NOAA Updates The Outlook For February, 2020 -Temperature Forecast Questionable

Written by Sig Silber

At the end of every month, NOAA issues an update to their Early Outlook for the following month, in this case, February 2020, which was issued on the Third Thursday of the Month. Today, fifteen days later, NOAA has issued their updated Outlook for February. It is dramatically different than the Early Outlook especially for temperature and reading the two discussions (the full month discussion and the Week 3 – 4 discussion) suggests that there remain some significant uncertainties especially in terms of the temperature forecast for California and Nevada.

Some housekeeping: On January 18, 2020, we published Part I of our analysis of the NOAA and JAMSTEC Three- to Four- Season Outlook and that can be accessed here. In that report, the February 2020 Early Outlook was issued. This article presents the NOAA update of their Early Outlook for February and the most recent Drought Update.

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An area of concern with the forecast has to do with this comment from the Discussion released today.

Above normal temperatures remain probable from California into the Great Basin, due to likely above normal temperatures at the start of February and increasing uncertainty following likely below normal temperatures in week 2.

This comment does not appear to be reflected in the Week 3-4 Forecast. So although we did not intend to do so we need to provide the Discussion that came with today’s Week 3 – 4 Forecast. We will provide that Week 3 – 4 Discussion a bit later in the article.

Now let us address the NOAA Update of the February 2020 Forecast.

We are now going to look at the forecast for the AO as that seems to be an important factor in the forecast. They are always in the Addendum of the LIVE ALL WEEK article for readers and these forecasts auto-update.

I have included the NAO also even though it was not mentioned in the monthly forecast discussion (but was mentioned in the Week 3 – 4 discussion and it is very related to the AO

You can see the impact of the different phases in the schematics below (Source: N.C. State Climatologist). PNA Positive in on the left and PNA Negative on the right. PNA Negative is a pattern that is more westerly located than PNA Positive. This has to do with storms entering CONUS in the Northwest and then moving south either closer to the coast or further inland.

………………………..PNA Positive…………………………….. PNA Negative……………..

PNA Negative kind of conflicts with a strong ridge of High Pressure in the Gulf of Alaska.

Back to our Normal Format and Discussion

A note about terminology; the deviations from climatology/normal are color-coded but also labeled “A” for more than (above) normal and “B” for less than (below) normal. The area designated EC means Equal Chances of being more or less than normal. In the Short Term forecasts, NOAA has switched from using EC to N for Normal. For most purposes, EC and N can be considered to mean about the same thing. “N” implies a bit more certainty that the variation from Normal/Climatology will be small compared to “EC”.

First, we will compare the NOAA Early Outlook for February 2020 with the newly issued update.

Early Outlook Temperature

Updated Temperature Outlook

Early Outlook Precipitation

Updated Precipitation

Here is the discussion released today:

30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2020

The updated temperature and precipitation outlooks for February 2020 are based on the latest guidance from the WPC temperature and precipitation forecasts for the first week of February, the CPC 8-14 day and Weeks 3-4 temperature and precipitation outlooks, and the latest NCEP CFS monthly forecasts. Although equatorial sea surface temperatures (SSTs) are 0.5 to 2 degrees Celsius above average across much of the western and central Pacific Ocean, the tropical atmospheric circulation is more consistent with ENSO neutral conditions. The Madden-Julian Oscillation (MJO) is weak with enhanced convection primarily centered just west of the Date Line. Although dynamical models forecast that the MJO will dissipate in the first week of February, model forecasts indicate that the MJO may reemerge and strengthen over the Maritime Continent within the first half of February. An MJO in this phase would lead to an increased chance of above normal temperatures across the eastern US in the next couple weeks. There is however considerable uncertainty in model MJO forecasts at this time.

