892
FXUS10 KWNH 160438
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1137 PM EST SAT FEB 15 2020
VALID FEB 16/0000 UTC THRU FEB 19/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z INITIAL MODEL EVALUATION WITH PREFERENCES & CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
UPPER TROUGH ACROSS GREAT LAKES AND NORTHEAST SUNDAY AND MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
BROAD CYCLONIC FLOW ALOFT OVER THE NORTH-CENTRAL U.S. WILL SUPPORT
THE PASSAGE OF A FEW SHORTWAVE PERTURBATIONS THROUGH THE BEGINNING
OF THE WORK WEEK. THE LEAD IMPULSE WILL TRACK EASTWARD ACROSS THE
GREAT LAKES ON SUNDAY AND THEN THE NORTHEAST ON MONDAY, WITH AN
ATTENDANT COLD FRONT REACHING NORTHERN NEW ENGLAND BY MONDAY
MORNING. THERE IS ENOUGH MASS FIELD AGREEMENT IN THE MODELS TO
MERIT A GENERAL MODEL BLEND FOR THIS FEATURE.
SHORTWAVE IMPULSE ACROSS UPPER MIDWEST MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF BLEND
CONFIDENCE: NEAR AVERAGE
BY MONDAY EVENING THE UPPER LEVEL FLOW PATTERN IS EXPECTED TO
BECOME MORE SEPARATED WITH A NORTHERN AND SOUTHERN STREAM
COMPONENT. TWO SEPARATE SHORTWAVES IN QUICK SUCCESSION ARE
PROGGED TO CROSS THE UPPER MIDWEST AND NORTHERN GREAT LAKES
REGION, WITH THE FIRST ONE TRACKING EASTWARD ACROSS THE UPPER
MIDWEST AND THE DAKOTAS ON MONDAY, AND THEN REACHING THE NORTHERN
GREAT LAKES BY EARLY TUESDAY. THIS WILL SUPPORT A WAVE OF LOW
PRESSURE ALONG A COLD FRONT ACROSS THIS REGION. SIMILAR TO
YESTERDAY, THE 00Z NAM REMAINS STRONGER AND SLOWER WITH THE
PASSAGE OF THE TROUGH AXIS, AND ITS SURFACE LOW IS NORTH OF THE
MODEL CONSENSUS ACROSS THE GREAT LAKES. THE UKMET IS SLIGHTLY
SLOWER WITH THE LOW AND THE NORTHERN PORTION OF THE FRONT. THE
GFS AND ECMWF ARE CLOSE TO THEIR RESPECTIVE ENSEMBLE MEANS, AND A
BLEND OF THESE TWO MODELS SHOULD SUFFICE AS A STARTING POINT.
SECOND SHORTWAVE IMPULSE REACHING THE GREAT LAKES TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/CMC
CONFIDENCE: NEAR AVERAGE
A MID LEVEL IMPULSE WILL QUICKLY FOLLOW IN PROGRESSIVE NORTHWEST
FLOW OVER NORTHERN MINNESOTA AND NORTHERN MICHIGAN ON TUESDAY, AND
EVENTUALLY CONSOLIDATE WITH THE PREVIOUS SHORTWAVE MENTIONED
ABOVE. THE MAIN DIFFERENCE IN THE MODELS IS THE 00Z NAM IS SLOWER
WITH THE TROUGH PASSAGE, AND THE GFS AND UKMET ARE SLIGHTLY
STRONGER. THE ECMWF AND CMC ARE IN THE MIDDLE AND WOULD BE A GOOD
STARTING POINT FOR MASS FIELDS.
BROAD UPPER LEVEL TROUGH BUILDING ACROSS THE INTERMOUNTAIN WEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z UKMET/00Z GFS/12Z CMC
CONFIDENCE: NEAR AVERAGE
THE SOUTHERN STREAM COMPONENT OF THE UPPER LEVEL FLOW IS FORECAST
TO EVOLVE INTO A BROAD TROUGH OVER THE INTERMOUNTAIN WEST BY
MONDAY NIGHT WHILST AN UPPER LEVEL RIDGE AXIS BUILDS JUST WEST OF
THE WEST COAST. SOME OF THE SHORTWAVE ENERGY MAY TRY TO UNDERCUT
THE RIDGE AND FORM A TEMPORARY BLOCKING PATTERN. THE 00Z NAM IS
ALSO MORE AMPLIFIED WITH THIS PORTION OF THE TROUGH, WHILST THE
ECMWF AND THE EC MEAN DON'T SHOW AS MUCH TENDENCY TO UNDERCUT THE
WEST COAST RIDGE BY WEDNESDAY MORNING.
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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