NC Update: More Cold Temperatures With Hybrid “FROST” in the Forecast for Tonight (8:30am, Sat., 3/4/17)

— Written By Barclay Poling
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Fig. 1. This is Omega Engineering’s latest model digital thermometer that is ideal for measuring blossom temperatures for strawberry frost and freeze management. How I wish more growers owned one of these this morning! Frankly, every serious strawberry grower should own one. Unfortunately, the price of this unit has gone up since I last bought one in 2012. This particular unit was raffled off at the April 26, 2016 Strawberry Twilight Tour and BBQ in Elm City. By the way, that particular program has been moved up to  April 11 (Tuesday) on account of this very early season (assuming we get through these freeze nights ok? The program will begin in Faison at around 2 p.m. (where we have large strawberry variety and advanced selection trial), and then move up to Elm City for the Twilight meeting and BBQ.

Hello again!

I’d like to say “good morning,” but I know many of you have been up most of the night with freeze protection operations, and I know you are not going to appreciate a forecast showing more freezing temperatures!

FORECAST IN DETAIL

It’s only March 4th, and we’ve already had 2 fairly serious cold events! Temperatures will be plunging again tonight and tomorrow morning. Thankfully, we have that increasingly powerful sun during the day today to help warm thaw us out from last night, and you can see the kinds of highs we’ll be experiencing across North Carolina today (Fig. 2).

HIGHS TODAY

Fig. 2. Maximum temps for today (Saturday).

LOWS TONIGHT

Fig. 3. Again, we are looking at some pretty threatening temperatures for strawberry blossoms in many areas of the state – this map shows the minimums for early Sunday morning.

Last night we had some extremely low dew points, making it difficult to “make frost.”  However, dew points are moving up tonight, and there is excellent potential for FROST in many areas.  Please let me caution though, that lower dew points are still going to be a concern tonight. And, if you are of the mind that you can simply delay sprinkling until you see frost forming on the ground, you could get tricked up! Let’s just think of tonight as being a hybrid between and old fashioned ‘white frost’ type of event (where you can wait to see frost before running water) and a ‘black frost.’

Dealing with turn on times for tonight:

Please study the AWIS Detailed Hourly forecast closely for a city/town near your farm to get an idea when frost might appear tonight (just look for the “F” in one of the bottom rows of the table). But, please also know that you need to be running water (if that is what you are using) before you see the “FROST” hour in this table.

Kenansville example:

In Kenansville, for example, FROST will possibly begin at 2200 (10 p.m.), and at this hour the air temp (at 2 meters) will be 33 F, but the wet bulb will already be sitting on 30 F. I WOULD NOT WAIT UNTIL YOU SEE FROST AT 10 p.m. I know water is now becoming a concern on some farms, and if you own a digital thermometer, you can start watering when you see the blossom reaching 32 F.

If you are reliant on hourly tables from various weather services for wet bulb information (LIKE THIS AWIS TABLE), to save some watering time, you may consider priming the system when wet bulb is 33 F, and try to be running before the wet bulb is 32 F.

Then, keep track tonight of how many minutes it takes before you see ice forming on the strawberry plants. If it forms immediately, you may have waited too long to start! If it doesn’t form for maybe 10-15 minutes, and you just see  “liquid water” before freezing, you hit it just right. If it takes 30 minutes or longer, you started a little too early, and you will want to incorporate this knowledge in your next go round with a cold event of this type.

Still, the bottom line to me is that every strawberry operations needs a digital thermometer to guide these decisions with confidence. And, it is shocking how few growers have them?

10-DAY DETAILED HOURLY WEATHER FORECASTS

Ahoskie-Tri-Cou Albemarle_AP Andrews Asheboro
Asheville_Munic Beaufort-Michae Boone_NC Burlington-Burl
Cape_Hatteras_AG Chapel_Hill-Hor Charlotte Cherry_Point
Clinton_NC Concord_NC Currituck_NC Edenton-Northea
Elizabeth_City Elizabethtown_NC Erwin-Harnett_C Fayetteville_AP
Fort_Bragg/Simm Franklin/Macon_C Gastonia-Gaston Goldsboro_AFB
Goldsboro_NC Greensboro Greenville_AP_NC Hickory
Jacksonville Jacksonville_(A Jefferson_AP_NC Kenansville-Dup
Kill_Devil_Hills Kinston_AP Lexington-David Lincolnton_AP
Louisburg_NC Lumberton_AP_NC Mackall_AAF Manteo/Dare_Co
Maxton Mcalf_Bogue_Fiel Monroe_AP_NC Morganton-Morga
Mount_Airy-Moun New_Bern North_Wilkesbor Oxford_NC
Piney_Island_Bom Pope_AFB Raleigh-Durham Reidsville_AP
Roanoke_Rap_AP Roanoke_Rapids_R Rockingham_NC Rocky_Mount-Wils
Roxboro_AP Rutherfordton Salisbury-Rowan Sanford_NC
Shelby_AP_NC Smithfield_AP Southern_Pines Southport_NC
Statesville-Sta Tarboro_AP Wadesboro_AP Washington-Warr
Whiteville_NC Wilmington_AP_NC Winston-Salem

After studying the AWIS table for the city/town closest to you, you will have also noted FROST again for Monday morning! Though the minimums are moving up some, there is still the likelihood of a frost that could cause damage to blooms.

Another night of Frost – Monday morning minimums…

Fig. 4. Minimum temperature map for Monday morning.

