Srain

If this pattern does indeed develop, the first full week of April may have some potential...severe weather wise across our Region.

CPC updated Day 8+ Analogs...

While our East Coast friends can only dream of some distant cold pattern that seems to be a mirage, our Region continues to benefit from the current pattern and that looks to continue into the extended Range.

The December 25th CPC Day 8+ Analogs suggests the coldest weather will remain entrenched across our Region. Temperature anomalies could range in the -25 to -35 range with the best chance of above normal precipitation across the Rockies and along the NW Gulf Coast into Louisiana.

The Updated CPC Day 8+ and Day 11+ Analogs and Prognostic Discussions suggest our Region will experience the coldest weather as we end 2014 and begin 2015... PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD 300 PM EST TUE DECEMBER 23 2014 6-10 DAY OUTLOOK FOR DEC 29, 2014 - JAN 02, 2015 TODAYS MODEL SOLUTIONS REMAIN IN GOOD AGREEMENT ACROSS THE WESTERN CONUS AND ALASKA. THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEANS FEATURE A TROUGH OVER THE BERING SEA, A RIDGE ACROSS THE NORTHEAST PACIFIC, AND A 500-HPA TROUGH EXTENDING FROM HUDSON BAY SOUTHWEST TO THE SOUTHERN ROCKIES. THE HIGH RESOLUTION MODEL RUNS ARE INCLUDED IN THE 500-HPA MANUAL BLEND AS THESE SOLUTIONS CONSISTENTLY INDICATE A CLOSED 500-HPA LOW OVER THE DESERT SOUTHWEST. HOWEVER, THE 12Z GFS IS MORE PROGRESSIVE WITH THE TROUGH. THE 0Z CANADIAN ENSEMBLE MEAN IS LIKELY AN OUTLIER SINCE ITS SOLUTION DOES NOT DEPICT THE POSITIVELY TROUGH OVER THE LOWER 48. MODEL AGREEMENT IMPROVED AMONG TODAY'S ODEL SOLUTIONS ACROSS THE EASTERN CONUS. THE HIGH RESOLUTION 6Z GFS AND 0Z ECMWF MODEL RUNS INDICATE A 1048 TO 1052-HPA SURFACE HIGH BUILDING SOUTH FROM THE CANADIAN PRAIRIES INTO THE ROCKIES EARLY IN THE PERIOD. TEMPERATURES ARE FORECAST TO AVERAGE AS MUCH AS 20 DEGREES F BELOW-NORMAL ACROSS THE ROCKIES AND HIGH PLAINS ON DAYS 6 AND 7. BELOW-NORMAL TEMPERATURES ARE LIKELY FOR MUCH OF THE WESTERN AND CENTRAL CONUS DUE TO THE ANOMALOUS TROUGH. TEMPERATURE GUIDANCE IS IN BETTER AGREEMENT TODAY WITH NEAR TO BELOW-NORMAL TEMPERATURES FAVORED FOR THE NORTHEAST, WHILE A SUBTROPICAL RIDGE FAVORS ABOVE-NORMAL TEMPERATURES ACROSS THE FLORIDA PENINSULA. SOUTHWEST FLOW ALOFT INCREASES CHANCES FOR ABOVE-MEDIAN PRECIPITATION ACROSS THE GULF COAST STATES NORTHEAST TO SOUTHERN NEW ENGLAND. THE HIGH RESOLUTION MODELS ARE IN GOOD AGREEMENT WITH MORE THAN ONE INCH OF RAINFALL OCCURRING ALONG THE CENTRAL GULF COAST WHERE THE HIGHEST PROBABILITIES FOR ABOVE-MEDIAN PRECIPITATION ARE FORECAST. UPSLOPE FLOW TILTS THE ODDS TOWARDS ABOVE-MEDIAN PRECIPITATION ACROSS THE SOUTHERN HIGH PLAINS. LITTLE OR NO RAINFALL IS EXPECTED ACROSS SOUTH FLORIDA WHERE BELOW-MEDIAN PRECIPITATION IS FAVORED. A DRY SIGNAL AMONG PRECIPITATION IS STRONGEST ACROSS THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA, ASSOCIATED WITH THE RIDGE OVER THE NORTHEAST PACIFIC AND ANOMALOUS OFFSHORE FLOW. SURFACE LOW PRESSURE OVER THE BERING