Friday, January 28, 2011

Model Flip Flop


7:20 AM Saturday Update... I will have a full update later today, but here are my thoughts this morning.

We still don't know the exact track of the surface low and the GFS has trended a little south over the past couple runs.  I still think this is a cold rain for us, but northern Arkansas will have to watch out for wintry conditions Tuesday.  Other models take the surface low much further to the north, but I'm not sure if I buy into that YET!  Arctic air has a habit of making it further south and stronger than forecast.

The GFS is forecasting highs in the 30s and lows in the 20s by the middle to end of next week.  I will more than likely have to take our high temperatures down in our 7 day forecast.  The Tuesday storm will lay down a fresh snow pack to our north.  With arctic air traveling across those fields of white, it will add an extra chill to the air.  Again, I will have a very in depth update here later today, but make sure you get outside and enjoy the weather!

2:30 PM Friday Update... It's a beautiful day for sure with another one coming Saturday.  Look for highs around 70 degrees this afternoon and again tomorrow.  I have had a chance to examine the 12Z models and thought it would be a good time to give you an update.  While we are very certain of a major and disruptive system Tuesday for much of the central United States, the details still need to be sorted out.  The models continue with a northward and warmer trend.  The GFS even takes highs into the mid 50s Tuesday, but at this time, I'm undercutting readings with highs in the 40s.  If you forecast based only on models, it's a cold rain for most of the state with a change over to some snow/ice before ending across the north.  While that is still very much possible, I think more swings in the data will offer different solutions until we get to Sunday or Monday.  Why?  The system is still offshore and hasn't been sampled well for the models to get an accurate read.  Also, the strength of the high and the low level arctic air will be a challenge for the models to analyze and it will be a challenge for them to correctly forecast the exact track of the low.  You also have to remember what happened earlier this week with the storm over eastern Arkansas and western Tennessee.  The models didn't have a clue 3 to 4 days prior to that event.  I think the same can be said here.  Right now, based on all the available data, it's a cold rain for most of the Natural State and that's what I'll have in my forecast, but I will also warn everyone to keep checking back to find out the latest.  More later....
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I just couldn't resist it.  I hope it gave you a good laugh.  The models are flipping and flopping all over the place once again.  They all agree there will be a storm next week, but the key disagreement is the placement of the surface low.  As we examine and watch all the data over the next several days, you must watch where the surface low tracks.  The further north... warmer... and the further south... colder.  Most of the computer models shifted a little north late Thursday and this would bring a cold rain to much of the state followed by a change over to a wintry mix on the back side of the system.

You must remember, we are dealing with low level arctic air next week and it naturally wants to spread downhill like water on a mountain.  I can't see the surface low tracking much further north into the colder air, but I guess anything is possible.  Check out the various computer model runs from last night and look at where the surface low is at 6 PM Tuesday according to the GFS, Euro, GEM, and UKMET  The other thing to look at on this map is the very strong high pressure in the northern plains.  This will bring the extremely cold air into our region next week.  Remember, the models rarely handle advancing arctic air masses well.   They typically arrive sooner and stronger than forecast.

00Z Euro valid 6 PM Tuesday.  Surface low directly over Little Rock.  This would bring nothing but a cold rain followed by a change over once the system departs.

06Z GFS valid 6 PM Tuesday.  Surface low near Shreveport. Freezing line at the surface is through northern AR.  The model usually underestimates the southern extent of the sub-freezing air
The 00Z UKMET valid 6 PM Tuesday.  Surface low a bit faster and to the southeast over Jackson, MS.  This would argue for a colder temperature profile and more wintry weather, especially to the northwest half of the state.
00Z GEM valid Tuesday at 6 PM.  Surface low near Memphis with a cold rain for most of the state.  This could bring a change over to wintry weather on the back side, especially Tuesday night over western and northern Arkansas

19 comments:

Anonymous said...

I sure hope this pans out and central and south Arkansas can get one more snowstorm!

Anonymous said...

We need that low over central louisiana i fear any any more north of that a cold nasty miserable plain rain. Lets hope it changes but time will tell. I just think uf the low is near little rock or memphis by the time the cold air arrived moisture would ve east of arkansas.

Snowbird Bob said...

