Saturday, October 25, 2014

Forecast in Progress

See title . . . running a bit behind schedule, and juts in case it's after midnight that I get this posted, I still want the time stamp to say Saturday. So there is no confusion if I refer to "today" and the time stamp said technically Sunday since it's after midnight. Forecast isn't really high impact, but we do have some changes in the works now, the ebb and flow of this season . . .

Thursday, October 23, 2014

Sunny Weekend With a Gradual Warming Trend

FORECAST:

Friday: Sunny. Cool. High 71, Low 43

Saturday: Sunny. Still somewhat cool. High 76, Low 45

Sunday: Mostly sunny. Mild. High 79, Low 50

EXTENDED OUTLOOK:

Monday: Mostly sunny. High 80, Low 53

Tuesday: Partly cloudy. High 79, Low 57

Wednesday: Partly cloudy with a slight chance of a passing shower. High 77, Low 59

Thursday: Partly cloudy. High 73, Low 52

NOTES:

Here is some information on Fall freeze climatology.

And if you want to learn more about the weather or other Earth Science, here are some free resources from NOAA.

DISCUSSION:




We had a mostly sunny day in Cullman with a High of 68 and a Low of 37. Hope you enjoyed the partial solar eclipse if you got to see it . . . we did have some high clouds at times, more than expected. We're still firmly under high pressure and going to stay mostly clear and cool for a while.


Tomorrow we should be sunny with surface high pressure and good northwest flow aloft. We should start out in the lower 40's and eventually warm to at least 70 degrees, maybe lower 70's.


Basically the same deal Saturday. Temperatures should start to slowly rebound into the mid-70's though.


We start to come under an upper-level ridge on Sunday, looks like a weak front may push through the area Saturday night. We may approach 80 degrees though.


On Monday our flow shifts firmly to the southwest, and we'll bring a few clouds back. The warming trend should slow. We'll probably still be somewhere around 80 degrees. Lows will probably be in the lower 50's by this point, with more moisture in the air.

And the clouds should increase a little more on Tuesday. Temperatures should stay about the same.


By Wednesday it looks like the cold front may be into our area enough for some widely scattered, light showers. With temperatures still in the upper 70's, guess we should see a thunderstorm somewhere. I am still somewhat skeptical of us getting any rain from this front. Model consistency hasn't been great, but both the GFS (used here) and the ECMWF have been consistent in showing some low-end rain chances at some point next week, with this front. I'm tempted to spread a low chance from late Tuesday through Thursday, but . . . probably will try to be more precise, even though the most precise thing to say would be to just admit that the rain chances are pretty low, nobody knows exactly where or when, but somebody in our region will probably get a little rain by next week. Sorry if that's not deep and scientific enough for some tastes.


According to this GFS guidance, on Thursday the front is gradually clearing the area, with slightly lower chances of scattered rain. The longwave trough is setting up over the area (and much of the country). Halloween is on Friday and slightly beyond the scope of this forecast, but at the moment, if this timing of the front is right, we may have another shot of cooler air on Halloween, maybe the coldest this season. Remains to be seen. I think it's too far out for there to be any skill in forecasting it. Even in days 4-7, the timing of this low chance of scattered showers is in question. However, the thought of a chilly, dry Halloween night is a nice one. Especially if there was just enough wind to rustle the leaves a little bit.

Well, what a difference a day can make. Moving across the Yucatan has pretty much destroyed what was our ninth tropical depression of the season. The remnants will likely move into the Caribbean Sea in another couple of days, and there's a very low chance it could try to regenerate. But it is much more likely to just be absorbed into a cold front.

I guess I'm going to have to relent on my skepticism; we may see a little rain with that front next week. The Hydrometeorological Prediction Center is forecasting a quarter-inch of rainfall accumulations around here, at most. I still doubt that everywhere will see rain. It will likely be hit-or-miss, widely scattered.

+Matt Graves
@thatweatherdude 

Wishing you a nice weekend. See you in the funny papers.