Dynamical models predict a likely circulation pattern change over the North American region during February 2020. During the first few days of February, negative height anomalies along with below normal temperatures are predicted over Alaska, while positive height anomalies over the western CONUS and an enhanced Pacific jet lead to a forecast of above normal temperatures over much of the CONUS. Dynamical models predict an amplification of ridging over the North Pacific and downstream troughing over the western CONUS towards the end of the first week of February, leading to increasing probabilities of below normal temperatures for the western and central CONUS in the second week of February. This circulation pattern is consistent with the possible emergence of an MJO signal with enhanced convection over the Maritime Continent, as predicted by some model forecasts. This pattern is inconsistent with the current phase of the MJO with enhanced convection over the central Pacific Ocean, as models predict this MJO signal to dissipate in the next few days. There is currently a strong polar vortex in the Arctic stratosphere with the signal extending through much of the troposphere. Statistically a strong stratospheric polar vortex supports a strengthening of the positive Arctic oscillation in the troposphere and an increase in the probabilities of above normal temperatures over the eastern CONUS, while enhancing the chances of below normal temperatures over parts of the western CONUS. Dynamical models predict the Arctic Oscillation to remain positive and strengthen over the next two weeks, with generally an amplified negative height anomaly over the Arctic and positive height anomalies at mid-latitudes. Model forecasts for weeks 3 and 4 from the ECMWF, JMA and NCEP CFS operational models and the Subseasonal Prediction Experiment (SubX) multi-model ensemble (MME) generally predict increased ridging over western Alaska and troughing extending from central Canada into the CONUS, leading to the advection of Arctic air into western Canada and potentially into the northern CONUS. Below normal temperatures appear most likely for southeastern mainland Alaska and the Alaska Panhandle and for parts of the northern tier of the CONUS, particularly over the northern Rockies and High Plains. The CPC Week 3-4 Outlook indicates high probabilities for above normal temperatures over the eastern CONUS and some enhanced probabilities of below normal temperatures over the Northwest.

With the variable circulation pattern predicted through February, the updated temperature outlook represents a significant change from the previous February outlook, released in mid-January. The area of likely below normal temperatures over the CONUS for the month of February has decreased significantly. Below normal temperatures remain likely from the Northern Rockies into western areas of the Northern Plains, with below normal temperatures in the week 2 outlook as well as in the week 3-4 outlook, related to northerly flow. Above normal temperatures are likely over a large area of the eastern CONUS with rising heights predicted from week 2 into week 3 and possibly week 4. Above normal temperatures remain probable from California into the Great Basin, due to likely above normal temperatures at the start of February and increasing uncertainty following likely below normal temperatures in week 2. Above normal temperatures remain likely for parts of western and northern Alaska, supported by decadal climate trends and predicted positive 500-hPa height anomalies from the end of week 2 into weeks 3 and 4. Below normal temperatures are likely for February over southeastern Alaska and the Alaska Panhandle, with likely below normal temperatures both early in February, under a predicted trough, and later in the month, under anomalous northerly flow.

Although the circulation forecast for February has changed, the precipitation pattern predicted for the first week of the month and the precipitation forecast for weeks 3 and 4 are somewhat consistent with the previous February precipitation outlook, released in mid-January. The precipitation outlook for week 2 is also consistent in most areas, except for increased chances of above normal precipitation from the Southwest into the Central Plains ahead of a predicted amplified trough. The ECMWF and JMA models and the SubX MME predict troughing into the western CONUS to be less amplified in weeks 3 and 4 leading to likely below median precipitation across the Southwest extending into the Central Plains in the dynamical model forecasts. Below normal precipitation remains likely for parts of California, Oregon and Nevada, in the February outlook, consistent with dynamical model forecasts throughout most of February.

Below normal precipitation continues to be likely for parts of the Central Plains, with likely above normal precipitation for this region limited to week 2. An area of likely above normal precipitation has expanded from the Northern Rockies into the High Plains and Northern Plains, as systems are likely to develop east of the Rockies throughout much of the month. A large area of likely above normal precipitation from the Gulf Coast across the Southeast to the Ohio Valley and Mid-Atlantic region is supported by WPC forecasts for precipitation in week 1, CPC precipitation forecasts for week 2, and continued likely above normal precipitation into weeks 3 and 4 for much of the region. Above normal precipitation is likely for northeastern mainland Alaska, ahead of predicted troughing particularly in week 2, and is likely for the Alaska Panhandle due to significant precipitation predicted early in the month by dynamical model forecasts.

Visual Consistency Testing.

It is useful to see how the full-month forecast fits with the set of partial-month forecasts that we have. These will continue to update in this article. It is important to remember that with the partial-month forecasts, we generally have about 25 days of the subsequent month to look at when we do this at the end of the month as we are doing now. It depends on what day of the week the month ends. So this month, which ended on a Friday, we are only missing a forecast specific to the last day of the month. So we are in very good shape to the visual consistency testing this month.

