Snow Looking Less Likely

Things seem to have changed in the last few hours. There was a slim possibility that parts of northeast Florida could see winter precip tonight. Now, it doesn't seem likely at all according to the NWS in Jacksonville:

WARM LAYER ABOVE THE SURFACE WILL LIKELY KEEP PRECIP ALL RAIN IN
FLORIDA. BY THE TIME THE PROFILE OVER FLORIDA BECOMES COLD ENOUGH
TO SUPPORT SNOW...THE MID AND UPPER LEVEL MOISTURE WILL BE
STRIPPED AWAY AND LACK OF ICE NUCLEATION WILL KEEP ANY PRECIP THAT
FALLS AROUND MIDNIGHT IN THE FORM OF LIGHT DRIZZLE. TEMPS SHOULD
REMAIN ABOVE FREEZING DURING THIS TIMEFRAME SO FREEZING DRIZZLE IS
NOT A CONCERN.

Also, from looking at radar, it seems the storm system is moving out a little faster than forecasts from yesterday revealed. The "back-side" precip is now passing over Gainesville. When this rain moves out, temperatures will still be above freezing and, therefore, winter precip is not likely.


Image source: WeatherTap.com

Expect the rain to taper off later this evening with drizzle possible later on. NWS-JAX issued a wind chill advisory for the area from 3 a.m. to 9 a.m. Saturday - which means wind chills in the low to mid 20s are likely. NWS-JAX is calling for a low of 31 tonight in Gainesville. Stay warm.

SnOMG?!

It has been a few weeks since my last post, which was on the possibility of winter precipitation in the area. Surprisingly, reports of sleet and snow came in from Ocala and Flagler County that early January night. Reports of sleet were even coming in south Florida.

Flash forward to the last couple of days where much of the United States has experienced what some have been calling "Snomagedon" or "Snopocalypse." The last two storm systems have broken many snowfall records and wrecked havoc for millions.

This next storm looks to be interesting, although this system doesn't seem to have many impacts on New England as the last two did. The southeast looks to be under the fire.

What's happening

Surface analysis from the Hydrometeorological Prediction Center (HPC) shows a low pressure system centered near Brownsville, Tx with an associated cold and warm front. Radar shows plenty of rain in southern Texas, southern Louisiana and southern Mississippi while snow is falling in northern Louisiana and north Texas. GFS and NAM guidance is showing a upper-level longwave trough (essentially a trough in the jet stream) over north Texas.

Friday's Synoptic Outlook

The system is expected to intensify and move east over the Gulf of Mexico. Starting Friday before noon, north Florida could start to see rain and pick up in intensity as the day wears on. The HPC forecasts, along with model guidance, seem to agree on the low reaching Florida near Tampa Bay around 7 pm Friday with the warm front remaining south of Gainesville.

So...snow?? Sleet? Anything?

The further north and west you go during the next 36 hours, the better the chances of winter precipitation. Within the last hour or so, sleet was reported in Crestview, FL (western panhandle) was well as Destin. There are some schools of thought of whether Gainesville could see anything.

NWS-Jacksonville is thinking of this (from their latest Area Forecast Discussion)...

SO...THE BEST CHANCE FOR A RA/SNOW MIX WILL EXIST ACROSS OUR NW GA
ZONES BEGINNING FRI MORNING. THE BEST CHANCE FOR POSSIBLE
ACCUMULATIONS WILL BE ACROSS THESE ZONES AFTER 18Z [2 PM EST] FRI AND
CONTINUING THROUGH 06Z [1 AM EST] SAT. THE BEST CHANCE FOR A WINTRY MIX
OF RA/S WILL BE ACROSS NE FL AFTER 21Z [4 PM EST] FRI AND FRI EVENING MAINLY
N OF THE I-10 CORRIDOR. THERE WILL BE A GOOD CHANCE FOR FLURRIES 06Z-12Z
[1 AM - 7 AM EST] SAT ACROSS A LARGE PORTION OF THE AREA DUE TO SHALLOW
WRAP-AROUND MOISTURE...MEAGER LIFT AND STRONG COLD AIR ADVECTION.

In other words, it would be a very slim chance for us. I have been warned by a fellow Twitterite and meteorologist that "warmer air from the Atlantic" could be a limiting factor by "not allowing the lower levels to cool enough." However, my thinking is if the temp is just cool enough below 850mb, we could enough moisture at the surface to have snow fall. He also suggests that the latest GFS and NAM runs don't really show any winter precip for the area.

