboroDude]

No, unless the forecast discussion on the previous page and winter weather advisory also get moved there.

 

I prefer to keep it here and the free WXSOUTH info. Let's keep the thread a rolling folks it's a good one.

[SN_Lover]

I think HPC has the max area right. i think these totals are pretty conservative though. 

 

HPC 1-5 day forecast below. 

[FoothillsNC]

This is going to be a really big deal. I've been sending out notices and alarms all week on this because its an important storm for many reasons. First, as primarily a synoptic forecast (as opposed to just modelologist) I love forecasting this type of event, and from the beginning stages on GFS it was apparent this could be a heavy duty item. When Euro caved in, it was a done deal, and this is looking like the mother of all cutoffs in Spring time, going back for quite a few years. We see weak upper lows take this track, but true cutoffs that completely detach like this and are held at bay by a blocking ridge in the Northeast, well it's kinda like our superstorm version of Sandy (hate to say that). 

If you look at individual frames on the GFS you can see that some strong vorts help to wobble the cutoff and affect it's direction. Both GFS and Euro show this nicely and in this case the wobbles and its orientation will play a big deal on how rain develops.  I was shocked that SPC still doesn't have any chance of hail under and south of the cutoff, because I know there will be some hailers in the afternoons as convection blossoms. This will happen in northern LA, MS as early as tomorrow, then probably repeat again Sunday in Alabama, then Monday for Georgia and western or central SC region.  If skies break, watch out in the afternoons. This cutoff is shown to be well developed, much more so than most, and since there is a big blocking high about 572 to 576 dm in the Northeast, this actually strengthens the cutoff and holds it back some, but also funnels in a continuous stream of RH on the northern quad of the circulation through its life time. Also, the contours are spaced in just the right distance apart, sometimes they are too broad or too concentric but this one is a true classic to be a big performer.

By Monday the models begin to rotate this cutoff more northeast  , after leaving central/north Georgia so usually when this happens, (after reaching inflection point)  on the northwest side there is going to be added lift from both the frontogentic forcing and upslope, as if there wasn't enough from the initial conveyor belt.  The contours take on a perfect look and orientation and track to really nail the northern regions of GA and northeast Alabama to southeast TN, and both western to central Carolinas. The track is similar to March 2009, only slower and deeper, thank goodness it's not Winter anymore, as that would be a really wicked Winter storm.

As for rain totals, my maps line up now with WPC but only more QPF in the smaller upslope areas of ne GA, nw SC, sw NC..but thats a resolution issue...real upslope events into Transylvania County and nw SC, northeast GA like this are humdingers and always underdone  on the models. The idea though is that is a max zone.

Where the dry slot develops after the first main conveyor band of the western Atlantic inflow arc is a tough call,  But since the low is so far south, this is very bad news likely for sw VA and most of western NC in the long run, because rain will quickly fill back in there, after the first band, and the center of circulation reaches its inflection point around Atlanta, which still shows some pinwheeling and steady inflow off the Atlantic around the core, so its going to be a bonus rain event roughly from ne Al, n GA and western NC, east TN I think.  Only Tuesday or Wednesday  (maybe even Thursday) does the circulation get so far removed as to finally wind down the rain chances.  But dont' look too far out, already more rain is showing up.

You gotta love this if you were hard up for rain fall in the last 10 years like me. (actually my drought ended 2 Summers ago).  Its amazing how mother nature remembers the old score and will reverse the tables. Sorry this type of flow didn't happen this Winter for all the snow lovers, if it had begun a few weeks earlier, what a difference the snow totals would have been.....pure bad timing.

Anyway, I'm sure we'll be seeing some bad pictures come in by Monday morning in some areas as rivers rise, and some rain rates of 1/2 " to 3/4" per hour will do some damage in the region...on top of really wet soil already. Then generally showery weather under the low (and some convection , hail possible afternoons) as well. Its a truly fascinating storm system with many aspects that I'm sure will be in case studies in many weather offices sometime

Some impacts I think we will see:

dam breaks

river flood stages (out of banks)

road closures

landslide, mudslide moutains

a few trees fall over

low topped severe on southeast and northwest quads of circulation (hail, weak twisters)

water spouts outer banks

water rescues

 

Good weekend to stay indoors and watch it rain. Stay dry!

robert

[LithiaWx]

I think HPC has the max area right. i think these totals are pretty conservative though. 

 

HPC 1-5 day forecast below.

Powder springs is going to get nailed. I have a creek on my property now and I can't wait to see what it looks like after this event. Luckily my home is situated high enough to where flooding won't be an issue for me.

[metalicwx366]

Oh my goodness! Great post!

[NavarreDon]

Awesome write up Robert! If I didn't know any better I would think you are excited about this system.

[WxFreak11]

Thanks Robert. Everyone be safe out there.

[calculus1]

This is going to be a really big deal.

...

The track is similar to March 2009, only slower and deeper, thank goodness it's not Winter anymore, as that would be a really wicked Winter storm.

...

As for rain totals, my maps line up now with WPC but only more QPF in the smaller upslope areas of ne GA, nw SC, sw NC..but thats a resolution issue...real upslope events into Transylvania County and nw SC, northeast GA like this are humdingers and always underdone  on the models. The idea though is that is a max zone.

...

