945
FXUS10 KWNH 050512
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1212 AM EST THU MAR 05 2020
VALID MAR 05/0000 UTC THRU MAR 08/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL PRELIMINARY EVALUATION WITH FINAL PREFERENCES AND
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..DEEPENING NORTHERN STREAM LOW MOVING OUT OF THE GREAT LAKES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z UKMET/ECMWF/ECENS/CMC THROUGH 36 HOURS, 12Z
UKMET/ECENS/ECMWF THEREAFTER
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A SOUTHERN STREAM WAVE LIFTING OUT OF THE GULF COAST WILL WEAKEN
TODAY AS THE NORTHERN STREAM BECOMES DOMINANT. SHORTWAVE MOVING
ACROSS THE GREAT LAKES WILL DEEPEN INTO A CLOSED LOW AS IT DIGS
SOUTHEAST TOWARDS THE MID-ATLANTIC FRIDAY. THE GFS/NAM ARE WELL
ALIGNED WITH THE TRANSLATIONAL SPEED OF THIS FEATURE, AS WELL AS
THE INTENSITY, BUT THEY ARE BOTH SLOWER THAN THEN NON-NCEP
CONSENSUS, AND THE GEFS MEAN. THE NON-NCEP SUITE IS IN VERY GOOD
AGREEMENT WITH THE LOW DEEPENING TO A CLOSED LOW TONIGHT, WITH
SLIGHT INTERACTION WITH THE SOUTHERN STREAM IMPULSE FRIDAY. THIS
WILL LEAD TO AN AREA OF DEFORMATION ACROSS UPSTATE NY AND
SOUTHEAST INTO THE MID-ATLANTIC, WITH SOME ENHANCED QPF. THE CMC
BEYOND 36 HOURS FEATURES A SIGNIFICANT CAPTURE OF THE SOUTHERN
STREAM IMPULSE, LEADING TO AN EASTWARD SHIFT AND STRONG WRAP UP OF
THE CLOSED LOW, AND SPREADS QPF MUCH FURTHER NORTH AND WEST INTO
NEW ENGLAND. THIS IS A CLEAR OUTLIER AND SHOULD BE USED WITH
CAUTION BEYOND 36 HOURS.
..LONGWAVE TROUGH MOVING INTO THE WEST COAST SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A DEEPENING LONGWAVE TROUGH DROPPING FROM THE GULF OF ALASKA WILL
APPROACH THE PACIFIC NORTHWEST TODAY AND THEN EXTEND DOWN TOWARDS
THE CA COAST FRIDAY BEFORE LIFTING ONSHORE BY THE WEEKEND. THE NAM
IS MUCH SHARPER AND DEEPER WITH THIS FEATURE WHEN COMPARED TO THE
OTHER AVAILABLE GUIDANCE, WHICH ARE OTHERWISE WELL CLUSTERED, AND
TRIES TO PIVOT THE SOUTHERN PERIPHERY OF THE TROUGH NEGATIVELY
INTO CA. WHILE THIS FEATURE WEAKENS QUICKLY AFTER COMING ONSHORE,
THE SIGNIFICANTLY DIFFERENT STRENGTH OF THE NAM LEADS TO ITS
EXCLUSION FROM THE PREFERENCE. OTHERWISE, THE REMAINING GUIDANCE
ALL SEEMS REASONABLE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
WEISS
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