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Category: Forecast Discussion
Permanent link to this article: https://indywx.com/2013/11/19/video-update-on-the-remainder-of-this-week-and-at-some-thanksgiving-week-wintry-mischief/
Nov 17
Monday Forecast: A Calmer, Colder Week Ahead…
Updated 11.17.13 @ 8:46pm
Zionsville, IN Sunday was a violent day across central Indiana, including multiple tornado touchdowns (Lebanon and Kokomo, for example), heavy rain (widespread 1″+ totals), and damaging straight line winds (numerous trees and power lines down across the region, fueled by 70-80 MPH wind gusts).
Thankfully the new work week will dawn with a much calmer weather pattern in place, albeit much cooler. High pressure will dominate our region, featuring dry and mostly sunny conditions both Monday and Tuesday. Monday will still be a bit breezy and we’ll note a stronger push of cold air arriving Monday night, setting the stage for a seasonably chilly Tuesday and Wednesday.
Our next weather maker will arrive as we wrap up the work week. The culprit will be a cold front blowing through the Hoosier state and while model data differs significantly on precipitation totals in the Thursday-Friday time period, we’re confident in rain falling followed by a big blast of cold air for the weekend.
Looking ahead to Thanksgiving week, the threat is there for some wintry “mischief” as southern branch low pressure attempts to attack the cold high to our north… We have plenty of time to watch this, but just make a mental note in the back of your mind for now as you prep for Thanksgiving holiday travel.
Monday: Mostly sunny; 40/ 51
Tuesday: Mostly sunny; 29/ 48
Wednesday: Increasing afternoon cloudiness; 30/ 51
Thursday: Cloudy and raw with rain likely; 43/ 49
Friday: Cloudy with rain likely; 44/ 49
Saturday: Mostly cloudy and colder; 30/ 39
Sunday: Mostly sunny and cold; 19/ 30
Permanent link to this article: https://indywx.com/2013/11/17/monday-forecast-a-calmer-colder-week-ahead/
Nov 17
Extremely Dangerous Severe Weather Outbreak Ahead…
Good morning! We’re waking up to sunshine this morning after a round of rain and thunderstorms overnight. Over 1″ of rain fell for many during the overnight period (1.53″ to be exact here at IndyWx.com HQ).
Unfortunately, skies now are clearing and this is only going to aid in the severe weather potential today, including some dangerous long-lived and strong tornadoes.
This is a very rare November high severe weather risk day and must be taken seriously by all.
The thinking here hasn’t changed in that we feel discrete super cells develop during the late morning and early afternoon before morphing into a squall line capable of producing damaging straight line wind. With the dynamics and energy in play here, any of these super cells could spawn a tornado. Additionally, it’s possible that a few of these tornadoes could be long tracked and very strong tornadoes. The latest high-resolution simulated radar data shows this well.
We still target a cold front passing through the region around, or just after, sunset and with this frontal passage the severe weather will come to an abrupt end. The latest HRRR data shows this well as dew points begin to crash behind the cold front, indicative a much drier, cooler, and more stable air mass arriving tonight.
Permanent link to this article: https://indywx.com/2013/11/17/extremely-dangerous-severe-weather-outbreak-ahead/
Nov 16
Late Saturday Night: Thunderstorms Develop Overnight; Update On Sunday
Good evening, Hoosiers! Showers are developing now, and these will increase in coverage and intensity as we progress through the overnight. As we move into the wee morning hours, don’t be surprised if you’re awoken with loud claps of thunder, gusty winds, brief heavy rain, and small hail. That said, we think overnight thunderstorms remain below what would officially be considered “severe.”
Here’s a look at the simulated radar later tonight, valid at 2am local time, courtesy of the HRRR model.
