30 Day Narrative

284 
FXUS07 KWBC 312000
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST THU JAN 31 2019
30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2019
THE UPDATED FEBRUARY 2019 TEMPERATURE OUTLOOK DEPICTS SUBSTANTIAL CHANGES FROM 
THE MID-MONTH OUTLOOK RELEASED TWO WEEKS AGO. CONSIDERABLE VARIABILITY 
ANTICIPATED DURING AT LEAST THE FIRST HALF OF THE MONTH MAKES FOR A CHALLENGING 
OUTLOOK. RIGHT AT THE START OF THE MONTH, THE HIGHLY AMPLIFIED, POTENT TROUGH 
RESPONSIBLE FOR MUCH BELOW-NORMAL AND RECORD COLD TEMPERATURES FOR MUCH OF THE 
CENTRAL AND EASTERN CONUS LIFTS OUT AND IS REPLACED WITH A VERY IMPRESSIVE, 
RAPID WARMUP, FIRST ACROSS THE WESTERN AND CENTRAL CONUS, THEN ACROSS THE 
EASTERN CONUS FROM THE SOUTHEAST TO MAINE. 
ALTHOUGH THERE IS STILL CONSIDERABLE DIFFERENCES IN THE NEXT STRONG TROUGH TO 
AMPLIFY AND EXTEND ACROSS THE CONUS, IT IS MOST LIKELY THAT A STRONG TROUGH MAY 
ORIENT ITSELF FROM CENTRAL CANADA SOUTHWESTWARD TO THE SOUTHWEST CONUS 
POSITIONING HIGH ODDS FOR BELOW-NORMAL TEMPERATURES FARTHER WEST ACROSS FROM 
THE NORTHERN PLAINS TO PARTS OF THE SOUTHWEST. THIS AREA THEN SLOWLY EXTENDS 
AND SHIFTS TO THE EAST AND SLIGHTLY TO THE NORTH WITH TIME AND THE UNCERTAINTY 
INCREASES DURING THE FINAL TWO WEEKS, AS IS TYPICAL, BUT IT APPEARS THAT 
TROUGHING, IN THE MEAN, MAY PERSIST ACROSS THE NORTH CENTRAL CONUS, WITH 
TYPICAL VARIABILITY IN SHORT WAVE TROUGHS ABOUT THIS MEAN POSITION, INTO THE 
EASTERN CONUS AT TIMES. 
THE OFFICIAL TEMPERATURE OUTLOOK FAVORS BELOW-NORMAL TEMPERATURES FOR MUCH OF 
THE WESTERN AND CENTRAL CONUS HIGHLIGHTING THAT EARLY MONTH WARMTH IS MOST 
LIKELY TO BE OVERCOME IN THESE AREAS BY THE AFOREMENTIONED STRONG TROUGH 
DEVELOPMENT ACROSS THE WEST CENTRAL CONUS ENTERING WEEK-2. THE GREATEST 
PROBABILITIES ARE LOCATED ACROSS THE NORTHERN PLAINS AND NORTHERN ROCKIES AS 
THESE AREAS ARE MOST LIKELY TO BE IN FAVORED AREAS OF BELOW-NORMAL TEMPERATURES 
FOR THE MAJORITY OF THE MONTH. ALTHOUGH CONSIDERABLY ABOVE-NORMAL TEMPERATURES 
ARE FAVORED FOR THE SOUTHEAST AND EASTERN SEABOARD DURING THE FIRST WEEK OF 
FEBRUARY, THE UNCERTAINTY AND VARIABILITY IN TROUGHING AND THE PHASE OF THE AO 
INDEX (CONTINUED IMPACT FROM THE SSW EVENT AT THE TURN OF THE YEAR) ACROSS THE 
EASTERN CONUS, RESULTS IN A DEPICTION OF "EC" FOR THE NORTHEAST AND NEARBY 
AREAS AND ONLY MODEST PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES FOR THE 
SOUTHEAST AND LOWER MID-ATLANTIC - WHERE THERE IS A GREATER LIKELIHOOD THAT 
EARLY MONTH WARMTH MAY HANG ON FOR THE EVENTUAL OBSERVED MONTHLY MEAN 
TEMPERATURES. THE FAVORED PATTERN TO AFFECT ALASKA SUPPORTS ANOMALOUS RIDGING 
AND ANOMALOUS SOUTHWESTERLY FLOW AND SO ELEVATED ODDS OF ABOVE-NORMAL 
TEMPERATURES ARE FORECAST FOR MOST OF THE STATE FOR FEBRUARY. 
