Climate Prediction Center - 6-10 and 8-14 Day Prognostic Discussions

Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks 
NWS Climate Prediction Center College Park, MD 
300 PM EDT Mon July 01 2024 
 
6-10 DAY OUTLOOK FOR JUL 07 - 11 2024 
 
Models are in very good agreement with the 500-hPa mean heights, and also the  
daily evolution of individual features. The ensemble means, deterministic GFS,  
and deterministic European Model (ECMWF) all show a strong mean mid-level ridge  
in western North America, with an axis aligned near the Pacific Coast and the  
largest 500-hPa height anomalies (near +90 dm) over the Pacific Northwest.  
Downstream, a relatively weak mid-level trough stretches from northern Canada  
southward through the Plains, Mississippi Valley, and parts of the Ohio Valley.  
The trough leads into another mid-level ridge downstream over the eastern  
contiguous U.S. (CONUS) and the western North Atlantic, with the highest  
500-hPa heights near Atlantic Canada. Meanwhile, subnormal mean 500-hPa heights  
cover most of Alaska. There is a little uncertainty regarding both the mean  
mid-level trough in central North America and the downstream ridge farther  
east. The GEFS shows a weaker mean mid-level trough over the central CONUS than  
the other two, which show a 500-hPa anomaly center over the Great Lakes as  
opposed to a north-south band of slightly below-normal 500-hPa heights in the  
GEFS. The stronger solutions of the Canadian and European ensemble means are  
favored since this is indicated by most of the tools. To the east, the  
mid-level ridge across eastern North America  is weaker and farther east in the  
Canadian ensemble mean than in other guidance, and again the stronger solution  
depicted by a majority of the tools is favored. This leaves a fairly amplified  
pattern across the CONUS. Elsewhere, subnormal mean 500-hPa heights are  
expected across most of Alaska, and slightly above normal mean heights are  
anticipated across Hawaii. 
 
The models are also very similar in the details of how the pattern evolves.  
Mid-level features move little and are generally less amplified at the end of  
the period. Heights climb closer to normal over Alaska, and remain slightly  
above normal across Hawaii. Meanwhile, the mid-level trough near the central  
CONUS retracts northward with time, leading to above-normal 500-hPa heights  
covering across most of the CONUS, with a ridge axis centered near the interior  
western CONUS, and another in the western North Atlantic. Some model solutions  
show a slower evolution toward broadly above-normal 500-hPa heights in the  
CONUS, but the favored models with more amplified mid-level features depict a  
quicker transition, so the outlooks lean in this direction. 
 
This pattern strongly favors enhanced chances for above-normal temperatures  
through most of the CONUS, and near normal temperatures over part of the  
central CONUS under the mean mid-level trough. Excessive heat is possible for  
much of the period across parts of the interior West through the California  
Valleys, where odds for above-normal temperature exceed 80 percent. Enhanced  
chances for above-normal temperatures are also forecast in much of the eastern  
CONUS, with odds exceeding 60 percent from the Appalachians to the Atlantic  
Coast. Subnormal 500-hPa heights should favor below-normal temperatures across  
Alaska which increase in western parts of the state. But near-normal  
temperatures are expected over Hawaii despite above-normal mean 500-hPa  
heights, as models depict a small area of subnormal 850-hPa temperature  
lingering over the Islands, which would keep temperatures relatively low. 
 
The highest chances for wetter than normal weather cover southern Texas.  
Tropical moisture, including some from the remnants of Hurricane Beryl, is  
expected to flow northward into this area due to a weakness in the subtropical  
ridge. Deep South Texas has odds exceeding 60 percent for wetter than normal  
weather. Conditions are less extreme elsewhere, with the western CONUS ridge  
expected to bring drier than normal weather to most of the western CONUS and  
the northern half of the Plains, especially near the greatest 500-hPa anomalies  
across the Pacific Northwest. Over the rest of the CONUS, cyclonic mid-level  
flow downstream from the mean trough slightly increases the odds for wetter  
than normal weather. The below-normal 500-hPa heights over Alaska increase  
chances for above-normal precipitation there somewhat, and a slight tilt of the  
odds favoring wetter than normal weather is also forecast across Hawaii. 
 
The official 6-10 day 500-hPa height blend consists of 15% of Today's 6z GFS  
Ensemble Mean centered on Day 8, 20% of Today's GFS Superensemble Mean centered  
on Day 8, 25% of Today's 0z European Ensemble Mean centered on Day 8, 15% of  
Today's operational 0z ECMWF centered on Day 8, and 25% of Today's 0z Canadian  
Ensemble Mean centered on Day 8  
  
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Above average, 4 out of 5, with  
good run-to-run continuity and model-to-model consistency offset by slight  
differences in the evolution of the mid-level pattern, and uncertainties  
regarding the tropical moisture expected to push into southern Texas. 
 
