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Extended Forecast Discussion
 
(Latest Discussion - Issued 1453Z Apr 26, 2018)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1052 AM EDT THU APR 26 2018

VALID 12Z SUN APR 29 2018 - 12Z THU MAY 03 2018

15 UTC UPDATE...

LATEST MODELS/ENSEMBLES REMAINED FAIRLY CONSISTENT WITH THE
FORECAST ISSUED OVERNIGHT, AND LITTLE TO NO SIGNIFICANT CHANGES
WERE NOTED. THUS, THE WPC FORECAST WAS KEPT VERY CLOSE TO
CONTINUITY, AND A SIMILAR BLEND WAS USED TO THE OVERNIGHT FORECAST
ISSUANCE, SIMPLY UPDATED FOR RECENT MODEL RUNS.

RYAN


PREVIOUS DISCUSSION (ISSUED AT 0610 UTC)...

...OVERVIEW...

WESTERN TROUGHING AND EASTERN RIDGING WILL DOMINATE THE MEDIUM
RANGE PERIOD (NEXT WEEK) WHICH WILL BRING RATHER SUMMERY WEATHER
TO MUCH OF THE EAST. THE MODELS/ENSEMBLES HAVE SLOWLY CONVERGED ON
A MORE COHESIVE SOLUTION THROUGH THE PERIOD, WITH THE GFS (WHICH
HAS TRENDED SLOWER) FINALLY CLOSER TO THE ECMWF/UKMET/CANADIAN
CLUSTER (WHICH HAS TRENDED A BIT QUICKER). AS SUCH, USED A
DETERMINISTIC BLEND FOR THE SUN-MON PERIOD AS THE EASTERN UPPER
LOW EXITS AWAY FROM NEW ENGLAND AND THE LEAD UPPER LOW IN OREGON
LIFTS INTO MONTANA/NORTH DAKOTA. REGARDING THE TRAILING SHORTWAVE
OUT OF THE NORTHEAST PACIFIC, THE UKMET WAS SLOWEST AND DID NOT
BRING ADDITIONAL HEIGHT FALLS TO SOUTHERN CALIFORNIA NEXT
TUESDAY-WEDNESDAY (INSTEAD ALLOWING RIDGING TO MOVE BACK IN) BUT
WAS DISCOUNTED AS ONLY A FEW ENSEMBLES MEMBERS SHOWED THIS
SCENARIO. RATHER, KEPT CONTINUITY VIA THE ENSEMBLES THAT ALLOWED
THE POSITIVELY TILTED TROUGH TO LINGER IN THE SOUTHWEST INTO NEXT
THURSDAY. RIDGING IN THE EAST MAY PEAK AROUND WEDNESDAY AS THE
NORTHERN PORTION MAY TRY TO SNEAK EASTWARD THROUGH THE GREAT
LAKES, BUT WOULD NOT BE SURPRISED IF THE DOWNSTREAM UPPER LOW AND
SOUTHWESTERN UPPER LOW WERE SLOW ENOUGH TO ALLOW THE RIDGE AXIS TO
STAY OVER THE NORTHEAST LONGER.


...WEATHER HIGHLIGHTS...

AFTER LINGERING CHILLY TEMPERATURES SUN/MON, MUCH ABOVE AVERAGE
TEMPERATURES WILL OVERSPREAD THE EAST BY WEDNESDAY. HIGHS WILL BE
IN THE 70S AND 80S OR ABOUT 5-15 DEGREES ABOVE AVERAGE. THE WEST
WILL SEE UNSETTLED WEATHER WITH MOSTLY LIGHT TO MODERATE RAIN AND
HIGH ELEVATION SNOW BUT LOWERING SNOW LEVELS WITH TIME AS HEIGHTS
FALL AND COOLER TEMPERATURES FILTER IN. AREAS TO THE NORTH OF THE
UPPER LOW TRACK (NORTHERN IDAHO INTO NW MONTANA) STAND TO SEE THE
MOST PRECIPITATION SUN-TUE WITH SEVERAL INCHES OF SNOW FOR THE
MOUNTAINS. HIGH PRESSURE IN THE EAST WILL ALLOW MOISTURE TO FLOW
NORTHWARD FROM THE WESTERN GULF THROUGH THE SOUTHERN PLAINS WHERE
CONVECTION WILL EXPAND ONCE THE FRONT GETS EAST OF THE FOOTHILLS.
THOUGH EXACT LOCATIONS ARE UNCERTAIN, PRECIPITATION COULD BE
HEAVY, ESPECIALLY IF THE FRONT SLOWS DOWN ENOUGH FOR A COUPLE
DAYS. THE EAST WILL BE MOSTLY DRY NEXT WEEK WITH PRECIPITATION
CONFINED TO NORTHERN MAINE AND SOUTHERN FLORIDA.


FRACASSO


ASSOCIATED WPC MEDIUM RANGE FORECASTS OF 500 MB HEIGHTS...SURFACE
SYSTEMS...WEATHER GRIDS...QUANTITATIVE PRECIPITATION FORECASTS
(QPF)...AND WINTER WEATHER OUTLOOK SNOW/SLEET PROBABILITIES CAN BE
FOUND AT...

http://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
http://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
http://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
http://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
http://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4