Hopefully, we’ll be out of the woods after Monday morning. Here is the temperature outlook for the next 7 days:NC Outlook

AWIS Weather Services, Inc. North Carolina Frost/Freeze Forecast
Produced at  504 a.m. CST on Sat Mar  4 2017

... Forecast for Tonight ... Northeast NC Coast                      
Currituck/Camden/Pasquotank/Tyrrell Counties      

**** FREEZING TEMPERATURES ****
****    PATCHY FROST  ****

Lowest Temperatures:      27 - 35
Elizabeth_City Min          27 
Durations at/below 32:     0 -  9
Durations at/below 28:     0 -  2
Range Dewpoint Temps:     14 - 26
Range Wetbulb  Temps:     25 - 36
AVG Wind Direction/Speed:   N  7                          
AVG Sky Condition:         Clear    

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)

  03/06/17  03/07/17  03/08/17  03/09/17  03/10/17  03/11/17
  --------  --------  --------  --------  --------  --------
   30 - 38   49 - 56   52 - 58   42 - 48   43 - 49   50 - 56
--------

East Central/SE NC Coast                
Carteret/Pamlico Counties                         

**** FREEZING TEMPERATURES ****
****    PATCHY FROST  ****

Lowest Temperatures:      28 - 33
Morehead_City Min           32 
Durations at/below 32:     0 -  6
Durations at/below 28:     0 -  0
Range Dewpoint Temps:     17 - 28
Range Wetbulb  Temps:     27 - 36
AVG Wind Direction/Speed:   N  4     Long Periods of Calm 
AVG Sky Condition:         Clear    

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)

  03/06/17  03/07/17  03/08/17  03/09/17  03/10/17  03/11/17
  --------  --------  --------  --------  --------  --------
   33 - 37   46 - 51   54 - 55   41 - 45   38 - 44   52 - 54
--------

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

**** FREEZING TEMPERATURES ****
****    PATCHY FROST  ****

Lowest Temperatures:      27 - 31
Elizabethtown Min           30 
Durations at/below 32:     2 -  7
Durations at/below 28:     0 -  3
Range Dewpoint Temps:     16 - 28
Range Wetbulb  Temps:     27 - 39
AVG Wind Direction/Speed:   V  2     Long Periods of Calm 
AVG Sky Condition:         Clear    

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)

  03/06/17  03/07/17  03/08/17  03/09/17  03/10/17  03/11/17
  --------  --------  --------  --------  --------  --------
   32 - 41   45 - 52   52 - 57   39 - 44   39 - 44   46 - 54
--------

North-Central NC                        
Franklin County Area                              

**** HARD FREEZE ****
****    PATCHY FROST  ****

Lowest Temperatures:      24 - 32
Louisburg Min               24 
Durations at/below 32:     0 - 10
Durations at/below 28:     0 -  5
Range Dewpoint Temps:     11 - 19
Range Wetbulb  Temps:     24 - 34
AVG Wind Direction/Speed:  NE  3     Long Periods of Calm 
AVG Sky Condition:         Clear    

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)

  03/06/17  03/07/17  03/08/17  03/09/17  03/10/17  03/11/17
  --------  --------  --------  --------  --------  --------
   28 - 37   44 - 50   44 - 52   36 - 42   37 - 43   46 - 51
--------

North/Central NC                        
Alamance County Area                              

**** FREEZING TEMPERATURES ****
****    PATCHY FROST  ****

Lowest Temperatures:      25 - 32
Graham_AG Min               28 
Durations at/below 32:     0 -  9
Durations at/below 28:     0 -  4
Range Dewpoint Temps:     14 - 19
Range Wetbulb  Temps:     26 - 34
AVG Wind Direction/Speed:  NE  3     Long Periods of Calm 
AVG Sky Condition:         Clear    

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)

  03/06/17  03/07/17  03/08/17  03/09/17  03/10/17  03/11/17
  --------  --------  --------  --------  --------  --------
   32 - 37   44 - 50   45 - 51   37 - 42   37 - 43   46 - 52
--------

South/Central NC                        
Richmond County Area                              

**** FREEZING TEMPERATURES ****
****    PATCHY FROST  ****

Lowest Temperatures:      27 - 34
Ellerbe Min                 29 
Durations at/below 32:     0 -  7
Durations at/below 28:     0 -  2
Range Dewpoint Temps:     16 - 25
Range Wetbulb  Temps:     27 - 38
AVG Wind Direction/Speed:  NE  3     Long Periods of Calm 
AVG Sky Condition:         Clear    

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)

  03/06/17  03/07/17  03/08/17  03/09/17  03/10/17  03/11/17
  --------  --------  --------  --------  --------  --------
   33 - 38   48 - 50   44 - 54   37 - 43   38 - 42   46 - 52
--------

Interior/EC-SE NC                       
Wayne County Area                                 

**** FREEZING TEMPERATURES ****
****    PATCHY FROST  ****

Lowest Temperatures:      27 - 30
Goldsboro_AG Min            30 
Durations at/below 32:     3 -  7
Durations at/below 28:     0 -  3
Range Dewpoint Temps:     17 - 25
Range Wetbulb  Temps:     27 - 34
AVG Wind Direction/Speed:   V  2     Long Periods of Calm 
AVG Sky Condition:         Clear    

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)

  03/06/17  03/07/17  03/08/17  03/09/17  03/10/17  03/11/17
  --------  --------  --------  --------  --------  --------
   31 - 35   46 - 49   50 - 56   40 - 42   39 - 42   46 - 51
--------

For more detailed information visit www.awis.com or call 888-798-9955. Copyright 2017 AWIS Weather Services, Inc. All rights reserved.