Beau Dodson's WeatherTalk Blog

9 AM update

Wednesday Update:

 

Sorry for the later than usual update.   I have been looking over all of the available guidance concerning Thursday through Saturday’s weather.

 

I know many of you have been asking me about the weekend.  There are weddings, charity fun-runs, and more.  I do not have good news.

 

If you have outdoor plans for Friday or Saturday then have a strong plan B.  Rain is likely to occur.  Some of the rain could be heavy.  Lightning is possible, as well.

 

Let’s just start with the weekend.  Widespread rain is possible on both Friday and Saturday.  I know there are some big events.

 

To make matters worse, temperatures on Saturday will be in the 50’s and 60’s.  Gusty winds possible, as well.

 

I continue to lean towards the area of low pressure passing through Arkansas and then tracking into Kentucky and Tennessee.  Perhaps straddling the border. 

 

The EC guidance has been north of that track (ensembles), but I think it is wrong.  I am leaning towards a southern track.  No change in that idea. 

 

If that track verifies then we would be on the cool side of the cyclone.

 

Not the best forecast, but that is what we are working with.

 

Let’s break it down.

 

Today:

 

Fog has mixed out and that has left us with partly to mostly sunny sky conditions.  It will be warm today with highs into the 80’s.  WELL above normal.  Gusty winds, from time to time.  Southerly winds.  Nice day!

 

A couple of thunderstorms might develop over west Tennessee and western Kentucky.  Further east and southeast you drive the better the chance for a few storms.  Severe weather is not anticipated.

 

If storms form today they will produce lightning, heavy downpours, pea size hail, and 40 mph winds.  Storms would be brief.

 

Tonight:

 

Mostly clear and mild.  Lows mostly in the 60’s.

 

Thursday:

 

Partly sunny morning with a small chance for a shower or thunderstorm (less than 20% risk).

 

Clouds increase and lower during the afternoon and evening.  A line of showers and storms will form along a cold front entering our area from the north and west.

 

A few of the storms will produce locally heavy rain, frequent lightning, dime size hail, and 40 to 50 mph winds.  There is a small risk for severe weather (severe means quarter size hail and/or 60 mph winds).

 

Thursday night:

 

Showers and storms in the evening.  A few heavy downpours possible.  Locally strong storms.

 

The cold front stalls and becomes a stationary front near the Kentucky and Tennessee state line.

 

This will keep rain chances continuing into Thursday night over the southern half of our region.

 

That would include southern Missouri, western Kentucky, and western Tennessee.  Perhaps some chances for showers north of there, as well.

 

Better coverage will be south vs north.

 

Friday:

 

Front remains stationary, but eventually heads back northward as a warm front.

 

Widespread showers and storms could develop in waves across Oklahoma, Missouri, Arkansas, and then into our area.

 

Friday night: 

 

Breezy conditions.  Showers and thunderstorms likely over our area.  It may not rain all of the time, but there will be showers and storms on radar.

 

Saturday:

 

Widespread showers and thunderstorms.  Some heavy downpours possible.  Chilly temperatures north of the low pressure center.

 

Highs on Saturday may remain in the 50’s and 60’s.  Coolest readings north vs south.

 

If the low moves slightly further north then strong storms will be possible in the Missouri Bootheel into the Kentucky and Tennessee border area.  Monitor updates.

 

Saturday night:

 

Showers and storms will move eastward.  Cool conditions.  Wrap around clouds and spotty showers will continue into Sunday morning.  Breezy, at times.

 

Sunday:

 

Some wrap around clouds are likely to remain in the area.  I can’t rule out a shower during the first half of the day.  Cooler with highs in the 60’s.

 

Normal highs for this time of the year are around 65 to 70.

 

Monday and Tuesday:

 

Sun returns.  Highs in the upper 60’s and lower 70’s.

 

Another storm system next Wednesday ~ Friday.  Storms possible.

 

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Need to track the rain?

