Fall 2013 Frost/Freeze Preliminary Story

As of October 26th, the vast majority of the the NWS Hastings coverage area in South Central Nebraska and North Central Kansas has reached 32°-or-colder at least once this fall. Compared to 30-year averages, most places within the area first reached the freezing mark roughly 10 days later than average, except for far southern counties in North Central Kansas, which were only slightly "late." However, it is worth noting that many areas have not recorded a true, hard killing freeze of 28°-or-colder yet this season. ** Despite this, NWS HASTINGS WILL NO LONGER ISSUE FROST ADVISORIES/FREEZE WARNINGS AGAIN UNTIL NEXT SPRING. **


** Fall 2013 Potential-for-Hard Freeze Forecast (Updated Oct. 26th) **:   Although nearly all areas have now experienced a freeze of 32°-or-colder this fall, much of the area, especially from the Tri-Cities southward, has yet to observe a true, hard killing freeze of 28°-or-colder. Some places that have already experienced a hard freeze include Ord, Greeley, Cambridge, Franklin and Alton KS. Looking ahead, there does not appear to be any high-confidence threats for a widespread hard freeze to occur through at least Saturday, Nov. 2. As a result, many areas could be looking at their latest hard freeze since 1998, when it held off until Nov. 10-11 across central and southern portions of the area. Please note this is preliminary information, and still subject to considerable change.


** What's Already Happened This Fall With Frost/Freeze? (Current as of Oct. 26th) **: 
Here is a brief summary of the progression of sub-freezing temperatures across the area this fall, in "reverse chronological" order. As is usually the case, far northern and western counties within the area were the first to experience freezing conditions this fall, with far southeast areas seeing their first freeze several days later: 

  • Oct. 21: Limited portions of the area observed the first hard freeze of the season: Central City and Burr Oak KS (cooperative observers) and the Aurora, York and Phillipsburg KS airports all dipped down to 28°. Cooperative observers at both Franklin and two miles southwest of Alton KS, along with an automated site near Lebanon KS recorded 27°.
  • Oct. 19: Several far-southeastern observation sites such as Hebron and Beloit dipped just below freezing on this morning, meaning that essentially the entire NWS Hastings coverage area has now dropped to 32°-or-colder at least once this season.
  • Oct. 18: Much of the Nebraska portion of the coverage area, especially along and north of the Highway 6 corridor and along/south of the Highway 92 corridor, experienced the first sub-freezing temperatures of the fall season on this morning, including readings of 30° at Grand Island, 31° at Hastings and 30° at Osceola. Ord recorded its first hard freeze with a low of 23°.
  • Oct. 16: Fairly widespread, slightly-sub-freezing temperatures were observed across western portions of the area, especially in Dawson/Gosper/Furnas counties and surrounding areas as well. Morning lows included 29° at Cambridge and Holdrege, 31° at Lexington airport and 32° at Kearney airport and Minden. However, central locations including Grand Island and Hastings, and essentially all areas along/east of the Highway 281 corridor did not observe freezing temperatures.

  • Oct. 13: It is likely that at least limited areas of frost developed within far northern parts of the area, generally in the Valley/Greeley/Nance county area. The low temperature at the Ord airport dropped to 28°, and the cooperative observer at Greeley reported 30°. At Greeley, this tied with 1997 for the latest first freeze on record during the past 30 years. However, the majority of South Central Nebraska/North Central Kansas remained above 36° on this morning.

  • Oct. 7: Limited areas did in fact report the first frost of the season on the morning of Oct. 7th as temperatures dropped into the mid-30s in the presence of light winds. A few official temperature sites such as Ord and Edison even dropped to 30° and 32°, respectively, marking the first known-occurrence of sub-freezing temperatures within the local 30-county area this fall. The greatest concentration of low temperatures 36°-or-lower (supportive of frost) on the morning of the 7th was in northern/western counties in South Central Nebraska such as Valley/Greeley/Buffalo/Dawson/Furnas. However, even localized spots in North Central Kansas also dropped into the mid-30s, including Burr Oak and Alton. 


    Before continuing, here are a few definitions
    :

- Frost occurs when there is a solid deposition of water vapor from the air. Frost will form when solid surfaces are cooled below the dew point. An air temperature range of 33-36° along with very light winds are usually needed to initiate frost formation. Minor damage is possible to some plants. One must keep in mind that a frost is not guaranteed at these temperatures if moisture in the air is lacking. The range of average dates for the first occurrence of fall frost across most of south central Nebraska and north central Kansas is between Sep. 23 - Oct. 7.

