813
FXUS10 KWNH 230429
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1228 AM EDT MON MAR 23 2020
VALID MAR 23/0000 UTC THRU MAR 26/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NOR'EASTER DEVELOPING OFF THE EAST COAST EARLY IN THE WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
SHORTWAVE IMPULSES IN THE NORTHERN AND SOUTHERN STREAMS ARE
PHASING OVER THE GREAT LAKES AND OHIO VALLEY REGION ON MONDAY,
SPURRING SURFACE CYCLOGENESIS OVER THE GULF STREAM AND EVOLVING
INTO A COASTAL LOW SOUTH OF LONG ISLAND BY MONDAY EVENING. THIS
STORM WILL INTENSIFY AS IT LIFTS TOWARDS THE NORTHEAST AND PASSES
OFFSHORE OF CAPE COD. THE MODELS HAVE CONSOLIDATED ON THE TRACK
AND INTENSITY OF THE LOW OVER THE PAST 24 HOURS, WITH ONLY
DIFFERENCES AS THE GFS IS SLIGHTLY FASTER BY TUESDAY MORNING AND
THE NAM SLIGHTLY CLOSER TO THE COAST. THESE DIFFERENCES ARE SMALL
ENOUGH TO MERIT A GENERAL MODEL BLEND FOR THIS REGION.
INITIAL CLOSED LOW OVER CALIFORNIA REACHING EAST COAST BY WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z CMC/00Z NAM
CONFIDENCE: NEAR AVERAGE
THE CLOSED LOW CURRENTLY OVER CENTRAL CALIFORNIA IS FORECAST TO
EVOLVE INTO AN OPEN WAVE AS IT CROSSES THE INTERMOUNTAIN WEST, BUT
STILL REMAINING INTACT AS IT REACHES THE PLAINS AND ULTIMATELY THE
EASTERN U.S BY MIDWEEK. THIS WILL RESULT IN LEE CYCLOGENESIS OVER
THE WESTERN HIGH PLAINS MONDAY NIGHT WITH THE SURFACE LOW REACHING
THE CENTRAL APPALACHIANS BY WEDNESDAY MORNING, WITH SECONDARY
CYCLOGENESIS IS LIKELY OFF THE MID-ATLANTIC COAST BY WEDNESDAY
AFTERNOON. IN TERMS OF THE MODELS, THE 12Z UKMET BECOMES WEAKER
WITH THE TROUGH OVER THE CENTRAL PLAINS AND THEN SLOWER. THE 18Z
GEFS MEAN IS SLIGHTLY SLOWER AND FARTHER NORTHER WITH THE SURFACE
LOW AS IT TRACKS TOWARDS THE OHIO VALLEY, WITH THE OPERATIONAL 00Z
GFS MORE IN LINE WITH THE NAM AND UKMET POSITIONS, AND THE ECMWF
AND EC MEAN ON THE MORE PROGRESSIVE SIDE.
BROAD UPPER LEVEL TROUGH OVER THE NORTHWESTERN U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF/12Z CMC
CONFIDENCE: NEAR AVERAGE
AN UPPER LOW SLOWLY DROPPING SOUTHEASTWARD ALONG THE BRITISH
COLUMBIA COAST IS FORECAST TO EVOLVE INTO A LARGE SCALE POSITIVELY
TILTED TROUGH BY TUESDAY AND INTO WEDNESDAY. A SHORTWAVE SHOULD
BREAK EASTWARD AWAY FROM THE PARENT TROUGH AND CROSS THE SOUTHERN
TIER OF CANADA, ALONG WITH A WELL-DEFINED SURFACE LOW, AND THE
MAIN PORTION SLOWLY SINKING SOUTHWARD ALONG THE WEST COAST. THE
NAM IS CONSIDERABLY STRONGER WITH THE NORTHERN SHORTWAVE, AND THE
GFS BECOMES SLIGHTLY MORE PROGRESSIVE BY TUESDAY NIGHT. THE UKMET
IS SLOWER WITH THE PROGRESSION OF THE TRAILING COLD FRONT ACROSS
THE UPPER MIDWEST.
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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