Windborne Freeze Tonight – Some Locations in Piedmont may now NEED TO PULL ROW COVERS (9am, Tue., April 15, 2014)

Dear NC Growers, Agents, Agronomists and Others,

I think the word “ridiculous” best sums up my impression of this strawberry season thus far.  Imagine, if you will, that I just had to send a text message at 6:55 am to Grace, the person helping me with our low tunnel trial in Kinston (Coastal Plain, NC),  that I need to delay our departure from Raleigh this morning on account of an advisory I need to write about a FREEZE coming  TONIGHT!

  • strawberryFig. 1.  Normally, once harvest season arrives, as it has in eastern NC, I am not accustomed to writing strawberry freeze alerts!  But, frigid air from Canada will blast to the south and east through tonight, erasing all notions,  in my mind at least,  that once you reach harvest season you should not have to be worrying about  FREEZES!! I mean, I could see having to issue a strawberry freeze alert for strawberry growers in New York State or New England on April 15th,  but not for most of the state of North Carolina (see Fig. 2).

NC WedFig. 2. All areas in pink, purple, gray, black, red and yellow will be below freezing (32 F) in the morning tomorrow morning. This forecast has definitely changed AGAIN, and not for the better!  Notice in the PIEDMONT how things have changed from yesterday’s forecast (Fig. 3).  Not only is most of the  Piedmont in PINK now (30-32), but there are areas that will be dropping into 28-30 range, and this definitely alters our plans!!

7daytemp.nc.4Fig. 3.  By comparison, this was what the weather people said on 4/14 that our state would look like tomorrow morning (4/16). NOTE THE NAVY BLUE AREAS IN THE PIEDMONT THAT TURNED PINK OVERNIGHT (SEE FIG. 2).

WE ARE NOW DEALING WITH A WINDBORNE FREEZE EVENT 

With a minimum of 28 F, or colder,  I would have to recommend row cover protectioneven if it means trying to handle “wet covers” to apply them.  I am afraid this new weather forecast for even colder temperatures tomorrow morning has really thrown us a curve ball. AND, WHAT IS REALLY MAKING THIS FORECAST A MESS, ARE THE WINDS!  We are now dealing with a true WINDBORNE FREEZE EVENT.  In a windborne freeze, winds are 10 mph or higher, and temperatures are below 32 F.  And, in a windborne freeze, it becomes extremely difficult to use sprinkler irrigation.  For windborne freeze events row covers provide the safest protection. And, when the temperatures are going to be in the range of 24 F, and lower, growers are advised to irrigate on top of the covers.  But, that should not be necessary.  Very very few areas will be getting that cold.

Locations in Piedmont where row covers are now needed:

With minimums of 30 F we can count on “getting by” as long as there are winds (and, there will be winds tonight).  But, the concern now is that if could even get down to 28 F and colder  in some areas of the Piedmont tomorrow morning, like Louisburg. 

The areas in the Piedmont that “could” now be “in some trouble” are:  Louisburg (27 F); Danbury (28); Durham (29); Henderson (29); Pittsboro (28); and Siler City (28).  And, though AWIS lists these locations as WNC, I think of locations like Yadknville (28); Statesville (28) and Mount Airy (26), as PIEDMONT.  All these locations should now apply row covers.

Here is the statewide minimum temp table:  NC AWIS Apr 15 to 22

RECOMMENDATION:  IF YOUR AREA IN THE PIEDMONT WILL HAVE A MINIMUM TEMP OF 29 OR BELOW, YOU SHOULD PULL A ROW COVER TODAY (GROWERS IN WNC, AND THE FOOTHILLS SHOULD HAVE ALREADY PULLED COVERS YESTERDAY).

If your area is right on the line (28 F), you can still take your chances that it will not get any colder than 28 F tonight, and you may get through this just fine.  But, that’s what makes this business of Strawberry Weather Forecasting both an art and science.  We really don’t know whether it may get even colder tonight than what AWIS and other services are calling for?  At a temperature below 28 F, all bets are off!  A temperature below 28 F for long enough duration will be damaging to all open blossoms, all popcorns, and may even cause some injury to green set fruit. It’s your decision – if it were me, and my location was going to be 28 F, or lower, I would put up with having to pull covers over the crop, even if they are now moist from some rains this early morning.

AWIS FREEZE ALERT ON APRIL 15th for North Carolina:

AWIS Weather Services, Inc.
North Carolina Frost/Freeze Forecast
Produced at  507 AM CDT on Tue Apr 15 2014

... Forecast for Tonight ...