8-14 DAY OUTLOOK FOR JUL 09 - 15 2024  
 
The progression toward increasing mid-level 500-hPa across the CONUS continues  
during week-2, which is an evolution generally favored by all ensemble means.  
During this period, the mid-level ridge in the western CONUS remains moderately  
amplified and meanders a little, although model differences increase  
uncertainty in the evolution of the mid-level pattern. The different ensemble  
means end week-2 with the ridge axis somewhere from the interior western CONUS  
to near the Great Plains. Given good model agreement, a mid-level ridge is  
expected to be centered somewhere over the western half of the CONUS, but there  
is no reason to favor the specific placement of the ridge axis in any one model  
relative to the others. Again, the Canadian ensemble mean shows the pattern  
evolving more slowly, with less of a rebound in 500-hPa heights across the  
eastern CONUS, but the faster solutions of the other models seem most likely at  
this time. Farther north, mid-level heights are expected to slowly increase  
across Alaska during the period while remaining slightly below normal, with  
little movement in mid-level features there. Slightly elevated 500-hPa heights  
are expected over Hawaii. 
 
The broadly above-normal 500-hPa heights favor warmer than normal weather  
throughout the CONUS, with excessive heat remaining possible at times from the  
California Valleys to the Rockies. Odds for above-normal temperature exceed 70  
percent across that region. A secondary maximum in the chances for above-normal  
temperatures covers the Northeast and parts of Florida, where 500-hPa heights  
should be above-normal longer than in areas farther west. Warmer than normal  
weather exceeds 60 percent there. Only parts of Deep South Texas, in an area of  
enhanced precipitation due to the influx of tropical moisture, has no increase  
in the likelihood of above-normal temperatures. Persisting below-normal  
mid-level heights across Alaska keeps elevated odds for colder than normal  
weather across the state, and the expected above-normal 500-hPa heights coupled  
with slightly below normal 850-hPa temperatures should keep temperature  
unremarkable across Hawaii. 
 
The tropical moisture influx into southern Texas should persist through at  
least part of week-2, maintaining significantly elevated chances (over 50  
percent) for wetter than normal weather. To the south of the positive 500-hPa  
height anomaly in the west, some tools indicate a surge of monsoon-related  
moisture in the Southwest, where chances for wet weather also exceed 50 percent  
in some areas. There is more uncertainty elsewhere. The drifting mid-level  
ridge generally favors suppressed precipitation from the northern Plains to the  
Pacific Northwest while cyclonic flow across the eastern CONUS (despite  
increasing 500-hPa heights) marginally favors above-normal precipitation there.  
Slightly enhanced chances for wetter than normal weather also encompass both  
Alaska and Hawaii, consistent with tools derived from the ensemble means. 
 
The official 8-14 day 500-hPa height blend consists of: 15% of Yesterday's 6z  
GFS Ensemble Mean centered on Day 10, 20% of Yesterday's GFS Superensemble Mean  
centered on Day 10, 15% of Yesterday's operational 0z GFS centered on Day 10,  
35% of Yesterday's 0z European Ensemble Mean centered on Day 10, and 15% of  
Yesterday's 0z Canadian Ensemble Mean centered on Day 10  
 
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Above average, 4 out of 5, with  
good run-to-run continuity among forecast models, offset by differences  
regarding the strength and position of some synoptic features, plus  
uncertainties inherent in the anticipated influx of moisture into southern  
Texas and the Desert Southwest. 
 
FORECASTER: Rich Tinker 
 
Notes: 
 
 
Automated forecasts are issued on Saturday and Sunday. Occasionally manual  
intervention is necessary to address quality control and consistency issues. In  
these cases, forecasts are manually drawn but a full discussion is not issued. 
 
 
The notation for the categorical forecast indicated on the maps is the same as  
that in the tables: A-above   N-near normal   B-below 
 
 
The temperature map shows regions with > 33% chance of being warmer (orange,  
"A"), colder (blue, "B"), or close to (unshaded, "N"). Historical average  
values for the calendar period of the forecast (dashes, "f").  Labels on the  
shaded lines give the probability (> 33%) of the more likely category (B or A).  
 Probability of N is always < 40%. 
 
 
The precipitation map shows regions with > 33% chance of being wetter (green,  
"A"), drier (tan, "B"), or close to (unshaded, "n"). Historical median values  
for the calendar period of the forecast (dashes, "inches").  Labels on the  
shaded lines give the probability (> 33%) of the more likely category (B or A).  
 Probability of N is always < 40%. 
 
