30 Day Ag Weather Outlook VA – TN- NC – SC (11:40am, 3/2/15)

— Written By Barclay Poling

Dear Growers, Agents, Agronomists & Friends,

We are starting  to see larger temperature swings from cold to warm that are typical of this time of year as the pattern that favors cold temperature in the eastern US  is weakening a bit as we approach the spring equinox.

There may be a few days that get above normal, but on the whole the pattern still  favors somewhat below seasonal average temperature over the next four weeks. This might be a good time to take a look under those row covers to see what your crop looks like!

close up Chandler in Pungo on Feb 25Example of a very impressive Chandler plant a year ago (2/25/14). You can easily tell this is a very nice multi-crown plant with minimal leaf burn from the winter season (last year) – this plant had been under row cover protection in Jan 2014.

tom baker on march 2 2015Photo taken today in VA Beach – the snow has melted, but it rained yesterday and much more rain in forecast this week. It doesn’t look good for being able to get covers off this week in VA Beach area.

baker 2The four rows to right of row cover did not have row cover protection at all this winter – should be very interesting to compare the condition of these crowns to the protected ones! In some years it has been possible to start fertigation by this time! One of the concerns with row covers staying on + rains –> potential for botrytis crown rot.

30 Day Ag Weather Outlook VA – TN- NC – SC

Period 1 (4 Mar – 6 Mar):

image001Chart 1. Valid through 3/5/15

Forecast discussion day 3 –  (4 Mar – 6 Mar) Temperatures start off  mild and wet then temperatures cool to below normal mid period A low pressure system will form in the Texas Panhandle region and move through the Great Lakes by mid period.  It is expected that the flow ahead of the low pressure system will bring a moderation of temperatures with a 24-hour period of precipitation as the accompanying cold front moves through the region by mid period.  Temperatures will be mild to start the period with high temperatures expected to range from mid 60s to high 40s and lows in the 30s. Temperatures cool later in period in the northwest flow behind the departing low pressure system and ahead of an approaching high pressure system. Temperatures drop with highs expected in the 30s and lows in the upper 10s – 20s.  Precipitation expected to be widespread early to mid-period in the 0.25” – 0.45” range.

clime 1Table 1. Climatology for these cities, 4 Mar – 6 Mar

Period two (7 Mar – 9 Mar):

image002Chart 2. Valid through 3/8/15

Forecast discussion day 12 – 14:  (7 Mar – 9 Mar) Temperatures stay below normal.  A cold, dry high pressure will slowly move through the area during this period.  Temperatures stay below normal with high temperatures expected to range from high 30s to mid-40s and lows in the upper 20s – low 30s. Little if any precipitation expected during this period in the 0.00” – 0.10” range.

clime 2Table 2. Climatology for these cities, 7 Mar – 9 Mar

Period three (10 Mar – 12 Mar):

image003Chart 3. Valid through 3/11/15

Forecast discussion day 9 – 11: (10 Mar – 12 Mar Temperatures start off cold then warm slowly to near normal late The cold high pressure will slowly moderate and depart the area moving northeast.  This will keep things mostly dry, with slowly rising temperatures to near normal for the season by late in the period.  This period will start off with high temperatures expected to range from low 40s to near 50 and lows in the high 20s – low 30s. Temperatures warm slightly by late in the period with high temperatures expected to range from high 40s to low 60s and lows in the low to mid 30s.

clime 3Table 3. Climatology for these cities, 10 Mar – 12 Mar

Period four (13 Mar – 15 Mar):

image004Chart 4. Valid through 3/14/15

Forecast discussion day 12 – 14:  (13 Mar – 15 Mar) Temperatures stay near normal, becomes wet late in period.  The  high pressure  moderates, will slowly depart the area moving northeast and will be replaced by a low pressure system that will  form in the southeast US and move northeast affecting the area by mid period.  The high temperatures expected to range from the 50s to low 60s and lows in the mid to high 30s.   Precipitation expected to be widespread in the 0.25” – 0.50” range.

clime 4

Table 4. Climatology for these cities, 13 Mar – 15 Mar

OUTLOOKS (16 Mar – 31 Mar)

Outlook discussion day 15 – 22 (16 Mar – 23 Mar): Near average temperatures. Expectations are that temperatures will continue to moderate during this period to near seasonal average temperatures, at least early in the period with periods of rain. A cool down is likely late in the period.

Outlook discussion day 23 – 30:  (24 Mar – 31 Mar): Near to slightly below average temperatures. Early indications are this period will continue near or slightly below the average temperatures for the season.

