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Thunderstorms in Florida and Central U.S.; Fire Weather Threats in North Plains

Strong to severe storms may linger in Florida as a slow moving cold front continues east. A weather system in the Central U.S. may produce strong thunderstorms in the Middle Mississippi Valley. A Canadian cold front will produce gusty winds and critical fire weather threats in the North Plains. Fire weather threats are also elevated in Guam. Heavy rain could cause flash flooding in Hawaii. Read More >

Dew and Frost occur due to radiational cooling.  Radiational cooling happens at night when outside objects release heat into the atmosphere cooling the object. At the same time, the atmosphere radiates heat back into the object. On a clear, calm night, however, the amount of heat lost from the object tends to exceed the heat gained from the atmosphere and the object becomes cooler than the surrounding air.

With sufficient cooling, the air adjacent to the object can cool to its dew point temperature (a measure of the water vapor content present in the air) and become saturated. If the air temperature is above freezing, dew will form.  If the temperature is near or below freezing, frost will develop.

In Colorado and Utah, the terrain varies considerably from high desert to river valleys to the Rocky Mountains. As such, average frost and freeze dates also vary considerably.  In fact, frost and freeze dates can differ by as much as 6 weeks.  For instance, the average last day of freezing temperatures for Grand Junction is April 22 while for Aspen it is Jun 16.  Of course, elevation plays a cruicial role in temperatures as can be seen in the preceding example.

 Average Last Freeze/Frost Dates (Colorado): 

  Station Temperature <28.6° F Temperature <32.6° F     Station Temperature <28.6° F Temperature <32.6° F
  Aspen

5/28

6/16

 

  Meeker

5/29

6/13

  Cedaredge

4/29

5/15

 

  Mesa Verde

5/2

5/15

  Collbran

5/9

5/29

 

  Montrose

4/27

5/10

  Cortez

5/9

5/25

 

  Norwood

5/20

6/9

  Craig

5/19

6/2

 

  Orch. Mesa

4/11

5/2

  Crested Butte

6/17

7/9

 

  Ouray

5/9

5/29

  Delta

4/28

5/11

 

  Pagosa Sp

6/14

6/27

  Durango

5/13

6/2

 

  Palisade

4/4

4/20

  Fruita

4/27

5/12

    Paonia

4/29

5/10

  Glenwood

5/1

5/18

    Rangely

5/1

5/16

  Grand Junction

4/6

4/22

    Rifle

5/7

5/19

  Gunnison

6/10

6/27

    Silverton

6/26

7/14

  Hayden

5/23

6/3

    Steamboat

6/13

7/5

  Ignacio

5/23

6/9

    Telluride

6/16

6/29

  Lake City

6/10

6/30

    Yampa

6/4

6/21

  Maybell

5/23

6/12

    Yellow Jacket

5/6

5/22

Average Last Freeze/Frost Dates (Utah): 

Station Temperature <28.6° F Temperature <32.6° F     Station Temperature <28.6° F Temperature <32.6° F
  Blanding

4/27

5/12

 

  La Sal

5/13

5/27

  Bluff

4/14

4/28

 

  Manila

5/11

5/24

  Canyonlands

4/21

5/2

 

  Mexican Hat

4/6

4/22

  Castle Valley

4/5

4/14

 

  Moab

3/30

4/16

  Cedar Point

5/8

5/21

 

  Monticello

5/12

5/30

  Dewey

4/18

5/5

 

  Ouray

4/27

5/5

  Dutch John

5/16

6/6

 

  Roosevelt

5/2

5/14

  Ft Duchesne

5/4

5/18

 

  Thompson

4/21

4/30

  Jensen

5/4

5/19

    Vernal

5/9

5/26

  

 

Average Spring Freeze Average Spring Frost

Click For a larger image of Freeze dates

Click for a larger image of Frost dates

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Average Spring Freeze

 

 

 

 

 

 

 

 

 

 

 

 

 

Average Spring Frost