320
FXUS10 KWNH 090502
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1201 AM EST SUN FEB 09 2020
VALID FEB 09/0000 UTC THRU FEB 12/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..DIGGING TROUGH OVER THE GREAT BASIN/SOUTHWEST ON SUNDAY
..ENERGY EJECTING EAST TOWARD THE SOUTHERN PLAINS BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z ECMWF/ECENS AND 18Z GEFS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A SPLIT IN THE UPPER FLOW DEVELOPING ACROSS THE WESTERN U.S. WILL
ALLOW FOR A SUBSTANTIAL AMOUNT OF SHORTWAVE ENERGY TO DIG
SOUTHWARD OVER THE GREAT BASIN AND INTO THE SOUTHWEST U.S. ON
SUNDAY AROUND THE EASTERN SIDE OF A STRONG DEEP LAYER RIDGE
DEVELOPING OFFSHORE OF THE THE WEST COAST. ALL OF THE GUIDANCE
SHOWS A WELL-DEFINED AND FAIRLY ROBUST UPPER LOW DEVELOPING AND
DROPPING SOUTH THROUGH CALIFORNIA BY SUNDAY EVENING. ON MONDAY,
THE ENERGY IS EXPECTED TO BEGIN MOVING EAST, AND BY TUESDAY SHOULD
BE EJECTING OUT ACROSS THE SOUTHERN PLAINS. THE 00Z GFS HAS
TRENDED SLOWER WITH ITS HEIGHT FALL EVOLUTION WITH THIS SYSTEM
COMPARED TO ITS LAST 12 TO 24 HOURS WORTH OF CYCLES, AND IS
GETTING CLOSER TO THE NON-NCEP MODEL CONSENSUS. HOWEVER, IT STILL
ULTIMATELY ENDS UP BEING THE MOST PROGRESSIVE SOLUTION AFTER ABOUT
48 HOURS AS THE HEIGHT FALLS EJECT OUT ACROSS THE SOUTHERN PLAINS
TUESDAY THROUGH EARLY WEDNESDAY AND IS STILL AN OUTLIER AS A
RESULT. THE 00Z NAM HAS MADE A DRAMATIC SHIFT IN TIMING AND IS
MUCH FASTER THAN 24 HOURS AGO WITH ITS HEIGHT FALL TIMING, WITH
THE NAM NOW OVERALL A LITTLE SLOWER THAN THE GFS, BUT FASTER THAN
THE NON-NCEP MODEL SUITE AS THE ENERGY REACHES THE SOUTHERN
PLAINS. OF THE NON-NCEP MODELS, THE 12Z ECMWF IS A LITTLE FASTER
THAN THE 12Z UKMET/CMC SOLUTIONS. ENSEMBLE CLUSTERING AT THIS
POINT FROM THE 18Z GEFS AND 12Z ECENS SUITES STRONGLY FAVOR THE
12Z ECMWF UPPER TROUGH EVOLUTION AND THUS A BLEND OF THESE
SOLUTIONS WILL BE PREFERRED AT THIS TIME.
..NORTHERN STREAM TROUGHING OVER THE NORTHERN PLAINS BY SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A PORTION OF THE UPPER TROUGH CURRENTLY OVER THE NORTHWEST U.S.
WILL QUICKLY EJECT DOWNSTREAM ACROSS THE NORTHERN ROCKIES,
NORTHERN PLAINS AND TOWARD THE UPPER MIDWEST GOING THROUGH SUNDAY.
ON MONDAY, THE ENERGY SHOULD BE SHEARING ACROSS THE GREAT LAKES
AND NORTHEAST. THE MODEL SPREAD IS MINIMAL, SO A GENERAL MODEL
BLEND WILL BE PREFERRED WITH THIS ENERGY.
..NORTHERN STREAM TROUGH/FRONT OVER THE MIDWEST BY TUESDAY
..ENERGY CROSSING THE GREAT LAKES/NORTHEAST ON WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: ABOVE AVERAGE
THE GUIDANCE INDICATES A NORTHERN STREAM TROUGH AND ATTENDANT COLD
FRONT DROPPING SOUTHEAST FROM CANADA AND CROSSING THE NORTHERN
PLAINS LATE MONDAY AND ARRIVING ACROSS THE MIDWEST ON TUESDAY. ON
WEDNESDAY, THIS ENERGY WILL CROSS THE GREAT LAKES, OH VALLEY AND
THE NORTHEAST. THE MODELS OVERALL SHOW GOOD AGREEMENT WITH THIS
SYSTEM, WITH SOME EXCEPTION TO THE 12Z UKMET WHICH BECOMES A
LITTLE DEEPER THAN THE REMAINING MODEL GUIDANCE AS THE ENERGY
ADVANCES TOWARD THE NORTHEAST. SO, WHILE MODEL SPREAD IS MODEST,
WILL PREFER A NON-UKMET BLEND WITH THIS FEATURE.