Editor’s note #1  – please be aware that Outlooks for the 2nd half of May are simply outlooks, and not forecasts. Remember, a “forecast” is always more reliable than an outlook.

Editor’s note #2 – with regard to SkyBit, it is important to note that the Min Air Temp, or Max Air Temp indicated for E-Weather Strawberry Canopy Forecast (e.g. Min Air Temp this morning was 37 F in Chesapeake, VA) may not be the same as the Min Air Temp indicated on COMBO product (just below E-Weather Strawberry Canopy Forecast). The reason for this is that a different algorithm is used to generate E-Weather Strawberry Canopy Forecast than the COMBO.

A grower pointed out today that his SkyBit COMBO showed slightly lower temps for Fri and Sat mornings than the Slybit E-Weather Strawberry Canopy Forecast. Why? This will occur because of the different methods E-Weather Strawberry Canopy Forecast and COMBO are using to generate Air Temps at Weather Shelter height of 2 m (6.56 ft).

20150302st1.VABFCcombo va beachCombo Product – this shows a minimum AIR TEMP of 18 F for Friday, March 6th, whereas the E-Weather Canopy Forecast is showing 19 F. This is not uncommon – it is due to different methodology being employed by these two products for estimation of Min Air Temps

Maybe the model just wasn’t good enough?

Final question from VA grower about why his SkyBit forecast was so far off the other day in Locust Grove VA (Sat. Feb 21, 8:20 a.m.)

Last night we had a low of 4 around 10:00. Skybit was calling for 11. This a.m. we had a low of 6 at 6:30 Skybit was calling for 12 at 4 a.m. and 13 at 7 a.m.

It’s not too big a PROBLEM now, but in April if they are off by 16 degrees or 8 degrees, we have a PROBLEM.

Just giving you a heads up.


Answer from Dr. Kenneth Waight, Meteorologist (who developed this product):


Checking the location, we have it a little east of Locust Grove, VA, I assume that’s right or at least close, probably not the problem.

Checking the afternoon forecasts from Thursday and Friday (for the Friday and Saturday morning lows), the Clayton forecasts look very good, but yes, the Locust Grove forecasts are significantly warm. It looks to me that the model was just having difficulty capturing the extreme situation. The model kept some wind all through the first night and a lighter wind the second night, but the obs at Culpeper show that it was alternating between windy and calm, and the temperature dropped a lot during the calms. So maybe the model just wasn’t good enough, or maybe the local area has low spots that can decouple from the flow more frequently, in which case you might see this happening frequently, which would be a problem. I don’t know where to check this myself (Melanie would) — is this an old or new site?

Another factor is the snow cover, they probably have more up there than we do. That can add quite a bit of cooling, and our model wouldn’t capture that very well. Hopefully this is a rare situation, but if we see that the site is always too warm, I can adjust it to try to make it a little more extreme (more like cranberry than strawberry). Give me a call if you want to talk about it, my cell is 919-302-3619.


Editor’s final note:  My experiences is that the E-Weather Canopy Forecast is very reliable for minimum temperature forecasts at the strawberry canopy level most all of the time, but as Dr. Waight explains,  maybe the local area in Locust Grove has low spots that can decouple from the flow more frequently? Or, maybe the product is not good enough to capture what is really happening at this location. Until we can get this site figured out, I would make sure to invest in a digital thermometer with thermocouple inserted in the plant crown to verify the true plant temperature. Most all VA growers received Omega Engineering digital thermometers 2 years ago under a VDACS grant program.

2015-03-02_12-28-19Watch this video to learn about how to accurately measure air, crown, flower bud and open blossom temperatures:  https://strawberries.ces.ncsu.edu/2009/12/mauris-sed-leo-aliquam-aliquam/

remove guess workUsing a thermocouple inserted into the open blossom is an excellent way to remove the guesswork about actual blossom temperature. VDACS paid for VA strawberry growers to get these units back in spring 2012. It is a essential tool for monitoring blossom minimum temperatures when you are using both row covers and irrigation for freeze protection. It is also quite useful for checking blossom temps during extremely warm periods.

Have a good week!

Dr. E. Barclay Poling

Professor Emeritus (Strawberry Plasticulture Researcher)
Department of Horticultural Science
Campus Box 7609, 162A Kilgore Hall
NC State University
Raleigh, NC 27695-7609
“An idealist believes the short run does not count. A cynic believes the long run does not matter. A realist believes that what is done or left undone in the short run determines the long run.”

Sidney J. Harris, In: Reclaiming a Lost Heritage – Land-Grant & Other Higher Education Initiatives for the Twenty-first Century