Wednesday, October 22, 2014

Patchy Frost Possible Tonight/Sunny and Cool Days Continue

FORECAST:

Thursday: Sunny. Cool. High 68, Low 38

Friday: Sunny. Cool. High 72, Low 41

Saturday: Mostly sunny. Still somewhat cool. High 75, Low 45

EXTENDED OUTLOOK:

Sunday: Mostly sunny. High 77, Low 48

Monday: Mostly sunny. High 78, Low 50

Tuesday: Partly cloudy. High 76, Low 53

Wednesday: Partly cloudy. High 75, Low 54

NOTES:

Here is some climatological information on fall freezes.

And as Jason Simpson noted, we have a solar eclipse coming up tomorrow.

DISCUSSION:



So with high pressure in place behind a weak cold front, we've had another sunny day in Cullman. We had a bit of a northerly breeze at times. Our High was 65, and the Low was 40.

We're in for another cold one tonight. Most areas will probably see upper-30's. There could be patches of light frost in the more sheltered areas anywhere in Cullman County or the Tennessee Valley, but the really significant chances of frost are to our north, where a Frost Advisory is in effect. This includes Limestone, Madison, and Jackson counties in Alabama; and Wayne, Lawrence, Giles, Lincoln, Moore, and Franklin counties in Tennessee.


Tomorrow looks like another sunny day. Winds should be light, in contrast to today. High pressure at the surface, but at the upper levels, wind flow is a little more zonal from the west. So we may warm a little more. High should be around 68 or 69.

Sunny again on Friday. Temperatures will gradually warm back up, but the flow turning back to the northwest should keep them from warming too quickly. Should see Highs in the lower 70's here and Lows in the lower 40's.

Should stay mostly sunny on Saturday with strong north/northwest winds aloft. We should still warm into the mid-70's, although that northerly flow will keep the warming trend in check.

We might actually warm into the upper 70's by Sunday, as the flow relaxes a little bit and turns back a little more westerly. Another dry/weak front should push through on Sunday.

That should slow down our warming trend on Monday. Few places around here will probably get back up to 80 degrees for this forecast period, but Monday would be the closest day. That weak front on Sunday will probably keep temperatures in the upper 70's, going no higher than that. Our wind flow turns back to the southwest ahead of our next frontal system.

On Tuesday we should see an increase in clouds, and that might knock temperatures down a degree or two, more toward the mid-70's. Lows by this time should be up into the mid/lower 50's just due to more moisture keeping us from cooling as much at night.


By Wednesday the GFS (which I used as the model for this whole forecast) is showing our next cold front pushing through. I think it is still too early to introduce rain chances, simply because yesterday, it was showing this happening on Tuesday. Now it has shifted it to Wednesday. The other major global model, the ECMWF, has not been in agreement with the GFS at all times. And finally, it's against our climatology. Usually October is our driest month, and these fronts end up passing through without any fireworks . . . or even sprinkles. So it isn't a huge deal, but overall I think rain is unlikely even at the end of this forecast. Will just mention increased clouds for Tuesday and Wednesday.



All right, let's take a look at the tropics. The disturbance in the Bay of Campeche strengthened to a tropical depression and is now getting ready to move through the Yucatan Peninsula. There is a Tropical Storm Watch in effect for that area just to play things safe, but the National Hurricane Center was saying it would likely be cancelled tonight. This will most likely stay at "depression" status, and we'll just have to see how well it survives interaction with land. If it does survive, it will probably be in the Caribbean Sea this weekend. Models are all over the place with what this will do, but I don't think it's worth looking into that unless and until it finishes moving over land. We'll see what is left of it and if it makes it into the Caribbean. At that point it would bear close monitoring. For now we just watch what it does the next several days.

+Matt Graves
@thatweatherdude 

Hope you stay warm tonight. See you in the funny papers.

Frost Advisory



NATIONAL WEATHER SERVICE HUNTSVILLE AL
205 PM CDT WED OCT 22 2014

...FROST ADVISORY FOR SOUTHERN MIDDLE TENNESSEE AND PORTIONS OF
NORTHERN ALABAMA FROM 4 AM CST UNTIL 9 AM CST...

