sardog1
New member
- Joined
- Nov 8, 2003
- Messages
- 2,579
- Reaction score
- 231
Okay, boys and girls, so it didn't happen the last time I cried "Winter!" And if you're a leather boot or Croc wearer, you probably have been smiling a lot recently. Well, read it and weep -- the NWS Gray/Portland forecast discussion from this evening (Saturday, 11/7/09):
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
TO SAY THAT THE MODELS ARE IN DISAGREEMENT WITH THE EXTENDED
FORECAST WOULD BE A HUGE UNDERSTATEMENT. LONG TERM MODELS TRACK
FAIRLY CLOSE THROUGH TUESDAY NIGHT...WITH HIGH PRESSURE DOMINATING
THE WEATHER OVER THE REGION. THINGS FALL APART PRETTY QUICKLY
AFTER THAT THOUGH.
STARTING WITH THE 12Z GFS. AT 00Z WEDNESDAY THE GFS HAS THE
REMNANTS OF IDA OVER THE CAROLINAS...ALONG WITH A COLD FRONT
MOVING THROUGH THE GREAT LAKES. THE GFS MERGES THESE TWO SYSTEMS
JUST SOUTH OF CAPE COD BY 18Z WEDNESDAY...WITH OVERRUNNING PUSHING
WELL INTO NORTHERN NEW ENGLAND. THIS IS WHERE THINGS TAKE A TURN.
THE GFS BASICALLY HALTS THE SYSTEM AND DEEPENS IT. THIS DRAGS COLD
AIR INTO THE NORTH SIDE OF THE SYSTEM AND PRODUCES OVER AN INCH OF
QPF IN THE FORM OF SNOW...OR A RAIN/SNOW MIX. PRECIPITATION WOULD
CONTINUE THROUGH THE DAY ON THURSDAY BEFORE THE SYSTEM MIGRATES
EAST OF THE AREA.
THE 12Z ECMWF HAS A MUCH DIFFERENT SOLUTION. AGAIN...STARTING AT
00Z WEDNESDAY THE ECMWF HAS THE REMNANTS OF IDA OVER MISSISSIPPI
AND ALABAMA. IT ALSO HAS THE FRONTAL BOUNDARY OVER THE EASTERN
GREAT LAKES. THE MODEL THEN BUILDS HIGH PRESSURE INTO THE OHIO
RIVER VALLEY...WHICH PUSHES THE REMNANTS OF IDA OFF THE SOUTH
CAROLINA COAST BY 00Z. THE RESULT FOR NORTHERN NEW ENGLAND ON
THURSDAY IS HIGH PRESSURE AND PLENTY OF SUN.
BELIEVE THAT THE ECMWF HAS A BETTER HANDLE ON THE FORECAST AND IS
MORE PROGRESSIVE WITH THE LARGE SCALE FEATURES. WILL FOLLOW
CLOSELY TO THE HPC GUIDANCE WHICH RELIES HEAVILY ON THE ECMWF AND
DISCOUNTS THE GFS.
Whad he say? Whazzat "QPF"? That's "Quantitative Precipitation Forecast. A spatial and temporal precipitation forecast that will predict the potential amount of future precipitation for a specified region, or area." Note that it is expressed in the liquid water equivalent. The significance of that point is about to manifest itself.
Snow often falls hereabouts at a ratio somewhere near 10:1. If an inch of liquid-equivalent precipitation is forecast by a model that thinks it will fall as snow, well . . . you do the math.
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
TO SAY THAT THE MODELS ARE IN DISAGREEMENT WITH THE EXTENDED
FORECAST WOULD BE A HUGE UNDERSTATEMENT. LONG TERM MODELS TRACK
FAIRLY CLOSE THROUGH TUESDAY NIGHT...WITH HIGH PRESSURE DOMINATING
THE WEATHER OVER THE REGION. THINGS FALL APART PRETTY QUICKLY
AFTER THAT THOUGH.
STARTING WITH THE 12Z GFS. AT 00Z WEDNESDAY THE GFS HAS THE
REMNANTS OF IDA OVER THE CAROLINAS...ALONG WITH A COLD FRONT
MOVING THROUGH THE GREAT LAKES. THE GFS MERGES THESE TWO SYSTEMS
JUST SOUTH OF CAPE COD BY 18Z WEDNESDAY...WITH OVERRUNNING PUSHING
WELL INTO NORTHERN NEW ENGLAND. THIS IS WHERE THINGS TAKE A TURN.
THE GFS BASICALLY HALTS THE SYSTEM AND DEEPENS IT. THIS DRAGS COLD
AIR INTO THE NORTH SIDE OF THE SYSTEM AND PRODUCES OVER AN INCH OF
QPF IN THE FORM OF SNOW...OR A RAIN/SNOW MIX. PRECIPITATION WOULD
CONTINUE THROUGH THE DAY ON THURSDAY BEFORE THE SYSTEM MIGRATES
EAST OF THE AREA.
THE 12Z ECMWF HAS A MUCH DIFFERENT SOLUTION. AGAIN...STARTING AT
00Z WEDNESDAY THE ECMWF HAS THE REMNANTS OF IDA OVER MISSISSIPPI
AND ALABAMA. IT ALSO HAS THE FRONTAL BOUNDARY OVER THE EASTERN
GREAT LAKES. THE MODEL THEN BUILDS HIGH PRESSURE INTO THE OHIO
RIVER VALLEY...WHICH PUSHES THE REMNANTS OF IDA OFF THE SOUTH
CAROLINA COAST BY 00Z. THE RESULT FOR NORTHERN NEW ENGLAND ON
THURSDAY IS HIGH PRESSURE AND PLENTY OF SUN.
BELIEVE THAT THE ECMWF HAS A BETTER HANDLE ON THE FORECAST AND IS
MORE PROGRESSIVE WITH THE LARGE SCALE FEATURES. WILL FOLLOW
CLOSELY TO THE HPC GUIDANCE WHICH RELIES HEAVILY ON THE ECMWF AND
DISCOUNTS THE GFS.
Whad he say? Whazzat "QPF"? That's "Quantitative Precipitation Forecast. A spatial and temporal precipitation forecast that will predict the potential amount of future precipitation for a specified region, or area." Note that it is expressed in the liquid water equivalent. The significance of that point is about to manifest itself.
Snow often falls hereabouts at a ratio somewhere near 10:1. If an inch of liquid-equivalent precipitation is forecast by a model that thinks it will fall as snow, well . . . you do the math.