As for Sunday, we continue to look over the latest data and our thoughts haven’t changed. It still appears the two biggest threats will be from damaging straight line winds and the possibility of quick spin-up tornadoes associated both within the squall line, itself, but also with any individual severe cells that develop before “morphing” into the squall line. It should also be pointed out that even outside thunderstorms, southwest winds will howl across central Indiana, periodically gusting upwards of 40-45 MPH even outside of thunderstorms. Hunker down…
The latest high-resolution NAM suggests the possibility of super cells entering western Indiana early Sunday afternoon before organizing into a squall line as it moves through central and western Indiana. This line will mean business as it moves east across the state, and latest data suggests the most significant severe threat for central Indiana will be from 12 noon through 6p, moving west to east. By sunset Sunday, most of central Indiana will see a much needed (and much colder) wind shift to the northwest, ending any threat of severe weather.
Permanent link to this article: https://indywx.com/2013/11/16/late-saturday-night-thunderstorms-develop-overnight-update-on-sunday/
Nov 14
Heavy Rain And Severe Outbreak Sunday
We continue to analyze the latest data concerning our pending severe weather episode ahead Sunday. Today’s information continues to point towards the threat of not only a damaging straight line wind event, but the potential of multiple tornadoes across the central Ohio Valley. The tornado threat would most likely occur with any individual super cells that develop Sunday afternoon. The damaging straight line wind event would then be associated with what’s likely to be a squall line associated with the cold frontal passage Sunday night. Needless to say, Sunday will be busy weather day across not only the Hoosier state, but for many folks across the Mississippi River Valley into the Ohio Valley. Additionally, widespread heavy rain is also a good bet. Let’s look at some data:
First, let’s look at some rainfall numbers. The ECMWF (European forecast model) and GEM (Canadian forecast model) are the most aggressive with rainfall totals approaching the 2″ mark for many areas of central Indiana between Sunday and Monday. The GFS isn’t as bullish, forecast a little more than half an inch on it’s latest run. Officially we’ll go with a blend of all three models and suggest widespread 1″ type rains across central Indiana during the Sunday-Monday period.
Before we go further, we also want to highlight that winds will be strong and gusty Sunday even well away from any thunderstorms. Winds will likely gust to 40-50 MPH simply by the tightening pressure gradient as surface low pressure begins to “bomb out” (rapidly intensify) on it’s journey into the Great Lakes region.
The dynamics are somewhat scary with this event and, as stated above, suggest not only an enhanced straight line damaging wind event, but also the potential of multiple tornadoes associated with any super cells that get going Sunday afternoon, well ahead of the squall line. Despite a cold, dry air mass in place currently, the aforementioned strong southerly winds will help transport dew points into the lower to middle 60s come Sunday afternoon. This will only help add fuel to the fire for storm development.
Let’s take a look at the official Severe Weather Outlook for Sunday, courtesy of the Storm Prediction Center. Some highlights from their most recent discussion:
SOME UNCERTAINTY LINGERS...BUT TRENDS IN THE MEDIUM RANGE FORECAST GUIDANCE ARE INCREASINGLY SUGGESTIVE OF THE DEVELOPMENT OF AN ENVIRONMENT SUPPORTIVE OF AN OUTBREAK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MIDDLE MISSISSIPPI VALLEY EASTWARD THROUGH MUCH OF THE OHIO VALLEY ON SUNDAY.
A 90+ KT 500 MB JET STREAK NOSING THROUGH THE OHIO VALLEY...COUPLED WITH STRENGTHENING SOUTHERLY WARM SECTOR 850 MB FLOW...PERHAPS IN EXCESS OF 70 KTS ACROSS PARTS OF THE OHIO VALLEY INTO THE LOWER GREAT LAKES...WILL CONTRIBUTE TO VERY STRONG DEEP LAYER WIND FIELDS AND SHEAR. IT ALSO APPEARS INCREASINGLY PROBABLE THAT THIS WILL COINCIDE WITH AN INFLUX OF SEASONABLY HIGH MOISTURE CONTENT AT LEAST AS FAR NORTH AND EAST AS THE LOWER OHIO VALLEY...CONTRIBUTING TO SUFFICIENT CAPE FOR VIGOROUS STORM DEVELOPMENT. SUPERCELLS WITH A RISK FOR TORNADOES WILL BE POSSIBLE...PARTICULARLY IN EARLY STAGES OF CONVECTIVE DEVELOPMENT...PERHAPS AS EARLY AS MID DAY ACROSS PARTS OF THE MIDDLE MISSISSIPPI INTO LOWER OHIO VALLEY VALLEY
EVENTUALLY...THOUGH...ACTIVITY PROBABLY WILL EVOLVE INTO A SQUALL
LINE WITH DAMAGING STRAIGHT-LINE WINDS BECOMING THE MOST PROMINENT
SEVERE THREAT.