Based on my look at temperature forecasts with some of the models, chances are slim for winter precip in the area. But that doesn't mean that it's impossible.

The winter precip event early last month had one limitation for Gainesville: surface dry air. During that night, radar indicated light precip in the area but it was not falling to the ground. Why? Too dry - it just evaporated before it even hit the surface.

Here are some examples of temperature profiles for snow (left) and sleet (right).



Image Source: NOAA

Summary

So, will we see snow or any winter precip in the area? Chances are slim, but you can count on dealing with lots of rain for most of your Friday. Bring that umbrella to school or work before you head out the door.

Also, keep any eye on my Twitter feed (twitter.com/daweathaman) for the latest. I might add a new weather post as conditions and free time warrant.

By the way, I always welcome discussion from meteorologists and other weather geeks for their expertise. I'm not too familiar with forecasting winter precip (wonder why?), so any advice would help. Let me know if you have any winter weather reports, too.

Snow? Here?

For the last few days, most of the United States has been plunged into the deep freeze as a persistent synoptic pattern keeps funneling cold Canadian air southward. For Florida, this trend is expected to continue well into early next week.

For the last few days, abundant discussion on social networking sites and around the proverbial water cooler have been on the $60,000 question: Will it snow in Florida? To most, it would seem like it given that it's been so cold for so long in this state.

Synopsis

An Alberta Clipper system (what's that?) and it's associated front, which is currently over the lower and middle Mississippi River valley, is bringing snow from Wisconsin to northern Mississippi and Alabama while bringing rain for central and southern Mississippi and Alabama and most of Louisiana. High pressure currently remains over the Florida panhandle. This helped keep the winds relatively calm overnight and skies clear to allow temperatures to fall to near-record territory across the state.

Preliminary figures from the NWS suggests that the low in Gainesville this morning was 21 degrees, which would break the old record of 22 set back in 1924. It may have been as low as 21 in Ocala, as well.

At the upper levels, a trough in the jet stream is beginning to fold in the upper Plains and New England while the subtropical jet stream passes over Florida. This may have aided in keeping south Florida mostly cloudy this morning (judging by infrared satellite imagery) and staving off colder weather for that area.


Jet Stream analysis from 1 a.m. ET today (left) and surface analysis at 7 am ET (right).

Later Today through Saturday.

Short-range forecasts from the HPC show the storm system moving east as the high over Florida now moves east. Early Friday morning, the front is expected to be over the panhandle and and be over central Florida at around 7 a.m. The front should be over south Florida by the end of Friday evening.

There are a few things to keep in mind. For starters, will it even be at or close to freezing at the time precipitation will pass through. One tip given (via Weather Prediction) is to see if temps are below freezing at the surface and 850-mb levels (Weather recap for the novice: As elevation increases, the pressure decreases). If so, "snow is the most likely precipitation." Also, it
s good to see what type of thermal advection (movement of air horizontally) is taking place.

With those of many tips given, lets look at the models. Remember, models are not forecasts etched in stone and things can change. These are used as a guidance.

The NAM at 7 pm ET Friday is showing spotty and isolated precip around the north central Florida area. I would count this as a slim chance of precip in the area. At this time, the air temps at 850 mb and 1000 mb are close to freezing. As the night wears on, precip increases over central Florida. For 7 am ET Saturday, temps at 1000 mb are at or below freezing for much of the north central and central Florida while the freezing line at 850 mb is around the I-10 corridor.

The GFS' 06-Zulu run shows the precip associated with the front passing through during the afternoon and evening on Friday. The freezing level at 850 mb is to the north of the Florida/Georgia state line at 7 pm ET Friday while the line is moved south to near Gainesville 12 hours later. The 1000-mb freezing line is over central Florida during the model runs for Friday evening and Saturday morning.

Those are two models with slightly different takes on precip and temperature above the surface. What could be the case? I am not too sure about snow for the northern half of the state. I will be really shocked if we do get it. I can say this: There will be a very slim chance of snow for the north central Florida area. It would depend on the timing of the precipitation.

How about sleet? It would be more plausible than snow, I think. Again, it would depend on the timing of the precipitation. If precip falls at night, it could happen. It also depends on thermal advection.

