Prognostic Discussion for Monthly Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT Thu Oct 31 2019


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.

----------- Previous outlook from 17 Oct 2019 follows ------------------

The outlook for temperature and precipitation for November of 2019 is largely 
influenced by dynamical model and statistical tool guidance, and to a lesser 
degree antecedent conditions. Dynamical models inputs are from daily 
initializations of the CFS and those in the NMME suite. 

For statistical tools, lagged temperature and precipitation conditions, based 
on observed soil moisture, have little skill in the cool season, so they were 
not considered in this outlook. Lagged impacts from MJO activity were 
considered, though the progression of the MJO across the Indian Ocean to the 
Maritime Continent, where teleconnections to North America are stronger, is 
highly uncertain with only the ECMWF predicting an amplified RMM2 state. Lagged 
impacts would favor more warmth over the Great Lakes and Mississippi Valley. 
Plots from recent initializations of the CFS 200-hPa height anomalies have some 
resemblance to lagged composites of MJO activity over the Indian Ocean. 
Therefore, the statistical predictors used in this outlook are trend (optimal 
climate normals, 15-year trends),constructed analogs, and lagged composites of 
MJO activity.

Trends would largely favor above normal temperatures, with the strongest signal 
from the Southwest to the Upper Great Lakes, with positive but weaker signals 
over much of the rest of the CONUS. Model output and MJO activity favor 
troughing inland over the Pacific Northwest and ridging over the Plains, 
allowing for periods of colder air to move from the Northern Plains to the 
Southern Appalachians. That pattern supports no signal over the Northwest and 
more uncertainty from the Northern Plains to the Tennessee Valley. Trends and 
model output strongly favor above normal temperatures form the Southwest to the 
Southeast, and from the Upper Great Lakes to the Northeast. Over Alaska, the 
sea ice edge is still far from the coast, so the probabilities for above normal 
temperatures are very high for the northern and northwestern coastal areas, 
decreasing to the south and east across the state.  

The same 200-hPa pattern would support above normal precipitation for Alaska, 
with ridging over the Central Pacific implying a storm track into Alaska and a 
trough near the Pacific Northwest. Signals for below normal precipitation along 
portions of California were stronger in earlier CFS runs, and have weakened but 
not completely disappeared from recent runs, so a small area of slightly 
enhanced below normal precipitation probabilities is indicated over northern 
California and Oregon. Ridging over the central portions of the CONUS would 
favor drying downstream. Earlier model runs had large areas of drier than 
normal conditions for the Mississippi Valley to the Gulf Coast, but recent 
model runs and MJO composites are showing the ridge slightly further east.  
That shift in the pattern shifts the probabilities toward above normal 
precipitation in the Rockies and the Central Plains, while shrinking the area 
where below normal precipitation is favored over the Southeast.

FORECASTER: Matthew Rosencrans

The climatic normals are based on conditions between 1981 and 2010, following
the World Meteorological Organization convention of using the most recent 3 
complete decades as the climate reference period.  The probability anomalies
for temperature and precipitation based on these new normals better represent
shorter term climatic anomalies than the forecasts based on older normals.

The next monthly outlook...for Dec ... will be issued on Thu Nov 21 2019

These outlooks are based on departures from the 1981-2010 base period.
$$