ALZ005-006-009-TNZ076-096-097-230300-
/O.NEW.KHUN.FR.Y.0004.141023T0900Z-141023T1400Z/
LIMESTONE-MADISON-JACKSON-MOORE-LINCOLN-FRANKLIN TN-
INCLUDING THE CITIES OF...ATHENS...HUNTSVILLE...SCOTTSBORO...
LYNCHBURG...FAYETTEVILLE...WINCHESTER
205 PM CDT WED OCT 22 2014

...FROST ADVISORY IN EFFECT FROM 4 AM TO 9 AM CDT THURSDAY...

THE NATIONAL WEATHER SERVICE IN HUNTSVILLE HAS ISSUED A FROST
ADVISORY...WHICH IS IN EFFECT FROM 4 AM TO 9 AM CDT THURSDAY.

* TIMING AND AREAS AFFECTED...FROM 4 AM TO 9 AM CDT THURSDAY FOR
  SOUTHERN MIDDLE TENNESSEE AND LIMESTONE...MADISON AND JACKSON
  COUNTIES IN NORTHERN ALABAMA.

* TEMPERATURE...33 TO 36 DEGREES.

* IMPACTS...AREAS OF FROST WILL DEVELOP...WHICH MAY HARM OR KILL
  SENSITIVE OUTDOOR VEGETATION.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FROST ADVISORY MEANS THAT WIDESPREAD FROST IS EXPECTED. SENSITIVE
OUTDOOR PLANTS MAY BE KILLED IF LEFT UNCOVERED AND OUTDOORS.

Tuesday, October 21, 2014

Sunny and Cool . . .

FORECAST:

Wednesday: Sunny. Cool. High 67, Low 43

Thursday: Sunny. Cool. High 69, Low 39

Friday: Sunny. Cool. High 72, Low 42

EXTENDED OUTLOOK:

Saturday: Sunny. High 75, Low 46

Sunday: Sunny. High 78, Low 50

Monday: Mostly sunny. High 80, Low 53

Tuesday: Partly sunny. High 79, Low 55

NOTES:

We will have a partial solar eclipse on Thursday. Thank you to Wes Wyatt for that reminder . . . also noticed that Jason Simpson posted about it here.

And here is some information on Fall Freeze Climatology.

DISCUSSION:



So a weak cold front is pushing through the area. Winds have been gusty from the Northwest at times today. It was another sunny day in Cullman with a High of 72 and a Low of 45.


By tomorrow the upper-level longwave trough will become a closed Low over the Mid-Atlantic states. That puts us in a great position for strong northwesterly wind flow aloft. And that should keep our temperatures down a little bit, in the upper 60's. Tonight we will likely cool into the lower-40's.


On Thursday that Low moves out into the Atlantic Ocean, and as surface High pressure moves into our region, our winds should be just a little more zonal from the west. That should allow temperatures to warm a degree or two during the day. Still sunny skies, of course. Morning temperatures may get down to 40 or slightly lower, though, with very low humidity while we're still under mostly northwest flow.



Sunny again on Friday. Temperatures are going to be slow to rebound, with good northwest wind flow at 500 mb. We might get back into the lower 70's though.

Saturday we stay sunny and may get into the mid-70's, but again, temperatures should be slow to rebound in this pattern.



Sunday we come under an upper-level ridge. We should stay mostly sunny, and with mostly northerly winds aloft, temperatures will be even slower to warm, despite all the sunshine.


On Monday the upper-level winds turn back to the southwest, and we might approach 80 degrees. Should stay mostly sunny.


By Tuesday it looks like we have another cold front coming our way, and we *might* see some rain with this one. I find it dubious, especially this far out, considering climatology (October usually being our driest month). But might include a 20% chance.


The ECWMF is also on board with the idea of rain though. I usually don't even mention a 20% chance of rain in the forecast unless it's a couple of days out. So with this seven days out . . . just keep in mind we might see rain, but usually this time of year these fronts end up being dry.

