Hurricane Ida is now moving into the open waters of the Gulf of Mexico as a powerful category 2 storm.  As you can see in the picture posted below, the center of the storm is tightly wrapped however there is some good news.  For starters the eye can not be seen and the storm looks slightly lopsided with most of the convection occurring on the western side.  Also, take a close look at the blue lines.  Those are surface temperatures of the water.  Notice how as the system continues to move northward it will move into some slightly cooler water.  This should keep the storm from developing into a major hurricane (Cat 3 or above).  Also even cooler temperatures and some wind shear (fast moving winds higher in the atmosphere) should also play there part to weaken the system before it makes landfall.

Right now the official hurricane track from the National Hurricane Center keeps the system well to our south.  While long range predictions can be hard to make, I also posted the most recent run of the NAM weather model.  That model shows the system moving farther north bringing heavy rain to the southern and central Appalachian Mountains.  While I think the chances of us here seeing rain the remnants of Ida are pretty small… it is a possibility we will have to watch out for as we head towards midweek.

For the last few days we have been enjoying some sun, and finally some warmer temperatures!  But it doesn’t look as if they are going to last much longer.  A large system out in the plains is slowly heading this way.  While we are already seeing the clouds, the rain will be soon to follow.  Between our computer model and the NAM (both pictured below) i looks as if the heaviest rain will be off to our west, with most of our area seeing between .5 to1.5 inches of rain.  While the heaviest rain looks like it will fall late Thursday night and Friday morning… shower will continue throughout the day and even the majority of Saturday.  High temperatures will also drop… most locations will struggle to get into the lower 50 come Saturday and Sunday afternoon.  Stay warm…. and Dry!

Check out the Calendar above…   If you look closely you will see only one day in October with a positive number… and is only a one above.  That means that we have had only one day this month with above average temperatures.  Over the last eight days 6 where over ten degrees below normal.  So far this month, it has been cold.  But thankfully nothing more then a couple flakes of wet snow have come with these abysmal temperatures.

Twenty years ago today we had a record snowfall of 4.8 inches.  While a snow like that is rare for the area they do happen.  Thankfully for us this cold weather is beginning to move out.  A ridge is beginning to build in which will get our temperatures back up to perhaps even surpassing our average highs.

Generally July, August, and most of September tend to be pretty cool as most of the northern hemisphere is mild to warm and there is little relatively little contrast in temperature from Canada to Mexico.  But as the fall presses on and the daylight hours fade, enough cool air builds up to start causing a little action across the states.  That’s exactly what we have going on tonight.

Our first powerful cold front is taking shape in the plains and is rapidly headed this way.

This line of showers and thunderstorms out to our west is the first beast we have to face tonight.  According to the S.P.C.  (Storm Prediction Center).  We are under a slight risk for severe weather tonight.

While I feel the showers and thunderstorms that move the the area will be relatively weak (little lightning, low chance for hail… rain only moderate to heavy for a very short period.)  The severe threat is with the wind.  Since winds tend to be a little faster higher up in the atmosphere, these showers / storms tonight have the potential to bring some of these higher winds down to the surface.  (So this may be one of those scenarios where we have a severe thunderstorm warning issued when the system does not even contain lightning!).

Then you have the winds directly behind the system.  At 9pm on Sunday evening the gusts have decreased just a hair.  But you can clearly see the front where the wind picks up and the barbs change to the Northwest.  Those winds will be enough to throw some lawn furnature and a few garbage cans around, perhaps even bring down a few old trees.

As the low pressure moves this way it looks as if those winds will be high and steady through much of Monday, so the weather service issued a wind advisory for us with a few high wind warnings up around the Great Lakes.

Look for winds to gradually decrease as we head through the night time hours on Monday… but still on the breezy side Tuesday.

Then to top it all off temperatures will struggle to get out of the 50s Tuesday and Wednesday.  If we see enough clearing Tuesday or Wednesday night some locations may even see their first 30s of the season!

-Erik Zarnitz

While it isn’t very likely… it’s still something we are all keeping a close eye on.   And if you’ve been watching the US Open already know about it.  It’s the low pressure system just off the coast of Delaware and New Jersey.  These systems normally move off to the north and east… (this common movement and the strong northeasterly winds at ground levelis actually why these kinds of systems are called Nor’easters!)

However in this case it looks as if the system is going to weaken and retrograde west… basically meaning that it may get close enough to the region to give us a chance for some rain on Saturday.

While computer models are starting to indicate that this will happen.  In my experience it may get close, even effect eastern Ohio.  But for it to get this far west of the mountains is a real task.  We’ll still have to watch it, and that’s why I put in a 10% chance for rain on Saturday… but I still don’t buy it just yet.