Here's what the National Weather Service in Jacksonville (NWS-JAX) has written in an earlier Area Forecast Discussion:

DUE TO THE SLOWER PROGRESSION OF PRECIP...HAVE ALSO INDICATED SOME
MIXED PRECIP DURING FRI MORNING ACROSS EXTREME SE GA WITH A COLD
RAIN EXPECTED ELSEWHERE. HOWEVER...WOULD NOT BE SURPRISED TO GET
REPORTS OF SOME SLEET MIXED WITH RAIN INTO EXTREME NE FL. NO
ACCUMULATIONS ARE EXPECTED...BUT STILL CONCERNED ABOUT WET ROADS
FREEZING DURING THE EARLY MORNING HOURS ON FRI IN SE GA AS COLDER
AIR FILTERS IN BEHIND THE FRONT. DAY SHIFT ISSUED A SPECIAL WX
STATEMENT ADDRESSING THIS...AND WILL REFRESH THIS PRODUCT WITH THE
LATEST THINKING.

MODELS STILL INDICATING SOME LINGERING MOISTURE OVER THE EXTREME
SE ZONES AS A DISTURBANCE MOVES ACROSS CENTRAL FL EARLY SAT. HAVE
INCLUDED A SLIGHT CHANCE OF RAIN OR SNOW OVER THIS AREA WITH A
SMALL AREA OF FLURRIES BEHIND IT GENERALLY SE OF A ST AUGUSTINE TO
OCALA LINE. AGAIN...MEASURABLE AMOUNTS ARE NOT EXPECTED.

Bottom line: Very, very low chance of snow. Sleet possible depending on temperatures aloft and timing of precipitation. Chances would be greater the farther north you go. However, just as NWS-JAX keeps mentioning in their forecast discussions: "Measurable amounts [of winter precip] are not expected."

The Next 24 Hours

Expect temps to increase slightly today into the 50s for the Gainesville area today with mostly sunny skies. Tonight, things will begin to change with a chance of showers and a low in the low 30s. Based on temp profiles aloft with guidance, I don't see much of a chance tonight for any winter precip. Friday, things will get interesting and may change. I might write another post if updates are necessary. Otherwise, keep any eye on my Twitter feed for the latest at twitter.com/daweathaman.

New Year Brings Cold

Good afternoon and Happy New Year, everyone. It's been a while since my last weather blog post. I am kind of making it a New Year's resolution to make more posts on here - at least once every few days. Hope it sticks.

At the moment, a cold front with associated showers have passed the Gainesville area late this morning. Skies continue to be mostly cloudy, but judging by visible satellite imagery clearing is expected in the area real soon as the cloud cover passes with the front.

At the upper levels, a deep trough in the jet stream, along with the passage of the surface low and its flow, will bring colder air to much of the midwest and eastern U.S. for the next few days according to guidance models. NWS-JAX is considering this as "one of the longest duration cold spells in quite some time" in this morning's Area Forecast Discussion.

However, the big question: How cold? NWS-JAX calls for lows in Gainesville in the low 30s tonight, but MOS guidance is mostly hinting in the upper 20s except for the NAM. I would have to agree with the NWS at this time since, based on experience, it might take a little longer for the coldest air to reach here after the passage of the front. Plus, winds created by pressure gradients after the passage of the low and associated cold front will inhibit radiational cooling and keep air temperatures a little warm. However, with any wind, it may feel colder.

Starting Saturday, the pressure gradient is expected to weaken and bring colder nighttime temps to much of Florida. NAM guidance seems to be treating this a little warm while GFS is calling for temps near 20. For now, I would wait before I call for an exact temperature reading. Regardless, by Florida standards, temperatures are expected to be very cold with below freezing temps each morning through at least Wednesday. Highs are expected to not get close to 60 degrees through Wednesday.

For now, I call for clearing skies in the area today with highs reaching into the upper 50s. Continued clearing with some wind is expected tonight in Titletown with a Saturday morning low near 32. Keep any eye on my Twitter and Facebook feeds for my predictions for the next few nights. Stay warm.

Severe Weather Threat for Wednesday

I think good 'ol El Nino is starting to flex its muscle on our weather patterns. It's only going to become more frequent, so get used to it.

Our first severe weather potential system is on its way to north central Florida starting tomorrow. This evening, me and another UF-AMS member discussed at the meeting the setup for the storm system which is churning in the Gulf of Mexico.

What's happening now...



