(emphasis mine)

Monday, 6 April 2009
Breaking News: Severe Weekend Freeze Hits US

Exactly two years ago, a record-breaking freeze hit the southern Plains and Deep South, setting the wheat market into a frenzy and marking the beginning of a bull run lasting more than a year. Wheat doubled in price from the time of the April 2007 freeze until the top of the market, a year later. Is history getting ready to repeat itself, asks Allen Motew of QT Weather?

It is certainly beginning to look that way. The Southern Plains saw a hard freeze Sunday morning. Lows in Kansas, Oklahoma and Texas will be even colder on Monday. Monday morning will be even colder than Sunday with teens in Kansas and low twenties in Oklahoma and N Texas...enough to cause widespread damage to the HRW crop, he says.

After that a third day of severe cold will hit the Southern Plains Tuesday, reaching the Lower Mississippi Valley and SRW crop too, adds Allen. Southern states will see readings far below freezing Wednesday morning hurting numerous perishable crops as well as hardy varieties too, very similar to the April 4-9, 2007 freeze, warns Allen.

The 2007 freeze was so destructive because it followed two to three weeks of well above normal temperatures (highs mainly in the 70s and 80s/lows mainly in the 50s and 60s). This kicked off the growing season a little early, with vegetation stressed when temperatures plummeted. The pattern this year seems strikingly similar with growing degree days well above average so far in 2009. Most states from the southern Plains to the Corn Belt and across the South saw a much warmer than normal March setting the stage for history to repeat itself, he warns.

The Soft Red Wheat crop across Arkansas and the Mid-Mississippi Valley will see record low temperatures Tuesday morning. The all-time lowest April temperature in Little Rock is 28 degrees F. Tomorrow QT Weather say that a low of 24 degrees will hit Little Rock, with potentially devastating results. In 2007, before the freeze hit, 6% of the crop was rated poor/very poor, post-freeze this number had shot to 64%. In Tennessee it went from 3% to 84%.

Tuesday's forecast lows:

Storm Exchange reports about the risk of freeze damage in Oklahoma and Kansas wheat.

Risk of Freeze Damage in Oklahoma and Kansas Wheat
WHEAT HIGHLIGHTS: Wake-Up Weather for Monday, April 6
By Gail Martell
Updated: April 6, 2009

Wheat will be exposed to potentially damaging temperatures tonight when temperatures fall into the low and mid 20s F.

Injury to jointing wheat will occur when temperatures fall to the mid 20s F for at least 2 hours, long enough to kill the growing point that is located above the soil surface. The stem growth will stop immediately above the growing point and yield losses will vary, depending on the extent of freeze damage in the affected stems. Mild stem injury does not appear to interfere with ability of wheat plants to take up nutrients from the soil and translocate them to developing grain, according to research conducted by Kansas agronomists.

Jointing was just beginning in Kansas on March 26th, reportedly 9% under way in the south-central district and 15% in central Kansas. Jointing was most advanced in the southwest district at 20%. Minimum temperatures tonight are expected to bottom out in the low to mid 20s F in Wichita (23), Dodge City (25), Garden City (22), Hutchinson (20), Medicine Lodge (23) and Liberal (22). These cities are all located in the southern half of the state.

Vulnerability to freeze damage is greater in Oklahoma, where crop development is more advanced. Statewide 62% of Oklahoma wheat was jointing March 26th while a few fields in the southwest part of the state had already reached the boot stage. Predicted lows for tonight are: Enid (22) Hobart (29) Lawton (26) Ponca City (24) and Stillwater (24). Temperatures will rebound into the low 40s F tomorrow night in Oklahoma and Kansas.

Storm Exchange reports that hard freeze and drought affect Oklahoma wheat.

Hard Freeze and Drought Affect Oklahoma Wheat

-Lows may drop below 20ºF in parts of Oklahoma by Tuesday morning
-Temperatures in the mid 20's for at least 2 hours can cause wheat damage
-Precipitation less than 50% of normal since December
By Daniel Greenstein
Updated: April 6, 2009

While drought across Oklahoma continues to negatively impact winter wheat, a potentially damaging freeze is in the cards for Monday night into Tuesday morning.

Early Monday morning, gusty winds in northwestern Oklahoma and the panhandle died down prior to sunrise allowing temperatures to drop into the low 20's, nearly 20ºF below normal. Throughout the rest of the state, winds stayed strong enough during the entire night to prevent significant radiational cooling from taking place. This process allows the coldest air to sink to the ground when under the influence of a cold air mass. When winds are strong, the air in continually mixing, preventing that very cold air from reaching the surface. In Oklahoma City, winds stayed near 20mph throughout the night with the mercury only dipping briefly down to 30ºF.

As the core of the high pressure moves towards Oklahoma by Monday night, winds will diminish statewide. When combined with clear skies, temperatures are likely to drop into the 20's Monday night across all of the major wheat areas in central and western Oklahoma.

According to Storm Exchange's Senior Agricultural Analyst, Gail Martell, 62% of Oklahoma winter wheat was in the jointing process as of March 26th. She states that when temperatures fall to the mid 20's for at least two hours, yield loss can occur as growth above the growing point will stop.

Monday night into Tuesday morning, temperatures across the major wheat areas may be below freezing for as much as 10 hours. With lows bottoming out in the low 20's and even upper teens in some low-lying locales, temperatures should easily be in the mid 20's, if not colder, for more than two hours. Some of the latest computer guidance shows more than six hours of temperatures below 25ºF around Enid, OK.
...

Below is a great graphic of US winter wheat from the USDA.




My reaction: A severe freeze is hitting US wheat crops

1) In April 2007, a record-breaking freeze hit the southern Plains and Deep South, sending the wheat market into a frenzy. Wheat doubled in price in the year following the 2007 freeze.

In 2007, before the freeze hit, 6% of the crop was rated poor/very poor, post-freeze this number had shot to 64%. In Tennessee it went from 3% to 84%.

2) The Southern Plains saw a hard freeze Sunday morning.

3) Monday morning was even colder than Sunday with teens in Kansas and low twenties in Oklahoma and North Texas, enough to cause widespread damage to the HRW crop.

4) A third day of severe cold will hit the Southern Plains, with Soft Red Wheat crops across Arkansas and the Mid-Mississippi Valley seeing record low temperatures Tuesday morning.

The all-time lowest April temperature in Little Rock is 28 degrees F. Tomorrow QT Weather say that a low of 24 degrees will hit Little Rock, with potentially devastating results.

5) Finally, Southern states will also see readings far below freezing Wednesday morning, further hurting crops.

6) Injury to jointing wheat occurs when temperatures fall to the mid 20s F for at least 2 hours, long enough to kill the growing point that is located above the soil surface.

7) < /span>Monday night into Tuesday morning, temperatures across the major wheat areas may be below freezing for as much as 10 hours.

8) The 2007 freeze was so destructive because it followed two to three weeks of well above normal temperatures.

9) Most states from the southern Plains to the Corn Belt and across the South saw a much warmer than normal March setting the stage for history to repeat itself.

Conclusion: On top of drought, we can now add a devastating freeze to the mix. 2009 crop yields are bound to be very poor.