Good weekend to stay indoors and watch it rain. Stay dry!

robert

 

Thanks for stopping by, Robert, and sharing your thoughts with the ol' gang.  An excellent writeup, as always.  I appreciate your forecasting abilities and your explanatory prowess.  (Sometimes the two of those don't go hand in hand.)  The only part that I disagreed with was the bolded section above.  I still wish it were winter and that we would get slammed by an historic snowstorm of this magnitude.

 

Anyway, I'll enjoy watching the rain gauge tick up.  Fortunately, I don't live near any creeks or streams, so it's always a game of sorts to just see how high the amounts can go.  I guess I'm competing against my amounts from last year.  So far in calendar year 2013, each month has had more rainfall IMBY than the corresponding month in 2012.  May is going to be the true test, though, as I had over 7.5 inches last year.  Hopefully, this weekend will get me started off well for the month...

 

[jburns]

This is going to be a really big deal. I've been sending out notices and alarms all week on this because its an important storm for many reasons. First, as primarily a synoptic forecast (as opposed to just modelologist) I love forecasting this type of event, and from the beginning stages on GFS it was apparent this could be a heavy duty item. When Euro caved in, it was a done deal, and this is looking like the mother of all cutoffs in Spring time, going back for quite a few years. We see weak upper lows take this track, but true cutoffs that completely detach like this and are held at bay by a blocking ridge in the Northeast, well it's kinda like our superstorm version of Sandy (hate to say that). 

If you look at individual frames on the GFS you can see that some strong vorts help to wobble the cutoff and affect it's direction. Both GFS and Euro show this nicely and in this case the wobbles and its orientation will play a big deal on how rain develops.  I was shocked that SPC still doesn't have any chance of hail under and south of the cutoff, because I know there will be some hailers in the afternoons as convection blossoms. This will happen in northern LA, MS as early as tomorrow, then probably repeat again Sunday in Alabama, then Monday for Georgia and western or central SC region.  If skies break, watch out in the afternoons. This cutoff is shown to be well developed, much more so than most, and since there is a big blocking high about 572 to 576 dm in the Northeast, this actually strengthens the cutoff and holds it back some, but also funnels in a continuous stream of RH on the northern quad of the circulation through its life time. Also, the contours are spaced in just the right distance apart, sometimes they are too broad or too concentric but this one is a true classic to be a big performer.

By Monday the models begin to rotate this cutoff more northeast  , after leaving central/north Georgia so usually when this happens, (after reaching inflection point)  on the northwest side there is going to be added lift from both the frontogentic forcing and upslope, as if there wasn't enough from the initial conveyor belt.  The contours take on a perfect look and orientation and track to really nail the northern regions of GA and northeast Alabama to southeast TN, and both western to central Carolinas. The track is similar to March 2009, only slower and deeper, thank goodness it's not Winter anymore, as that would be a really wicked Winter storm.

As for rain totals, my maps line up now with WPC but only more QPF in the smaller upslope areas of ne GA, nw SC, sw NC..but thats a resolution issue...real upslope events into Transylvania County and nw SC, northeast GA like this are humdingers and always underdone  on the models. The idea though is that is a max zone.

Where the dry slot develops after the first main conveyor band of the western Atlantic inflow arc is a tough call,  But since the low is so far south, this is very bad news likely for sw VA and most of western NC in the long run, because rain will quickly fill back in there, after the first band, and the center of circulation reaches its inflection point around Atlanta, which still shows some pinwheeling and steady inflow off the Atlantic around the core, so its going to be a bonus rain event roughly from ne Al, n GA and western NC, east TN I think.  Only Tuesday or Wednesday  (maybe even Thursday) does the circulation get so far removed as to finally wind down the rain chances.  But dont' look too far out, already more rain is showing up.

You gotta love this if you were hard up for rain fall in the last 10 years like me. (actually my drought ended 2 Summers ago).  Its amazing how mother nature remembers the old score and will reverse the tables. Sorry this type of flow didn't happen this Winter for all the snow lovers, if it had begun a few weeks earlier, what a difference the snow totals would have been.....pure bad timing.

Anyway, I'm sure we'll be seeing some bad pictures come in by Monday morning in some areas as rivers rise, and some rain rates of 1/2 " to 3/4" per hour will do some damage in the region...on top of really wet soil already. Then generally showery weather under the low (and some convection , hail possible afternoons) as well. Its a truly fascinating storm system with many aspects that I'm sure will be in case studies in many weather offices sometime

Some impacts I think we will see:

dam breaks

river flood stages (out of banks)

road closures

landslide, mudslide moutains

a few trees fall over

low topped severe on southeast and northwest quads of circulation (hail, weak twisters)

water spouts outer banks

water rescues

 

Good weekend to stay indoors and watch it rain. Stay dry!

robert

 

Great post.  I would like to thank Wilkes, for allowing you to post this.

[jburns]

I prefer to keep it here and the free WXSOUTH info. Let's keep the thread a rolling folks it's a good one.

 

Dude I've tried everything else so that leaves me with only this.

 

STFU

[rosie]

Dude I've tried everything else so that leaves me with only this.

 

STFU

Thank you!

[Isopycnic]

Dude I've tried everything else so that leaves me with only this.

 

STFU

+1

[andyhb]

+1

 

+∞

[LithiaWx]

FFC is all in. I give them props for being on this threat for days now. Much like Robert they are taking this threat very seriously. Upped totals to 3.5 - 5.5". I'm located on the line between the two green shades. Unfortunately there is no longer an open area for my rain gauge so I won't be able to post a total.