Interactive Weather Radar Page.  Choose the city nearest your location:  Click this link—

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This forecast update covers far southern Illinois, far southeast Missouri, and far western Kentucky. See the coverage map on the right side of the blog
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April 18, 2017
Tuesday Night Forecast Details:
Forecast: Partly cloudy.  A slight chance for evening storms over Kentucky and Tennessee.
Temperatures:  MO ~ 58 to 64   IL ~ 58 to 64    KY ~ 60 to 65     TN ~ 60 to 65
Winds: East winds becoming south and southeast at 4 to 8 mph.  Gusty winds from time to time.
My confidence in the forecast verifying: High.  This forecast should verify.
What impacts are anticipated from the weather? Wet roadways.  Perhaps lightning.
Is severe weather expected?  No.
The NWS defines severe weather as 58 mph winds or great, 1″ hail or larger, and/or tornadoes
What is the chance of precipitation?  MO ~ 10%  IL ~ 10%    KY ~ 20%   TN ~ 20%
Coverage of precipitation: Isolated
Should I cancel my outdoor plans?  No, but check radars.

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April 19, 2017
Wednesday Forecast Details
Forecast:  A mix of sun and clouds.  Warm for April. Isolated to scattered storms possible (mainly over KY/TN)
Temperatures:   MO ~  78 to 84     IL ~ 78 to 84     KY ~ 78 to 84     TN ~ 78 to 84
Winds:  South and southwest at 7 to 14 mph with gusts to 25 mph.
What impacts are anticipated from the weather? Wet roadways.  Lightning.
My confidence in the forecast verifying: High.  This forecast should verify.
Is severe weather expected?  No.
The NWS defines severe weather as 58 mph winds or great, 1″ hail or larger, and/or tornadoes
What is the chance of precipitation?  MO ~ 20%  IL ~ 20%   KY ~ 30%   TN ~ 30%
Coverage of precipitation:  Isolated to perhaps spotty
Should I cancel my outdoor plans?  No, but check radars
Sunrise will be at 6:12 a.m. and sunset will be at 7:33 p.m.

Wednesday Night Forecast Details:
Forecast: Partly cloudy.  Isolated storm possible (may remain completely dry).
Temperatures:  MO ~ 62 to 65   IL ~ 62 to 65     KY ~ 62 to 65     TN ~ 62 to 65
Winds: South and southwest at 6 to 12 mph.  Winds may become gusty overnight with gusts above 20 mph.
My confidence in the forecast verifying: Medium.  Some adjustments are possible.
What impacts are anticipated from the weather? Wet roadways.  Perhaps lightning.
Is severe weather expected?  No
The NWS defines severe weather as 58 mph winds or great, 1″ hail or larger, and/or tornadoes
What is the chance of precipitation?  MO ~ 10%  IL ~ 10%    KY ~ 20%   TN ~ 20%
Coverage of precipitation: Isolated (if anything at all)
Should I cancel my outdoor plans?  No, but check radars.

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April 20, 2017
Thursday Forecast Details
Forecast:  Cloudy.  An increasing chance for showers and thunderstorms.  Precipitation will move in from the north/northwest and spread south/southeast.  Some questions remain on coverage.
Temperatures:   MO ~  75 to 80     IL ~ 75 to 80     KY ~ 75 to 80     TN ~ 75 to 80
Winds:  South and southwest at 7 to 14 mph with gusts to 20 mph.
What impacts are anticipated from the weather? Wet roadways.  Lightning.  Monitor updates concerning strong storms.
My confidence in the forecast verifying: Medium.  Some adjustments are possible.
Is severe weather expected?  A few strong storms possible.
The NWS defines severe weather as 58 mph winds or great, 1″ hail or larger, and/or tornadoes
What is the chance of precipitation?  MO ~ 60%  IL ~ 60%   KY ~ 60%   TN ~ 60%
Coverage of precipitation:  Scattered to perhaps numerous.
Should I cancel my outdoor plans?  No, but monitor updated forecasts and radars.  Rain is likely during at least part of the day. 
Sunrise will be at 6:11 a.m. and sunset will be at 7:34 p.m.

