900
FXUS10 KWNH 120755
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
354 AM EDT THU SEP 12 2019
VALID SEP 12/0000 UTC THRU SEP 15/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
08Z UPDATE: THE REST OF THE 00Z GUIDANCE SHOWED FAIRLY GOOD
AGREEMENT ACROSS MUCH OF THE CONUS WITH RESPECT TO THE LARGE SCALE
MASS FIELDS. HOWEVER THE ONE EXCEPTION IS WITH THE TROPICAL
DISTURBANCE OVER THE BAHAMAS. THE NON-NCEP GUIDANCE ALL SHIFT
EASTWARD WITH THE LOW TRACKING OFF THE FLORIDA COAST THROUGH DAY
3. THIS IS IN CONTRAST WITH THE GFS (NEAR CENTRAL GULF OF MEXICO
BY DAY 3) AND NAM (OFF THE WESTERN FL PENINSULA). FOR NOW, WILL
PREFER A CONSENSUS APPROACH WITH THE LOW TRACKING ACROSS THE FL
PENINSULA AND POTENTIALLY ACROSS THE PANHANDLE THROUGH DAY 3, BUT
ADMITTEDLY THE FORECAST CONFIDENCE HERE IS BELOW AVERAGE.
---PREVIOUS DISCUSSION---
THE SYNOPTIC PATTERN OVER THE CONUS FEATURES AN ANOMALOUS UPPER
LEVEL TROUGH OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS WITH A
STRONG RIDGE OVER THE SOUTHEAST U.S. ANOTHER CLOSED UPPER LOW WILL
MOVE ONSHORE THE PACIFIC NORTHWEST DURING THE FORECAST PERIOD
WHILE AN AREA OF DISTURBED WEATHER AND DISORGANIZED
SHOWERS/THUNDERSTORMS OVER THE BAHAMAS WILL SLOWLY DRIFT WESTWARD
TOWARD FLORIDA BY DAY 3.
THE LATEST MODEL GUIDANCE IS IN ABOVE AVERAGE AGREEMENT ACROSS THE
NORTHERN TIER OF THE US DURING THE NEXT 3 DAYS WITH THE EVOLUTION
OF THE UPPER LEVEL SHORTWAVE AS IT LIFTS NORTHEASTWARD INTO THE
HUDSON BAY AREA. A SURFACE LOW DEEPENING OVER THE AREA IS ALSO
WELL REPRESENTED AND TIGHTLY CLUSTERED WITH THE LATEST
DETERMINISTIC GUIDANCE. IN GENERAL, MASS FIELDS ACROSS THE CONUS
ARE IN GOOD AGREEMENT SUCH THAT A GENERAL MODEL BLEND SUFFICES.
THE LARGEST MODEL VARIABILITY EXISTS WITH THE TROPICAL DISTURBANCE
NEAR THE BAHAMAS. OVER THE NEXT 3 DAYS, MOST OF THE GLOBAL
DETERMINISTIC GUIDANCE SHOWS SLOW DEVELOPMENT. THE 00Z GFS IS A
FASTER AND WESTWARD SOLUTION, WITH ITS LOW REACHING LOUISIANA BY
84 HOURS. MEANWHILE, THE UKMET IS THE FURTHEST EAST, WITH ITS LOW
POSITION NEAR JACKSONVILLE AT 84 HOURS. THE CMC/ECMWF OFFER A GOOD
PROXY FOR CONSENSUS AT THIS TIME.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
TAYLOR
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