 
In the southwest and other climatologically dry regions - there will be a  
greater than 33.3% chance of no precipitation and occasionally even a normal  
(i.e. Median) value of zero - especially during the dry seasons.  In such cases  
a forecast of near normal is effectively a forecast of little or no  
precipitation. 
 
 
The climate prediction center uses 1991-2020 base period means as reference in  
the climate outlooks. 
 
The next set of long-lead monthly and seasonal outlooks will be released on  
July 18. 
 
 
Analogs to the 5 day mean observed pattern centered 3 days ago (D-3) 
for the region from 20N to 70N latitude and 175E to 60W longitude 
include the 5 day periods centered on the following dates:  
19650630 - 19940715 - 19920615 - 19880614 - 19580710 
 
 
Analogs to the 7 day mean observed pattern centered 4 days ago (D-4) 
for the region from 20N to 70N latitude and 175E to 60W longitude 
include the 7 day periods centered on the following dates:  
19510610 - 19520610 - 19530610 - 19540610 - 19550610 
 
 
6-10 DAY OUTLOOK TABLE 
Outlook for Jul 07 - 11 2024 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  A    B     OREGON      A    B     NRN CALIF   A    B      
SRN CALIF   A    N     IDAHO       A    B     NEVADA      A    B      
W MONTANA   A    B     E MONTANA   A    B     WYOMING     A    B      
UTAH        A    B     ARIZONA     A    N     COLORADO    A    B      
NEW MEXICO  A    N     N DAKOTA    N    B     S DAKOTA    N    B      
NEBRASKA    N    B     KANSAS      N    N     OKLAHOMA    A    A      
N TEXAS     A    A     S TEXAS     A    A     W TEXAS     A    A      
MINNESOTA   N    N     IOWA        N    N     MISSOURI    N    A      
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   N    N      
ILLINOIS    N    A     MISSISSIPPI A    A     MICHIGAN    A    A      
INDIANA     A    A     OHIO        A    A     KENTUCKY    A    A      
TENNESSEE   A    A     ALABAMA     A    A     NEW YORK    A    A      
VERMONT     A    A     NEW HAMP    A    A     MAINE       A    A      
MASS        A    A     CONN        A    A     RHODE IS    A    A      
PENN        A    A     NEW JERSEY  A    A     W VIRGINIA  A    A      
MARYLAND    A    A     DELAWARE    A    A     VIRGINIA    A    A      
N CAROLINA  A    A     S CAROLINA  A    A     GEORGIA     A    A      
FL PNHDL    A    A     FL PENIN    A    N     AK N SLOPE  B    A      
AK ALEUTIAN B    A     AK WESTERN  B    A     AK INT BSN  B    A      
AK S INT    B    A     AK SO COAST B    A     AK PNHDL    B    A      
  
                            
 
8-14 DAY OUTLOOK TABLE 
Outlook for Jul 09 - 15 2024 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  A    B     OREGON      A    B     NRN CALIF   A    N      
SRN CALIF   A    A     IDAHO       A    B     NEVADA      A    N      
W MONTANA   A    B     E MONTANA   A    B     WYOMING     A    N      
UTAH        A    A     ARIZONA     A    A     COLORADO    A    N      
NEW MEXICO  A    A     N DAKOTA    A    B     S DAKOTA    A    N      
NEBRASKA    A    N     KANSAS      A    N     OKLAHOMA    A    A      
N TEXAS     A    A     S TEXAS     N    A     W TEXAS     A    A      
MINNESOTA   A    B     IOWA        A    N     MISSOURI    A    N      
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   A    N      
ILLINOIS    A    N     MISSISSIPPI A    A     MICHIGAN    A    N      
INDIANA     A    A     OHIO        A    A     KENTUCKY    A    A      
TENNESSEE   A    A     ALABAMA     A    A     NEW YORK    A    A      
VERMONT     A    A     NEW HAMP    A    A     MAINE       A    A      
MASS        A    A     CONN        A    A     RHODE IS    A    A      
PENN        A    A     NEW JERSEY  A    A     W VIRGINIA  A    A      
MARYLAND    A    A     DELAWARE    A    A     VIRGINIA    A    A      
N CAROLINA  A    A     S CAROLINA  A    A     GEORGIA     A    A      
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  B    A      
AK ALEUTIAN B    A     AK WESTERN  B    A     AK INT BSN  B    A      
AK S INT    B    A     AK SO COAST B    A     AK PNHDL    B    A      
  
                           LEGEND 
TEMPS WITH RESPECT TO NORMAL     PCPN WITH RESPECT TO MEDIAN 
A - ABOVE   N  - NEAR NORMAL     A - ABOVE   N - NEAR MEDIAN 
B - BELOW                        B - BELOW 
  
THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL 
VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE 
AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE. 
  
FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS 
PMDMRD. 
 
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