602
FXUS10 KWNH 051829
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
129 PM EST WED FEB 05 2020
VALID FEB 05/1200 UTC THRU FEB 09/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
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..EVOLVING FULL LATITUDE TROUGH OVER THE CENTRAL US THROUGH THU
..SURFACE WAVE(S) DEVELOPING OVER THE LOWER MS VALLEY
MOVING
INTO THE INTERIOR MID ATLANTIC LATE
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~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE TO SLIGHTLY ABOVE AVERAGE
19Z UPDATE: THERE IS CONTINUED STRENGTHENING CONGRUENCE, EVEN IN
THE TIMING/SPACING OF THE TWO WAVES INTERACTING THROUGH THE GULF
AND INTO THE SOUTHEAST/MID-ATLANTIC. THE UKMET APPEARS TO HAVE
SLOWED SUFFICIENTLY WITH LESS OVER DEEPENING AS WELL. THE CMC
FLOPPED ACROSS THE TIMING TO BECOME A FASTER OVERALL SOLUTION,
NEAR THE UKMET BUT AGAIN NOT TERRIBLY OUT OF TOLERANCE. THE ECMWF
TRENDED A TAD FASTER TOO, SO OVERALL A GENERAL MODEL BLEND CAN BE
AFFORDED. YET, THERE REMAINS MODERATE SMALLER SCALE DIFFERENCES,
TO HAVE SOME CONTINUED REDUCED CONFIDENCE, BUT IT IS MUCH IMPROVED
OVERALL.
---PRIOR DISCUSSION---
GOES-EAST WV DEPICTS FULL LATITUDE TROUGH CONTINUING TO ADVANCING
INTO THE FAR SOUTHERN PLAINS, NORTHERN MEXICO. THE OTHER MAIN
SHORTWAVE ENERGY IS SEEN ACROSS MT STARTING ITS SOUTHWARD TRACK TO
INTERACT WITH THE BASE (WITH ASSOCIATED JET STREAK) LATE THURSDAY
INTO FRI. THE BASE SHORTWAVE/HEIGHT-FALLS ADVANCING TODAY, WILL
SUPPORT A DEEPENING SURFACE WAVE ACROSS THE LOWER MS VALLEY THAT
RIDES NORTHEAST ALONG THE STATIONARY FRONTAL ZONE THROUGH THE
SOUTH INTO EASTERN KY BY EARLY THURSDAY. OVERALL MODEL GUIDANCE
APPEARS TO BE GETTING MUCH STRONGER IN AGREEMENT WITH THIS SURFACE
WAVE. HOWEVER, THERE REMAINS UNCERTAINTY WITH THE TIMING/SPACING
BETWEEN THE UPSTREAM SHORTWAVE COMING OUT OF THE ROCKIES ROUNDING
THE BASE ON THURSDAY AND SUPPORTING A SECONDARY SURFACE LOW THAT
EMERGES FROM THE CENTRAL GULF AND LIFTS ALONG THE SPINE/JUST EAST
OF THE S APPALACHIANS BY FRI MORNING. THE UKMET REMAINS QUITE
STRONG, GREATER NEGATIVE TILT ROUNDING THE BASE WITH GREATER
MOISTURE FLUX NORTHWARD, EVEN OUTPACING THE 12Z NAM/GFS, WHICH
CONTINUE TO TREND A TAD SLOWER. THE 00Z ECMWF/ECENS MEAN SUGGEST
A SLIGHTLY FASTER PACE, SO THERE IS INCREASING AGREEMENT IN
TIMING. THOUGH LIKE THE UKMET BEING TOO FAST, THE CMC IS
GENERALLY MUCH WEAKER GIVEN THE SPACING BETWEEN THE LEAD WAVE AND
UPSTREAM SHORTWAVE IS MOST DISTANT. ALL CONSIDERED A ECMWF
DOMINANT BLEND WITH THE 12Z NAM/GFS AND THE GEFS/ECENS BLEND IS
PREFERRED AT AVERAGE TO SLIGHTLY BELOW AVERAGE CONFIDENCE.
...ELONGATED SHORTWAVE (PAIR OF SHORTWAVES) OVER-TOPPING RIDGE IN
BC ON THURS/FRI DROPS INTO MID-MS VALLEY SAT SUPPORTING A WEAK
SURFACE WAVE...
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~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: AVERAGE TO SLIGHTLY ABOVE AVERAGE
19Z UPDATE: THE 12Z UKMET BACKED OFF THE OVER-AMPLIFIED WAVE
THROUGH THE MO VALLEY, BUT CONTINUES TO OUTPACE THE REST OF THE
GUIDANCE THROUGH THE OHIO VALLEY BY 84HRS, IF JUST SLIGHTLY SO
OVER THE GFS. THE ECMWF/CMC WERE A BIT SLOWER AS TO BE EXPECTED,
RELATIVE TO THE GFS/UKMET...BUT NOT TOO SIGNIFICANTLY TO DISMISS
EITHER CAMP. AS SUCH THE NAM IS THE SOLE OUT OF TOLERANCE
SOLUTION TO SUPPORT A NON-NAM BLEND AT SLIGHTLY ABOVE AVERAGE
CONFIDENCE.