First Temperature

The new monthly forecast is to the right. Does it appear to be reflective of the four parts of the month for which we have forecasts? →			↑ ← The Week 3 – 4 forecast was updated today so we will not need to update the commentary when the Week 3 – 4 update is reissued. At this point, we have forecasts for 28 days of the 29 days in February and the fit looks pretty good. But we have some questions about the warm anomaly in the Extreme Southwest (California and Nevada).

And Precipitation

The new monthly forecast is to the right. Does it appear to be reflective of the four parts of the month for which we have forecasts? →			↑ ←The Week 3 – 4 forecast was updated today so we will not need to update the commentary when the Week 3 – 4 update is reissued. At this point, we have forecasts for 28 days of the 29 days in February and the fit looks pretty good. But we do not understand the reason for the dry anomaly shown just east of the Rockies as it does not show up in any of the short-term forecasts.

This then requires us to provide the Week 3 – 4 Discussion that was also released today. We are trying to understand if the assumptions and analysis in the full-month discussion are different than the assumptions and analysis in the Week 3- 4 discussion. NOAA says that their full month discussion fully incorporates the Week 3 – 4 analysis.

Week 3-4 Forecast Discussion Valid Sat Feb 15 2020-Fri Feb 28 2020

A complicated perspective emerges when considering possible tropical drivers of the midlatitude circulation as of late January. Over the past week the RMM index tracks the Madden-Julian Oscillation (MJO) inside the unit circle with an accompanying uncharacteristic westward shift driven by equatorial Rossby wave activity, with a recent re-emergence over the West Pacific (Phase 6). Decomposition of canonical equatorial waves suggests this signal is tied to a Kelvin wave near the antimeridian, while dynamical model forecasts of the RMM show the MJO re-emerging over the Indian Ocean or Maritime Continent by the second week of February. At the lower frequencies, the sea surface temperature (SST) gradient remains robust across the Pacific in an east-west sense, with the latest Nino 4 SST anomalies of +0.9 degrees C and Nino 1+2 checking in at -0.2 degrees C. Persistent negative outgoing longwave radiation anomalies have been observed near and just west of the Date Line since late November. Given this complex perspective, any possible MJO influence is downplayed as the envelope appears to be in flux at present with the Phase 6 signal being tied to Kelvin wave activity that typically fails to couple with the extratropics. The convective pattern over the Pacific does project weakly onto a subseasonal El Nino-like response, despite SSTs increasing from east to west. As a result, the resultant Week 3 and 4 outlook primarily leverages dynamical model guidance with some deference to long-term trends and a slight adjustment toward canonical El Nino conditions.

Dynamical model circulation guidance generally features a robust negative Pacific-North American (PNA) pattern with a positive North Atlantic Oscillation (NAO), both of which are consistent with the Week-2 forecast. These patterns translate into an amplified 500-hPa pattern featuring anomalous ridging south of the Aleutians, positively-tilted troughing over the West, and ridging extending from Mexico through New England. The outliers lacking this pattern come from the Subseasonal Experiment (SubX) model suite, in the way of the CCSM4, GEFS, and FIM models. These three models feature more ridging over the west and weakness or troughing in the East, in line with the typical MJO response to a Phase 6 event. Given the apparent Phase 6 signal being Kelvin-wave oriented, these models are discounted in the construction of the final outlook.

Much to the chagrin of any snow lovers in the East, the continued NAO+ outlook and enhanced subtropical ridge over the Southeast favors a tilt toward above-normal temperatures, while the MJO re-emerging over the Maritime Continent would likely further lock in east coast warmth. Troughing across the West results in below-normal temperatures being favored, although there is some uncertainty regarding how far south and east any cold air mass would extend. A west-east dipole favoring above- and below-normal temperatures respectively is forecast across Alaska tied to the forecast ridge-trough pattern across the Pacific and western North America. El Nino influence across the Northern Tier tends to wash out long-term trends which are slightly below-normal, while decadal trends further support the increased chances for above-normal temperatures in the east, resulting in these probabilities being enhanced relative to the dynamical model guidance.

The PNA- pattern supports a suppressed Pacific jet resulting in below-normal precipitation chances for areas adjacent to the Gulf of Alaska and along the West Coast. Dynamical models extend below-normal precipitation chances across the Southwest, further supported by decadal precipitation trends being negative for the region. There is some uncertainty with how far north and east this dry pattern would extend, further confounded by upslope precipitation potential along the High Plains tied to below-normal temperatures behind the anomalous trough. A mean frontal zone can be inferred at the trough-ridge interface, resulting in above-normal precipitation chances being elevated from the Lower Mississippi Valley through Ohio Valley.

