648
FXUS10 KWNH 150648
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
247 AM EDT TUE OCT 15 2019
VALID OCT 15/0000 UTC THRU OCT 18/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z FINAL MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GREAT LAKES CLOSED LOW AND NORTHEAST SURFACE LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 12Z THURSDAY, THEN
GFS/ECMWF/EC MEAN
CONFIDENCE: AVERAGE
A POTENT AND PROGRESSIVE NORTHERN STREAM SHORTWAVE CURRENTLY OVER
THE NORTHERN PLAINS IS FORECAST TO EVOLVE INTO A CLOSED LOW OVER
THE WESTERN GREAT LAKES REGION BY TUESDAY EVENING. IT WILL
CONTINUE TO DEEPEN AS IT TRACKS EASTWARD AND REACHES NEW ENGLAND
BY THURSDAY MORNING, ACQUIRING NEGATIVE TILT IN THE PROCESS. THIS
WILL SUPPORT THE DEVELOPMENT OF A NOR'EASTER OVER THE GULF OF
MAINE AS THE TRIPLE POINT LOW BECOMES THE DOMINANT LOW BY 12Z
THURSDAY.
THE DETERMINISTIC MODELS INDICATE GOOD OVERALL AGREEMENT THROUGH
ABOUT 12Z THURSDAY. BEYOND THAT TIME, THE 00Z NAM BECOMES MUCH
SLOWER WITH THE LOW AND LOSES ENSEMBLE SUPPORT. MEANWHILE, THE
00Z GEFS MEAN TRENDED CLOSER TO THE MODEL CONSENSUS DURING THIS
SAME TIME COMPARED TO THE 18Z GEFS MEAN. A BLEND OF THE
GFS/ECMWF/EC MEAN WORKS WELL FOR THE LAST 24 HOURS OF THE FORECAST
PERIOD.
SHORT WAVE ENERGY AFFECTING TEXAS THROUGH MIDWEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NAM/CMC/ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE
A SOUTHERN STREAM SHORTWAVE TROUGH OVER THE DESERT SOUTHWEST ON
TUESDAY IS EXPECTED TO BECOME DETACHED FROM THE WESTERLIES. IT
SHOULD SLOWLY TRACK EASTWARD ACROSS NEW MEXICO AND WESTERN TEXAS
WHILE EMBEDDED WITHIN AN UPPER LEVEL RIDGE. THIS WILL SUPPORT AN
INVERTED SURFACE TROUGH OVER THE WESTERN GULF COAST BY THURSDAY.
THE 00Z GFS IS DISPLACED TO THE EAST OF THE MODEL CONSENSUS. THE
00Z UKMET HAS TRENDED CLOSE TO THE CONSENSUS COMPARED TO ITS 12Z
RUN. THE NAM, CMC, UKMET, AND ECMWF APPEAR RELATIVELY WELL
CLUSTERED ACROSS TEXAS AND A BLEND OF THESE SHOULD WORK WELL AS A
FORECAST STARTING POINT.
WESTERN U.S. LONGWAVE TROUGH
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
THE UPPER LEVEL RIDGE OVER THE WESTERN U.S. AT THE BEGINNING OF
THE FORECAST PERIOD WILL PROGRESS EASTWARD ACROSS THE PLAINS BY
MIDWEEK AS A LONGWAVE TROUGH APPROACHES THE WEST COAST. A LEAD
SHORTWAVE PERTURBATION WILL QUICKLY PASS ACROSS BRITISH COLUMBIA
TUESDAY NIGHT, FOLLOWED BY A MUCH STRONGER SHORTWAVE ARRIVING BY
WEDNESDAY EVENING. THIS WILL SPUR THE DEVELOPMENT OF A SURFACE
LOW AND COLD FRONT ACROSS THE INTERMOUNTAIN WEST THAT SHOULD REACH
THE CENTRAL AND NORTHERN PLAINS BY FRIDAY MORNING. THE 00Z GFS IS
A BIT STRONGER WITH THE TROUGH APPROACHING THE CALIFORNIA COAST
WEDNESDAY NIGHT, AND THEN THE ECMWF TRENDS STRONGER BY FRIDAY
MORNING ACROSS THE DESERT SOUTHWEST. HOWEVER, THESE DIFFERENCES
DON'T APPEAR TO BE THAT SIGNIFICANT AND THERE IS ENOUGH SYNOPTIC
SCALE MODEL AGREEMENT TO SUPPORT A GENERAL MODEL BLEND FOR THIS
TROUGH.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
HAMRICK
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