Thursday Night Forecast Details:
Forecast: Partly to mostly cloudy.  A chance for showers and thunderstorms.
Temperatures:  MO ~ 48 to 54   IL ~ 48 to 54     KY ~ 50 to 55     TN ~ 50 to 55
Winds: Becoming west and then north and northwest at 4 to 8 mph with gusts to 15 mph.
My confidence in the forecast verifying: Medium.  Some adjustments are possible.
What impacts are anticipated from the weather? Wet roadways.  Perhaps lightning.
Is severe weather expected?  Monitor updates.
The NWS defines severe weather as 58 mph winds or great, 1″ hail or larger, and/or tornadoes
What is the chance of precipitation?  MO ~ 60%  IL ~ 60%    KY ~ 60%   TN ~ 60%
Coverage of precipitation: Perhaps numerous.
Should I cancel my outdoor plans?  Monitor updates.

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April 21, 2017
Friday Forecast Details
Forecast:  Increasing clouds.  Cooler.   A chance for showers and some thunderstorms.
Temperatures:   MO ~  58 to 64     IL ~ 58 to 64     KY ~ 60 to 65     TN ~ 60 to 65
Winds:  Northeast and east at 8 to 16 mph.  Gusty, at times.
What impacts are anticipated from the weather? Wet roadways.  Lightning.
My confidence in the forecast verifying: Medium.  Some adjustments are possible.
Is severe weather expected?  No
The NWS defines severe weather as 58 mph winds or great, 1″ hail or larger, and/or tornadoes
What is the chance of precipitation?  MO ~ 60%  IL ~ 50%   KY ~ 50%   TN ~ 50%
Coverage of precipitation:  Scattered to perhaps numerous.
Should I cancel my outdoor plans?  Monitor updates.  Rain is possible.
Sunrise will be at 6:10 a.m. and sunset will be at 7:35 p.m.

Friday Night Forecast Details:
Forecast: Cloudy.  Showers and thunderstorms likely.  Temperatures may rise late at night.
Temperatures:  MO ~ 52 to 60   IL ~ 52 to 58     KY ~ 54 to 60     TN ~ 54 to 60
Winds: East at 8 to 16 mph with gusts above 20 mph.
My confidence in the forecast verifying: Medium.  Some adjustments are possible.
What impacts are anticipated from the weather? Wet roadways.  Perhaps lightning.
Is severe weather expected?  No
The NWS defines severe weather as 58 mph winds or great, 1″ hail or larger, and/or tornadoes
What is the chance of precipitation?  MO ~ 60%  IL ~ 60%    KY ~ 60%   TN ~ 60%
Coverage of precipitation: Perhaps numerous.
Should I cancel my outdoor plans?  Monitor updates.

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April 22, 2017
Saturday Forecast Details
Forecast:  Cloudy.  Breezy.  Showers and thunderstorms likely.  Locally heavy rain possible.  WIDE range of temperatures from north to south.
Temperatures:   MO ~  56 to 74   IL ~ 56 to 75     KY ~ 60 to 72     TN ~ 68 to 74
Winds:  Winds will vary depending on your location in the area in relation to the track of the area of low pressure.  North of the low the winds will be out of the east.  South of the low winds will be from the south.  Wind speeds of 15 to 30 mph.
What impacts are anticipated from the weather? Wet roadways.  Lightning.  Downpours.  Monitor updates concerning thunderstorms.
My confidence in the forecast verifying: Medium.  Some adjustments are possible.
Is severe weather expected?  Monitor updates.  If the low tracks far enough north then some strong storms will be possible.
The NWS defines severe weather as 58 mph winds or great, 1″ hail or larger, and/or tornadoes
What is the chance of precipitation?  MO ~ 70%    IL ~ 70%    KY ~ 70%    TN ~ 70%
Coverage of precipitation: Widespread
Should I cancel my outdoor plans?  Have alternative plans.  At this time, rain appears likely.  Plan for rain and hope for the best. 
Sunrise will be at 6:09 a.m. and sunset will be at 7:36 p.m.