- Freeze occurs when the air temperature drops to 32° or lower. A freeze will result in significant damage to many unprotected plants, especially if the temperature remains at the freezing mark for a few hours. The range of average dates for the first freeze of the fall across most of south central Nebraska and north central Kansas is between
Sep. 28 - Oct. 16.


- Hard Freeze occurs when the temperature reaches 28° or lower for at least a few hours. It usually means that many types of plants and most seasonal vegetation will be destroyed. The range of average dates for the first hard freeze of the fall across most of south central Nebraska and north central Kansas is between Oct. 5 - Oct. 25.


The Midwestern Regional Climate Center produces maps that update DAILY, depicting sites across the region that have fallen to at least 32 or 28 degrees so far this fall.  Check out statewide maps of Kansas and Nebraska by clicking on the images below. Again, these maps automatically update daily, and originate from the  Midwest Climate Watch website.

(Click images to enlarge)

Kansas observed 32 degrees or below so far this fall

Nebraska observed 32 degrees or below so far this fall

Kansas observed 28 degrees or below so far this fall

Nebraska observed 28 degrees or below so far this fall

 



Below is a table and set of maps, primarily focused on average dates for reaching particular temperature frost/freeze thresholds. However, there is often tremendous variation from year-to-year and between any given location across the area (see bottom of page for details on unusually early freeze in September 1974).

Examining the table below, here are a few things to consider:

- The first column lists 9 chosen locations in south central Nebraska and 4 in north central Kansas with long histories of being NWS Cooperative Observer sites (except for Grand Island and Hastings airports, which are automated systems). This is just a small sampling of dozens of observing locations within the NWS Hastings coverage area, and these sites are generally organized from north to south down the column.

- The second column shows the average date of the earliest observance of 36, 32, and 28 degree temperatures during the most recent 30-year period from 1983-2012. Please note that differences in average freeze dates between these locations are NOT purely a function of "north versus south", but also depend on a variety of factors including local terrain. For example, Alton, KS, in Osborne County is typically prone to earlier freezes in the fall than some locations farther north, thanks to efficient cold air drainage along the South Fork Solomon River valley.

- The third and fourth columns reveal the earliest first freeze date and latest first freeze date (32 degrees or colder) observed during the past 30 years, covering the period 1983-2013. It is readily apparent that the phrase "average freeze date" is quite relative, as most sites have a 5-7 week difference between the earliest and latest dates. For the majority of locations, the earliest last freeze during the past 31 years occurred between Sep. 15th-22nd in years such as 1991 and 1993. On the opposite spectrum, for many locations the latest freeze during the past 31 years occurred between Oct. 23th- Nov. 4th in years such as 1997 and 1998.

- The final column on the right is a work in progress, revealing the date that 36, 32 and 28-degree thresholds are first met THIS FALL within the area. A blue-shaded date indicates a location that reached a temperature threshold more than 7 days before the average date, while red-shaded dates indicates that this threshold was met more than 7 days after the average date.

 Climatological Data For South Central Nebraska and North Central Kansas
(all averages based on 30-year observations from 1983-2012)

 

Average First 
Date of...

36 Degrees
32 Degrees
28 Degrees

Earliest Date 
1983-2013 of...

32 Degrees
or Colder 

Latest Date 
1983-2013 of...

32 Degrees
or Colder 

First Fall 2013  
Occurence of...

36 Degrees
32 Degrees
28 Degrees

 Greeley

Sep. 23
Sep. 28
Oct. 5

Sep. 15,1993 

Oct. 13, 2013
Oct. 13,1997

Sep 21 (34°)
Oct. 13 (30°)
Oct. 18 (26
°)

 Osceola

Sep. 30
Oct. 8
Oct. 13

Sep. 19, 1991

Nov. 3, 1998

Oct. 17 (35°)
Oct. 18 (30
°)
Oct. 24 (28°)

 Kearney Airport
(NWS Observer)

Sep. 26
Oct. 5
Oct. 15

Sep. 19, 1991

Oct. 25, 1997 

Oct. 5 (36°)
Oct. 16 (32
°)
Nov. 6 (28°)