A deepening surface low is in place with an associated warm front and stationary front over the western Gulf of Mexico. Infrared satellite imagery shows moderate convection in the gulf while radar shows rain streaming into the Florida panhandle, Georgia and Alabama. Radar also shows rain - associated with an upper-level low - over eastern Texas moving into Louisiana.

Wednesday...

Models have the upper-low over Texas open up and move towards the northeast along the subtropical jet stream. This should aid in negative tilting in the upper-levels and help support instability (more about negative tilting). At the surface, the warm front to our south will move north later and will place the area in the warm sector. NWS-JAX notes that the surface low in the gulf should be in southern Mississippi by 7 a.m. EST. Short-range forecasts have the low racing off to the northeast.

It's looking like the squall line that would bring the worst weather should arrive sometime in the afternoon, but leave the Gainesville area before 8 p.m.

The primary threat seems be strong winds with thunderstorms, including threat a of bow-echoed storms. A low-level jet of nearly 60 knots will also keep the threat of severe weather alive. This is all despite the fact that very little insolation is expected and is one limiting factor for instability.

As of now, the Storm Prediction Center has most of Florida under a slight risk category for Wednesday. Things might change once I wake up in the morning. Therefore, keep an eye on my Twitter feed for the latest.

Forecast...

Mostly cloudy for Wednesday with a good chance of showers and thunderstorms. Some storms could be severe with strong winds. It's a good day for a rain coat at UF. Storms should start to clear out later in the evening.

Stay informed, and be safe!

Kickoff Forecast: Florida at South Carolina

It's been a rough week and a half, but I am back into the forecasting game and I start off with today's college football game with Florida at South Carolina. Here's a look into the future (weatherwise).

Currently...
High pressure currently dominates the weather over the southeast as it sits over the central gulf coast with the pesky low sitting off shore of North Carolina. Isobars (lines of equal barometric pressure) show a slight pressure gradient, but winds seem relatively light inland. Temps are currently in the 60s in the area with fair skies being reported at Columbia Owens Downtown Airport.

Forecast...
The low over the Atlantic will slowly move out to sea through the end of the weekend. The pressure gradient will be weaker with NWS-Columbia calling for light winds today and tonight (maybe at 6 mph at the most from the west near kickoff time). Current weather conditions will persist and the weather should be very nice for today and tonight.

Kickoff (3:30 pm EST)...
Look for a temperature near 74 and mostly sunny with some upper-level cloudiness and light winds out of the west. Temps should be in the low 60s when the game ends this evening.

Go Gators!

Kickoff Forecast: Florida vs Mississippi

Here's another gameday forecast for a Florida game. This time, it's an away game at Mississippi State in Starkville.

Now (in Starkville)...
A cold front has passed the area and is currently over eastern Alabama. Winds are mostly out of the west across the region with temperatures in the 50s.

Saturday...
High pressure to the southwest and a west to northwest flow should help keep conditions really nice for the next couple of days. Models seem to indicate highs in the 60s with lows in the upper 30s for Saturday night / Sunday morning.

Kickoff...
With kickoff at 7:30 PM ET, the temperature should be near 56 with mostly sunny skies with temperatures falling quickly afterwards. In other words, jacket weather.

Those going to the game: Have fun, be safe, and Go Gators!

Cooler Weather is Here!

Just got back in town from Orlando this evening after leaving Gainesville Friday to temps well above normal and very muggy. When we arrived in town, the temperature difference was highly noticeable. I was almost shocked. It has been so long since it has been this nice.

Now...
It's 52 degrees at Gainesville Regional Airport at the moment and 55 degrees at my apartment in southwest Gainesville. The cold front that passed Friday is just south of the Florida Keys while the low is offshore near 30 degrees north latitude. Dewpoints remain really low (in the 40s) with winds mostly from the northwest in inland Florida and points north. There is some high cloudiness to our north over southern Georgia.

Tonight...
Clear skies are over Gainesville with temps in the 50s, but the winds at 15 mph (sustained, 25 mph gusts at KGNV), it feels colder. The cloudcover over south Georgia is on it's way towards the area (it can been seen on the infrared satellite imagery and the last few frames of the visible).

There are two things that can make this forecast tricky tonight:

1) The wind. Wind may make it FEEL cold, but it could help keep the air temperature warmer than it would be if the winds were calm. This is because winds stir up any heat at the surface can keeps radiational cooling in check.