The official word from the HPC is no rain for this forecast period in the Tennessee Valley. And I agree with that. Even by Tuesday, the chance is pretty low.

The tropics are actually interesting. That system south of the Azores is probably going to fizzle out as it drifts west/southwest at 10-15 mph. The Low in the Bay of Campeche might develop into a tropical cyclone tomorrow, due to favorable upper-level winds, before moving into the actual state of Campeche. People in the Yucatan Peninsula will want to monitor this. Warnings could be required without much advance notice, if this thing were to pulse up tonight or tomorrow before moving inland. Long-term, it will probably end up in the Caribbean Sea, but it may get picked up by a cold front. I'm not sure it's worth guessing where it goes long-term, just yet. People in the Bay of Campeche and the Yucatan Peninsula just need to keep an eye on this thing in case it intensifies tonight/tomorrow. It should move inland tomorrow night and Thursday, whatever its strength. It might remain a tropical low, but if it gets better organized by tomorrow, then those areas may be dealing with a tropical cyclone. Once in a while they do intensify to tropical storm or even minimal hurricane strength rapidly. Just in case that were to happen, I would watch it carefully if in the path down there. More likely it will just be some strong showers and thunderstorms. But we have to allow for the other possibility.

+Matt Graves
@thatweatherdude 

I want to thank Holly Allen from the National Weather Service office in Birmingham for an enjoyable SKYWARN class tonight. See you in the funny papers.

Monday, October 20, 2014

Sunny/Cool Pattern Continues

FORECAST:

Tuesday: Sunny. Cool. High 72, Low 46

Wednesday: Sunny. Cool. High 68, Low 42

Thursday: Sunny. Cool. High 69, Low 39

EXTENDED OUTLOOK:

Friday/Saturday: Sunny. Highs in the low-to-mid-70's and Lows in the low-to-mid-40's.

Sunday/Monday: Mostly sunny. Highs in the mid-to-upper-70's and Lows around 50 or so. 

NOTES:

Here is a look at our Fall Freeze Climatology in the Tennessee Valley.

And on the note of climate, the Climate Prediction Center has issued its speculations about this winter.

DISCUSSION:



So we had another sunny day in Cullman. The High was 71. The Low was 42. We've barely had any clouds, despite that upper-level trough moving through.


Tomorrow that trough still looks like it will be well to our north/northeast, leaving us with ample northwest wind flow. That means sunny skies and temperatures not much above what they were today. Tonight is tough to call for temperatures. It's 54 degrees now. The Dewpoint is 51. We do have some moisture around, but not enough for much cloud cover. I think it's safe to go with a Low at least in the upper 40's, maybe a little cooler than that.

STill looks like Wednesday this develops into a Closed Low over the Mid-Atlantic states. And we have sunny skies and plenty of cool air filtering in on the back side of that trough. We may not even make it up to 70 degrees. Lows back down in the lower 40's.

The upper-level winds look a little more zonal on Friday, from the west, so temperatures might rebound just a little bit, few degrees. Still sunny skies.

Temperatures will be slow to rebound, though. High pressure should dominate our weather until Sunday and Monday, when we might bring back a few clouds as the winds aloft shift back to the southwest.

No rain is expected for this forecast period.


People from the Bay of Campeche to the Yucatan Peninsula will want to monitor this tropical low that is slowly moving east. It has a very decent chance of becoming a tropical cyclone within the next two or three days. Despite whatever you might see on other blogs or social networking sites, it is way too soon to know how this will develop or where it will go. And the more responsible bloggers/social networkers have made note of this. For my own part, I'm not even calling attention to wild possibilities by showing model "spaghetti plots" at this point. Those are worthless right now. If an Air Force plane goes in there to check this thing out tomorrow, then the models will have decent data to work with, for at least a starting point. They do not have that yet. 

+Matt Graves
@thatweatherdude 

Hope you're enjoying a more normal October weather pattern. See you in the funny papers.