Saturday Night Forecast Details:
Forecast: Cloudy.  Showers and thunderstorms likely.
Temperatures:  MO ~ 48 to 55   IL ~ 48 to 55     KY ~ 50 to 56     TN ~ 52 to 56
Winds: Winds  becoming north and northwest at 10 to 20 mph.  Gusty winds.
My confidence in the forecast verifying: Medium.  Some adjustments are possible.
What impacts are anticipated from the weather? Wet roadways.  Perhaps lightning.
Is severe weather expected?  No
The NWS defines severe weather as 58 mph winds or great, 1″ hail or larger, and/or tornadoes
What is the chance of precipitation?  MO ~ 60%  IL ~ 60%    KY ~ 60%   TN ~ 60%
Coverage of precipitation: Perhaps numerous.
Should I cancel my outdoor plans?  Have alternative plans.  It may rain.

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Don’t forget to check out the Southern Illinois Weather Observatory web-site for weather maps, tower cams, scanner feeds, radars, and much more!  Click here

An explanation of what is happening in the atmosphere over the coming day

Severe thunderstorm outlook.

Remember that a severe thunderstorm is defined as a thunderstorm that produces 60 mph winds or higher, quarter size hail or larger, and/or a tornado.

Tuesday  night:  An isolated thunderstorm possible.  Most of the area will remain dry.  Severe weather is not anticipated

Wednesday and Wednesday night:  A slight chance for a thunderstorm in west Tennessee and areas to the east of LBL  Even smaller chances, elsewhere.  Lightning is the concern.

Thursday and Thursday night: A cold front moves into the local area.  A band of showers and thunderstorms will accompany the front.  Wind fields will be stronger with this system compared to the last.  I can’t completely rule out severe weather, but the chances will probably be small.  Lightning will be a concern for outdoor events.  Monitor updates.

Friday through Sunday:  Another system will move through the area on Friday into the weekend.  The track of the area of low pressure will be key to our weather conditions.  If the low tracks to the north then strong storms are possible.  If the low tracks to our south then thunderstorms are possible, but severe weather concerns would be minimal.

Monitor updates concerning the weekend storm system.

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Weather analysis for the next few days:

Tuesday night into Wednesday night:

Mostly dry weather will cover the area through Wednesday night.  Yes, there will be small chances for showers and thunderstorms over western Kentucky and western Tennessee, but most areas should remain dry.

A mix of sun and clouds is anticipated on Wednesday.  Some of the data shows mostly clouds.  It will be warmer on Wednesday.  High temperatures will likely top out in the 80’s by the afternoon hours.  Well above normal.  Normal highs are still between 65 and 70.

If a thunderstorm develops on Wednesday then lightning would be the primary concern.  I am not anticipating severe weather.  Again, most areas will remain dry.

Here is the temperature anomaly map for Wednesday.  How many degrees above normal will temperatures be?

Thursday into the weekend:

An active pattern is unfolding for Thursday, Friday, and Saturday.  If you have outdoor plans, during this time period, then you will want to monitor updated information.  Several periods of showers and storms are likely to occur.  Some of the rain will be locally heavy.

A cold front will move into the region on Thursday and Thursday night.  This front will move in from the north and spread southward.

Showers and thunderstorms are forecast to develop along and ahead of the cold front.  Some of the storms could produce gusty winds, lightning, small hail, and downpours.

Here is the forecast rainfall totals for Thursday (from the NAM guidance).  Remember, this is just one models opinion on what might happen.  Models vary on totals.

Rainfall totals on Thursday will likely vary.  If thunderstorms form then locally heavier totals will occur.  At this time, I will forecast 0.25″ to 0.50″ of rain.  Again, thunderstorms can easily double those numbers.

If some of the guidance is correct then a few spots may miss out on measurable rainfall.  Let’s monitor updates.  Plan on precipitation showing up on radar Thursday into Thursday night.

NAM

PWAT values will be quite high on Thursday.  PWAT is a measure of moisture in the entire atmosphere.  The higher the PWAT numbers, the greater the chance for locally heavy downpours.

What are PWAT values?  Great question!  Here is the answer – Link

PWAT values for 1 pm on Thursday.  You can see how the higher PWAT values pool ahead of the front.  The darker colors are the higher numbers.

See the lighter colors north of St Louis?  That is behind the cold front.  Moisture pools ahead of the cold front.  It is like a bulldozer in the atmosphere.

4 pm Thursday PWAT value map

These numbers are in the 1.5 to 1.8″ range.  Those are high numbers for April.

