475
FXUS10 KWNH 150640
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
139 AM EST SAT FEB 15 2020
VALID FEB 15/0000 UTC THRU FEB 18/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z FINAL MODEL EVALUATION WITH PREFERENCES & CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NORTH-CENTRAL U.S. TO THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND, AND LESS GFS AFTER 60 HOURS
CONFIDENCE: ABOVE AVERAGE
BROAD CYCLONIC FLOW ALOFT WILL EXIST ACROSS THE NORTH-CENTRAL U.S.
THIS WEEKEND AFTER THE DEPARTURE OF THE STRONG COLD FRONT ON
FRIDAY. A STRONG SHORTWAVE WILL CROSS THE DAKOTAS AND UPPER
MIDWEST ON SATURDAY AND THEN CROSS THE GREAT LAKES ON SATURDAY
NIGHT, BUT GIVEN THE PAUCITY OF MOISTURE AVAILABLE, THIS SHOULD
NOT BE AN IMPACTFUL EVENT. THERE IS VERY LITTLE ENSEMBLE SPREAD
AND THE DETERMINISTIC MODELS ARE IN VERY GOOD AGREEMENT OVERALL.
THE GFS GETS SLIGHTLY MORE AMPLIFIED BY MONDAY MORNING ACROSS
SOUTHERN CANADA WITH THE NEXT SHORTWAVE PERTURBATION TO PIVOT
AROUND THE LARGER PARENT LOW THAT IS WELL TO THE NORTH. THERE IS
SIMILAR AGREEMENT ON THE TIMING OF THE COLD FRONTAL PASSAGE. THE
00Z ECMWF TRENDED A LITTLE LESS AMPLIFIED WITH THE TROUGH AXIS
REACHING THE EAST COAST MONDAY MORNING.
TROUGH BUILDING IN ACROSS THE WESTERN U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/00Z ECMWF/12Z EC MEAN
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
ZONAL FLOW THAT WILL INITIALLY BE OVER THE WEST COAST REGION IS
FORECAST TO BECOME MORE AMPLIFIED BY SUNDAY NIGHT AS A SHORTWAVE
TROUGH TRACKS SOUTHEASTWARD FROM THE GULF OF ALASKA. THIS WILL
RESULTING IN HEIGHT FALLS ACROSS MUCH OF THE WESTERN U.S. TO BEGIN
THE WEEK. DIFFERENCES WITH THE 00Z NAM BECOME APPARENT AS EARLY
AS 36 HOURS INTO THE FORECAST PERIOD WITH A GREATER DEGREE OF
AMPLIFICATION OVER BRITISH COLUMBIA, AND THIS BECOMES MORE
APPARENT WITH THE NORTHERN STREAM COMPONENT OVER THE NORTHERN
PLAINS BY MONDAY NIGHT. THIS IN TURNS INDUCES A STRONGER SURFACE
LOW OVER THE UPPER MIDWEST THAT HAS LITTLE SUPPORT FROM THE
REMAINING GUIDANCE. THE 00Z ECMWF TRENDED SLIGHTLY SLOWER WITH
THE HEIGHT FALLS ACROSS THE INTERMOUNTAIN WEST ON MONDAY COMPARED
TO THE 12Z RUN, AND IS FASTER WITH THE NORTHERN STREAM TROUGH OVER
THE GREAT LAKES BY THE END OF THE FORECAST PERIOD ON TUESDAY
MORNING, WITH ITS SURFACE LOW TRENDING FARTHER NORTH OVER THE
NORTHERN GREAT LAKES.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
HAMRICK
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