Permanent link to this article: https://indywx.com/2013/11/14/heavy-rain-and-severe-outbreak-sunday/
Nov 13
No Secret Behind The Early Bitter Shots Of Air
As I write this, many Hoosiers are awaking to temperatures at downright bitter levels, despite the fact it’s only mid November. The official low here at IndyWx.com HQ was a frosty 18 degrees and a far cry from the normal low of 37.
The early season bitter air mass has even settled in across portions of the Deep South and Coastal Plain. Amazingly, snow was reported along the Carolina coastline last night (almost unheard of for mid November). Note the deep freeze penetrating far into the Deep South. My home town of Auburn, AL dipped to a frigid 27 degrees this morning. Again, very rare for so early in the season.
It’s my job to look at what is behind these expansive early season bitter attacks of air (by the way, another bitterly cold air mass is ahead next week). In my opinion, a lot of the early shots of impressive arctic air has to do with the widespread early snow and ice pack developing across the Northern Hemisphere. We wrote about this first back on October 17th and the snow and ice pack has only been growing since. The latest image shows a very impressive and vast snow and ice pack for so early in the season. As early season cold moves south into the Lower 48, it doesn’t have much time to modify as it passes over the growing early season snow pack.
As we look ahead, despite the weekend warm-up, another impressive shot of arctic air will plow into the Hoosier state early next week (perhaps even colder than this current air mass). The European forecast model, once again, shows temperatures 12-18 degrees below normal by early next week.
Temperatures currently are running well below normal in similar areas modeling is sticking the “heart” of the cold next week.
As we continue rumbling into the colder, snowier months ahead, one has to at least wonder what the overall impact of the early season expansive snow and ice cover during October and November will leave on the winter of 2013-2014…
Permanent link to this article: https://indywx.com/2013/11/13/no-secret-behind-the-early-bitter-shots-of-air/
Nov 10
Monday Forecast: Snow Develops By Evening
Updated 11.11.13 @ 8:30a
Zionsville, IN Despite some wind (top wind gusts this weekend reached around 30 MPH) and a chilly Sunday, the weekend was a beautiful one, complete with lots-o-sunshine! A more active time of things is ahead to kick off the work week. We discuss below…
Monday: Increasing cloudiness with PM rain showers transitioning to light snow (0.50″); 28/ 46
The day will dawn with some sunshine, but clouds will be on the increase and showers won’t be far behind. This is all part of the early season arctic cold front we’ve been talking about. We think showers (initially rain) arrive into north-central Indiana as early as the early to mid afternoon hours before pushing fairly rapidly south. It’s towards late afternoon/ early evening rain begins to transition to snow. Light snow will continue into the nighttime hours and potentially accumulate to around half an inch across most of central Indiana.
There are a couple of items we’ll have to monitor closely through the overnight and that’s the exact placement of what should be some impressive bands of lake effect snow streaming off Lake Michigan. While the more significant accumulations, upwards of half a foot for the Indiana snow belt, will remain well north of us, there is the chance a more concentrated band of snow could reach as far south to impact portions of north-central Indiana late Monday night into Tuesday morning and result in accumulations of an inch or two for localized communities. Again, this will have to be handled as a “NowCast” scenario and isn’t set in stone. If locally heavier snow accumulations do develop with the localized lake enhancement, the majority of this would be north of our immediate coverage area.
