179  
FXUS02 KWBC 311959  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
259 PM EST MON JAN 31 2022  
 
VALID 12Z THU FEB 03 2022 - 12Z MON FEB 07 2022  
 
...HEAVY RAINFALL LIKELY FROM THE CENTRAL GULF COAST THROUGH  
TENNESSEE VALLEY ON THURSDAY, WITH A SIGNIFICANT WINTER STORM FROM  
THE MIDWEST TO GREAT LAKES AND INTERIOR NORTHEAST...  
 
   
..OVERVIEW
 
 
EXPECT A POSITIVELY TILTED MEAN TROUGH ALOFT TO PREVAIL ACROSS  
MUCH OF THE CONUS THROUGH THE MEDIUM RANGE PERIOD, AS STRONG UPPER  
RIDGING BUILDS OVER THE EASTERN PACIFIC (PERIODICALLY EXTENDING  
INTO PARTS OF THE WEST) WHILE A STRONG WESTERN ATLANTIC RIDGE  
GRADUALLY WEAKENS/MOVES EASTWARD. THE MOST CONFIDENT PART OF THE  
FORECAST INVOLVES THE COMBINATION OF A ROCKIES SHORTWAVE AND  
NORTHERN STREAM FLOW THAT WILL DRIVE A POTENT AND WAVY COLD FRONT  
THROUGH THE EASTERN U.S. THURSDAY-FRIDAY, BRINGING WIDESPREAD  
HEAVY RAIN TO THE SOUTH AND A POTENTIALLY SIGNIFICANT WINTER STORM  
FROM THE OHIO VALLEY TO THE INTERIOR NORTHEAST. AFTER FRIDAY THERE  
IS GREATER UNCERTAINTY OVER DETAILS OF ADDITIONAL SHORTWAVES  
DROPPING DOWN THE EAST SIDE OF THE RIDGE IN THE WEST, AND MAYBE  
ENERGY LINGERING FROM THE FIRST SHORTWAVE, PLUS THE INFLUENCE OF  
NORTHERN STREAM FLOW (SUPPORTING A SERIES OF NORTHERN TIER WAVES).  
DETAILS OF THESE FEATURES AND THEIR POSSIBLE INTERACTION WILL  
DETERMINE HOW MUCH PRECIPITATION MAY FALL OVER PARTS OF THE EAST  
FROM THE WEEKEND INTO THE START OF NEXT WEEK.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
A GENERAL BLEND OF 00Z/06Z MODEL GUIDANCE PROVIDED A GOOD  
REPRESENTATION OF CONSENSUS FOR DAYS 3-4 THURSDAY-FRIDAY, WITH THE  
ONLY ADJUSTMENTS FROM CONTINUITY BEING TYPICAL RUN-TO-RUN DETAIL  
CHANGES. IN THIS TIME FRAME, FRONTAL WAVES OVER THE EAST SHOULD  
CONSOLIDATE INTO A SINGLE LOW THAT ULTIMATELY TRACKS AWAY FROM NEW  
ENGLAND WHILE A WEAK WAVE AND FRONTAL SYSTEM REACH THE NORTHERN  
TIER.  
 