This time of year is pretty quiet in the Miami Valley.  The heat (not this year!) begins to loosen its grip and slightly cool, the severe storms of the spring are past us, and the winter snows are still months away.  However this year with our cool summer the only type of advisory anywhere close to us is a Frost Advisory.  Not to normal for August but still a sign of whats to come in just another month or two for us.

While the weather remains tranquil in our part of the country things are beginning to pop to our south.  In the Atlantic an area of disturbed weather has been identified as a “probable” area for development.

While the system is pretty far south for a tropical cyclone it appears to have a trajectory to the northwest.  With any luck this system will take the same path as Bill and stay out to sea.  The only problem is that the trough that protected the eastern seaboard from Danny and Bill looks like it will break down by the end of the week.  With the water in the Carribean still extremely warm this system will have to be watch closely. 

In the Pacific Hurricane Jimena has its eye set on the Gulf of California.  While the system is a powerful category four storm the mountains around the Gulf will weaken this system before it makes it into the US.  The only problem maybe an enhancement of the Monsoons over the southwest.  Areas in New Mexico and Arizona could see some solid moisture from this system leading to possible flash flooding later this week.

Tropical storm Claudette is about to make landfall in Florida and as of 9pm on Sunday night its top winds are 45 knots or about 50 mph. 

While winds and storm surge from the ocean aren’t typically large problems with a system of this magnitude, flooding rain is.  The circulation brings in deep tropical moisture and if it is a slow enough mover can cause extreme flooding.

Right now the path for this system takes it into the Tennessee Valley.  Even though the system will be much weaker then it is currently, with the amount of humidity around and temperatures generally in the 80’s the lingering left over circulation will be a bulls eye for heavy rain.  While the path from the National Hurricane Center stops at Tuesday 1Am we can extrapolate a little further.

Usually a system of this size will follow the 500mb flow.  As you can see from the wind barbs this system has some forcing to the west pushing the low north and east.  Right now I would put Kentucky and West Virgina as the main track for the remnants of Claudette but we can’t be ruled out of the equation.

Things can change however… with no real strong current in place right now this system may decide to twist and turn a little more along the Gulf before moving northwards.  So continue to watch the forecast!  We’ll have to continue to monitor this situation.

While much of the west coast has been breaking record highs left and right (Portland, Seattle, Spokane),  We here in the east have been dealing with the exact opposite… Chilly temperatures!  The numbers are in for the month of July and while we got close… we were just off of the mark for the number one spot of coldest July on record.

Here are the numbers from Dayton….   The numbers are a little different from what we were posting about a week ago, the records however have now been corrected.

1.  69.2  1947

2.  69.6  2009

3.  69.9  1984

4.  71.6  2007

5.  71.9 2000

Over all this July came in as the second coolest on record.  The reason for it… a large east coast trough, you can see it in the picture below.

With the jet stream to our south cooler air from Canada has had an easy time getting down into the Midwest and Northeast.  While this pattern will continue to hold firm this week… there are a few bubbles that will briefly push the jet northward for a few days.  The first will come on Monday and Tuesday allowing temperatures to get to about average.   The second will take place Friday and go into the weekend.  Right now it looks like some of the warmest air this season could push numbers as high as the lower 90s by the time Saturday and Sunday roll around.  Of course forecasts can change… but it looks like some August heat is on the way.

Soggy, rainy July day.

Welcome to Seattle…. I mean Dayton!  Overall this summer has been cool, but for the year we are still below average when it comes to rainfall.  So while we may want some warmer temperatures the rain is still nice.  Wednesday around 9:10 am this is what the radar looked like.  Nothing really heavy… but a nice swath of steady rain.  The kind that the soil can really absorb.  Often times in the summer we will see short bursts of heavy rain with long periods of dry weather.  This kind of precipitation doesn’t help out our gardens, farms and yards to much as most of the rain runs off into streams and rivers.  What we are getting today… slow and steady, really helps the soil and all the plants around.

I posted a few of the model runs below to give you a better idea of how much rain will fall.  The NAM has scaled things back slighly…. but as you can see the GFS is still shooting for a solid 1.5 to 2 inches of rain.  Personally… think 2 inches is a little much with this system… but if thunderstorms form this afternoon you cant even rule that out.  So for the Miami Valley it looks like a solid 1-2 inches of rain!  Enjoy

An upper level low is the reason temperatures have been so cool all week… its also the reason why July 4th was so cool with rain.  However temperatures look to get much warmer as we head through the week as our pattern begins to reverse shoving a ridge right into the heart of the United States.

