February 12, 2021 Weather Impacts On Economic Activity – Updated

Written by Sig Silber

Updated at 6:10 pm EST to incorporate the Week 3-4 forecast which generally favors a reduction in cold air intrusions into CONUS.

We cover the monthly ENSO Update which raises the possibility, that already has been discussed, that this could be a double-dip La Nina which could be a disaster for the Southwest. It is certainly too soon to know for sure. We have quite a few agriculture reports including a NASS Executive Briefing which is mostly about Citrus but we also have two other NASS reports one on labor rates in agriculture and a very good report on vegetables. As usual, we include a lot of other information including an intermediate-term weather forecast.

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ENSO Update issued on February 11, 2021

And here is a graphic that I extract from another regular NOAA product.

Flash Drought Webinar. The full presentation with live links can be found here. What you see below are images from the summary report so what looks like live links are not as they are in the image of the document where the links were live.

A mini-NASS Executive Briefing.

This may provide a little more information

I found the two NASS Reports so here they are

Farm Labor

And here is a very complete report on vegetables.

Severe Weather

Let’s look at the current drought situation.

And the week to week change

Here we look at four-time periods: one week, one month, six months, and a full year.

The result is very dry soil conditions

February Drought Outlook

Intermediate-Term Weather Forecast

Showing from left to right, Days 1- 5, 6 – 10, 8 – 14, and Weeks 3 – 4 You can click on these maps to have them enlarge. Also, the discussions that go with these forecast maps can be found here (first two weeks) and here (Weeks 3 and 4).

First Temperature

And then Precipitation

The Week 3-4 Discussion is always interesting.

Week 3-4 Forecast Discussion Valid Sat Feb 27 2021-Fri Mar 12 2021

A coherent subseasonal signal continues to interfere with the La Nina pattern over the West Pacific, primarily across the Southern Hemisphere. This increased West Pacific convection has contributed to a midlatitude response that allowed an outbreak of Arctic air across the central CONUS. Dynamical model MJO index forecasts depict a fairly rapid weakening of this tropical signal over the next week, with a retrogression towards the Maritime Continent that is consistent with equatorial Rossby wave activity. This breakdown in the signal may help effect a pattern change across North America, and indeed recent dynamical model runs show a rapid retreat of cold air from the eastern and central CONUS during the Week-2 period. Multiple ensemble members from the ECMWF and GEFS depict a return of West Pacific convection by late Week-2, however, which increases uncertainty for the Weeks 3-4 period. Statistical guidance based on the MJO, ENSO, and trends show a potential for additional cold air outbreaks across the central and eastern CONUS; however, the GEFS shows a near-term weakening of the negative AO pattern, which may limit the availability of Arctic air masses to invade the midlatitudes.

500-hPa height anomaly forecasts for Weeks 3-4 from the ECMWF, JMA, Canadian, and GEFS all depict ridging over the southern tier of the CONUS, with troughing limited to western Canada and the Pacific Northwest. The CFS is an outlier, maintaining below-average height anomalies across much of the northern tier, hence allowing more penetration of cold air into the central and eastern CONUS. Therefore, the outlook favors below-average temperatures across the Pacific Northwest, extending eastward to the Dakotas. Above-average temperatures are favored under the forecasted above-average mid-level heights across the southern tier, with the highest probabilities across the south-central CONUS. Strong ridging anticipated over Greenland and the North Atlantic may extend into parts of northern New England, therefore above-average temperatures are slightly favored for Maine. Equal chances are maintained for the Midwest through the Mid-Atlantic, where uncertainty is highest. The forecast height patterns tend to favor westerly flow, which would encourage a fairly transient pattern. Across Alaska, mean northerly flow with ridging to the west and troughing near or to the east favors below-average temperatures for southern Alaska. Above-average temperatures are favored for the North Slope due to below-normal ice coverage over the adjacent Arctic Ocean.

Precipitation forecasts from the dynamical model suites are fairly consistent with climate anomalies associated with La Nina. Most models favor below-average precipitation across the southern tier and along the Eastern Seaboard, and both the precipitation guidance and the 500-hPa height pattern suggest the potential for a weakly enhanced Ohio Valley storm track. Above-average precipitation is also favored for parts of the northern Intermountain West and the northern High Plains. Uncertainty is high for the Pacific Northwest, where dynamical models generally favor below-average precipitation, but the La Nina signal and the Sub-X multi-model ensemble favor above-average precipitation. Therefore, equal chances for below- and above-median precipitation are maintained. Offshore flow supports an enhanced potential for below-median precipitation across southern Alaska.

SST anomalies around Hawaii remain above normal, leading to an increased probability of above normal temperatures throughout the forecast period. Both the operational dynamical models and the Sub-X MME precipitation anomaly forecasts indicate above-median precipitation for the week 3-4 period for Hawaii, particularly over the northwestern islands.

International

This week we have a map.

In the box are shown the major resources we use. We will not be using them all each week but the reader is welcome to refer to these resources.

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