AFTER FRIDAY THE PAST 12 HOURS OF GFS RUNS HAVE TRENDED NOTICEABLY  
SHARPER AND SLOWER WITH SHORTWAVE ENERGY COMING INTO WESTERN NORTH  
AMERICA, WITH THE GFS CONTINUING TO BE SLOWER THAN CONSENSUS  
(INCLUDING THE GEFS MEAN) FOR NORTHERN STREAM FLOW THROUGH THE  
REST OF THE PERIOD. THIS DIFFERENCE CAUSES THE GFS TO BE SLOWER  
(AND IN THE 06Z RUN, QUITE SUPPRESSED) WITH THE NEXT NORTHERN TIER  
SYSTEM AND THEN TO LOWER SURFACE PRESSURES MORE OVER THE EAST WITH  
MUCH BROADER COVERAGE OF PRECIPITATION. THERE IS SOME AGREEMENT ON  
LOW PRESSURE DEVELOPING OFF THE EAST COAST BY NEXT MONDAY THOUGH.  
MEANWHILE THERE IS A GENERAL SIGNAL FOR INCOMING WESTERN U.S.  
ENERGY TO DROP INTO A TROUGH/UPPER LOW NEAR THE WESTERN HALF OF  
THE U.S.-MEXICO BORDER, WITH LOW CONFIDENCE IN DETAILS GIVEN THE  
SMALL SCALE OF THE POTENTIAL UPPER LOW. BY DAY 7 MONDAY THE  
GEFS/ECMWF MEANS PROVIDE A GOOD INTERMEDIATE SOLUTION FOR A  
SHORTWAVE THAT MAY APPROACH THE PACIFIC NORTHWEST, WEAKER THAN THE  
00Z ECMWF BUT BETTER DEFINED/SLOWER THAN SOME GFS RUNS. BASED ON  
THESE CONSIDERATIONS, THE UPDATED FORECAST BASED ON GUIDANCE  
THROUGH THE 06Z CYCLE LOWERED GFS WEIGHT STARTING DAY 5 SATURDAY  
AND INCREASED 06Z GEFS/00Z ECMWF MEAN INPUT SO THAT MODELS AND  
MEANS HAD EQUAL WEIGHT BY DAY 7 MONDAY. THE NEW 12Z ECMWF PROVIDES  
SOME ADDED INTRIGUE, WITH PARTIAL TRENDS IN THE GFS DIRECTION FOR  
NORTHERN STREAM FLOW WHILE KEEPING WEEKEND INTO MONDAY SHORTWAVE  
ENERGY MORE PHASED (ELIMINATING THE COMPACT CLOSED LOW DROPPING  
INTO THE SOUTHWEST).  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
AMPLIFIED TROUGH EMERGING FROM THE SOUTHWEST ON THURSDAY AND  
LEADING WAVY COLD FRONT WILL CONTINUE THE THREAT FOR HEAVY  
RAINFALL AND A SIGNIFICANT WINTER STORM TO THE NORTH INTO THE  
THURSDAY-FRIDAY TIME PERIOD. AMPLE GULF MOISTURE STREAMING  
NORTHWARD AHEAD OF THE UPPER TROUGH AND ASSOCIATED SURFACE COLD  
FRONT WILL PROMOTE WIDESPREAD MODERATE TO HEAVY PRECIPITATION FROM  
THE LOWER MISSISSIPPI VALLEY INTO THE NORTHEAST. BEST CHANCE FOR  
HEAVY RAINFALL EXTENDS FROM THE CENTRAL GULF COAST INTO OHIO  
VALLEY ON THURSDAY THEN EXTENDING INTO THE SOUTHERN/CENTRAL  
APPALACHIANS AND INTERIOR EAST. THE OVERALL PATTERN CONTINUES TO  
SUPPORT A THREAT FOR EXCESSIVE RAINFALL/FLASH FLOODING. ALTHOUGH  
PLENTY OF UNCERTAINTIES IN THE DETAILS LINGER, MODELS SEEM TO BE  
GRAVITATING TOWARD THE IDEA OF THE GREATEST THREAT BEING FROM THE  
CENTRAL GULF COAST INTO THE TENNESSEE VALLEY WHERE ANOMALOUS  
PRECIPITABLE WATER VALUES, LIFT ENHANCED BY FAVORABLE UPPER JET  
DYNAMICS, AND MODERATE INSTABILITY SHOULD SUPPORT SEVERAL INCHES  
OF RAINFALL ACROSS THIS REGION.  
 