 Grand Island
 (airport)

Sep. 29
Oct. 8
Oct. 14

 Sep. 19, 1991

 Oct. 26, 2007

Oct. 16 (36°)
Oct. 17 (32
°)
Nov. 5 (28°)

 York

Oct. 2
Oct. 10
Oct. 20

 Sep. 19, 1991

Nov. 4, 1998

Oct. 7 (36°)
Oct. 17 (32
°)
Oct. 21 (27°)

 Cambridge

Sep. 24
Oct. 2
Oct. 12

Sep. 15, 2008

 Oct. 25, 1997

Oct. 7 (36°)
Oct. 16 (29°)
Oct. 25 (28°)

 Holdrege

Oct. 2
Oct. 9
Oct. 20

Sep. 20, 1991

Nov. 4, 1998

Oct. 5 (34°)
Oct. 16 (29
°)
Oct. 21 (26°)

 Hastings
(NWS Office/airport)

Sep. 29
Oct. 8
Oct. 18

Sep. 20, 1991

 Nov. 3, 1998

Oct. 16 (33°)/Oct. 16 (33°)
Oct. 18 (31°)/Oct. 17 (31
°)
?/Nov. 2 (28°)

 Hebron

Sep. 30
Oct. 10
Oct. 19

 Sep. 19, 1991

 Oct. 26, 2007

Oct. 12 (36°)
Oct. 19 (30°)
?

 Smith Center KS

Oct. 4
Oct. 13
Oct. 19

 Sep. 21, 1983

 Nov. 4, 1998

Oct. 16 (35°)
Oct. 19 (29°)
?

 Alton KS

Sep. 27
Oct. 3
Oct. 13

 Sep. 15, 1993

 Oct. 23, 2007

Oct. 7 (33°)
Oct. 13 (30°)
Oct. 21 (27°)

 Plainville KS

Oct. 7
Oct. 15
Oct. 25

Sep. 20, 1995

 Nov. 3, 1998

Oct. 16 (32°)
Oct. 16 (32°)
Nov. 6 (28°)

 Beloit KS

Oct. 6
Oct. 16
Oct. 25

 Sep. 22, 1995

 Nov. 10, 1998

Oct. 17 (34°)
Oct. 19 (31°)
?

 


Median Dates of First Fall Freeze and Hard Freeze (1981-2010)
(Midwestern Regional Climate Center)

(click images to enlarge)

Median Date of First 32-Degree Freeze Median Date of First 28-Degree Hard Freeze

 


 

South Central Nebraska and North Central Kansas 
30-Year Average First Frost/Freeze Dates (1983-2012)

(click images to enlarge)

Average 36-Degree Date (First Possible Frost)
Average 32-Degree Date (First Freeze)
Average 28-Degree Date (First Hard Freeze)

 


Nebraska First Fall Frost/Freeze Averages (maps courtesy NWS Omaha/Valley)
(click images to enlarge)

Average date of first 36-degree temps

Average date of first 32-degree temps

Average date of first 28-degree temps

 



 Average First Fall 32-Degree Dates for Kansas (courtesy the Kansas State Climatologist)

(click to enlarge)



A Look Back At The Unusually Early Frost/Freeze of September 1974:

One of the earliest freezes on record in parts of South Central Nebraska occurred the first week of September in 1974, as many locations dropped below the freezing mark on September 3rd. A surface weather map (see below, far left thumbnail image) from September 3, 1974 depicted just why such cold temperatures were observed. An unseasonably cold airmass roared into the region behind a strong cold front. Eventually, surface high pressure set up over the region, creating an ideal situation for a record early freeze. In fact, note the hand written comment "Record early damaging frosts, corn belt area" at the top of the weather map. Cooperative Observation forms for Gothenburg and Greeley, Nebraska are also shown below. The Gothenburg observer noted "Clear. Froze. Ice. Crop Damage" on the right side of the form on the 3rd. Finally, it is interesting to note both Gothenburg and Greeley recorded freezing temperatures again just ten days later on September 13, 1974.  

September 3, 1974 Weather Map

(click to enlarge)

Gothenburg, NE Observation Form
September 1974

(click to enlarge)

Greeley, NE Observation Form
September 1974

(click to enlarge)

 

This page was composed by the staff at the National Weather Service in Hastings, Nebraska.

 



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