Hello Everyone, I am going ahead & put myself out on a limb again early, So far I have done well! I know the models are flipping around alot, & I maybe wrong with my idea I am about to give you, here goes, I am thinking this will be a Major Winter Storm from OK City down to DFW over to Little Rock & South down to the I-20 corridor of N-La, I beleive this is when the low will intensify & then make the turn more towards the Northeast, If this track holds, the damage will be done for our area already, I may be wrong.. I am thinking this will be a mostly sleet & snow with a good bit of freezing rain,The further North & West towards OKC & Northwest Ark should be a mostly snow event but with lighter amounts, The heavy precip amounts should fall as a primary sleet & freezing rain in the other areas I have outlined, As far as details, I will wait another 48 hours before giving amounts..Also, I beleive the coldest airmass of the winter season will follow this event..To me very similar to the opening week of Feb. 1996 as I have been stating for the last 3 weeks... We Shall See

Jason H said...

Im with you Bob. I just dont see no way out of a pretty good Ice event with the artic high to the North and a strong Low shooting warm Gulf moisture straight into it. Someone that starts out as sleet and changes over to snow pretty fast should see close to, or over a foot. We shall see!

Drake said...

I love snowbirds optimisim!

Anonymous said...

Just praying no Severe Weather for us Tuesday! Sure hope the low is south of us! I hate storms! Thanks!

Anonymous said...

I watced the Ky3 weather a second ago and it said depending on how deep or shallow the cold air is, We might have a classic setup for heavy snow or heavy ice. And also they said the patterns going to change. Meaning low pressure systems will have mre of an effect for northern half of arkansas instead of it being the southern half. I guess its a wait and see situation as far as who gets what.

Kendra said...

very sad right now. Wish the models would come back with a wintry event! :(

Will said...

Don't be sad. I'm no weather expert like Snowbird and Ninja but just from what I can see on some of the model runs and listening to other I think we've got a fairly significant weather event coming our way next week. As SNBob says......We shall see!

cb6000 said...

Sounds like this storm may have plenty of bust potential, depending on what the forecast is and the end results. Here's hoping we get a good snowfall event out of it.

Amy said...

There is still so much time left with this storm. Yesterday, all signs pointed to an icy, wintry event. Today all signs point to rain....and tomorrow is another day. I'm no weather expert either, and I don't know what it is about this set up that seems very interesting to me, but I'm really feeling some winter weather for us next week. Cold air sinks fast, low tracks south....we could have a really fun snow, or a really serious icing. I think this will keep us guessing and wishcasting right up till the last minute...but that makes for blog excitement. I'm with SB all the way!!! Everybody, THINK SNOW!!! One question, Todd. This hazardous weather map you tweeted from the NWS....is that something they issue regularly, or is that special for this event and other big bouts of precipitation?? Is it like a model, or are they saying that is what they really think is going to happen?? Do they typically issue something like this when so many storm details are up in the air??? Thanks!

Alan said...

If I remember some of those that were in the "know" and making the medium term forecasts some thought the week of Feb 6 would have just as much snow or more snow in the Arkansas area.

As we have gotten closer anyone want to jump in with thoughts on the week of the 30 vs 6?

I know you may not want to jump over this upcoming event but it could be interesting to see what others are thinking about the next one also.

Anonymous said...

Okay so im starting to scratch my head a lil bit todd lol. If the low is a lil more north which is my thinking. Im thinking freezing rain along the missouri arkansas border a a plain rain elsewhere. Now if the low goes south. It would be all snow across the north and central arkansas would get in on some winter weather to. Still three days away and im sure its gonna change a million times. lol

jimmylee42 said...

Todd, I see what you mean about the GFS trending South a little bit. They were predicting Fayetteville for a dusting to 1 inch in the 120 hour snow forecast yesterday. Now they are predicting 4 to 8 inches from Fayetteville to Gentry and over 10 inches north of Joplin. I have seen this kind of a setup in the past change drastically less than two days out. I remember canceling a sales trip a few years ago because of a forecast of 8 to 10 inches of snow for Springfield, Mo. They got flurries and not even a trace. The snow moved much further South. The low pressure dropped all the way to the gulf and brought ice and snow to Northern La and Southern Ark as I recall.

nlrweatherman said...

Remember what happened earlier this week when the models moved the low 500 to th west. This kind of change could really happen again. We really have to keep a close eye on it

Anonymous said...

It appears the NWS is jumping into the fray now. They went from just rain Tues/Wednesday to a good chance of some type of wintry precip Tuesday night and early Wed. Fun watching people going back and forth. Going to be interesting.

Anonymous said...

Any chance of the wintry stuff tracking farther south?

Snowfreak13 said...

Has anyone looked at the 12z NAM then the18z NAM. What a dramatic change!!!!

Anonymous said...

I will be SO disappointed if we don't get any measurable snow out of this. Please GOD make the low go further south so we can get a good snow. Thank you in advance!

Snowbird Bob, weather ninja what are your thoughts?


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