2) Cloudcover. This also keeps radiational cooling in check. It helps keep heat remaining in the troposphere (where all the weather occurs in the atmosphere) to escape back into space. In other words, cloudcover acts as a blanket over us and helps keep things warmer than it would be with clear skies.

NWS-JAX is calling for 41 tonight in Gainesville. However, am beginning to question this forecast a little. Cloudcover to our north may dissipate (as it is starting to show in the IR sat imagery). However, guidance models seem to have winds remain at around 10 knots (11.5 mph).

For tonight, partly cloudy skies for later on. Otherwise, mostly clear. I'm going to be slightly conservative at the moment and call for a low near 44.

If you plan on celebrating the win against Arkansas tonight (WoOt, Gators!) or going downtown, bring a nice coat.

Sunday looks really nice with clear skies and a high near 65. Sunday night might be the coldest night of during this spell. I'll post my predictions tomorrow evening on Twitter and Facebook.

WHERE'S FALL??????

So, yea. For over a week, Florida has been under some ungodly weather for this time of year. Let's put things into perspective of where things should be in our area...

- Fall is usually considered in Florida when the average daily minimum temperatures fall below 60 degrees F. In Gainesville, it usually happens the second or third week of October (Winsberg, 2003). It's week two (approaching week 3) and we're still mostly in the 70s.
- The normal low for this morning is 61 (NOAA). It was 69 with dewpoints in the upper 60s.

In other words, it's been terrible.

What is happening now...
A stationary front is over the area with temps mostly in the 80s with showers and storms around the area. However, based on surface observations and the NWS-JAX discussion, the front appears to be diffused.

Next couple of days...
Fog could be an issue tomorrow since low-level moisture persists with the possibility of temperature inversions at some spots. On Monday and Tuesday, the HPC notes a wave of low pressure to move along the front (as it moves north during the next two days). Guidance models (NGM and GFS) show a continued surface and 850mb-level SE flow and should continue to bring in moisture. NWS-JAX notes that favorable dynamics aloft and shortwave energy could enhance thunderstorm development with a chance of a few strong ones. They have left the area at a 50-50 chance of rain Monday and 40 percent Tuesday.

Later this week...
It looks like the awful heat has a chance to vamos this weekend. A developing low is expect to bring the front back north. This low should be amplified by a upper trough that guidance models are picking up on over the southeast. The frontal passage, which could be Friday night/Saturday based on HPC surface forecasts, could bring some cooler weather to the area. However, NWS-JAX is hinting at a severe weather risk based on the possibility of a southwesterly low-level jet and sufficient instability. Time will tell whether this holds up - it's a little too early to call that threat.

In a nutshell...
Hot and gross for the next few days. Friday, good chance of storms with a cooler temps this weekend. We'll see how this forecast holds up.

Keep an eye on my Twitter updates for the latest.

Sources: Winsberg, Morton D. "Florida Weather, Second Edition" University Press of Florida, 2007

Kickoff Forecast: Florida at LSU

Good morning from balmy north central Florida. It's 84 at my apartment complex and partly cloudy. It looks like we might get a chance of a shower or two this afternoon per NWS-JAX forecast. But I'm not writing to talk about Gainesville's weather. It's time to scope in on Baton Rouge, Louisiana for tonight's Florida and Louisiana State football game.

Currently, NWS radar from Slidell shows a southwest to northeast line of showers moving east and the last of it is passing over Baton Rouge. This is associated with a cold front that passed this morning. However, NWS-New Orleans notes in their AFD that the "frontal trough bisects the area and has stalled." This would help set the stage for the front to move back northeast and would create an environment for showers and thunderstorms later today and this evening.

Both the 0Z (8 pm EDT) NAM and GFS runs seem to show high precip over the area around 8 p.m. However, I am waiting on the 12Z runs to see how what they show and might give another update later today. GFS precipitable water amounts seem to creep back up from the south near kickoff.

It looks like chances are good that we could see some rain during the game this evening as this front pushes back a little this PM. I think that KBTR will not be in the warm sector and temps will remain slightly cool (for Florida standards); therefore, the temps should be around 66 at kickoff.

Kickoff forecast: Mostly cloudy with a good chance of showers. Temp: near 66.

I'll be at home with Erin and a friend watching the game in HD. I'll also be watching the radar. Keep an eye on my Twitter account for updates.

Go Gators!!