Written by Sig Silber
Updated at 5:10 p.m. EDT November 1, 2019 to reflect the new Week 3 – 4 Forecast
At the end of every month, NOAA issues an update to their Early Outlook for the following month, in this case, November, which was initially issued on the Third Thursday of the Month. The key sentence and a half from their Discussion are:
The temperature outlooks indicate a monstrous transition in the pattern from the first half of the month to the second half, increasing uncertainty in the outlook. The bone chilling cold likely early in the month across the Great Plains, Great Lakes and Northeast is weighted more heavily than the warming forewarned by many of the models for the eastern CONUS,
Some housekeeping: On October 18, 2019 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 November Early Outlook was issued. This article presents the NOAA update of their Early Outlook for November.
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Now let us address the NOAA Update of the November, 2019 Forecast.
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 November 2019 with the newly issued update.
Early Outlook Temperature
Updated Temperature Outlook
Early Outlook Precipitation
Updated Precipitation
October 17, 2019 Forecast for November | October 31, 2019 Forecast for November | |
Temperature | ||
Precipitation |
Here is the discussion released today:
Visual Consistency Testing.
It is useful to see how the full month forecast fits with the set of shorter forecasts that we have. These will continue to update in this article. It is important to remember that of the short term 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 so this month we do not have the last eight days of the month represented by short-term forecasts. By tomorrow, that number will be down to one or none.
First Temperature
And Precipitation
Here is the discussion that was released with the Week 3 – 4 Update
Week 3-4 Forecast Discussion Valid Sat Nov 16 2019-Fri Nov 29 2019
The Week 3-4 temperature and precipitation outlooks are based on the evolving circulation pattern from Week-2, dynamical model forecasts from the NCEP CFS, ECMWF, and JMA, and SubX multi-model ensemble of experimental and operational ensemble prediction systems. Long-term trends and anomalous snow cover were also considered. ENSO-neutral conditions continue across the tropical Pacific Ocean. The Madden-Julian Oscillation (MJO) propagated eastward from the Indian Ocean to the western Maritime Continent during late October. However, the amplitude of the MJO decreased as its enhanced phase reached the Maritime Continent. This amplitude decrease was a result of the MJO destructively interfering with the ongoing positive Indian Ocean Dipole. Dynamical models indicate that the MJO continues to propagate eastward with its enhanced phase overspreading the Western Hemisphere later this month, although model spread is large on its amplitude. This continued eastward propagation would favor a colder outcome for the eastern U.S. during the outlook period, but confidence is tempered on how much influence the MJO provides on the mid-latitude circulation pattern.
A highly amplified pattern persisted for much of October over North America with 30-day temperatures averaging much below normal throughout the West and Great Plains. During the next two weeks, the GFS and ECMWF models indicate a highly amplified trough across eastern North America. Recent model runs are consistent that this trough weakens late in Week-2. During Weeks 3 and 4, dynamical models are in good agreement with an upper-level trough anchored over the Aleutians with an upper-level ridge over western North America. This longwave pattern would likely result in an upper-level trough downstream over eastern North America although the CFS and ECMWF models differ on the trough axis and amplitude. The SubX multi-model ensemble (MME) also depicts a trough with negative 500-hPa anomalies over the Aleutians. However, the MME indicates a eastward displacement of the ridge-trough longwave pattern over North America, resulting in a more expansive coverage of above normal temperatures across the eastern U.S. Ridging aloft along with a consensus among temperature tools supports the highest probabilities of above normal temperatures across the western U.S. Due to the likelihood of anomalous cold during Week-2, an upper-level trough of varying amplitude among dynamical models, and the predicted evolution of the MJO, forecast confidence in the temperature outlook is lowest over the eastern U.S. Equal chances of below or above normal temperatures are forecast across the upper Mississippi Valley, Great Lakes, and Northeast where the ECMWF model indicates enhanced odds for below normal temperatures.