SST anomalies in the vicinity of Hawaii continue to range from +1 to +2 degrees C, supporting above-normal temperatures being favored across the islands. Model guidance supports a weak gradient in precipitation with wetter (drier) conditions favored across eastern (western) portions of the state, in line with observed conditions across the state in early 2020.

Sometimes it is useful to compare the three-month outlook to the forecast for the first of the three months. It shows how much the pattern changes over the three-month period.

One can mentally subtract the First-Month Outlook from the Three-month Outlook and create the Outlook for the last two months in the three-month period.

And with respect to drought, this was also issued on January 31, 2019.

Discussion for the Monthly Drought Outlook

Tools used in the U.S. Monthly Drought Outlook (MDO) include the Climate Prediction Center (CPC) temperature and precipitation outlooks for February, various short- and medium-range forecasts and models such as the 7-day quantitative precipitation forecast (QPF) from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC extended-range forecasts (ERFs), the Week 3-4 outlooks and tools from CPC, dynamical models at the monthly time scale, the 384-hour total precipitation forecasts from several runs of the GFS, and February Climatology. Initial conditions are based on the January 28, 2020 U.S. Drought Monitor. ENSO-neutral conditions are present, and are favored through the Northern Hemisphere spring 2020 (60% chance) and continuing through summer 2020 (50% chance).

The Northeast region is currently drought free. There are some pockets of dryness at 30-, 60-, and 90-days, but at 4-months, precipitation across most of the Northeast is at or above-normal. There was only a small D0 area on the Delmarva Peninsula which had missed out on recent heavy precipitation events, but with moderate totals predicted on the 7-day QPF, above-normal precipitation odds in both the 6-10 and 8-14 day ERFs, EC (eastern) to above-normal (western) totals on the Week 3-4, and EC (New England) to above-normal (mid-Atlantic) precipitation on the updated February 2020 LLF, no new development is expected through February 29.

Forecast confidence is high for the Northeast.

Abnormal dryness recently developed along the coasts of South and North Carolina and southeastern Virginia, along with D0 in western Florida and southwest Alabama. A small D1 area remained in northwest Florida near Apalachicola. But like the Northeast and even more so, the 7-day QPF is quite wet across the Southeast (including 3-4″ over the D1 area and parts of Georgia and the Carolinas), along with good odds for above-normal precipitation in the 6-10 and 8-14 day ERFs, the Week 3-4, and updated February 2020 precipitation LLF. Similar to the Northeast, this wet forecast during February favors removal of the D1 in northwest Florida, and no new development.

Forecast confidence is high for the Southeast.

The forecast for the South is somewhat perplexing. The SDO [FMA’20] made 2 weeks ago showed improvement for the southern Plains, and some USDM improvement was made in central, northern, and eastern sections of Texas, but some deterioration occurred in southern sections. The February outlooks are a mixed bag, with dryness early in the period (QPF and 6-10 day ERF), but then above-normal rain odds in the 8-14 day ERF (entire region), Week 3-4 (eastern areas), and updated 1-month LLF (southeast areas). Plus, subnormal precipitation is favored in western Texas in the Week 3-4. But since most of northern and central Texas recently received rain and drought improvement, it should take a while for these recently improved Texas areas to deteriorate in the cooler February air and somewhat dry February climatology. Thus, with the favorable February storm track and available Gulf moisture expected for southern and eastern Texas, improvements were depicted there. Further north in Oklahoma and Kansas, the two small drought areas should persist as recent precipitation shrunk these areas, but February forecasts are mostly dry.

Forecast confidence is moderate for the South.

There was no drought or D0 in the Midwestern States, and the last 30-and 60-days saw surplus precipitation across the Midwest. Some 90-day deficits remained in parts of northern Missouri, southern Iowa, and northern sections of Illinois, Indiana, and Ohio, but the recent precipitation eliminated any previous D0 there. Although the short-term forecast is mostly dry (QPF), both ERFs and Week 3-4 favor EC to above-normal precipitation, although the updated 1-month LLF tilts the odds toward subnormal precipitation over Missouri, southern Iowa, Illinois, and western Indiana. Even so, with the colder winter temperatures, lack of evaporation and crop growth, frozen and snow-covered ground (northern areas), and no reported impacts, no development is expected during February.