ON THERE NORTH SIDE OF THE PRECIPITATION SHIELD, THE THREAT FOR A  
SIGNIFICANT WINTER STORM INTO PARTS OF THE OHIO VALLEY/GREAT  
LAKES/INTERIOR NORTHEAST WILL CONTINUE FROM THE SHORT RANGE  
PERIOD. HEAVY ACCUMULATING SNOW IS LIKELY, WHILE POSSIBLE  
IMPACTFUL SLEET AND FREEZING RAIN JUST TO THE SOUTH WITHIN THE  
TRANSITION ZONE BETWEEN THE RAIN TO THE SOUTH AND SNOW TO THE  
NORTH. EXACT AMOUNTS OF ANY WINTRY PRECIPITATION REMAIN HIGHLY  
DEPENDENT ON THE LOWER-CONFIDENCE DETAILS OF EJECTING SHORTWAVE  
ENERGY, FRONTAL WAVES, AND TIMING OF COLDER TEMPERATURES.  
 
ELSEWHERE, NORTHERN TIER SYSTEMS MAY PRODUCE A COUPLE EPISODES OF  
LIGHT AND SCATTERED SNOWFALL. MOSTLY LIGHT RAIN/MOUNTAIN SNOW  
SHOULD ACCOMPANY A COUPLE SYSTEMS BRUSHING THE PACIFIC NORTHWEST  
AND POSSIBLY EXTENDING INTO THE NORTHERN ROCKIES. SIGNIFICANT  
GUIDANCE DIFFERENCES WITH SEPARATE STREAMS OF ENERGY ALOFT LEAD TO  
LOW CONFIDENCE IN THE COVERAGE AND AMOUNTS OF PRECIPITATION OVER  
THE SOUTH AND EAST FROM THE WEEKEND INTO THE START OF NEXT WEEK.  
SOME PRECIPITATION TYPE ISSUES MAY COME INTO PLAY DEPENDING ON HOW  
FAR NORTH THE MOISTURE SHIELD EXTENDS.  
 
AREAS AHEAD OF THE EASTERN U.S. COLD FRONT WILL SEE ABOVE AVERAGE  
TEMPERATURES THURSDAY-FRIDAY, WITH PLUS 10-15F ANOMALIES FOR HIGHS  
AND UP TO PLUS 20-30F ANOMALIES FOR MORNING LOWS. ARCTIC HIGH  
PRESSURE DIVING INTO THE CENTRAL U.S. BEHIND THE COLD FRONT WILL  
BRING VERY COLD TEMPERATURES TO THE CENTRAL U.S. AND MIDWEST AFTER  
MIDWEEK. ON THURSDAY-FRIDAY EXPECT WIDESPREAD DAYTIME HIGHS (AND  
SLIGHTLY LESS EXTREME OVERNIGHT LOWS) AS MUCH AS 10-25 DEGREES  
BELOW AVERAGE WITH VALUES AS MUCH AS 30-35 BELOW NORMAL OVER PARTS  
OF OKLAHOMA/TEXAS/EASTERN NEW MEXICO ON THURSDAY. DURING THE  
WEEKEND A MODIFIED FORM OF THIS COLD AIR WILL REACH PORTIONS OF  
THE EAST WHILE THE SOUTHERN PLAINS GRADUALLY MODERATE BUT REMAIN  
WELL BELOW NORMAL. MEANWHILE THE PATTERN WILL FAVOR ABOVE NORMAL  
TEMPERATURES OVER THE NORTHERN PLAINS SATURDAY-MONDAY WITH SOME  
AREAS SEEING ONE OR MORE DAYS OF PLUS 10-20F ANOMALIES. THE WEST  
COAST STATES SHOULD BE NEAR NORMAL INTO WEEKEND, TRENDING SLIGHTLY  
WARMER THE REST OF THE PERIOD OWING TO AMPLIFIED RIDGING ACROSS  
THE EAST PACIFIC.  
 
RAUSCH/SANTORELLI  
 
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDICES ARE AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
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