Below is a posting of the 2oomb maps showing the location of the Jetstream by Thursday evening.  While it has moved to our north by this point it is close enough to let in some much warmer weather.  the 850 mb chart also has a plot of temperatures showing how the warmer air is working in aloft.

The raw data is posted above…. posted below is the 850 temperature chart with some embellishments.

I circled Ohio (in black) so that it would be a little easier to see… but that huge ridge in the middle of the country is going to gradually build in.  With that system humidity levels will rise and temperatures will warm back into the upper 80’s and low 90s.  Right now the models only have the heat building in temporarily with another cool front moving through by next weekend, but the further we get into July and August the shorter our cool downs will be.

Last week temperatures in the upper 80s and low 90s kept air conditioners humming across the Miami Valley but this week, whether your a fan of summer or not, temperatures will break.  The reason?  an upper level low… but it isn’t all peaches and cream.  Every once in a while a set up like this can breed strong to even severe storms.

Here is why.  An upper level low is pressing the jetstream south of our area.  While that will bring in cooler temperatures and drier air it also lowers the temperature in which a parcel (imaginary balloon of air) needs to rise too in order to go up (thats how clouds form, rising air). 

With plenty of cold air around in the upper levels of the atmosphere temperatures in the mid to upper 70s will be all that we need to get those afternoon clouds going and as the low moves further south on Wednesday the chances for those clouds, showers and thunderstorms will dramatically rise.  Since the air is cooler then normal, hail can form in much weaker showers/thunderstorms.  So perhaps in a normal situation this time of your you would need a 30,000 foot tall storm to create some 1 inch hail, with so much cool air around a 20,000 foot tall storm can do the same.  Also with winds at the surface and aloft generally out of the same direction, straight line winds could also be a concern.

Another important factor to watch will be weak little boundaries circulating around the upper level low.  These can also enchance rotation leading to stronger storms and in some cases tornadoes.  So while temperatures may be cooler then average if we see enough sun in the morning conditions may be right for some pop-up severe.

This temperature profile of the United States also give you a good idea of whats going on. (by the way these temperatures are in Celsius).  Last week  850mb temperatures varried from 18 to 21C.  This week come Tuesday and Wednesday they will be close to 8-10C.

Cooler… yes.  Severe weather free…  possibly not.  One way or another enjoy the Summer time version of the January thaw….  or the June cool down!

A little meso low spun up along our warm front leading to some very heavy rain.  Rainfall rates greater then 2 inches an hour fell across much of the Miami Valley.  While no official flood advisories or flood warnings were issued places like Union and Bellbrook were inundated with over 1.5 inches of rain in 2 hours.  Here are some of the totals.

Here is what the Storm Prediction Center has posted for us as of Monday night..

SPC keeps most of the severe weather to our south… with a slight risk for extreme southern Ohio.  While I agree the best threat for severe weather is south of here, I think we will have enough instability to get a few showers and storms that could be on the severe side as well by the time Tuesday evening rolls around.

Here is what the NAM and GFS have to say…

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Both models are showing heavy rain building with a shortwave Tuesday evening and early Wednesday morning… that means we will have to be on our toes for possible severe weather.   Look for SPC to adjust that slight risk further north on Tuesday morning.

With 2-3 inches of rain falling in some areas Thursday night flooding on area streets was quite common but in some areas front lawns turned into small lakes!  Take a look at the pictures below!

These pictures are from Germantown and Clayton Oh… plenty of rain.  Now if we could only see some sun!  I’m sure there are plenty of garden that need to dry out and lawns that need to be mowed!

Here are just a few of the Hail pictures that we used on the air earlier this week!  Between the strong storms morning morning, Hail and severe weather Tuesday afternoon and steady rains Wednesday we are finally getting a break.

Speaking of rain.. here are some of the rainfall totals from Wednesday… most spots coming in with .25 to .5 inches.  Just enough rain to perk up those flowers and green up the grass.

Over the next few days High pressure will dominate bringing perfect late spring weather for the weekend!  And dont forget the Strawberry Festival up in Troy!

A strong cold front moved through the Maimi Valley Tuesday afternoon.  With surface winds and winds aloft on the weak side long lived super cells were not possible… but one cell popped up over Preble county prompting a tornado warning and dropping 2.00 to 2.5 inch hail across the county.

Here is a link to some more of the pictures posted on our site.

http://www.wdtn.com/dpp/weather/WDTN_Severe_Weather_Pictures_June_2

Interesting weather on Sunday afternoon.  High clouds helped keep temperatures in check during the afternoon but we were soooo close to getting some rain.

