582
FXUS10 KWNH 301843
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
243 PM EDT MON MAR 30 2020
VALID MAR 30/1200 UTC THRU APR 3/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLOSED LOW OVER NORTHEAST U.S. AND OFFSHORE SURFACE LOW EARLY THIS
WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: HIGH
A BROAD UPPER LEVEL LOW OVER NEW ENGLAND, WITH SHORTWAVE ENERGY
PIVOTING AROUND IT, WILL CONTINUE TO SUPPORT OFFSHORE SURFACE LOW
DEVELOPMENT WITH A SECONDARY COLD FRONT EXITING THE EAST COAST
LATER TODAY. THERE IS ENOUGH MODEL AGREEMENT HERE TO MERIT A
DETERMINISTIC MULTI-MODEL BLEND. NO CHANGES TO THE MODEL
PREFERENCE AFTER THE ARRIVAL OF THE 12Z NON-NCEP GUIDANCE.
CENTRAL PLAINS SHORTWAVE AND SOUTHERN U.S. SURFACE LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/12Z ECMWF
CONFIDENCE: MODERATE-HIGH
A STRONG SOUTHERN STREAM SHORTWAVE EXITING THE ROCKIES AND
EMERGING OVER THE CENTRAL PLAINS WILL SUSTAIN A WELL DEVELOPED
SURFACE LOW ACROSS THE SOUTHERN TIER STATES THROUGH TUESDAY
EVENING. THE LOW THEN EMERGES OVER THE WESTERN ATLANTIC AND THEN
TRACKS TO A POSITION JUST NORTH OF BERMUDA BY WEDNESDAY EVENING.
THERE IS GOOD OVERALL SYNOPTIC SCALE AGREEMENT AS THE SYSTEM
TRACKS EASTWARD ACROSS THE GULF COAST REGION. THE 00Z UKMET IS
FARTHER SOUTH WITH THE OFFSHORE TRACK, AND THE 00Z CMC BECOMES A
SLOWER SOLUTION. BOTH THE GFS AND ECMWF HAVE GOOD ENSEMBLE
SUPPORT, AND THUS A BLEND OF THESE TWO MODELS IS GOOD. THE 12Z
UKMET TRENDED CLOSER TO THE MODEL CONSENSUS WHILE THE 12Z CMC IS
STILL SLIGHTLY SLOWER.
BROAD UPPER LEVEL GYRE OVER NORTHWEST WITH NORTHERN TIER COLD FRONT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/12Z GFS/00Z EC MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE
AN UPPER LEVEL LOW INITIALLY NEAR THE BRITISH COLUMBIA COAST WILL
GRADUALLY REFORM OVER ALBERTA AND REMAIN NEARLY ANCHORED IN PLACE
FOR THE NEXT FEW DAYS, WITH A COUPLE OF SHORTWAVES PIVOTING AROUND
IT. THIS WILL SUPPORT A SURFACE LOW JUST NORTH OF THE CANADIAN
BORDER, AND A SECOND LOW OVER THE DAKOTAS. OVERALL DETERMINISTIC
TRENDS SINCE YESTERDAY SHOW GREATER DEFINITION WITH THESE
SHORTWAVES TRACKING ACROSS THE NORTHWEST. THE ENSEMBLE MEANS SHOW
RELATIVELY GOOD AGREEMENT WITH THESE FEATURES, WITH THE NAM
SLIGHTLY FASTER TO BRING MID-LEVEL HEIGHT FALLS TO THE REGION, AND
THE 00Z UKMET NOT QUITE AS AMPLIFIED AS THE OTHER MODELS WITH THE
500MB PATTERN. THE 12Z UKMET TRENDED MORE AMPLIFIED OVER NORTH
DAKOTA BY WEDNESDAY EVENING WITH THE SHORTWAVE TROUGH, AND THE GFS
IS NOW AMONG THE DEEPER SOLUTIONS BY THE END OF THE FORECAST
PERIOD ACROSS SOUTHERN CANADA.
SOUTHWEST SHORTWAVE AND HIGH PLAINS CYCLOGENESIS MIDWEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/12Z CMC/00Z EC MEAN
CONFIDENCE: MODERATE
A BROAD SOUTHERN STREAM TROUGH PIVOTING EASTWARD AROUND THE UPPER
LEVEL GYRE OVER SOUTHWEST CANADA WILL CROSS THE SOUTHERN ROCKIES
AND SUPPORT LEE SURFACE CYCLOGENESIS OVER EASTERN COLORADO, WITH A
FRONTAL BOUNDARY EXTENDING WESTWARD ACROSS THE INTERMOUNTAIN WEST.
THE MAIN MODEL DIFFERENCES NOTED HERE IS THE FASTER GFS AND A
NORTHWARD DISPLACEMENT OF THE 6Z GEFS MEAN WITH THE SURFACE LOW
OVER THE WESTERN HIGH PLAINS. THE 12Z GEFS MEAN TRENDED CLOSER TO
THE OTHER DETERMINISTIC GUIDANCE WITH RESPECT TO THE SURFACE LOW.
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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