North Carolina AWIS Frost / Freeze Forecast for Tonight (12:30pm, Sunday, 3/4/18)

— Written By

Fig. 1. By having gravel-filled nylon mesh bags that hold down row covers closer together, you can prevent row covers from “floating away” in times of exceptionally high winds, such as we have just experienced this weekend.

Good afternoon,

It is still fairly windy up here in Williamsburg today – presently about 10 mph! I was really pleased to see Dr. Mark Hoffmann’s mention of a good wind forecast product in Friday evening’s advisory (http://www.windy.com).

Also, I just now glanced at overall weather conditions across NC on AccuWeather Professinal’s State Roundup, and it looks like winds are still very much of a factor in some areas of the state this afternoon. For example, Burlington, NC, is still at 10-12 mph. However, all that is going to change tonight and tomorrow morning. For example, winds in Burlington will diminish to 1 mph at 7 p.m., and be very very low all night Burlington AWIS Hourly

In studying the Burlington forecast, I did not see an indication for frost in that area for Monday morning, even though winds will be very calm in the morning and the minimum air temp will be 28 F at 7 a.m.

Reason? They (meaning AWIS) are still calling for low dewpoints tonight for this area of the state. When the low of 28 F is reached at 7 a.m. in Burlington, the dewpoint will only be 18 F. That is a very low dewpoint! And, essentially there is not enough “moisture in the air” to get a “white frost” when the air is this dry. My experience has been that open strawberry blooms can tolerate temperature minimums of 28 F (assuming NO FROST), but I am talking about the strawberry canopy level, and not up at the weather shelter height (~6.5 ft). At the strawberry canopy level near the ground, it can be significantly COLDER WITH DEWPOINTS IN TEENS.

And, the worry is that if the temperature at the strawberry canopy level goes below 28 F in the morning, you could get what I call a “black frost.”  In a black frost you get BLOSSOM KILL without seeing any frost. One way to approach the question of how cold it might be at the canopy level, is to examine a weather product like SkyBit to see what the minimum temperature might be at the canopy vs. weather shelter. I happen to have handy the SkyBit for a farm over in Randolph County (near Climax) and you can see how the canopy temperature there will be 27 F tomorrow morning vs. weather shelter temp of 31 F. that the differential is 4 F between the weather shelter height and the ground level. That’s a lot! And, 27 F at the strawberry canopy level will DEFINITELY KILL OPEN STRAWBERRY BLOSSOMS AND POPCORNS AS WELL.

A grower thinking that with a “forceast” minimum of 31 F that he/she is ok, needs to think again, especially on these low dewpoint nights/mornings, such as western and central Piedmont NC will be having tonight/tomorrow morning – it is always colder at the ground level! And, remember, a lot of damage can be done in matter of minutes at the ground level if that air temp dips below 28 F.

FIG. 2. PLEASE NOTE THE VIP DIFFERENCE BETWEEN MIN CAN TEMP OF 27 F IN SKYBIT FORECAST FOR MON MORNING, AND THE MIN AIR TEMP AT WEATHER SHELTER HEIGHT OF 31 F — THAT’S A 4 F DIFFERENTIAL.

Let’s now examine what may be happening over the Sandhills tomorrow morning. Because I had today’s SkyBit for John Gross’s farm handy, I am reproducing that here to show you that over in Sanford there will “potentially” be a MIN CANOPY TEMP of 31 F vs. 35 F for weather shelter height. Now, I would not be worried with a minimum temp of 31 at canopy height as far as getting open blossom cold temperature injury, except, at this farm there is a very high probability of WHITE FROST. YOU SHOULD DEFINITELY STUDY THE AWIS HOURLY DETAILED FORECAST FOR YOU LOCATION TO SEE IF FROST IS BEING INDICATED FOR YOUR AREA? (Sanford AWIS Hourly)

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

(cont’d)

In the Sanford AWIS hourly you can see “F” (for FROST) starting at 3 and lasting until 7 a.m. (sunrise 6:42 a.m.). And, what you should also notice about Sanford is how much more moisture there is in the air than over in Burlington or Climax, NC. In these 2 piedmont locations (Burlington and Climax), dewpoints are relatively low, meaning it is “harder to make frost”, but with a dewpoint in mid-20s (not teens), there is plenty of moisture in the air to get an excellent white frost, and that frost will damage the open blooms! Remember (FROM MY LAST ADVISORY), John has some 15 + open blossoms on his Sweet Charlie, and  I am guessing nearly 10 open Camarosa blossoms per plant. He is at high risk tomorrow morning, and I am glad that he has already applied his row covers.

