Written by Sig Silber
At the end of every month, NOAA issues an update to their Early Outlook which was issued on the Third Thursday of the Month. Usually the changes are minor but not this month. The changes are not really a surprise as we track the forecasts out to approximately twenty-five days and they have deviated from the Early Outlook so we expected substantial revision but not quite this much.
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Now let us address the NOAA Update of the November, 2018 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. I believe this was a recommendation of a Focus Group. I find those new graphics harder to read especially if printed in black and white. For most purposes, EC and N can be considered to mean about the same thing.
First we will compare the NOAA Early Outlook for November 2018 with the newly issued update.
Early Outlook Temperature
Updated Temperature Outlook
Early Outlook Precipitation
Updated Precipitation
And here is the NOAA discussion released with the November Update. It is worth reading.
30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2018
THE REVISED NOVEMBER FORECAST CONTAINS A LOT OF UNCERTAINTY, ESPECIALLY WITH RESPECT TO THE TEMPERATURE OUTLOOK. THE FORECAST EVOLUTION OVER THE EARLY PART OF THE MONTH FAVORS A MEAN ANOMALOUS TROUGH OVER THE EAST-CENTRAL CONUS, WITH THE ECMWF AND GEFS SOLUTIONS NOW DIVERGING A BIT THROUGH THE COURSE OF THE WEEK-2 PERIOD. THE CFS FAVORS A VERY MILD SOLUTION OVER MUCH OF THE CONUS FOR THE ENTIRE MONTH, DUE IN LARGE PART TO A VERY MILD SECOND HALF OF THE MONTH. THE LATEST WEEKS 3-4 GUIDANCE FROM THE ECMWF DEPICTS A VERY DIFFERENT SOLUTION FOR THE LATTER PART OF NOVEMBER WITH BELOW-NORMAL TEMPERATURES DEPICTED OVER MUCH OF THE EAST-CENTRAL U.S. THE OFFICIAL FORECAST RELIED HEAVILY ON THE OBJECTIVE GUIDANCE THAT INTEGRATES CALIBRATED GUIDANCE FROM THE GEFS AND CFS OVER THE COURSE OF THE UPCOMING MONTH: THIS YIELDS A MUCH COOLER SOLUTION THAN THE MONTHLY MEAN CFS FORECAST ALONE. BELOW-NORMAL TEMPERATURES ARE NOW FAVORED WITH MODEST PROBABILITIES CENTERED OVER THE MISSISSIPPI VALLEY. THE FORECAST EVOLUTION OF THE MJO DOES SLIGHTLY FAVOR THE CFS SOLUTION LATER IN NOVEMBER, PRECLUDING A MORE DRAMATIC SHIFT TOWARD A COLDER FORECAST OVER THE EAST-CENTRAL CONUS. ABOVE-NORMAL TEMPERATURES ARE FAVORED OVER THE EAST COAST AND MUCH OF THE WESTERN CONUS. OVER ALASKA, ABOVE-NORMAL TEMPERATURES ARE STILL STRONGLY FAVORED OVER COASTAL REGIONS, BUT EQUAL CHANCES OF ABOVE-, NEAR-, OR BELOW-NORMAL TEMPERATURES IS NOW FAVORED OVER MUCH OF THE INTERIOR EXTENDING TO THE NORTHEASTERN PART OF THE STATE.
THE PRECIPITATION OUTLOOK HAS MUCH MORE COVERAGE THANKS TO SKILLFUL SHORT TERM PRECIPITATION FORECASTS. ABOVE-NORMAL PRECIPITATION IS NOW FAVORED OVER ALL OF THE EASTERN AND CENTRAL CONUS, CONSISTENT WITH THE PREPONDERANCE OF MODEL GUIDANCE. THE HIGHEST PROBABILITIES OVER THE OHIO VALLEY AND NORTHEAST ARE COINCIDENT WITH THOSE AREAS WHERE WPC INDICATES THE LARGEST QPF TOTALS OVER THE FIRST SIX DAYS OF THE MONTH. BELOW-NORMAL PRECIPITATION IS NOW CONFINED TO PARTS OF NORTHERN CALIFORNIA EXTENDING EASTWARD ACROSS NEVADA AND PARTS OF UTAH, CONSISTENT IN PART WITH THE 0.5-MONTH LEAD OUTLOOK AND MODIFIED BY THE LATEST GUIDANCE. VARIOUS MODEL TOOLS REMAIN MIXED OVER ALASKA, WITH EQUAL CHANCES INDICATED OVER MUCH OF THE STATE, WITH THE EXCEPTION OF THE SOUTHEASTERN PART OF THE STATE WHERE ABOVE-AVERAGE PRECIPITATION IS SLIGHTLY FAVORED.
Visual Consistency Testing.
It is useful to see how the month forecast fits with the set of shorter forecasts that we have. These will continue to update in this article.
First Temperature
And Precipitation
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 issued today.
Looking back on October and this is preliminary data and one day short of a full month.
The purpose of this article was to present the updated Outlook for November 2018 with the Early Outlook. It is not to critique the updated Outlook for November. 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. We do have forecasts for November from other meteorological agencies but the objective in this article was simply to present the new forecast. In reality these forecasts are obsolete when issued as the situation changes day by day or six hours by six hours i.e. each not model run. In our other articles including the Drought Article which will be published tomorrow, 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 8, IRI/CBC will issue their ENSO forecast and on November 9 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 so our analysis is pretty much ongoing.
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