494  
FXUS02 KWBC 010719  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
318 AM EDT WED JUN 01 2022  
 
VALID 12Z SAT JUN 04 2022 - 12Z WED JUN 08 2022  
 
...HEAVY RAIN THREAT OVER FLORIDA DUE TO TROPICAL MOISTURE INFLOW  
AND A POSSIBLY FORMING TROPICAL SYSTEM...  
 
   
..OVERVIEW
 
 
ONE NOTABLE FEATURE TO WATCH THIS WEEKEND WILL BE THE POSSIBILITY  
FOR A TROPICAL CYCLONE TO DEVELOP OVER THE NORTHWESTERN CARIBBEAN  
SEA/SOUTHEASTERN GULF OF MEXICO PARTIALLY FROM ENERGY FROM WHAT  
WAS AGATHA IN THE EASTERN PACIFIC (WHICH HAS NOW DISSIPATED OVER  
MEXICO). THE NATIONAL HURRICANE CENTER CURRENTLY SHOWS A HIGH  
CHANCE FOR A TROPICAL CYCLONE TO DEVELOP, AND ITS MOST LIKELY  
TRACK WOULD BE NORTHEASTWARD NEAR OR OVER THE FLORIDA PENINSULA  
AROUND SATURDAY AND THEN DEEPENING AS IT GOES INTO THE WESTERN  
ATLANTIC. THOUGH THE EXACT TIMING FOR DEVELOPMENT AND THE TRACK  
ARE UNCERTAIN, HEAVY RAIN WILL BE A THREAT ACROSS SOUTHERN FLORIDA  
REGARDLESS. FARTHER NORTH, FAIRLY FLAT FLOW IS FORECAST OVER THE  
LOWER 48, BUT WITH SHORTWAVES AND SURFACE FRONTAL BOUNDARIES  
PROVIDING FOCI FOR THUNDERSTORMS AND POTENTIAL FOR HEAVY RAINFALL  
OVER MUCH OF THE CENTRAL CONUS.  
 
   
..MODEL GUIDANCE EVALUATION/PREFERENCES
 
 
REGARDING THE POSSIBLY FORMING TROPICAL CYCLONE, MODEL GUIDANCE  
SHOWS CONSIDERABLE VARIATIONS ON WHEN IT WOULD FORM DURING THE  
SHORT RANGE PERIOD, AS AN ELONGATED AREA OF ENERGY AND LOW  
PRESSURE IS PRESENT ACROSS THE BAY OF CAMPECHE/YUCATAN/WESTERN  
CARIBBEAN SEA WITH QUESTIONS AS TO HOW MULTIPLE FEATURES COULD  
CONSOLIDATE INTO A TROPICAL DEPRESSION OR STORM. DURING THE MEDIUM  
RANGE PERIOD, MODELS HAVE CONTINUED WITH A FASTER TREND FOR THE  
TRACK OF THE TROPICAL LOW, REACHING AND QUICKLY CROSSING THE  
FLORIDA PENINSULA AROUND SATURDAY. GFS RUNS HAVE BEEN ON THE  
SOUTHERN SIDE WITH THE LOW TRACK, BUT HAVE TRENDED NORTHWARD WITH  
THE 18Z RUN AND THE NEWER 00Z RUN, AND THUS CLOSER TO THE  
ECMWF/UKMET RUNS. THE LATTER CLUSTER WITH A SLIGHTLY MORE NORTHERN  
TRACK IS WHAT THE WPC/NHC COLLABORATED FORECAST HAS BEEN LEANING  
TOWARD. MODELS CONTINUE TO INDICATE STRENGTHENING AS IT EJECTS  
NORTHEASTWARD IN THE WESTERN ATLANTIC AND AWAY FROM LAND, BUT WITH  
NORTH/SOUTH SPREAD (THE ECMWF STAYS THE FARTHEST NORTH).  
 
ACROSS THE REST OF THE CONUS, GOOD MODEL AGREEMENT IS SEEN OVER  
THE WEEKEND WITH THE GENERAL SYNOPTIC PATTERN, INCLUDING AN UPPER  
LOW OFF BRITISH COLUMBIA PRODUCING TROUGHING ACROSS THE WEST COAST  
AND A PERSISTENT SOUTH-CENTRAL CANADA UPPER LOW, BUT WITH MORE  
VARIATION AND THUS LESS CERTAINTY IN SMALLER-SCALE SHORTWAVES THAT  
COULD HELP DRIVE FRONTAL POSITIONS AND LOCATIONS OF ENHANCED  
CONVECTION. BUT THESE DIFFERENCES INCREASE BY MONDAY-TUESDAY AS  
THERE IS POTENTIAL FOR ENERGY STEMMING FROM THE WESTERN LOW TO  
POSSIBLY INTERACT WITH AND JOIN WITH THE CANADA LOW. THIS  
INTERACTION CAUSING THE FORMATION OF A SLIGHTLY DEEPER CENTRAL  
U.S. TROUGH IS INDICATED BY GFS RUNS IN PARTICULAR, BUT ECMWF AND  
CMC RUNS MAINTAIN SOME LOW AMPLITUDE RIDGING IN BETWEEN THE  
FEATURES THROUGH TUESDAY. THERE IS CONSIDERABLE SPREAD IN THE  
ENSEMBLE MEMBERS WITH THE WIGGLES OF THE PATTERN, SO CONFIDENCE IS  
LOW. BUT OVERALL THE 12/18Z GFS RUNS SEEMED TOO QUICK TO MERGE THE  
FEATURES AND PREFERRED THE ECMWF AND CMC AND THOSE MODELS'  
ENSEMBLE MEANS INSTEAD.  
 