One thing growers can do when there is POTENTIAL FOR A FROST, is be sure to apply a floating row cover in the mid-afternoon (around 2:30-3 p.m.), to be on the safe side of things.  The cover has to go on during the day when it is sunny out to build up the maximum amount of heat for the “heat reservoir” under the cover that will help to keep the blossom temperatures high enough so that you don’t get cold injury.

As much as we would like to believe that we have this frost business completely figured out, the truth is we don’t. We can utilize the best forecast information available to us at 1:30 p.m. on Sunday March 4th to make an informed decision about tomorrow morning, but a lot can change between now and tomorrow morning. So, before I share with you all the latest AWIS information for North Carolina, I am going to share this cautionary tale from Mr. Clyde Gurosik

———————————————————————————————–

Friends,

Last night I watched the temperatures and wind,walked the fields, worried, planned, but DOUBTED the BEST FORECASTS AVAILABLE. As expected, from experience and some REAL TIME DATA, the winds dropped off from about 0230 until 0630 and a serious ground frost occurred. We protected strawberries with overhead sprinkling.

Every agricultural producer I know experiences similar frustrations, because we “DON”T HAVE ACCESS TO A STANDARD,REAL TIME, AUTOMATED SYSTEM”, only NON-REAL TIME forecasts. We can & should do better.

The wind speed is the “MOST INACCURATE, BUT MOST IMPORTANT PARAMETER OF ALL FREEZE RELATED FORECASTS”.

Before I learned about the UGA weather service, that could provide me with 24/7 REAL TIME DATA from locations north and west of Augusta, I called friends and asked them,” What is it doing there, as it will be here in 1.5 hours”?

Now, I just pull up www.weather.uga.edu. With the click of a mouse, that system allows me to “SEE, and MORE ACCURATELY DETERMINE THE FUTURE” vs antiquated, non-real time forecasts. After only a momentary wait, I can put the mouse over ANY of the many real time temperature dots, that represent satellite up-links, and also read dew points, wind direction, wind speed and wind gusts. That is just as important to agriculture interests & CROP PROTECTION STRATEGIES as it is to have the turn-out switch set properly on a rail track to prevent DISASTERS.

When a clipper or frost is coming, I can observe the real time progression, providing ACCURATE insight into the future. That is an invaluable tool for all agricultural interests, BUT most states don’t have it!!!!

Please go to www,weather.uga.edu. After the statewide map appears, just scroll over any of those dots west or north of Augusta to better understand what is really coming, “REAL TIME”. What a wonderful legacy it would be if that service were available CONSISTENTLY in all states of “ONE NATION UNDER GOD”, the USA.

Maybe some of you can share this with Sonny Purdue and obtain some assistance and priority. If anyone knows of a better system, please share it with me.

Sincerely,
Clyde Gurosik

—————————————————————————

In summary, I’d like to make these several points:

  1.  Hey everyone, it’s MARCH!
  2. And, when its March in the Carolinas, you can expect just about anything! If you don’t believe me, just go back and read a few of the advisories I wrote last March (you can search March 2017 on this website – it truly is unbelievable what happened last year right about NOW).
  3. For sure, we don’t know what is going to happen in real time tonight, and tomorrow morning, and that is why you need to monitor things YOURSELF – I recall years ago how Andy Myer of the Piedmont Research Station used to poke fun at me for relying too heavily on AWIS for frost information and I would say things like: “FROST will begin at 4 a.m., according to AWIS, in the Salisbury area,” and he would call me the next day and say, it started at 11 p.m. Thank goodness Andy was closely monitoring my research plots at Piedmont to “catch” my mistake.
  4. It’s all about “knowing what to do” in real time – Clyde had the presence of mind to run his sprinklers — thank goodness! Maybe you don’t have a row cover? That’s ok. You can also use sprinkler irrigation for frost protection, though I realize fewer and fewer growers are doing it these days. I am personally a huge fan of BOTH row covers and sprinklers.  No doubt, one huge advantage of the covers is you can apply them in the afternoon, and you are pretty much done. With the sprinkling program, there is a lot more to it. You really need to be on top of things like wet bulb temperatures, and knowing the exact hour when the wet bulb is likely to drop below 32-33 F (that is when you need to “turn on” on low dewpoint nights). If your dewpoints are up in the mid-20s, then you can pretty much rely on the old rule of starting up sprinkling when you see first evidence of ice crystals forming on lay-flat hoses, or rolled up row covers.
  5. Murphy’s Law is definitely in operation during any strawberry frost season that I have ever worked, and I have been through about 37 of them now. And, it is always best to have a solid back up contingency plan when things don’t go according to plan! I have seen all kinds of crazy scenarios with row covers and sprinkling over the years, but the craziest one of all is when you actually get a “frost under the cover,”  but not outside the cover? …. I don’t see that potential tomorrow morning, but it is something a number of us are now keenly aware of…
  6. Be aware that we have some very crazy weather ahead, and that is why I have asked a meteorologist friend of mine to resume the 2-week outlooks…we will post that this evening (you can read it after you have applied your row covers).