SEA COUPLED WITH RIDGING OVER THE NORTHEAST PACIFIC ENHANCE ODDS FOR ABOVE-NORMAL TEMPERATURES AND ABOVE-MEDIAN PRECIPITATION ACROSS ALASKA. TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 15% OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF TODAY'S OPERATIONAL 0Z GFS CENTERED ON DAY 8, 10% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 8, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 10% OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8 MODEL OF THE DAY: 0Z ECMWF ENSEMBLE MEAN FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 4 OUT OF 5, DUE TO IMPROVED MODEL AGREEMENT ACROSS THE EASTERN CONUS AMONG THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEANS AND TEMPERATURE GUIDANCE. 8-14 DAY OUTLOOK FOR DEC 31, 2014 - JAN 06, 2015 THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEANS FEATURE A RIDGE EXTENDING FROM THE NORTHEAST PACIFIC NORTH TO ALASKA, A POSITIVELY TILTED TROUGH OVER THE WEST-CENTRAL CONUS, AND A SUBTROPICAL RIDGE CENTERED ACROSS THE BAHAMAS AND CUBA. SPREAD AMONG THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEMBERS IS MODERATE TO LARGE WITH THE POSITION AND AMPLITUDE OF THE RIDGE (TROUGH) OVER THE NORTHEAST PACIFIC (WEST-CENTRAL CONUS). TEMPERATURE TOOLS ARE IN REASONABLY GOOD AGREEMENT BUT LOWER PROBABILITIES, COMPARED TO THE 6-10 DAY OUTLOOK, REFLECT THE LARGER SPREAD AMONG ENSEMBLE MEMBERS. THE UPPER-LEVEL TROUGH FAVORS BELOW NORMAL TEMPERATURES ACROSS THE SOUTHWEST, CENTRAL/SOUTHERN ROCKIES, CENTRAL/SOUTHERN PLAINS, AND MIDWEST. BELOW-NORMAL TEMPERATURES FORECAST FOR THE PACIFIC NORTHWEST ARE DUE TO ANOMALOUS COLD EARLY IN WEEK-2, WHILE A WARMING TREND IS EXPECTED ACROSS CALIFORNIA. TEMPERATURES ARE EXPECTED TO BE CLOSE TO AVERAGE FOR MUCH OF THE EAST COAST. A FRONT IS EXPECTED TO STALL EARLY IN WEEK-2 AND INCREASE CHANCES FOR ABOVE-MEDIAN PRECIPITATION ACROSS THE GULF COAST STATES NORTHEAST TO SOUTHERN NEW ENGLAND. SOUTHEAST FLOW TILTS THE ODDS TOWARDS ABOVE-MEDIAN PRECIPITATION ACROSS THE RIO GRANDE VALLEY. BELOW-MEDIAN PRECIPITATION IS EXPECTED TO PERSIST ALONG THE WEST COAST DUE TO UPPER-LEVEL RIDGING. ALTHOUGH BELOW-MEDIAN PRECIPITATION IS FAVORED FOR THE NORTHERN/CENTRAL HIGH PLAINS, THE POTENTIAL THAT UPSLOPE FLOW RETURNS LATER IN WEEK-2 LIMITS THE PROBABILITY. THE TROUGH OVER THE BERING SEA INCREASES CHANCES FOR ABOVE-NORMAL TEMPERATURES AND ABOVE-MEDIAN PRECIPITATION ACROSS ALASKA. TODAY'S ENSEMBLE MEANS INDICATE A RIDGE STRENGTHENING ACROSS ALASKA WHICH COULD EVENTUALLY RESULT IN DRIER CONDITIONS LATER IN WEEK-2. THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 20% OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED ON DAY 11, 20% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 11, AND 60% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11 FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: AVERAGE, 3 OUT OF 5, DUE TO GOOD AGREEMENT AMONG THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEANS OFFSET BY MODERATE TO LARGE SPREAD AMONG THE GFS AND ECMWF ENSEMBLE MEMBERS. FORECASTER: BRAD PUGH