..QUASI-STATIONARY FRONT OVER THE GULF COAST STATES BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND...12Z ECMWF/ECENS AND 18Z GEFS WEIGHTED
CONFIDENCE: AVERAGE
THE MODELS ALL AGREE IN PLACING A QUASI-STATIONARY FRONT ACROSS
THE GULF COAST STATES BY TUESDAY, WHICH IS EXPECTED TO PLAY A KEY
ROLE IN WHAT IS LIKELY TO BE A MULTI-DAY EXCESSIVE RAINFALL EVENT
(SEE LATEST QPFERD) FOR THE REGION. THE BOUNDARY SHOULD REMAIN
DRAPED ACROSS THE REGION THROUGH WEDNESDAY WITH SOME SOUTHWARD
DRIFT AS A WEAK SURFACE WAVE EXITS THROUGH THE MID-ATLANTIC
REGION. THE MODEL SPREAD WITH THE PLACEMENT OF THE FRONT IS MODEST
WITH THE GLOBAL MODELS, BUT THE 00Z NAM IS SEEN AS PLACING ITS
BOUNDARY A BIT FARTHER NORTH RELATIVE TO THE LOWER MS AND TN
VALLEY WHICH RESULTS IN A NORTHWARD DISPLACEMENT OF ITS HEAVIER
QPF SWATH COMPARED TO THE GLOBAL MODELS.
THE SLOWER TREND OF THE 00Z GFS WITH ITS UPSTREAM HEIGHT FALL
EVOLUTION ACROSS THE SOUTHWEST AND SOUTHERN PLAINS FAVORS ITS
FARTHER SOUTH FRONTAL PLACEMENT IN CONCERT WITH THE NON-NCEP SUITE
OF GUIDANCE. THE EJECTING HEIGHT FALLS ACROSS THE SOUTHERN PLAINS
TUESDAY AND WEDNESDAY IS EXPECTED TO FOSTER A HIGHLY DIVERGENT
FLOW PATTERN ALOFT ACROSS THE LOWER MS VALLEY AND PORTIONS OF THE
TN VALLEY IN VICINITY OF THE FRONT AND WILL BE ONE OF SEVERAL KEY
INGREDIENTS COMING TOGETHER FOR A SIGNIFICANT MULTI-DAY RAINFALL
EVENT. ADDITIONALLY, THERE IS EXPECTED TO BE AN AREA OF LOW
PRESSURE THAT DEVELOPS NEAR THE UPPER SOUTHEAST TX COASTAL PLAIN
BY EARLY WEDNESDAY IN RESPONSE TO THE STRONGER HEIGHT FALLS
APPROACHING FROM THE WEST. THE 00Z GFS IS SEEN AS BEING A TAD TOO
STRONG WITH THIS DEVELOPMENT AT LEAST THROUGH EARLY WEDNESDAY. THE
MODEL PREFERENCE AT THIS TIME FOR THE LOWER MS VALLEY/TN VALLEY
AND ENTIRE GULF COAST REGION IS WEIGHTED TOWARD A NON-NAM
CONSENSUS GIVEN CONCERNS ABOUT THE NAM FRONTAL PLACEMENT, BUT WITH
STRONG WEIGHTING TOWARD THE ECMWF AND THE GEFS/ECENS MEANS GIVEN
THE UPSTREAM PREFERENCES OVER THE SOUTHWEST U.S.
..SHORTWAVE CROSSING BRITISH COLUMBIA MONDAY NIGHT
..ENERGY DROPPING SOUTHEAST ACROSS THE NORTHERN ROCKIES TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE
LARGE UNCERTAINTY STILL EXISTS WITH A SHORTWAVE THAT WILL ADVANCE
EAST ACROSS THE GULF OF AK ON MONDAY AND THEN VERY QUICKLY
SOUTHEAST ACROSS BRITISH COLUMBIA MONDAY NIGHT. THE ENERGY IS
EXPECTED TO SLIDE DOWN ACROSS THE NORTHERN ROCKIES ON TUESDAY
WITHIN STRONG DEEP LAYER NORTHWESTERLY FLOW. THE 00Z NAM BY FAR IS
A VERY SLOW OUTLIER WITH THIS PROGRESSION OF THIS FEATURE. THE 12Z
CMC IS ON THE SLOW SIDE AS WELL, BUT THE 00Z GFS/12Z UKMET AND 12Z
ECMWF SOLUTIONS ARE ALL MORE PROGRESSIVE AND HAVE MUCH BETTER
ENSEMBLE SUPPORT FROM THE 18Z GEFS/12Z ECENS SUITES. THE UKMET
THOUGH OVERALL APPEARS TOO FLAT, SO AT THIS POINT, A BLEND OF THE
GFS AND ECMWF WILL BE PREFERRED.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page