Northeast NC Coast                      
Currituck/Camden/Pasquotank/Tyrrell Counties      
**** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** 

Lowest Temperatures:      36 - 43
Elizabeth_City Min          37 
Range Dewpoint Temps:     33 - 58
Range Wetbulb  Temps:     35 - 58
AVG Wind Direction/Speed:   N 22                          
AVG Sky Condition:     Mostly Cloudy

Extended Forecast: Range of Lowest Min Temperatures in the Above Zones
Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets)

  04/17/14  04/18/14  04/19/14  04/20/14  04/21/14  04/22/14
  --------  --------  --------  --------  --------  --------
   38 - 45   44 - 51   47 - 54   47 - 54   46 - 53   47 - 53
--------

East Central/SE NC Coast                
Carteret/Pamlico Counties                         

*** No Frost And/Or Freeze Danger Tonight ***

Lowest Temperatures:      41 - 43
Morehead_City Min           41 

Extended Forecast: Range of Lowest Min Temperatures in the Above Zones
Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets)

  04/17/14  04/18/14  04/19/14  04/20/14  04/21/14  04/22/14
  --------  --------  --------  --------  --------  --------
   38 - 41   45 - 48   51 - 53   49 - 51   47 - 50   47 - 50
--------

Southeast NC                            
NWS FORECAST ZONES 87-90,96-101                   

**** FREEZE COLD LOCATIONS  ****
**** LITTLE IF ANY FROST DUE TO WIND **** 

Lowest Temperatures:      32 - 39
Elizabethtown Min           36 
Durations at/below 32:     0 -  0
Range Dewpoint Temps:     29 - 49
Range Wetbulb  Temps:     33 - 53
AVG Wind Direction/Speed:  NW 19                          
AVG Sky Condition:     Partly Cloudy

Extended Forecast: Range of Lowest Min Temperatures in the Above Zones
Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets)

  04/17/14  04/18/14  04/19/14  04/20/14  04/21/14  04/22/14
  --------  --------  --------  --------  --------  --------
   31 - 39   41 - 47   47 - 52   47 - 52   46 - 51   46 - 51
--------

North-Central NC                        
Franklin County Area                              

**** FREEZE COLD LOCATIONS  ****
**** LITTLE IF ANY FROST DUE TO WIND **** 

Lowest Temperatures:      27 - 38
Louisburg Min               27 
Durations at/below 32:     0 -  4
Durations at/below 28:     0 -  1
Range Dewpoint Temps:     26 - 44
Range Wetbulb  Temps:     30 - 49
AVG Wind Direction/Speed:  NW 15                          
AVG Sky Condition:     Partly Cloudy

Extended Forecast: Range of Lowest Min Temperatures in the Above Zones
Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets)

  04/17/14  04/18/14  04/19/14  04/20/14  04/21/14  04/22/14
  --------  --------  --------  --------  --------  --------
   27 - 39   37 - 45   42 - 49   41 - 48   44 - 50   42 - 49
--------

North/Central NC                        
Alamance County Area                              

**** FREEZING TEMPERATURES ****
**** LITTLE IF ANY FROST DUE TO WIND **** 

Lowest Temperatures:      28 - 33
Graham_AG Min               32 
Durations at/below 32:     0 -  3
Durations at/below 28:     0 -  0
Range Dewpoint Temps:     20 - 44
Range Wetbulb  Temps:     27 - 49
AVG Wind Direction/Speed:  NW 15                          
AVG Sky Condition:     Partly Cloudy

Extended Forecast: Range of Lowest Min Temperatures in the Above Zones
Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets)

  04/17/14  04/18/14  04/19/14  04/20/14  04/21/14  04/22/14
  --------  --------  --------  --------  --------  --------
   29 - 34   38 - 43   44 - 48   42 - 47   45 - 50   44 - 49
--------

South/Central NC                        
Richmond County Area                              

**** FREEZE COLD LOCATIONS  ****
**** LITTLE IF ANY FROST DUE TO WIND **** 

Lowest Temperatures:      30 - 36
Ellerbe Min                 36 
Durations at/below 32:     0 -  2
Range Dewpoint Temps:     22 - 49
Range Wetbulb  Temps:     29 - 53
AVG Wind Direction/Speed:  NW 18                          
AVG Sky Condition:     Partly Cloudy

Extended Forecast: Range of Lowest Min Temperatures in the Above Zones
Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets)

  04/17/14  04/18/14  04/19/14  04/20/14  04/21/14  04/22/14
  --------  --------  --------  --------  --------  --------
   33 - 36   40 - 44   46 - 50   44 - 49   48 - 49   47 - 49
--------

For more detailed information visit www.awis.com or call 888-798-9955.
Copyright 2014 AWIS Weather Services, Inc. All rights reserved.

DETAILED HOURLY FORECAST FOR THESE NC LOCATIONS:

Check the location nearest you for minimum temp forecast as well as wind speed info.  If you have some concerns, you can text message Barclay Poling at 919 418 9687.  Sorry, no time for phone calls today.  You can also email:  strawberrydoc@gmail.com

5-DAY DETAILED HOURLY WEATHER FORECASTS 

Good luck!

Barclay

p.s. I have decided that due to seriousness of this situation we face, I will not be heading down to Kinston to harvest berries afterall.  I will be right here doing advisory work all day.

Dr. E. Barclay Poling
Interim Executive Director, NC Strawberry Association Inc.
& Professor Emeritus (Strawberry Plasticulture Researcher)
Department of Horticultural Science
Campus Box 7609, 162A Kilgore Hall
NC State University
Raleigh, NC 27695-7609
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Written By

Dr. Barclay PolingFormer Professor and Extension Specialist, Strawberries and Muscadines (919) 515-5373 (Office) Horticultural Science - NC State University

Posted on Apr 15, 2014

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