The afternoon Updated CPC Day 8+ Analogs and Discussions prove interesting as we begin to get closer to the end of December and early January for our Region. Of interest is the noisy sub tropical jet in place after the cold air arrives particularly for portions of Central and Eastern Texas extending into portions of Louisiana. The guidance is attempting to develop a Coastal wave New Years Eve after the cold air is entrenched across the Southern Plains/Southern Rockies/Texas and portions of Louisiana. PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD 300 PM EST MON DECEMBER 22 2014 6-10 DAY OUTLOOK FOR DEC 28, 2014 - JAN 01, 2015 TODAYS MODEL SOLUTIONS ARE IN GOOD AGREEMENT ACROSS THE WESTERN CONUS AND ALASKA. THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEANS FEATURE A TROUGH OVER THE BERING SEA, A RIDGE ACROSS THE NORTHEAST PACIFIC, AND A TROUGH EXTENDING FROM HUDSON BAY SOUTHWEST TO THE SOUTHERN ROCKIES. THE 0Z CANADIAN ENSEMBLE MEAN IS DISMISSED AS AN OUTLIER SOLUTION DUE TO ITS MUCH DIFFERENT FORECAST ACROSS THE NORTH PACIFIC. POOR MODEL CONTINUITY EXISTS EAST OF THE ROCKIES WITH TODAY'S 0Z ECMWF ENSEMBLE MEAN INDICATING MUCH HIGHER 500-HPA HEIGHTS ALONG THE GULF COAST AND EASTERN CONUS COMPARED TO ITS MODEL RUN FROM YESTERDAY. SPREAD IS RELATIVELY SMALL AMONG TODAY'S 0Z ECMWF ENSEMBLE MEMBERS AND SUPPORTS THE 0Z ECMWF ENSEMBLE MEAN SOLUTION EAST OF THE ROCKIES. TELECONNECTIONS UPON A POSITIVE 500-HPA ANOMALY CENTER WEST OF BRITISH COLUMBIA (50N 135W), PREDICTED BY ALL MODEL SOLUTIONS, SUPPORTS THE ORIENTATION OF A POSITIVELY TILTED LONGWAVE TROUGH DEPICTED BY THE 0Z ECMWF ENSEMBLE MEAN AND THE FLOW DOWNSTREAM OVER THE EASTERN CONUS. THEREFORE, THE 500-HPA MANUAL BLEND IS WEIGHTED MOST HEAVILY WITH THE 0Z ECMWF ENSEMBLE MEAN BUT FORECAST CONFIDENCE IS REDUCED DUE TO POOR MODEL CONTINUITY. TODAY'S HIGH RESOLUTION 12Z GFS MODEL IS IN REASONABLY GOOD AGREEMENT WITH THE 0Z ECMWF ENSEMBLE MEAN. THE COVERAGE OF BELOW-NORMAL TEMPERATURES ACROSS THE SOUTHEASTERN CONUS, ON YESTERDAY'S TEMPERATURE OUTLOOK, IS REDUCED DUE TO HIGHER 500-HPA HEIGHTS PREDICTED BY THE PREFERRED 0Z ECMWF ENSEMBLE MEAN. MEANWHILE, FORECAST CONFIDENCE ACROSS THE WESTERN AND CENTRAL CONUS IS ABOVE-AVERAGE AS A 1044-HPA SURFACE HIGH IS EXPECTED TO BUILD SOUTH FROM CANADA ON DAYS 6 AND 7. TEMPERATURES ARE FORECAST TO AVERAGE AS MUCH AS 20 DEGREES F BELOW-NORMAL ACROSS THE NORTHERN/CENTRAL PLAINS BY DAY 7. BELOW-NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE WESTERN/CENTRAL CONUS DUE TO THE ANOMALOUS COLD PREDICTED EARLY IN THIS PERIOD. ABOVE-MEDIAN PRECIPITATION IS FAVORED ALONG THE TRACK OF A SHORTWAVE TROUGH ON DAY 6. THAT SHORTWAVE TROUGH IS EXPECTED TO MOVE NORTHEAST FROM THE LOWER MISSISSIPPI VALLEY TO NEW ENGLAND. SOUTHWEST FLOW ALOFT TILTS THE ODDS TOWARDS ABOVE-MEDIAN PRECIPITATION ACROSS CENTRAL AND EASTERN TEXAS. A BUILDING SUBTROPICAL RIDGE INCREASES CHANCES FOR BELOW-MEDIAN PRECIPITATION ACROSS SOUTH FLORIDA, WHILE THE AMPLIFIED RIDGE CENTERED OVER THE NORTHEAST PACIFIC IS LIKELY TO SUPPRESS PRECIPITATION ALONG THE WEST COAST. ANOMALOUS SOUTHERLY FLOW, EAST OF THE TROUGH OVER THE BERING SEA, INCREASES CHANCES FOR ABOVE-NORMAL TEMPERATURES AND ABOVE-MEDIAN PRECIPITATION FOR MUCH OF ALASKA. TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 10% OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, AND 80% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8 MODEL OF THE DAY: 0Z ECMWF ENSEMBLE MEAN FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO POOR MODEL CONTINUITY AND LARGE DIFFERENCES AMONG THE ENSEMBLE MEANS ACROSS THE EASTERN CONUS.