The precipitation outlook during Week 3-4 is a forecast challenge since the equal weighted model guidance from the CFS, ECMWF, and JMA models feature little to no anomalies throughout much of the CONUS. This is a result in part due to conflicting output from those three dynamical models. The expansive area favoring below normal precipitation, extending east from California and the Rockies to the Midwest, is consistent with predicted ridging aloft and is also supported by the SubX multi-model ensemble. Precipitation tools are in reasonably good agreement for elevated odds of above normal precipitation across the Pacific Northwest and southern Texas.
The dynamical models feature an amplified upper-level trough over the Aleutians and a downstream ridge over or just east of mainland Alaska. This longwave pattern yields enhanced odds for above normal temperatures throughout Alaska. This highest probabilities for above normal temperatures are forecast along coastal areas of western and northern mainlands Alaska due to the influence of above normal sea surface temperatures. The upper-level trough over the Aleutians is expected to result in an active storm track across the North Pacific with above normal precipitation most likely for the Alaska Panhandle. Precipitation tools also support increased chances for above (below) normal precipitation for the North Slope of Alaska (western mainland Alaska).
Weekly sea surface temperature (SST) anomalies, centered on October 23, are running more than 0.5 degree C above normal surrounding Hawaii. Based on these SST anomalies along with dynamical model guidance, above normal temperatures are likely for Hawaii. The CFS model features a weak precipitation signal throughout the Hawaiian Islands although there there is a slight tilt in the odds for below (above) normal precipitation across the Big Island (Kauai).
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 October 31, 2019.
Looking back on October to relate the forecast for November to the actuals in October.
First October Temperature (30 out of 31 days).
And then October Precipitation (30 out of 31 days).
We then show the new forecast and the prior month actuals (less one day) side by side.
Prior Month (usually missing one day) | Forecast for current Month | |
Temperature | ||
Precipitation |
We now present the discussion released with the new November Outlook
30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2019
The updated temperature and precipitation outlooks for November reflect the latest model guidance (including CFS, GEFS, ECMWF, and ECCC), official outlooks from WPC and CPC, and observed conditions. The temperature outlooks indicate a monstrous transition in the pattern from the first half of the month to the second half, increasing uncertainty in the outlook. The bone chilling cold likely early in the month across the Great Plains, Great Lakes and Northeast is weighted more heavily than the warming forewarned by many of the models for the eastern CONUS, so moderate probabilities of below normal temperatures are favored for much of the east, except over Florida. Across the western CONUS, all signals point toward above normal temperatures, potentially enhanced where below normal precipitation is also favored. Across Alaska, the ice edge is still far from the coast, which strongly favors above normal temperatures for the immediate coastal areas, whereas trends and recent model output favor above normal temperatures. That signal over Alaska weakens from west to east.
Compared to the mid-month outlook, the precipitation outlook expands the area where below normal precipitation is favored over the west, while also moving the area of highest odds to the Great Basin. The latest official outlooks and model guidance through the first two weeks show the possibility of some precipitation in the Pacific Northwest, with some of that extending to Montana. November is a relatively drier part of the year for central and eastern Montana, so even small precipitation amounts there early in the month would favor above normal precipitation for the month. For much of Montana, the 7-day (November 1-7) precipitation forecast is for amounts greater than the threshold for below normal precipitation for the month. The storm track into the Pacific Northwest is not likely to spread precipitation southward into the Sierra Nevada and Great Basin, where the outlooks through the first 14 days favor below normal precipitation. North of the predicted mean baroclinic zone and in the core of the colder air forecast for the first half the month, drier than normal conditions should prevail in the Middle Mississippi Valley. Along the mean baroclinic zone, above normal precipitation is forecast for the Southeast, and over west Texas and eastern New Mexico where the western ends of fronts can sometimes trigger precipitation events over climatologically dry regions.
The purpose of this article was to present the updated Outlook for November. 2019 and compare it with the Early Outlook. It is not to critique the updated Outlook for November 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. We do not have a November forecast by JAMSTEC as they only provide three-month forecasts but we do have a prior September/October/November forecast from them last month. 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 November 14, 2019, 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.