January 28, 2014 this Pre-Dawn Tuesday morning 727 AM CST * * * * Dangerous Ice Storm for all of the Southeast Louisiana region, blended with sleet & some SNOW, especially Northern parishes * * * * * * * * Expect many bridge closures, road closures, and power outages * * * * * * * * Do not travel on the motorways from Tuesday, through Wednesday, 1/28-1/29 * * * * * * * * 4 - Star Writing, especially for New Orleans, near the windy lake * * * * ►I. Introduction.◄ Bigger. Bolder. And Louder, than the last teaser from Friday, 1/24. Freezing rain, ICE, sleet, and snow. This one will bring it all, to Southeast Louisiana and it all starts TODAY, Tuesday, 1/28/2014. Travel SHOULD BE AVOIDED! Do not travel on the motorways, unless its an absolute emergency, after precipitation begins. Turn your heaters UP, HIGHER than you have before, in the event your location suffers electrical power outages between this afternoon through Wednesday morning, as it will turn BITTERLY cold, as youve never seen before this winter season, with the wind chills that Im expecting. ►II. Timing on the Precipitation for New Orleans.◄ For the New Orleans area, I am expecting the freezing rain and ice to begin this morning around mid-morning. Forecast model time series shows that we should reach freezing at or near 32° around 9 AM, and we will stay in the lower 30s throughout the day today. More specifically, I give to you: ♦♦ 6 AM to 12 Noon, Tuesday, 1/28: In New Orleans, Temperatures starting in the upper 30s around sunrise, lowering down to the low 30s, by late morning. Light rain, before 10 AM; then Freezing Rain beginning around late morning & continuing. Wind chills 19-21°, (feels-like temperature). Windy. North winds of 15-25 mph & gusty. Ice Accumulation in this 6-hourly period of 0.08. ♦♦ 12 Noon to 6 PM, Tuesday, 1/28: In New Orleans, Freezing rain & ice increasing during the afternoon, possibly mxing with sleet around 6 PM. Ice accretion building & becoming obvious by late in the day. Many icicles can be seen on elevated objects, traffic signs, roof eaves, tree limbs, etc. Temperatures holding in the lower 30s for much of the afternoon. Wind chills 19-22° feels-like temperatures with a breezy North wind of 15-25 mph & gusty. Ice accumulation in this 6-hourly period: 0.28. Some power outages beginning. All bridges should be closed during this time. ♦♦ 6 PM, Tuesday to 12 AM, Midnight Wed., 1/29: For New Orleans area, Freezing rain mixing sleet, (ice pellets), between 6 PM and 9 PM Tuesday night, 1/28. Measureable precipitation tapering-down between 9 PM and 2 AM. A chance for snow between 9 PM to 2 AM: 30% to 40%. IF...IF it occurs, then accumulations to be a Trace to 1/2, but dont be expecting it. Temperatures holding in the low 30s. Wind chills brutal, 17-20°, with a North wind of 15-25 mph, & frequently gusty. More power outages, especially occuring near the Lakefront of New Orleans where winds will peak at 26-28 mph sustained, & even higher wind gusts to 40 mph there, causing downed power lines, downed tree limbs, and damage, from ice. Ice accumulation this 6-hourly period, 0.15. ♦♦ 12 AM, Midnight, Wed., 1/29 - 6 AM Wednesday: For New Orleans area, temperatures starting in the low 30s with a slight drop in to the upper 20s with lows near sunrise of 26-29°. Bitterly, arctic wind chills of 13-19°. Measureable precipitation over; perhaps a few snow flurries or light flakes and trace amounts of sleet around Midnight or shortly thereafter. Total Ice Accumulations in New Orleans of 1/2. Many iced & glazed areas will be seen by Wednesday morning, with HUGE, photo-worthy quality icicles. All cars will be glazed with a thick sheet of ice. Some tree limbs & branches will have fallen. All bridges & many roads will be closed. Several areas of power outages will have occured by now, especially in the New Orleans area, with the strong fetch of winds across the lake acting upon the iced power lines. ►III. Timing & Precipitaton for Baton Rouge.