These are typically a forecaster adjusted blend of the Euro, GEFS and GEM 500mb ensembles and a blend of what the forecaster believes is the best fit for the pattern expects... 8-14 DAY OUTLOOK FOR DEC 27, 2014 - JAN 02, 2015 THE ENSEMBLE MEAN PREDICTIONS OF THE 500-HPA HEIGHT PATTERN FOR THE WEEK-2 PERIOD ARE IN FAIR AGREEMENT OVER NORTH AMERICA. A RIDGE IS PREDICTED OVER THE GULF OF ALASKA, ASSOCIATED WITH POSITIVE 500-HPA HEIGHT ANOMALIES OFF THE WEST COAST. A HIGH AMPLITUDE TROUGH IS ANTICIPATED OVER THE CENTRAL AND EASTERN CONUS, WITH NEGATIVE 500-HPA HEIGHT ANOMALIES ACROSS MOST OF THE CONUS. THE ENSEMBLE SPAGHETTI DIAGRAMS INDICATE MODERATE SPREAD ACROSS THE FORECAST DOMAIN. THERE ARE ENHANCED PROBABILITIES FOR NEAR- TO ABOVE-NORMAL TEMPERATURES FOR THE CALIFORNIA COAST, AHEAD OF THE RIDGE OFF THE WEST COAST. BELOW-NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE NORTHERN, CENTRAL AND EASTERN CONUS DUE TO ANOMALOUS NORTHERLY FLOW. THERE ARE ENHANCED PROBABILITIES FOR NEAR- TO ABOVE-NORMAL TEMPERATURES FOR ALASKA, ALEUTIANS AND THE PANHANDLE RELATED TO THE SOUTHWESTERLY WINDS, EAST OF THE SURFACE LOW PRESSURE OVER THE BERING SEA. BELOW-MEDIAN PRECIPITATION IS FAVORED FOR THE WESTERN CONUS IN ASSOCIATION WITH THE FORECAST RIDGE OFF THE WEST COAST. THERE ARE ENHANCED PROBABILITIES OF NEAR- TO BELOW-MEDIAN PRECIPITATION FOR THE MIDDLE MISSISSIPPI VALLEY CONSISTENT WITH THE BIAS CORRECTED PRECIPITATION FROM THE ECMWF ENSEMBLES AND GFS ENSEMBLES. NEAR- TO ABOVE-MEDIAN PRECIPITATION IS FAVORED FOR THE NORTHERN ROCKIES, THE GREAT PLAINS, IN ASSOCIATION WITH EXPECTED UP-SLOPE FLOW OVER THE SURFACE. ABOVE-MEDIAN PRECIPITATION IS ALSO FAVORED FOR THE SOUTHEASTERN CONUS AND NEW ENGLAND, AHEAD OF THE TROUGH. THERE ARE ENHANCED PROBABILITIES OF NEAR- TO ABOVE-MEDIAN PRECIPITATION FOR WEST ALASKA AND THE ALEUTIANS. THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 20% OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED ON DAY 11, 20% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 11, 20% OF YESTERDAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 10, 20% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 20% OF YESTERDAY'S 12Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 10 FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOUT AVERAGE, 3 OUT OF 5, DUE TO FAIR MODEL AGREEMENT WITH SOME DISAGREEMENT BETWEEN TOOLS FROM THE ECMWF AND GEFS ENSEMBLES ACROSS THE EASTERN CONUS. FORECASTER: QIN GINGER ZHANG

Yet another day of very strong signals in the Day 11+ Analogs with below normal temperatures and above normal precipitation across the Inter Mountain West throughout the Plains.

