256  
FXUS02 KWBC 310714  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
312 AM EDT TUE MAY 31 2022  
 
VALID 12Z FRI JUN 03 2022 - 12Z TUE JUN 07 2022  
 
...HEAVY RAIN THREAT INCREASING OVER FLORIDA DUE TO TROPICAL  
MOISTURE INFLOW AND A POSSIBLY FORMING TROPICAL SYSTEM...  
 
   
..OVERVIEW
 
 
WHILE THE OVERALL PATTERN ACROSS MUCH OF THE LOWER 48 WILL REMAIN  
FAIRLY STAGNANT LATE WEEK INTO EARLY NEXT WEEK, WITH WEST COAST  
TROUGHING AND A SOUTH-CENTRAL CANADA UPPER LOW SENDING SOME LOW  
AMPLITUDE TROUGHING ACROSS THE CENTRAL TO EASTERN U.S. BUT THE  
MAIN NOTABLE FEATURE TO WATCH DURING THE MEDIUM RANGE PERIOD WILL  
BE THE POSSIBILITY FOR A TROPICAL CYCLONE TO DEVELOP OVER THE  
NORTHWESTERN CARIBBEAN SEA/SOUTHEASTERN GULF OF MEXICO PARTIALLY  
FROM ENERGY FROM WHAT IS CURRENTLY TROPICAL STORM AGATHA OVER  
MEXICO. AT THIS TIME, A LOW TRACK NORTHEASTWARD NEAR OR OVER THE  
FLORIDA PENINSULA IS POSSIBLE, BUT WITH FAIRLY LOW CONFIDENCE IN  
THE TRACK, TIMING, AND STRENGTH OF A TROPICAL SYSTEM. REGARDLESS,  
HEAVY RAIN IS POSSIBLE LATE WEEK INTO THE WEEKEND WITH MOISTURE  
STREAMING AHEAD OF THIS POTENTIAL SYSTEM AND THEN NEAR ITS  
POSSIBLE EVENTUAL TRACK.  
 
   
..MODEL GUIDANCE EVALUATION/PREFERENCES
 
 
RECENT MODEL GUIDANCE IS IN REASONABLY GOOD AGREEMENT FOR THE  
OVERALL SYNOPTIC PATTERN LATE THIS WEEK. AN UPPER LOW SPINNING  
OFFSHORE OF BRITISH COLUMBIA SHOWS GOOD CONSENSUS WITH ITS  
POSITION AND A SLOW DRIFT NORTHWARD THROUGH THE WEEKEND, WITH  
GENERAL TROUGHING FOR THE U.S. WEST COAST SHOWN BY ALL THE  
GUIDANCE. THERE ARE SOME DIFFERENCES ARISING BY MONDAY OF NEXT  
WEEK THOUGH--GFS RUNS HAVE BEEN PERSISTENT IN INDICATING SHORTWAVE  
TROUGHING TRACKING INTO THE NORTH-CENTRAL U.S. WHEREAS THE  
ECMWF/CMC RUNS HOLD THE ENERGY BACK ACROSS THE NORTHWEST, YIELDING  
RIDGING IN THE ROCKIES TO HIGH PLAINS. PREFERRED THE LATTER AT  
THIS TIME GIVEN THE GFS CAN HAVE A BIAS FOR FASTER SYSTEMS  
SOMETIMES, BUT THERE IS QUITE A BIT OF SPREAD FROM THE ENSEMBLE  
MEMBERS, LOWERING CONFIDENCE. MEANWHILE THE SOUTH-CENTRAL CANADA  
UPPER LOW IS FORECAST TO PERSIST BUT BE SLOWLY WEAKENING AND  
POSSIBLY ELONGATING AT TIMES. WHILE ON THE LARGE SCALE THIS SEEMS  
IN GOOD AGREEMENT, SHORTWAVE TROUGHING STEMMING FROM THAT FEATURE  
COULD PUSH A SERIES OF FRONTS ACROSS CENTRAL AND EASTERN PARTS OF  
THE U.S. AND PROVIDE FOCI FOR RAIN/CONVECTION, AND THESE DETAILS  
ARE MORE VARIABLE AMONG GUIDANCE. BUT WITH THE REASONABLE LARGE  
SCALE AGREEMENT, THE WPC FORECAST UTILIZED A BLEND OF THE 18Z GFS  
AND THE 00Z ECMWF, UKMET, AND CMC FOR THE EARLY PART OF THE  
FORECAST PERIOD, INCORPORATING SOME GEFS AND EC ENSEMBLE MEANS  
LATER IN THE PERIOD AND REDUCING THE DETERMINISTIC GFS COMPONENT.  
 