AWIS Weather Services, Inc. North Carolina Frost/Freeze Forecast
Produced at  504 a.m. CST on Sun Mar  4 2018

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

**** FREEZE COLD LOCATIONS  ****
** PATCHY FROST COLDEST PROTECTED AREAS **

Lowest Temperatures:      31 - 39
Elizabeth_City Min          31 
Durations at/below 32:     0 -  2
Range Dewpoint Temps:     19 - 32
Range Wetbulb  Temps:     29 - 41
AVG Wind Direction/Speed:   N 11                          
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)

  03/06/18  03/07/18  03/08/18  03/09/18  03/10/18  03/11/18
  --------  --------  --------  --------  --------  --------
   31 - 39   44 - 50   37 - 43   35 - 41   35 - 41   44 - 50
--------

East Central/SE NC Coast                
Carteret/Pamlico Counties                         

**** NEAR FREEZING COLD LOCATIONS  ****
** PATCHY FROST COLDEST PROTECTED AREAS **

Lowest Temperatures:      34 - 37
Morehead_City Min           36 
Range Dewpoint Temps:     23 - 32
Range Wetbulb  Temps:     30 - 41
AVG Wind Direction/Speed:   N  9                          
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)

  03/06/18  03/07/18  03/08/18  03/09/18  03/10/18  03/11/18
  --------  --------  --------  --------  --------  --------
   29 - 37   46 - 47   34 - 38   32 - 37   34 - 38   47 - 49
--------

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

**** FREEZE COLD LOCATIONS  ****
****  WIDESPREAD FROST   ****

Lowest Temperatures:      30 - 35
Elizabethtown Min           34 
Durations at/below 32:     0 -  3
Range Dewpoint Temps:     23 - 30
Range Wetbulb  Temps:     30 - 40
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)

  03/06/18  03/07/18  03/08/18  03/09/18  03/10/18  03/11/18
  --------  --------  --------  --------  --------  --------
   34 - 38   41 - 48   33 - 37   29 - 35   32 - 37   41 - 51
--------

North-Central NC                        
Franklin County Area                              

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

Lowest Temperatures:      28 - 34
Louisburg Min               28 
Durations at/below 32:     0 -  5
Durations at/below 28:     0 -  0
Range Dewpoint Temps:     15 - 22
Range Wetbulb  Temps:     27 - 38
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)

  03/06/18  03/07/18  03/08/18  03/09/18  03/10/18  03/11/18
  --------  --------  --------  --------  --------  --------
   30 - 38   34 - 43   28 - 36   26 - 34   28 - 35   37 - 45
--------

North/Central NC                        
Alamance County Area                              

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

Lowest Temperatures:      28 - 34
Graham_AG Min               32 
Durations at/below 32:     0 -  5
Durations at/below 28:     0 -  0
Range Dewpoint Temps:     15 - 21
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)

  03/06/18  03/07/18  03/08/18  03/09/18  03/10/18  03/11/18
  --------  --------  --------  --------  --------  --------
   33 - 38   34 - 40   29 - 34   27 - 32   29 - 34   38 - 43
--------

South/Central NC                        
Richmond County Area                              

**** FREEZE COLD LOCATIONS  ****
**** LITTLE/NO FROST DUE TO DRY AIR **** 

Lowest Temperatures:      31 - 34
Ellerbe Min                 33 
Durations at/below 32:     0 -  2
Range Dewpoint Temps:     13 - 28
Range Wetbulb  Temps:     30 - 40
AVG Wind Direction/Speed:   N  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)

  03/06/18  03/07/18  03/08/18  03/09/18  03/10/18  03/11/18
  --------  --------  --------  --------  --------  --------
   33 - 42   37 - 45   30 - 35   28 - 34   31 - 35   41 - 46
--------

Interior/EC-SE NC                       
Wayne County Area                                 

**** FREEZE COLD LOCATIONS  ****
****  WIDESPREAD FROST   ****

Lowest Temperatures:      31 - 35
Goldsboro_AG Min            34 
Durations at/below 32:     0 -  3
Range Dewpoint Temps:     27 - 31
Range Wetbulb  Temps:     32 - 40
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)

  03/06/18  03/07/18  03/08/18  03/09/18  03/10/18  03/11/18
  --------  --------  --------  --------  --------  --------
   32 - 35   42 - 45   33 - 36   32 - 34   33 - 36   43 - 46
--------

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