◄ I see the Baton Rouge area as collecting 1/3 to 1/2 of ice accumulation, too, from freezing rain that begins EARLY this morning carrying in to early afternoon. So freezing rain should go between 6 AM through about 2 PM. By around 2-3 PM this Tuesday afternoon, 1/28, I have it estimated at that time Baton Rouge, will begin seeing a mixture of freezing rain, changing over to sleet by or a little before 3 PM today. Then, between 3 PM up to around 8 PM, Baton Rouge is eligible to have a chance for snow; about 60% chance is where I put it at. Higher than this North of Baton Rouge; lower than this, closer to Lake Pontchartrain. Total snow accumulations will be anywhere from 1/2 up to 2. Extreme Northern Northshore parishes could have up to 3 or even a few isolated locations of 4 close to SW Miss. ►IV. Forecast Precipitation Amounts for New Orleans.◄ Here is the 7-model suite of data from overnights forecast cycle output, centered on New Orleans. This is MELTED, liquid-equivalent precipitation forecast here. Model #1 -->> 0.33 Model #2 -->> 0.44 Model #3 -->> 0.59 Model #4 -->> 0.46 Model #5 -->> 0.73 Model #6 -->> 0.35 Model #7 -->> 0.37 This gives me a 7-model average of 0.47 of storm-total precipitation for today & tonight on Tuesday, 1/28. So, I still think 1/4 to 3/4 of measureable precipitation looks good for the New Orleans metro area, consistent with my writing I furnished you yesterday. ►V. Snowfall -- What the models show.◄ First comes the freezing rain and ice today; then comes a transition to sleet, and IF theres still some moisture left-over, then the final transition will be made at the very end of the event, to snow. For snowfall, your ECMWF model has the most amount of snowfall of any of the forecast models, calculated for later today & tonight. In particular, it shows between 2-3 inches for all of the Northshore parishes, and between 1/2 to 2 for Southshore parishes. I have to disagree with these totals, particularly speaking on the Southshore areas. I think it will be much less and perhaps little, between just a Trace, thats non-measureable, up to 1/2 accumulation, if any occurs at all, South of the lake. Its a probabilistic chance that I have ascribed a 30% to 40% chance for the New Orleans area & Southshore parishes. In New Orleans, thicknesses are running really high at 546 to 547 dm at 9 PM to Midnight. 700 mb temp is only -1°C, and there are warm layers of above-freezing air continuing between 521 meters & 766 meters-deep, ALOFT, with average temperatures within those layers of 1.5° to 1.7°C, and thats right at ENDING time of the MEASUREABLE precipitation, too. As for the other forecast models, Gfs shows no measureable snow for New Orleans, and neither does Nam. C-Gem gives a Trace up to 1/2 for Southshore parishes, and provides a compromise between the stingy Gfs & Nam models, and the way liberal ECMWF. So thats where Ill hang an optimistic hat at! But its just a chance. As for Northshore parishes, C-Gem awards 1/2 to 1 1/2 of snow across Northshore parishes, and Nam does not give any snow to Baton Rouge or Slidell, but instead only snow to Washington parish. Gfs awards St. Tammany parish, only, with between 1/10 to 9/10 of snow. This is generally less than 1 of snow, but nowhere else in SE Louisiana. So, theres huge disagreements on snowfall amounts, as well as placement, amongst the models. I have already posted a couple snowfall maps, the more grand ones, on to my Southeast Louisiana Weather Facebook page. Further afternoon updates from here on out will now be posted on to my Southeast Louisiana Weather Facebook page, located at this weblink: https://facebook/SoutheastLouisianaWeather
Posted on: Tue, 28 Jan 2014 13:28:39 +0000
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