SIMILAR TO THE TEMPERATURE OUTLOOK, THE PRECIPITATION FORECAST IS SIGNIFICANTLY 
CHANGED FROM THE MID MONTH RELEASE. THE ANTICIPATED WEST-CENTRAL MEAN TROUGH 
AND INDICATIONS OF A CONTINUED ENERGIZED SOUTHERN STREAM DURING PERIODS OF THE 
FIRST  HALF OF FEBRUARY, AND EVEN INTO THE WEEK 3-4 PERIOD, FAVORS AN ACTIVE 
PATTERN WITH ABOVE-NORMAL MONTHLY TOTAL PRECIPITATION AMOUNTS FOR MUCH OF THE 
CONUS. THE ODDS ARE GREATEST FOR CENTRAL AND SOUTHERN CALIFORNIA AND PARTS OF 
THE SOUTHWEST WHERE A FEW STRONG STORMS ARE LIKELY TO IMPACT THESE AREAS EARLY 
IN THE MONTH AND POTENTIALLY ONCE AGAIN NEAR THE MIDDLE OF THE MONTH. AN ACTIVE 
STORM TRACK ASSOCIATED WITH THE WEST-CENTRAL NORTH AMERICA TROUGH AND ITS 
VARIABILITY ALSO SUPPORTS HIGHER ODDS FOR ABOVE-NORMAL PRECIPITATION FOR PARTS 
OF THE LOWER MISSISSIPPI VALLEY, OHIO VALLEY AND GREAT LAKES. AS MENTIONED 
EARLIER, THE ANTICIPATED LARGE SCALE PATTERN FOR MUCH OF THE MONTH NEAR ALASKA 
ALSO FAVORS HIGHER ODDS OF ABOVE NORMAL PRECIPITATION FOR WESTERN ALASKA AS 
WELL. 
FOR SOME AREAS IN THE CENTRAL AND EASTERN CONUS PROBABILITIES ARE MORE MODEST 
AS THERE IS LIKELY TO BE CONSIDERABLE VARIABILITY IN THE STORM TRACK OVER THE 
COURSE OF MUCH OF FEBRUARY. RIDGING NEAR AND TO THE WEST OF WESTERN NORTH 
AMERICA FAVORS BELOW-NORMAL PRECIPITATION FOR AN AREA IN THE PACIFIC NORTHWEST 
AND ALASKA PANHANDLE FOR FEBRUARY. 
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************* PREVIOUS MID-MONTH DISCUSSION (ROSENCRANS) **********************
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THE TEMPERATURE AND PRECIPITATION OUTLOOKS FOR FEBRUARY 2019 ARE BASED ON THE 
BACKGROUND ENSO STATE, POTENTIAL MJO ACTIVITY, AS WELL AS DYNAMICAL MODEL 
GUIDANCE.  DYNAMICAL MODEL GUIDANCE AND STATISTICAL TOOLS THAT TYPICALLY 
SUPPORT THE WEEK 3-4 PERIOD, WHICH COVERS THE FIRST HALF THE MONTH, WERE ALSO 
USED.  
THE OBSERVED TEMPERATURE ANOMALY PATTERN DURING EARLY DECEMBER OVER THE CONUS 
EXHIBITED A DIPOLE STRUCTURE WITH COLDER THAN NORMAL EAST AND WARMER THAN 
NORMAL WEST. THE PATTERN THEN FLIPPED DURING LATER DECEMBER. JANUARY STARTED 
WITH A WARM EAST, BUT IS LIKELY TO FINISH WITH A COOLER THAN AVERAGE EAST AND 
WARMER THAN AVERAGE WESTERN CONUS.  THE MJO LIKELY PLAYED A ROLE IN THESE NOTED 
SWITCHES, AND THE MJO IS PREDICTED TO REMAIN ACTIVE INTO FEBRUARY, THOUGH THE 
AMOUNT OF INFLUENCE CAN VARY MONTH TO MONTH DUE TO SEVERAL FACTORS. THE COLDER 
EASTERN CONUS ANTICIPATED IN LATER JANUARY IS CONSISTENT WITH A SUDDEN 
STRATOSPHERIC WARMING EVENT THAT TOOK PLACE IN EARLY JANUARY.  ATTRIBUTION OF 
THE PATTERN IS STILL ONGOING.