---PRIOR DISCUSSION---
STRONG FLOW OVER-TOPPING A BROAD BUT DOMINANT EASTERN PACIFIC/WEST
COAST RIDGE WILL STAY IN PLACE THROUGH THE REMAINDER OF THE WEEK.
THE ASSOCIATED JET SUPPORT AN ELONGATED SHORTWAVE ENERGY THAT
SLIDES INTO THE CENTRAL PLAINS BY LATE THURSDAY INTO FRIDAY, WITH
LITTLE FANFARE IN THE WAKE OF THE EXITING LONG WAVE TROF.
HOWEVER, THE TAIL END OF THE JET/SLIGHTLY ENHANCED SHORTWAVE
SHEARS THROUGH THE ROCKIES ON FRIDAY, EVENTUALLY SLIGHTLY
AMPLIFYING ACROSS THE LOWER MO RIVER VALLEY SAT MORNING. HERE,
THE BIAS OF THE NAM AS WELL AS THE UKMET SUGGEST GREATEST
AMPLIFICATION INCREASING MOISTURE FLUX OFF THE WESTERN GULF
ALLOWING FOR INCREASED QPF THROUGH THE LOWER MS VALLEY. ENSEMBLES
AND OPERATIONAL SOLUTIONS FROM THE ECMWF/GFS AND CMC SUGGEST A
BULK OF FLATTER SOLUTIONS AND THEREFORE LESS LOW LEVEL RESPONSE.
GIVEN THE WAVE(S) POSITION BETWEEN STRONGER SYSTEMS, THERE IS
INCREASED LIKELIHOOD FOR A FLATTER SOLUTION AND THEREFORE WILL
FAVOR A 12Z GFS AND 00Z ECMWF/CMC BLEND FOR THESE FEATURES WITH
CONFIDENCE ENHANCED BY THE ENSEMBLES.
...APPROACHING RAPIDLY DEEPENING CYCLONE TOWARD PACIFIC NW BY
SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
19Z UPDATE: THE 12Z UKMET SHIFTED MUCH FASTER, THE 12Z ECMWF MADE
SMALL ADJUSTMENTS TOWARD THE GFS AND THE CMC SLOWED ENOUGH TO BE
WITHIN TOLERANCE AS WELL PROVIDING AN INCREASED OVERALL CONFIDENCE
TOWARD A NON-NAM BLEND AT SLIGHTLY ABOVE AVERAGE.
---PRIOR DISCUSSION---
A STRONG CLOSED LOW WILL ADVANCE THROUGH THE ALEUTIAN ISLANDS AND
AK PENINSULA BY FRI, WITH STRONG SHORTWAVE ENERGY DIGGING INTO THE
WESTERN GULF OF AK... MODERATE LONGWAVE RIDGING REMAINS EVEN AFTER
THE ENTRANCE TO THE SYNOPTIC JET EXITS (RELATIVELY) WITH THE
SHORTWAVE DESCRIBED IN PARAGRAPH ABOVE. THIS ALLOWS FOR A
PROGRESSIVE BUT RAPIDLY EVOLVING SHORTWAVE THAT APPROACHES
BC/VANCOUVER ISLAND TOWARD THE START OF THE WEEKEND. THE 12Z GFS
IS QUITE OPEN WITH THE WAVE WITH LESS OF A COMPACT INNER
CORE/VERTICALLY STACKED LOW BY 00Z SAT. THIS IS SUPPORTED BY THE
CMC. WHILE THE 00Z UKMET AND 12Z NAM ARE VERY STRONG/COMPACT,
THIS SLOWS BOTH SOLUTIONS RELATIVE TO THE ENSEMBLE SUITE AND IS IN
LINE WITH TYPICAL NEGATIVE BIAS OF OVER AMPLIFICATION BY THE END
OF DAY 3. THE ECMWF IS MORE CENTRAL AND SENSIBLE RELATIVE TO BOTH
CAMPS WITH A MAJORITY OF THE ECENS SOLUTIONS A BIT SLOWER. THIS
FAVORS THE ECMWF OVERALL BY TRADITIONAL VERIFICATION WITHIN THE
OVERALL SUITE AND THE EVOLUTION LOOKS QUITE REALISTIC GIVEN THE
REX ANTICYCLONE DEVELOPMENT ACROSS AK ITSELF. AS THE WAVE ENTERS
THE NW, THE GFS/CMC SLOW TO ADJUST CLOSER TO THE ECMWF. SO ALL IN
ALL, A ECMWF DOMINANT BLEND IS PREFERRED WITH SOME INCLUSION OF
THE FASTER GFS/GEFS AND SLOWER ECENS MEAN TO ACCOUNT FOR THE
MODEST UNCERTAINTY.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
GALLINA
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