416
FXUS10 KWNH 020527
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1226 AM EST MON MAR 02 2020
VALID MAR 02/0000 UTC THRU MAR 05/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z GFS/NAM/UKMET EVALUATION WITH MODEL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ANY INITIALIZATION ERRORS IN THE NAM/GFS DO NOT SEEM TO DEGRADE
THEIR SHORT RANGE FORECASTS.
SHORTWAVE CROSSING THE UPPER MIDWEST/GREAT LAKES BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS AGREEABLE SOLUTIONS WITH THIS FEATURE. A
COMPROMISE OF THE 00Z UKMET, 00Z GFS, 00Z NAM, 12Z CANADIAN, AND
12Z ECMWF IS PREFERRED HERE.
SHORTWAVE OVER THE NORTHERN PLAINS/MIDWEST BY TUESDAY
WEAK SURFACE WAVE/ENERGY LIFTING OVER CROSSING THE OH VALLEY
DEEPENING LOW CENTER OVER NORTHERN NEW ENGLAND BY WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/UKMET COMPROMISE
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THERE IS GREATER THAN NORMAL DISPERSION NEAR THE LOW STREAKING UP
THE OHIO VALLEY INTO THE NORTHEAST OVER THE NEXT FEW DAYS, BOTH
WITHIN THE 12Z GLOBAL ENSEMBLE GUIDANCE AND 12Z/00Z DETERMINISTIC
GUIDANCE. THE 00Z NAM/18Z GEFS MEAN LIE ON THE EAST SIDE WHILE
THE 12Z CANADIAN LIES ON THE WEST SIDE. DUE TO THE ABOVE
UNCERTAINTY, WHICH IS DUE TO PROGRESSION AND DEPTH ISSUES, CHOSE A
SOLUTION CLOSEST TO THE MIDDLE OF THE SPREAD, WHICH WOULD BE A 00Z
UKMET/00Z GFS COMPROMISE. CONFIDENCE IN THIS SOLUTION IS SLIGHTLY
BELOW AVERAGE.
SHORTWAVE APPROACHING BRITISH COLUMBIA ON TUESDAY
AMPLIFYING IN THE NORTHERN PLAINS EARLY THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CANADIAN BLEND
CONFIDENCE: AVERAGE
AS A RIDGE AMPLIFIES UPSTREAM, A SHORTWAVE MOVING ALONG THE
WESTERN US/CANADIAN BORDER BEGINS TO AMPLIFY. THE GUIDANCE
DISAGREES ON THE AMPLIFICATION EXPECTED AND THE LATITUDE OF THE
BUNDLE OF ENERGY/POSSIBLE CLOSED LOW THURSDAY MORNING. THE APEX
OF THE DEVELOPING SHORTWAVE RIDGE IN THE STREAM TO ITS NORTH IS
~68N WHICH ARGUES FOR A POSSIBLE CLOSED LOW ~48N, RIGHT WHERE THE
00Z UKMET/00Z GFS HAVE IT. HOWEVER, THE WAVELENGTH IN THE
NORTHERN STREAM OF THE WESTERLIES IS LONG, WHICH ARGUES FOR A MORE
OPEN SHORTWAVE. THE ABOVE MAY EXPLAIN THE VARIANCE IN THE
GUIDANCE. EVEN SO, THE 12Z CANADIAN LOOKS TOO WEAK WITH THIS
FEATURE SO IT WAS NOT CONSIDERED PLAUSIBLE. A COMPROMISE OF THE
00Z NAM, 00Z GFS, 00Z UKMET, AND 12Z ECMWF IS PREFERRED WITH
CONFIDENCE NO BETTER THAN AVERAGE.
SOUTHERN STREAM SYSTEM MOVING FROM NORTHERN MEXICO
THROUGH THE SOUTHEAST MONDAY INTO THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
THE GUIDANCE (OUTSIDE OF THE NAM) HAS TRENDED STRONGER ALOFT AND
MORE NORTHWEST WITH THE SURFACE LOW TRACK NEAR THE GULF COAST AND
DEEP SOUTH SINCE THIS TIME YESTERDAY. PROGRESSION ISSUES IN THE
DETERMINISTIC GUIDANCE ARE QUITE SMALL CONSIDERING THE BROAD 12Z
GLOBAL ENSEMBLE SPREAD SEEN IN THE 5640 METER 500 HPA HEIGHT LINE
SPAGHETTI PLOTS. THE 12Z ECMWF ENSEMBLE MEAN IS SHOWING AN
INTERESTING ISSUE THAT IS NORMALLY ASSOCIATED WITH STRENGTHENING
LOWS, BOTH TROPICAL AND OTHERWISE -- ALLOWING DEEPER OFFSHORE
SOLUTIONS TO WEIGHT THE MEAN SURFACE LOW SOLUTION OFFSHORE DESPITE
EQUAL DISPERSION ON AND OFFSHORE THE GULF COAST. PREFER A
COMPROMISE OF THE 12Z ECMWF, 00Z UKMET, 00Z CANADIAN, 00Z NAM, AND
00Z GFS UNTIL THE GUIDANCE STABILIZES WITH CONFIDENCE NO BETTER
THAN AVERAGE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ROTH
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