241
FXUS10 KWNH 190643
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
142 AM EST WED FEB 19 2020
VALID FEB 19/0000 UTC THRU FEB 22/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z INITIAL MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 36 HOURS; THEN
UKMET/ECMWF/GEFS MEAN
CONFIDENCE: NEAR AVERAGE FOR MOST AREAS
THE PATTERN AT THE BEGINNING OF THE FORECAST PERIOD WEDNESDAY
MORNING IS FEATURED WITH A WEST COAST RIDGE, ZONAL FLOW ACROSS THE
CENTRAL/SOUTHERN PLAINS AND GULF COAST REGION, AND A LONGWAVE
POSITIVELY TILTED TROUGH DROPPING SOUTHEASTWARD ACROSS THE
NORTHERN ROCKIES AND THE DAKOTAS. THE TROUGH WILL THEN REACH THE
EASTERN U.S. BY EARLY FRIDAY AND INDUCE SURFACE CYCLOGENESIS OVER
THE OFFSHORE WATERS BETWEEN THE CAROLINAS AND BERMUDA. WITH THE
UPPER LEVEL RIDGE AXIS PROGRESSING TO THE SOUTH-CENTRAL U.S. BY
THE WEEKEND, A SOUTHERN STREAM CLOSED LOW ALOFT REACHES CALIFORNIA
AND HERALDS A PATTERN CHANGE FOR THIS REGION.
THROUGH THURSDAY MORNING, A GENERAL MODEL BLEND WILL SERVE AS A
GOOD STARTING POINT SINCE THERE ARE RELATIVELY MINIMAL
DETERMINISTIC DIFFERENCES AND LITTLE IN THE WAY OF ENSEMBLE
SPREAD. BY THURSDAY EVENING, DIFFERENCES BECOME APPARENT WITH THE
500MB TROUGH CROSSING THE OHIO VALLEY AND MIDWEST STATES, WITH THE
NAM AND TO A LESSER EXTENT THE GFS BECOMING MORE AMPLIFIED THAN
THE NON-NCEP GUIDANCE SUGGESTS. THIS HAS IMPLICATIONS FOR
OFFSHORE SURFACE LOW DEVELOPMENT EAST OF THE CAROLINAS, WITH THE
NAM BEING A NORTHWESTERN OUTLIER WITH THE TRACK OF THE LOW, THUS
BRINGING MORE IMPACTFUL WEATHER TO THE INTERIOR SOUTHEAST. THE
CMC BECOMES A LITTLE MORE PROGRESSIVE WITH THE LOW TRACK, WITH
GOOD AGREEMENT AMONG THE ECMWF, UKMET, AND THE ENSEMBLE MEANS.
FOR THE LONGWAVE TROUGH AND DEVELOPING CLOSED LOW FOR THE WEST
COAST REGION, THERE IS NOW BETTER AGREEMENT WITH THE SHORTWAVE
CROSSING THE PACIFIC NORTHWEST THURSDAY EVENING COMPARED TO
EARLIER MODEL RUNS OF THE NAM AND GFS. IN REGARDS TO THE CLOSED
LOW REACHING SOUTHERN CALIFORNIA BY SATURDAY MORNING, THE UKMET IS
SLIGHTLY MORE PROGRESSIVE BUT STILL CLOSE TO THE ENSEMBLE MEANS,
AND THE GFS IS SLIGHTLY SLOWER. THE CMC AND ECMWF ARE CLOSEST TO
THE MODEL CONSENSUS.
THE MAIN DIFFERENCE NOTED WITH THE 00Z ECMWF COMPARED TO THE 12Z
RUN IS A TREND TOWARDS A MORE AMPLIFIED UPPER LEVEL TROUGH
CROSSING THE OHIO VALLEY AND SOUTHEAST U.S., AND THE SURFACE LOW
OFF THE COAST OF NORTH CAROLINA TO THE NORTHWEST OF ITS 12Z RUN
AND CLOSER TO THE 00Z GFS. THE EC MEAN IS STILL FARTHER OFFSHORE
COMPARED TO MOST OF THE OTHER GUIDANCE, WITH THE 00Z GEFS MEAN
DEPICTING A REASONABLE COMPROMISE BETWEEN THE EC MEAN AND THE
GFS/ECMWF.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
HAMRICK
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