Prognostic Meteorological Discussion
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000
FXUS10 KWNH 290457
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1157 PM EST WED JAN 28 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 NAM/GFS ALONG WITH PRELIMINARY
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...

PRELIMINARY PREFERENCE: BLEND OF THE 00Z NAM/12Z ECMWF
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE WATER VAPOR IMAGERY TONIGHT SHOW A PAIR OF DISTINCT IMPULSES
TRACKING THROUGH THE MIDDLE MS VALLEY AND NORTHERN
PLAINS...RESPECTIVELY. THE CORRESPONDING SURFACE WAVES WILL BOTH
MIGRATE EASTWARD TOWARD THE GREAT LAKES REGION CARRYING 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 12Z CMC FOLLOWS
SUIT WITH ITS ENSEMBLE MEAN BEING OFF TO THE EAST AS WELL. THERE
IS MORE UNCERTAINTY IN HOW WOUND UP THIS SYSTEM GETS ALONG WITH
THE LENGTH OF TIME IT LINGERS JUST OFFSHORE OF ME. THE 00Z NAM/12Z
ECMWF DEPICT A SOLUTION TUCKED BACK TOWARD THE SOUTHWEST AS THE
LOW CONTINUES TO DEEPEN. GIVEN THE AMOUNT OF DEEPENING TAKING
PLACE...WOULD PREFER TO STAY IN THIS DIRECTION AND WILL THUS
RECOMMEND A BLEND OF THE 00Z NAM/12Z ECMWF.


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

PRELIMINARY PREFERENCE: BLEND OF THE 12Z ECMWF/UKMET
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 AN ADDITIONAL SHORTWAVES DROPPING
DOWN FROM NORTHERN CA. THIS COMPLEX MERGER LEADS TO SOME
SMALLER-SCALE DIFFERENCES AS A NUMBER OF VORTICITY MAXIMA SWIRL
AROUND THE CYCLONIC FLOW. OVERALL THE 00Z NAM/GFS AND 12Z 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 THE GULF OF BAJA
CA BY 01/1200Z. WOULD PREFER TO STAY CLOSER TO THE CENTER OF THE
SPREAD HERE WITH THE 00Z NAM/12Z CMC BEING MORE PROGRESSIVE WHILE
THE 00Z GFS ENDS UP ON THE FAR WEST SIDE OF THE SPREAD. THIS WOULD
FAVOR A COMBINATION OF THE 12Z ECMWF/UKMET.


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

PRELIMINARY PREFERENCE: BLEND OF THE 12Z ECMWF/UKMET
FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE

MODELS SHOW AN AREA OF HEIGHT FALLS DIGGING THROUGH THE NORTHERN
ROCKIES BY MIDDAY SATURDAY WITH POTENTIAL AMPLIFICATION
DOWNSTREAM. AMONG THE MORE AMPLIFIED SOLUTIONS ARE THE 00Z NAM/12Z
CMC WHICH SHOW MUCH GREAT AMOUNTS OF PRECIPITATION ACROSS THE
CENTER OF THE CONUS ON DAY 3. THE 00Z GFS HAS SUBTLY MOVED IN THIS
DIRECTION BUT UNSURE IF THIS WILL OCCUR GIVEN THE TROF IS
AMPLIFYING INTO AN AREA OF MID-LEVEL CONFLUENCE FLOW. WILL PLAY IT
A BIT MORE CONSERVATIVELY AND LEAN ON THE 12Z ECMWF/UKMET.



...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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