NOTABLE MODEL DIFFERENCES CONTINUE TO BE SEEN WITH THE POTENTIAL  
FOR A TROPICAL SYSTEM TO DEVELOP IN THE SOUTHEASTERN  
GULF/NORTHWESTERN CARIBBEAN. THE GENERAL TREND OVER THE PAST DAY  
OR SO HAS BEEN FOR A FASTER TRACK OF A TROPICAL LOW EJECTING  
NORTHEASTWARD OUT OF THE LARGE, COMPLEX AREA OF LOW PRESSURE OVER  
THE BAY OF CAMPECHE/YUCATAN/NORTHWESTERN CARIBBEAN. THE  
DETERMINISTIC GFS AND CMC RUNS HAVE ALWAYS BEEN FASTER THAN THE  
ECMWF RUNS, WITH CONSIDERABLE TIMING SPREAD IN ENSEMBLE MEMBERS.  
BUT EACH ECMWF RUN THROUGH THE MOST RECENT 00Z RUN HAS SHOWN A  
FASTER TREND, AND MODEL GUIDANCE INDICATES A SYSTEM COULD REACH  
FLORIDA BY SATURDAY IF IT DEVELOPS, THEN TRACK INTO THE WESTERN  
ATLANTIC. TIMING AND TRACK DIFFERENCES ARE ALSO RELATED TO THE  
STRENGTH OF THE POSSIBLE SYSTEM. THE ECMWF SHOWS A STRONGER LOW  
WITH MORE CONSOLIDATED ENERGY THAN THE CMC AND GFS, WITH A TRACK  
FARTHER NORTH ACROSS CENTRAL FLORIDA RATHER THAN SOUTHERN FLORIDA  
OR THE FLORIDA STRAITS LIKE OTHER GUIDANCE INCLUDING THE GFS/CMC  
AND MANY GEFS ENSEMBLE MEMBERS. OVERALL THERE IS AMPLE UNCERTAINTY  
WITH THE POSSIBLE DEVELOPMENT OF A TROPICAL CYCLONE AND ITS  
STRENGTH, TRACK, AND TIMING. SEE NHC TROPICAL WEATHER OUTLOOKS FOR  
MORE ON THIS SYSTEM'S POTENTIAL FOR DEVELOPMENT AND STAY UP TO  
DATE WITH THE LATEST FORECASTS.  
 
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
TROPICAL STORM AGATHA HAS CURRENTLY MOVED INTO MEXICO AND WILL  
WEAKEN QUICKLY OVER UNFAVORABLE TERRAIN THERE. BUT ITS ASSOCIATED  
DEEP TROPICAL MOISTURE WILL STREAM INTO SOUTHERN FLORIDA FRIDAY,  
INCREASING THE LIKELIHOOD OF RAIN AND THUNDERSTORMS BECOMING MORE  
FREQUENT AND WIDESPREAD, FIRST AHEAD OF THE REMNANT DISTURBANCE  
AND THEN WITH THE POTENTIAL FOR A TROPICAL LOW TO DEVELOP  
(POSSIBLY PARTIALLY FROM AGATHA'S REMNANTS) AND TRACK OVER OR NEAR  
THE STATE. MOISTURE ALOFT FROM THE FAR EASTERN PACIFIC AND LOWER  
LEVEL MOISTURE FROM THE CARIBBEAN SHOULD LEAD TO HEAVY RAINFALL,  
EVEN IF THE SYSTEM'S TIMING IS IN QUESTION. EVEN IN THE CYCLONE'S  
WAKE, ITS CONVERGENT TAIL APPEARS TO BE STUCK IN THE VICINITY OF  
SOUTH FLORIDA AND THE KEYS, KEEPING THE THREAT OF MODERATE TO  
HEAVY RAINFALL IN PLAY INTO EARLY NEXT WEEK. SLIGHT RISKS ARE IN  
PLACE IN WPC'S EXPERIMENTAL DAYS 4 AND 5 EXCESSIVE RAINFALL  
OUTLOOK.  
 
ELSEWHERE, RAIN CHANCES ARE EXPECTED TO INCREASE IN THE NORTHWEST  
LATE WEEK INTO THE WEEKEND GIVEN THE TROUGH AXIS NEAR THE WEST  
COAST AND ONSHORE FLOW. HOWEVER, THE SOUTHWEST SHOULD REMAIN DRY  
AND HOT, WITH DEATH VALLEY EXPECTED TO MEET OR EXCEED 110F HIGH  
TEMPERATURES THIS WEEKEND INTO EARLY NEXT WEEK. FARTHER EAST,  
FRONTS ARE EXPECTED TO SPARK ROUNDS OF SHOWERS AND THUNDERSTORMS  
ACROSS THE CENTRAL AND EASTERN U.S., WITH THE CAROLINAS AN AREA OF  
FOCUS ON FRIDAY AND PARTS OF THE PLAINS AND MISSISSIPPI VALLEY  
SEEING CONVECTION FRIDAY INTO THE WEEKEND AND EARLY NEXT WEEK AS  
FRONTS MEANDER THERE, WITH THE USUAL UNCERTAINTIES IN PLACEMENT.  
 
A RELATIVELY FLAT PATTERN ALOFT COMPARED TO THE MORE AMPLIFIED  
SHORT RANGE PERIOD SHOULD PRODUCE LESSER TEMPERATURE ANOMALIES  
LATE THIS WEEK INTO EARLY NEXT WEEK. COOLER THAN AVERAGE SPOTS  
WILL BE ACROSS THE CENTRAL/SOUTHERN PLAINS FRIDAY WITH RAIN COOLED  
AIR, BUT SHOULD SWITCH TO ABOVE NORMAL IN TEXAS BY 10-15F BY EARLY  
NEXT WEEK. PERIODIC TROUGHING IN THE NORTHERN TIER SHOULD LEAD TO  
SLIGHTLY BELOW AVERAGE TEMPERATURES BY AROUND 10F. THE WESTERN  
U.S. COULD BE WARMER THAN NORMAL BY 5-10F LATE IN THE WORKWEEK BUT  
COOLER TEMPERATURES ARE FORECAST BY THE WEEKEND UNDER THE  
TROUGHING INFLUENCE AND AS A COLD FRONT MOVES THROUGH THE AREA.  
 
TATE  
 
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, EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK, 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/#PAGE=ERO  
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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