Weather forecasting question...

[The Tradition]

How do you tell from a weather forecast whether dew will form in the morning? I know there's the "dew point" based on a combination of relative humidity and temperature (and I'm sure wind plays a part), but it's a rather obscure prediction featured in weather forecasts, and I'm not sure if it means dew will form if temps drop above or below the dew point?

Basically, I just want to know if my car will be wet in the morning if I park it outside.

TIA.

 

[IANDFAN]

Answer

 

[The Tradition]

Answer

That's great except it doesn't tell me how to tell if there will be dew tomorrow morning from what I can glean from weather.com.

 

[QChawks]

I bet she knows

 

[TJ8869]

I bet she knows

My occluded front is now stalled over the Dakotas.

 

[IANDFAN]

That's great except it doesn't tell me how to tell if there will be dew tomorrow morning from what I can glean from weather.com.

That's great except it doesn't tell me how to tell if there will be dew tomorrow morning from what I can glean from weather.com.

If you go to weatherunderground.com it will show you what the temperature and dew point will be hour by hour.

 

[Kelsers]

That's great except it doesn't tell me how to tell if there will be dew tomorrow morning from what I can glean from weather.com.

Can you read? It's in the link.

 

[The Tradition]

If you go to weatherunderground.com it will show you what the temperature and dew point will be hour by hour.

Okay, now we're getting somewhere! So that tells me that the ambient temperature will not fall below the dew point tonight! So to be clear, that means there WILL NOT be any dew on my car tomorrow?

 

[Fan In Black]

I don't know

 

[Mayland]

That's great except it doesn't tell me how to tell if there will be dew tomorrow morning from what I can glean from weather.com.

Temperature can never fall below the dew point. Dew point temperature is much less dynamic than air temperature, so if you look at your hourly forecast before you go to bed and if at any time those two are equal you will definitely have dew.
Also important to note that at night, especially cloudless and calm nights, the surface will be colder than the measured air temp, which is measured 5 feet off the ground. So even if air temp is not predicted to reach dew point temp, the surface may hit that temp, so you could still have dew form.

 

[The Tradition]

Temperature can never fall below the dew point. Dew point temperature is much less dynamic than air temperature, so if you look at your hourly forecast before you go to bed and if at any time those two are equal you will definitely have dew.
Also important to note that at night, especially cloudless and calm nights, the surface will be colder than the measured air temp, which is measured 5 feet off the ground. So even if air temp is not predicted to reach dew point temp, the surface may hit that temp, so you could still have dew form.

THANK YOU!

See? GIAHROT can be educational AND helpful.

 

[Mayland]

THANK YOU!

See? GIAHROT can be educational AND helpful.

I took micro-climatology in college; one of the coolest classes I ever had. My job is pretty dependent on the weather, so I use that info a lot.

 

[The Tradition]

I took micro-climatology in college; one of the coolest classes I ever had. My job is pretty dependent on the weather, so I use that info a lot.

So based on your guidance, the forecast on wunderground.com says that we'll get real close in the wee hours tomorrow, but dew should not form (52 temp.; 48 dew point).

But the whole "car is higher than the ground" part leads me to believe I'm too close for comfort?

 

[IANDFAN]

Okay, now we're getting somewhere! So that tells me that the ambient temperature will not fall below the dew point tonight! So to be clear, that means there WILL NOT be any dew on my car tomorrow?

According to the forecast 😄. The closer they are the more likely.

 

[bagdropper]

You do realize, your new car will get wet. You live in Florida, not Arizona.

Time to get over it.

 

[Kelsers]

Okay, now we're getting somewhere! So that tells me that the ambient temperature will not fall below the dew point tonight! So to be clear, that means there WILL NOT be any dew on my car tomorrow?

It's all included in weather.com

 

[Mayland]

So based on your guidance, the forecast on wunderground.com says that we'll get real close in the wee hours tomorrow, but dew should not form (52 temp.; 48 dew point).

But the whole "car is higher than the ground" part leads me to believe I'm too close for comfort?

Your car is exactly like the ground surface in this instance. The surface of your car will cool at a faster rate than the air. My guess is your car’s getting wet.

 

[Mayland]

So based on your guidance, the forecast on wunderground.com says that we'll get real close in the wee hours tomorrow, but dew should not form (52 temp.; 48 dew point).

