Prognostic Meteorological Discussion
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000
FXUS10 KWNH 291136
PMDHMD

MODEL DIAGNOSTIC DISCUSSION...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
138 AM EST THU JAN 29 2015

VALID JAN 29/0000 UTC THRU FEB 01/1200 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

...AN EVALUATION OF THE 00Z MODEL GUIDANCE ALONG WITH FINAL
PREFERENCES/FORECAST CONFIDENCE...

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.


...PAIR OF SHORTWAVES CROSSING THE OH VALLEY MIDDAY THURSDAY...
...ADDITIONAL ENERGY SINKING DOWN INTO THE GREAT LAKES BY THURSDAY
NIGHT...
...SURFACE LOWS PHASING OVER NEW ENGLAND...

FINAL PREFERENCE: BLEND OF THE 00Z NAM/ECMWF
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE WATER VAPOR IMAGERY TONIGHT SHOWED A PAIR OF DISTINCT IMPULSES
TRACKING THROUGH THE MID MS VALLEY AND NORTHERN PLAINS. THE
CORRESPONDING SURFACE WAVES WILL BOTH MIGRATE EASTWARD TOWARD THE
GREAT LAKES URGING A FRONTAL ZONE TOWARD THE EASTERN SEABOARD.
THROUGH 30/0600Z...THE MODELS SHOW PRETTY STRONG MODEL AGREEMENT
BEFORE SPREAD EMERGES IN THE COASTAL LOW DEVELOPMENT OFFSHORE OF
NEW ENGLAND BY EARLY FRIDAY. CONSIDERING ENSEMBLE LOW SCATTER
PLOTS...THE 12Z GEFS/ECMWF ENSEMBLE MEMBERS ARE IN DECENT
AGREEMENT WHILE THE 12Z CMC ENSEMBLE MEMBERS ARE DISPLACED MORE
OFFSHORE. THE 00Z CMC SOLUTION LIES NEAR ITS OLD ENSEMBLE MEAN.
THERE IS MORE UNCERTAINTY IN HOW WOUND UP THIS SYSTEM BECOMES
ALONG WITH THE LENGTH OF TIME IT LINGERS JUST OFFSHORE OF ME. THE
00Z ECMWF SHOWED A SLIGHTLY MORE OFFSHORE TREND. HOWEVER...SUBTLE
CHANGES SHOULD STILL OCCUR AS THE FORECAST GETS CLOSER SO WILL
STICK WITH PREVIOUS PREFERENCE WHILE INCORPORATING THE NEW ECMWF
RUN.


...BROAD CLOSED LOW LINGERING ACROSS BAJA CA/WESTERN MEXICO...

FINAL PREFERENCE: BLEND OF THE 00Z GFS/ECMWF
FORECAST CONFIDENCE: AVERAGE

AN ELONGATED AXIS OF VORTICITY ANCHORED AROUND 25N LATITUDE WILL
GRADUALLY LIFT NORTH AND EAST TOWARD BAJA CA. THERE IS AN EXPECTED
INTERACTION WITH THIS FEATURE AND ADDITIONAL SHORTWAVES DROPPING
DOWN FROM NORTHERN CA. THIS COMPLEX MERGER LEADS TO SOME
SMALLER-SCALE DIFFERENCES AS A NUMBER OF VORTICITY MAXIMA SWIRL
WITHIN THE CYCLONIC FLOW. OVERALL, THE 00Z NAM/GFS/CMC ARE A BIT
QUICKER EJECTING THIS CLOSED LOW RELATIVE TO OTHER
DETERMINISTIC/ENSEMBLE GUIDANCE. EVENTUALLY THE 00Z GFS CARRIES
THIS VORTEX SOUTHWARD CENTERED OVER THE CENTER OF SEA OF CORTEZ BY
01/1200Z. WHILE THE 00Z GFS WAS PREVIOUSLY THE MOST WESTERN
SOLUTION BY SUNDAY MORNING...THE 00Z UKMET MOVED EVEN FARTHER TO
THE WEST. THE MOST CENTERED SOLUTION WOULD FEATURE A COMBINATION
OF THE 00Z GFS/ECMWF. PREFER TO STAY CLOSER TO THE CENTER OF THE
SPREAD GIVEN THE COMPLEXITIES OF DEALING WITH A CLOSED LOW.


...HEIGHT FALLS MOVING THROUGH THE CENTRAL U.S. BY 01/1200Z...
...FRONTAL ZONE SINKING SOUTHWARD...

FINAL PREFERENCE: BLEND OF THE 00Z ECMWF/12Z ECMWF ENSEMBLE MEAN
FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE

MODELS SHOW AN AREA OF HEIGHT FALLS DIGGING THROUGH THE NORTHERN
ROCKIES BY MIDDAY SATURDAY WHICH LEADS TO POTENTIAL AMPLIFICATION
DOWNSTREAM. AMONG THE MORE AMPLIFIED SOLUTIONS ARE THE 00Z NAM/CMC
WHICH SHOW GREATER AMOUNTS OF PRECIPITATION ACROSS THE NORTHERN
TIER OF THE COUNTRY ON DAY 3 -- SEE WPC QPF AND HEAVY SNOW/ICING
DISCUSSIONS FOR MORE DETAILS ON THE PRECIPITATION FORECAST. IT
APPEARS TOO MANY OF THE 00Z MODELS HAVE MOVED TOWARDS THE MORE
AMPLIFIED SCENARIO TO IGNORE. THE 00Z UKMET HAS MOVED AGGRESSIVELY
IN LIFTING AN INVERTED TROUGH UP INTO THE WESTERN GREAT LAKES
SPREADING PRECIPITATION WELL TO THE NORTH OF OTHER SOLUTIONS.
GIVEN THE CURRENT SPREAD...WILL LEAN MORE TOWARD THE STABILITY OF
THE 00Z ECMWF AND ITS ENSEMBLE MEAN HERE. THERE IS TOO MUCH
WAFFLING NOTED IN THE GUIDANCE NOTED TO TRUST ANY SINGLE
DETERMINISTIC SOLUTION AT THIS TIME.



...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

RUBIN-OSTER
$$




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