Temperatures will plummet Monday night into the lower to middle 20s on a gusty northwest wind. Needless to say, slick spots could develop on area roadways Monday night.
Tuesday: Scattered AM snow showers (localized 0.50″); 22/ 35
We’ll keep an eye to area radars Tuesday, particularly in the morning hours as scattered snow showers (potential lake enhanced snow for localized spots) continue. Conditions will be much more like winter than fall so plan to bundle up. In fact, temperatures will average close to 20 degrees below average for afternoon highs. Any lingering snow showers or flurries will begin to dissipate during the afternoon, paving way for a clear and very cold Tuesday night.
Wednesday: Sunny; 19/ 42
High pressure will be overhead Wednesday and help supply a day filled with sunshine, although it’ll remain MUCH colder than normal. We’ll awake to the upper teens followed by highs reaching the lower 40s Wednesday afternoon.
Thursday: Partly cloudy; 28/ 49
Temperatures will begin to moderate slowly Thursday as high pressure moves to our east. This will set the stage for a return southwesterly air flow and corresponding milder regime, albeit slowly. After yet another cold and frosty night, temperatures will make a run at 50 degrees Thursday afternoon.
Friday: Mostly cloudy; 35/ 49
A weak weather system will scoot through the region Friday and lead to an increase in cloud cover. Thinking, at least for now, has the area trying to recover from the cold, dry air mass in place so any sort of precipitation will, most likely, be tough to come by. That said, we’ll continue to monitor to see if we need to introduce a scattered light shower into our Friday forecast.
Saturday: Cloudy with developing light rain; (0.25″) 39/ 52
The early look at next weekend places the region under a southerly flow of air with moisture making a return north, potentially out ahead of a rather significant storm system we’ll have to deal with early next week. The end result will initially be a rather cloudy, gloomy time of things, including developing light rain Saturday.
Permanent link to this article: https://indywx.com/2013/11/10/monday-forecast-snow-develops-this-evening/
Nov 10
Video Update On Snow Accumulation & The Cold
Here’s a quick video update taking a look more closely at the forecast data for accumulating snow ahead Monday evening, as well as the impressive early season shot of cold…
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Permanent link to this article: https://indywx.com/2013/11/10/video-updated-on-snow-accumulation-the-cold/
Nov 06
Thursday Forecast: Eyeing Snow Next Week?
Updated 11.06.13 @ 10:26p Zionsville, IN For the most part, rainfall totals today have been under what model guidance suggested. For an area still wetter than normal, that’s not a…
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Permanent link to this article: https://indywx.com/2013/11/06/thursday-forecast-eyeing-snow-next-week/
Nov 05
Two Totally Different Solutions For Next Week!
I wanted to quickly post on two totally different scenarios for next week. Two of the more powerful forecast models we use to look into the mid-long range are in separate worlds when it comes to the weather pattern the middle to latter part of next week.
Here’s a look at the GFS upper air pattern:
Note the eastern ridging which would lead to well above normal temperatures during the middle to latter part of next week (by as much as 10 degrees above average), along with dry conditions.
HOWEVER, here’s a look at the European’s forecast upper air pattern late next week:
This would certainly be quite the significant storm for the Northeast, but the implications here are vastly different from that which the GFS shows above. Instead of warmth and dry conditions, we’d deal with highs in the middle 30s and overnight lows in the lower to middle 20s. Additionally, we’d also “enjoy” (okay, some folks would “enjoy”) snow showers and snow squalls the middle to latter portion of next week, as noted per the European below, including a lake Michigan connection.
Needless to say, we have a lot to sort out in the coming days. We’ll be here to do just that. Make it a great Tuesday!
Permanent link to this article: https://indywx.com/2013/11/05/two-totally-different-solutions-for-next-week/