THE COLDER THAN NORMAL CONDITIONS ACROSS THE EASTERN CONUS ARE LIKELY TO 
CONTINUE FOR THE FIRST HALF OF FEBRUARY, WITH TEMPERATURES DURING THE LATTER 
HALF OF THE MONTH BEING LESS CERTAIN. DYNAMICAL MODELS DEPICTING THE FULL MONTH 
OUTLOOK INDICATE NEAR TO BELOW NORMAL CONDITIONS FOR MUCH OF THE EASTERN CONUS, 
WITH THE STRONGEST SIGNALS FOR COLD FROM THE GREAT LAKES TO TENNESSEE VALLEY 
AND TO THE SOUTHEAST. THE MULTIPLE LINEAR REGRESSION (MLR) TOOL THAT EXPLICITLY 
ACCOUNTS FOR THE MJO INFLUENCE INDICATES WARMER SIGNALS OVER THE EASTERN CONUS, 
SO THE PROBABILITIES IN THE OFFICIAL OUTLOOK ARE TEMPERED FROM THAT IN MANY OF 
THE DYNAMICAL MODELS, ESPECIALLY THOSE TOOLS GEARED TOWARD THE FIRST HALF THE 
MONTH.  ACROSS THE WESTERN CONUS, A FORECAST FOR ABOVE NORMAL TEMPERATURES IS 
SUPPORTED BY DYNAMICAL MODEL PREDICTIONS AND TRENDS. THE MLR TOOL HAS A MUCH 
WEAKER SIGNAL ACROSS THE WESTERN CONUS, SO PLAYS LESS OF A ROLE.  ACROSS 
ALASKA, TRENDS AND DYNAMICAL MODEL GUIDANCE FAVOR ABOVE NORMAL TEMPERATURES, 
THOUGH THE EXACT PLACEMENT OF THE AREAS WITH THE HIGHEST ODDS HAVE VARIED WITH 
RECENT MODEL RUNS. THE OFFICIAL OUTLOOK PLACES THE HIGHEST ODDS ACROSS SOUTHERN 
ALASKA AND THE ALASKA PANHANDLE AS THOSE LOCATIONS ARE LIKELY TO EXPERIENCE 
SOUTHERLY MEAN FLOW AT THE SURFACE. THERE IS SOME POTENTIAL FOR PERIODS OF COLD 
AIR TO SPILL INTO THE ALASKA PANHANDLE IF RIDGING OVER WESTERN CANADA SLIPS 
WESTWARD.
THE PRECIPITATION OUTLOOK LARGELY REFLECTS DYNAMICAL MODEL GUIDANCE AND TRENDS, 
AS EXPRESSED IN BOTH THE SEASONAL OCN AND THE MLR TOOL.  A MEAN STORM TRACK 
INTO SOUTHERN ALASKA FAVORS ABOVE NORMAL PRECIPITATION FOR SOUTHERN ALASKA AND 
THE ALASKA PANHANDLE, WITH THE MEAN STORM TRACK THEN DIPPING DOWN OVER THE 
NORTHERN GREAT PLAINS. ANOMALOUS RIDGING IS LIKELY TO PREVAIL ALONG THE WEST 
COAST DURING THE EARLY PORTIONS OF FEBRUARY, LIMITING THE POTENTIAL FOR LONG 
PERIODS OF WET WEATHER DURING A CLIMATOLOGICALLY WET PERIOD, SO BELOW NORMAL 
PRECIPITATION IS FAVORED FOR MUCH OF OREGON, CALIFORNIA, PORTIONS OF THE GREAT 
BASIN, AND PARTS OF THE SOUTHWEST. MEAN NORTHERLY FLOW, SUPPORTING THE COLDER 
THAN NORMAL TEMPERATURE OUTLOOK, ALSO FAVORS BELOW NORMAL PRECIPITATION FROM 
THE GREAT LAKES TO THE TENNESSEE VALLEY. ALONG THE GULF COAST AND EAST COAST, 
THE PLACEMENT OF THE MEAN FRONTAL ZONE COULD RESULT IN ABOVE NORMAL 
PRECIPITATION, BUT UNCERTAINTY IS TOO HIGH TO DEPICT A SIGNAL.
FORECASTER: JON GOTTSCHALCK
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 MAR ... WILL BE ISSUED ON THU FEB 21 2019
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD.
$$