Check out Live doppler 2x.  This first image is from about 6pm

There are a few showers on the map, but is more important is the outflow boundary.  You can just make it out in Central Greene and Clark counties.  When a storm begins to die, the cool damp within the storm pours towards the ground and then spreads out.  Sometimes these “out-flow” boundaries are enough to get more storms going.

The picture above is only around one hour later.  Sunday night that wasn’t enough… but if we see the same conditions tomorrow expect some more action.  Temperatures higher up in the atmosphere actually acted like a cap holding back these storms.  On Monday temperatures aloft will actually be a little cooler… allowing for a few more storms to pop up.

Get ready for a cold night!  All of the elements are in place to set some record lows… some frost is even possible.

This weatherbug camera image pretty much tells the entire story.  Skies are clear… which means the heat of the day can easily escape out into space.  The winds which were between about 10-20 mph are backing off with the sunset.  The big one is actually the dew point.  Water in the air acts like a huge moderator with temperature.  When it gets really humid, even with clear skies, temperatures are very warm.  Just think about those warm muggy nights in the middle of July!  When the air is dry, things bounce all over the place… which is why deserts tend to have such a HUGE diurnal (between day and night)  range.  Super hot during the day… and very chilly at night.  With high pressure over head and some extremely dry air our temperatures will bounce all over the place as well with lows in the 30s and low 40s both Monday and Tuesday morning.  When Wednesday rolls around we will have more of a southerly flow in place bringing in some more humidity.

With conditions almost perfect… we do have a chance of breaking the record low for Monday morning.  Right now I’m forecasting a low of 34 but it is very possible temperatures can be slightly cooler.  This is where microscale features come into play.  If you are surrounded by trees, buildings or close to a lake… better shot temperatures will stay a little warmer.  If your out in the open or in a valley… better shot temperatures will be a little colder.

If you have a chance post some of your morning lows here!  I’m sure Jamie could use them!

Temperatures this weekend were pretty amazing…  Highs on both Saturday and Sunday rocketed into the mid 80’s.  While the humidity remained fairly low….

But when ever the wind is cranking… you know a storm system is close by…  First the wind lets talk about the wind.  Su Berry was kind enough to send in this picture from the OSU game on Saturday. (Awesome pic by the way!)

Winds during the afternoon on both Saturday and Sunday gusted into the low 30s with sustained winds much of the day at about 20.  As soon as the sun set and temperatures began to cool the wind began to lift.  It was still around… just a little higher in the atmosphere.   Here are some wind observations from about 9pm on Sunday.  The peak wind gusts from the day are on the right… the current wind speeds in the center.  Just 30 minutes after sunset the winds almost completely backed off!

The reason for all the wind… and warmth is that powerful area of High pressure off to our east.  This is a fairly common pattern during the summer, but it can’t last very long this time of year. 

Where the High pressure (or sinking air) is a little weaker… storms tend to form, and thats exactly whats going on from Texas northward to Wisconsin.  In fact the storms are so explosive… the storm prediction center issued a “High Risk” for Sunday… a title reserved mostly for Tornado Outbreaks.  Looks like the brunt of the action will occur in North Texas through OK and Kansas.

Now the big question… as high pressure slides off to the east, will we see the same severe weather here?  Right now it looks like as the system works east this system will loose some steam… but the most important factor seems to be the time of day.  The NAM model has the cold front gradually pushing through on Tuesday morning.

The GFS stalls the front a little longer and has it come through early afternoon on Tuesday.  With little forcing, the time of day is critical… if it slides through 4am – 2pm (which seems most likely) we will just see some showers with a few isolated thunderstorms.  However if the front gets delayed further… 4pm and on… we will have to be prepared for some strong storms.

Pretty amazing how this weekend turned out…  rainy and cold for most of last week, then the sun pops out for the weekend…. and now its going to hide for a few more days.

It looks like  our next system will pretty much have the same track as the low that moved through early last week.  We’ll be on the cool, cloudy and rainy side of the warm front, keeping our chances for severe weather pretty low.

Here is the outlook from the Storms Prediction Center out of Norman Oklahoma.  While we will have the possibility of some scattered thunderstorms there isn’t a very high risk that we will have any organized severe weather.  Most of that should stay to our south and west.  Since the low will be moving right on top of us… there is plenty of spin in the atmosphere but it will be the convection that will be lacking. 

It doesn’t look like this system offers us to many things to be worried about.  Looking at the precipitation forecast totals for the 60 hour period numbers to be around 1.5 inches over Monday and Tuesday.  Wet, yes… but manageable.