But the whole "car is higher than the ground" part leads me to believe I'm too close for comfort?

I should have asked; is it forecast to be cloudy and/or windy (like 5 mph or more) there tonight?

 

[Moral]

I bet she knows

 

[Kelsers]

I should have asked; is it forecast to be cloudy and/or windy (like 5 mph or more) there tonight?

Why would cloudy matter?

 

[Mayland]

Why would cloudy matter?

Surfaces cool by emitting long wave radiation. This is one of the tenets of global warming. CO2 absorbs this long wave radiation and prevents it from escaping to space. This heat is essentially ‘trapped’ and can be emitted back to Earth. Clouds act the same way, except much more efficiently. Clouds absorb this long wave radiation and have the potential to emit it back to earth. Same concept as covering plants with a piece of plastic in early spring and late fall to prevent them from freezing.

 

[Mayland]

Why would cloudy matter?

Also, csb time. About 6-7 years ago it was forecast to be about 31 degrees or so in early September. I live in north central ND and believe it or not we grow a decent amount of soybeans. Even the early maturing varieties we grow would have been susceptible to this frost and experienced a pretty severe yield hit. What the forecasters missed was cloud cover. It was cloudy most of the night; the clouds started to move out from west to east, iow areas to the west saw cloud cover move out about 6 in the morning, areas to the east it didn’t happen until after sunrise when the sun started to heat the earths surface again. You could almost draw a line where the cloud cover moved out ‘too soon’ and those areas saw a killing frost (at least on soybeans).
It was amazing how a degree (or a fraction of a degree) could have that much of an impact.

 

[Mayland]

How do you tell from a weather forecast whether dew will form in the morning? I know there's the "dew point" based on a combination of relative humidity and temperature (and I'm sure wind plays a part), but it's a rather obscure prediction featured in weather forecasts, and I'm not sure if it means dew will form if temps drop above or below the dew point?

Basically, I just want to know if my car will be wet in the morning if I park it outside.

TIA.

Well? The entire GIAOT community is on the edge of their seats wondering if your car had dew this morning.

 

[HROT]

America’s (and sexually inadequate men) lamest game show: Is it wet?

 

[Hawk_4shur]

Cool thread.

Now do fog.

 

[alaskanseminole]

How do you tell from a weather forecast whether dew will form in the morning? I know there's the "dew point" based on a combination of relative humidity and temperature (and I'm sure wind plays a part), but it's a rather obscure prediction featured in weather forecasts, and I'm not sure if it means dew will form if temps drop above or below the dew point?

Basically, I just want to know if my car will be wet in the morning if I park it outside.

TIA.

Just to throw out the "science" behind it, dew forms when the temperature of an object, such as your car, drops below the dew point temperature of the surrounding air. The dew point is the temperature at which the air becomes saturated with moisture, leading to condensation.

Then to your actual question, weather forecasters typically provide information on the dew point alongside temperature and relative humidity. If the forecast indicates that the overnight temperature will fall below the dew point temperature, there's a good chance that dew will form, potentially leaving your car wet in the morning if parked outside. Keep in mind that factors like wind speed can affect dew formation as well, as stronger winds may inhibit the buildup of dew on surfaces.

Also, it matters who's forecasting the weather. Adam Krueger is probably pretty accurate.

 

[TheCainer]

So based on your guidance, the forecast on wunderground.com says that we'll get real close in the wee hours tomorrow, but dew should not form (52 temp.; 48 dew point).

But the whole "car is higher than the ground" part leads me to believe I'm too close for comfort?

Trad, I just saw your post this morning. In my line of work, we used to paint steel products for new DOT projects in various paint shops which had a controlled environment. Given that, we were told never to paint unless the Dew Point temperature was at least 5 degrees warmer than the steel temperature. We followed that rule very strictly.

 

[Sharky1203]

How do you tell from a weather forecast whether dew will form in the morning? I know there's the "dew point" based on a combination of relative humidity and temperature (and I'm sure wind plays a part), but it's a rather obscure prediction featured in weather forecasts, and I'm not sure if it means dew will form if temps drop above or below the dew point?

Basically, I just want to know if my car will be wet in the morning if I park it outside.

TIA.

So, at the max temp of the day...you take the dewpoint at that time and if the temp falls, anytime in the day or night, to within 2 deg of the max temp-dew point, dew is formed.