The Day 11+ analogs are bringing back some vivid memories of notable events for our Region.

The Day 11+ Analogs continue to advertise a big pattern change as we end December and head into the New Year.

The updated Day 11+ Analogs are beginning to show some memorable Winters. 1976 is back as well as 1989. We kept seeing those analog years showing up during the November cold spell if you recall.

The Day 11+ Analogs suggest cold air returns to the Great Basin and the Inter Mountain West and spreading into the Plains after Christmas.

The over night ensembles continue to advertise an active Southern storm track with a strong storm signal late this week tracking across N Mexico into Texas and the Southern Plains. This storm looks to begin the process of ushering in a signicant pattern change that continues into the Christmas Holiday period. The longer range guidance is suggesting the possibility of a NW Gulf Coastal low developing around the 24th +/- a day or two ushering much colder temperatures and additional Southern tracking storms as the polar jet buckles rather far S and a + PDO/+PNA/-EPO/-AO regime develops. The time frame into New Year looks cold and stormy from the Great Basin into the Plains.

The medium range pattern certainly looks very promising with at least 3 additional Southern tracking storms bringing beneficial moisture across California, the Desert SW, Southern Rockies into the Southern and Central Plains.

As Jeff alluded to late yesterday evening, the Global ensembles are in rather good agreement with the expected pattern change around the 20th of December. The ensembles are indicating a very active Southern Storm track with each storm assisting in buckling the jet stream pattern across North America that would tend to suggest that the stormy and progressively colder weather would develop across the Desert SW, Southern Rockies into the Southern Plains and on East. The longer range ensembles develop a West Coast Ridge easing the parade of storms currently affecting the W Coast but allow disturbances in the Eastern Pacific to track across Mexico, Texas and the Gulf Coast States before turning NE. The Polar jet should have embedded disturbances dropping S out of Canada and snow looks to begin building across the Plains lending to less and less airmass modification. This is a typical weak El Nino pattern and it appears we are well on the way to witnessing a big pattern shift that will bring a very active period that will last into the New Year.

The GEFS as well as the CFS remain steady in suggesting a significant pattern change near the Christmas timeframe.

The 12Z guidance continues to advertise a very promising pattern from the West Coast into the Southern Rockies of New Mexico/Colorado into the Southern Plains. Higher elevation snows and even some potential for heavy elevated storms developing next weekend. In the cold sector, there is a snow and ice threat across the front range into W/NW Texas into portions of Oklahoma as the 5H low deepens. Depending on the eventual track, portions of Missouri into Arkansas may get into the winter weather side of this strong storm. The pattern certainly appears to be transitioning toward a stormier/colder regime as we near the Christmas/New Year timeframe.

As andyhb mentioned in the Texas thread and we have been mentioning since last week concerning the severe potential in the busy pre Thanksgiving timeframe, the GFS is suggesting a robust 5H shortwave crossing our Region during the upcoming weekend. If the Gulf opens up as some of the guidance is suggesting, we could see a rather impressive severe weather threat across portions of the Southern Plains into the Northern Gulf Coast.

The chatter picked up again today from the various Texas WFO's regarding this potential. 93E is looking better by the hour and the 12Z guidance would be a welcomed relief to what has been an extremely dry October across Texas.

A firehose of Pacific moisture looks to bring sorely needed lower elevation rains and higher elevation snows to the Pacific NW and portions of California over the next week. The pattern appears to transition as a -AO/-EPO/+PNA regime develops and may bring our first real shot of cold Continental air very far S into Northern Mexico and Texas as we begin November.

A welcomed change is ahead for the Pacific NW into N California as the pattern changes increasing a tropical connection from the Central Pacific and a zonal flow brings welcomed rains to a Region that has been very dry.

NOAA released their Winter Outlook today... http://www.noaanews.noaa.gov/stories2014/20141016_winteroutlook.html

We will be watching the oscillating boundary across Texas this weekend as the remnants of Simon pass across the Southern/Central Plains. The NW Gulf should be wide open with a strong southerly flow and the 5H low is nearing 3 standard deviations below normal via the 12Z Euro. Certainly worth monitoring.

The latest Euro and parallel GFS are slowly coming into agreement with a full latitude trough across the Central US as the AO drops extremely negative by October standards early next week.