Dew points ahead of the cold front will pool well into the 60’s.  Remember, dew points of 58 and above are what I look for when I think about stronger storms.

Dew points alone won’t produce severe weather.  They will, however, mean an increasing chance for heavy downpours.

Here is the dew point map for 1 pm on Thursday.  Lot of moisture.  It will feel humid.

Dew point is a measure of moisture in the lower atmosphere (the surface).

Let’s look at future-cast radar for Thursday.  There remains some questions above precipitation coverage and intensity.

I suspect a band of showers and thunderstorms will form along the front.

Here is the 1 pm future-cast radar from the NAM model.  This is what radar MIGHT look like on Thursday.

The showers and storms will move south and east through the area.

4 pm Thursday

7 pm Thursday

Here is the higher resolution future-cast radar for 4 pm and 7 pm Thursday.  Timing is a bit different.

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The front should stall just to our south on Thursday night.  The front will then return as a warm front on Friday.

Some showers and storms may redevelop ahead (north) of the warm front on Thursday night into Friday.

The front moves back north as a warm front on Friday.

Future-cast radar shows that nicely.

Here is the 10 am future-cast radar from the NAM.  This is what radar might look like on Friday morning.  The band would move northeast through the area.

Weekend system:

Locally heavy rain and gusty winds.

Another system (much larger system) will push into the area Friday night into Saturday night.

An area of low pressure will develop over Oklahoma and Texas on Friday and Friday night.  This low will then track into Arkansas on Saturday.  The low will then track into Kentucky/Tennessee on Saturday afternoon and evening.

The track of the low is still questionable, but I am leaning towards the above mentioned track.  There is still time for adjustments in this forecast.

The track of the low is important.  Why is it important?  If you are north and west of the low then the atmosphere is not as unstable.  Rain will develop.  Rain may be locally heavy.  Gusty winds, as well.

The north and west side of the low is considered the cool sector.

The warm sector, on the other hand, is to the east and southeast of the area of low pressure.

Remember, low pressure rotates counterclockwise.  Ahead of the low you will experience southerly winds.  That typically means warmer air.

Check out the large temperature spread on Saturday.  You can figure out where the low is.

If the low tracks over our area then we can expect rain and some storms.  The greatest severe threat, however, would be to the east and southeast of the low.

If the low tracks to our north, then that places us solidly in the warm sector.  That spells heavier thunderstorms.  It can also mean severe thunderstorms.

At this time, I am forecasting the low to pass either just to our south or perhaps into west Kentucky and Tennessee.  That would mean most of the severe weather would remain to our south and east.

Confidence on the track of the low is now medium.  There could be adjustments.  Thus, monitor updates.

Here is an example of low pressure, warm front, and cold front.
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Rain and gusty winds will develop on Friday night and especially on Saturday.  If the low tracks as anticipated, then widespread rain will occur.  It is possible that it could rain most of Saturday.

If you have outdoor plans Friday into Saturday night, then monitor updates.

Rainfall totals could range from 0.80″ to 1.60″ with locally higher totals possible.  The track of the low will also determine how much rain falls.

Let’s look at some data-sets.

Here is the EC ensembles.  This shows you will it wants to track the area of low pressure.  The cluster represents one run of the model.  The model is run repeatedly.  If the lows are tightly clustered together, then that means a higher confidence level in the eventual outcome.

Some of the lows are to our north, some to our south, and some right on top of us.

The GFS guidance tracks the low through western Tennessee.

Here is the future-cast map from the GFS.  This is for 1 pm on Saturday.  You can see the closed isobars (equal lines of pressure) over SW MO and NW AR.  That is the center of the low pressure.  Tight isobars over our area.  Windy conditions.

Green represents rain.

This next map is for 7 pm Saturday

The low is near Poplar Bluff.

This next image is for 1 am on Sunday

The GFS is tracking the low over our area.

This last image is for CAPE

CAPE is a measure of energy.  Energy for thunderstorms to tap into.  Remember, the most unstable air is normally to the east and southeast/south of the area of low pressure.

The colors represent CAPE.  Notice how they increase in the areas I mentioned.

This will need to be closely monitored.

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