Forecast confidence is high for the Midwest.

With the exception of some D0 and drought in western Kansas, parts of Colorado, and western Wyoming, the High Plains has observed surplus to excessive precipitation, especially the Dakotas. And with many northern locations under snow cover, frozen ground, and having a dry February climatology, this also favors no development. Farther south, recent precipitation has fallen on parts of the central Plains, easing drought in Oklahoma, Kansas, and Colorado. With good chances for above-normal precipitation in the northern Plains (updated 1-month LLF, QPF, both ERFs, and Week 3-4) and somewhat lower odds in the central High Plains, no development is expected for this region. It is possible that some slight improvement may occur in the central Rockies based upon both ERFs, but the other forecast periods are not confident enough (EC) to draw for this.

Forecast confidence is high for the northern High Plains; moderate for the central High Plains.

With high pressure expected off the California coast for much of February, the updated February 2020 LLFs favored subnormal precipitation and above-normal temperatures for much of California and Nevada. The ERFs and Week 3-4 keep it dry, but with near to below-normal temperatures. However, with a more northerly Pacific storm track, moisture should funnel into Washington early in the month, then weaken later in February. This may be enough precipitation for improvement in northern Washington. During the past 30-days, surplus precipitation has fallen on the Northwest, improving WYTD basin average precipitation and Snow Water Content (SWC) after a rather dry November and December. In contrast, the Southwest was wet during Nov-Dec 2019, but very dry during the past 30-days. In-between the Northwest and Southwest (e.g. southern Oregon and northern California), dry weather occurred during Nov’19 and Jan’20, and normal precipitation during Dec’19. As a result, WYTD SNOTEL basin average precipitation is close to normal (between 90-110%) in most western basins, although drier (60-80%) in the southern Cascades and Sierra Nevada. But since it was relatively cold during OND’19, more of the precipitation fell as snow and built up the snowpack, leading to Jan. 29 SWC basin averages at or above normal in much of the West, except lower in the Sierra Nevada and central Idaho.

Based upon the forecasts and current conditions, development is possible south of the 2 drought areas in WA/OR and Idaho where it has been drier than surrounding areas since November, and is now in D0. In California, even though the February forecasts are for dry and mild conditions, there is still March and April remaining in the wet season that could overcome any dryness in February. So drought development is possible in California, but more-likely to occur in March or April when the wet season starts winding down. Fortunately, the major California reservoirs are in good shape. In the Four Corners region, the February outlooks were a mixed bag (mostly EC), and with a wet ND’19 and dry Jan’20, no clear February signal was there, so persistence was forecast.

Forecast confidence for the West is moderate.

All drought (D1 or drier) was recently removed from Alaska and Puerto Rico with wetter conditions, and with most February forecasts (except the Week 3-4) expected to favor above-normal precipitation (Alaska) or EC (Puerto Rico), no development was made. In Hawaii, the rainy season has been quite wet leading to recent improvements in the islands, and that pattern is expected to continue during February, with additional improvements expected.

Forecast confidence is high for Alaska; moderate to high for Hawaii and Puerto Rico.

Looking back on January to relate the forecast for February to the actuals in January.

First January Temperature (30 out of 31 days).

And then January Precipitation (30 out of 31 days).

We then show the new forecast and the prior month actuals (less one day) side by side.

Conclusion

The purpose of this article was to present the updated Outlook for February 2020 and compare it with the Early Outlook. It is not to critique the updated Outlook for February based on our opinions but we point out possible inconsistencies if we find them. We have assessed the extent to which the monthly outlook seems to fit with the other forecasts provided by NOAA. In reality, all forecasts are obsolete when issued as the situation changes day by day or six hours by six hours i.e. each new model run. In our other articles, we continually examine the current forecasts from NOAA including the Day 1- 5, 6-10, 8-14 and Week 3 and 4. So we are continually looking at approximately 25 days into the future.

On February 13, 2020, IRI/CBC will issue their ENSO forecast and we will present that and critique it. It is an ongoing process and we attempt to provide our readers with the best current assessment of the next approximately 25 days (except when we cover the Four-Season Analysis or medium-frequency cycles such as ENSO), so our analysis is pretty much ongoing. We also publish a “LIVE All WEEK” Weather Article which updates in real-time to reflect NOAA Weather Headlines. All of our reports including past versions of these reports can be located via the Directory/Archive which can be accessed here.