THE WPC FORECAST BEGAN WITH A BLEND OF 12/18Z DETERMINISTIC  
GUIDANCE, BUT WITH LESSENING INFLUENCE FROM THE GFS SUITE AS THE  
PERIOD PROGRESSED WHILE ADDING IN AND INCREASING THE PROPORTION OF  
THE EC AND CMC ENSEMBLE MEANS.  
 
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
REGARDLESS OF THE TIMING OF DEVELOPMENT OF A TROPICAL SYSTEM, DEEP  
TROPICAL MOISTURE IS FORECAST TO STREAM INTO SOUTHERN FLORIDA AND  
CAUSE THE POSSIBILITY FOR HEAVY RAINFALL AND FLASH FLOODING  
PARTICULARLY THROUGH SATURDAY, WITH SOME POSSIBILITY OF HEAVY RAIN  
IN CENTRAL/NORTHERN FLORIDA AS WELL. A SLIGHT RISK IS IN PLACE IN  
WPC'S EXPERIMENTAL DAY 4 EXCESSIVE RAINFALL OUTLOOK FOR THE  
SOUTHERN FLORIDA PENINSULA. GUSTY WINDS COULD ALSO BE A THREAT IF  
THE TROPICAL SYSTEM DEVELOPS, WITH STRONGER WINDS FOR A TROPICAL  
STORM THAN A TROPICAL DEPRESSION (BY DEFINITION). LINGERING  
CONVERGENCE ACROSS SOUTH FLORIDA AND THE KEYS COULD PROMOTE  
ADDITIONAL RAIN AND THUNDERSTORMS THERE THROUGH AT LEAST THE FIRST  
HALF OF NEXT WEEK.  
 
ELSEWHERE, RAIN CHANCES ARE EXPECTED TO INCREASE IN THE NORTHWEST  
INTO THE WEEKEND GIVEN THE TROUGH AXIS NEAR THE WEST COAST AND  
MOIST 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 PARTS OF THE PLAINS AND  
MISSISSIPPI VALLEY SEEING CONVECTION OVER THE WEEKEND AND EARLY  
NEXT WEEK AS FRONTS MEANDER THERE. THE AXES OF ENHANCED RAINFALL  
WILL BE HIGHLY DEPENDENT ON WHERE INDIVIDUAL BOUNDARIES SET UP,  
AND IT COULD TAKE INTO THE SHORT RANGE TO RESOLVE THESE  
DIFFERENCES BETWEEN MODELS ON PLACEMENT OF EXCESSIVE RAINFALL, BUT  
THE INGREDIENTS ARE CERTAINLY IN PLACE FOR HEAVY RAINFALL IN SOME  
AREAS ACROSS THE CENTRAL U.S. INTO EARLY NEXT WEEK. SOME SHOWERS  
AND THUNDERSTORMS COULD PRESS INTO THE EASTERN U.S.  
MONDAY-WEDNESDAY AHEAD OF A COLD FRONT.  
 
A RELATIVELY FLAT PATTERN ALOFT COMPARED TO THE SOMEWHAT MORE  
AMPLIFIED SHORT RANGE PERIOD SHOULD PRODUCE LESSER TEMPERATURE  
ANOMALIES THIS WEEKEND INTO THE FIRST HALF OF NEXT WEEK. PERIODIC  
TROUGHING IN THE NORTHERN TIER SHOULD LEAD TO SLIGHTLY BELOW  
AVERAGE TEMPERATURES BY AROUND 10F. MEANWHILE MUCH OF THE SOUTHERN  
TIER CAN EXPECT ABOVE NORMAL TEMPERATURES BY AROUND 5-10F BUT  
REACHING +15F ANOMALIES IN TEXAS EARLY NEXT WEEK. THE WEST COAST  
SHOULD BE A BIT COOLER THAN NORMAL OVER THE WEEKEND UNDER THE  
TROUGHING INFLUENCE, BUT MODERATING AND WARMING TO ABOVE NORMAL IN  
CALIFORNIA BY AROUND MIDWEEK.  
 
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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