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Undertakerson
Rank: F5 Superstorm
57 years old
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Blue Mtn, N of Hbg, PA
Born May-22-1960
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Undertakerson

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8 Nov 2017
OK - I guess the other thread (created by MJ and covering the 10-11) was not intended to discuss this time periods threat - a threat which was indicated, long ago, by the BSR.

Not without confusion, I (and others) were posting in the other thread but intending this time frame.

So this one is to discuss the late weekend, early next week system (and relates to the appropriate time lag of the BSR) Much of the thoughts that Pocono Snow, me, et al, on this time frame, can be found in that threadhttp://forums.accuweather.com/index.php?showtopic=33353&pid=2251783&st=0&#entry2251783

WPC discussion (abridged)

QUOTE
MODELS STILL CONTINUE TO STRUGGLE WITH WHETHER TO SHOW A MORE
PHASED SOLUTION EVOLVING THROUGH THE CENTRAL U.S. ON SATURDAY.
WHILE THE RECENT RUNS OF THE GFS HAVE BEEN ON THE QUICKER
SIDE...THE 00Z RUN ARRIVED WITH A MUCH SLOWER SOLUTION WHICH IS
EVEN WEST OF THE 12Z ECMWF. THIS 00Z GFS IS ALSO A BIT MORE SUBTLE
WITH THE AMPLIFICATION PROCESS WHICH LEADS TO A MORE MODEST WAVE
OF LOW PRESSURE. THE 18Z GFS/12Z ECMWF WERE STRONGER THAN THE
REMAINING SOLUTIONS AS THE 00Z/12Z CMC/UKMET CARRY A MUCH FLATTER
WAVE. EVENTUALLY THE SYSTEM WILL REACH THE EASTERN SEABOARD BY
LATE SUNDAY/EARLY MONDAY INDUCING AN AREA OF LOW PRESSURE OFF THE
COAST. MOST MODELS ARE MORE SUBTLE WITH THIS DEVELOPMENT ALTHOUGH
THE 00Z CMC HAS MOVED TOWARD A MORE EXTREME SOLUTION AS A RAPIDLY
STRENGTHENING COASTAL STORM TAKES SHAPE ON TUESDAY OFF THE UPPER
MID-ATLANTIC COAST. TURNING THE FOCUS TOWARD THE ACTIVE PACIFIC
STORM TRACK...THE LEAD UPPER TROUGH HAS BEEN WELL ADVERTISED FOR
THE PAST SEVERAL DAYS. SHORT-TERM ENSEMBLE TRENDS SHOW A SLOWING
WHICH THE 00Z UKMET HAS FOLLOWED AFTER ITS FORMER SOLUTION WAS A
PROGRESSIVE OUTLIER. BY 14/0000Z...THE 00Z GFS/CMC/UKMET ARE IN
REMARKABLY CLOSER AGREEMENT WITH HEIGHT FALLS MOVING INTO EASTERN
WA/OR WHILE THE 12Z ECMWF IS A HAIR QUICKER. THE DIFFERENCES EVEN
OUT TO DAY 7/NOVEMBER 15 ARE NOT TERRIBLY LARGE WHICH SUGGESTS
SLIGHTLY ABOVE AVERAGE FORECAST CONFIDENCE. ON THE HEELS OF THIS
LEAD SYSTEM...STRONG HEIGHT FALLS LOOM OFFSHORE WITH ENSEMBLE
MEANS IN SOLID AGREEMENT WITH ONE ANOTHER. SOME RUN-TO-RUN CHANGES
WERE NOTED IN THE GUIDANCE...PARTICULARLY THE CMC.
HOWEVER...ENSEMBLE SPAGHETTI PLOTS DO NOT SHOW A TREMENDOUS AMOUNT
OF SPREAD.

GIVEN A DECENT SIGNAL OF ALL RELEVANT SOLUTIONS DURING THE
PERIOD...WAS ABLE TO KEEP A GOOD CHUNK OF OPERATIONAL GUIDANCE IN
THE MIX THROUGHOUT. DID NOT INTRODUCE ANY ENSEMBLE MEANS UNTIL
MONDAY WHILE DEDICATING SLIGHTLY MORE WEIGHTING TOWARD THE 12Z
ECMWF/ECMWF ENSEMBLE MEAN...60 PERCENT...RELATIVE TO THE 18Z
GFS/GEFS MEAN. MAINTAINED THIS RATIO FOR THE ENTIRE PERIOD WITH
THE 12Z ECMWF/ECMWF ENSEMBLE MEAN GIVEN A TAD MORE WEIGHT GIVEN
ITS STRONGER CONSISTENCY THE PAST FEW DAYS.


...SENSIBLE WEATHER HIGHLIGHTS/THREATS...

EXCEPT FOR SATURDAY WHICH WILL BE DOMINATED BY BELOW AVERAGE
TEMPERATURES...THE HEAVY INFLUENCE OF PACIFIC AIR MASSES SHOULD
CONTRIBUTE TO READINGS CLOSER TO CLIMATOLOGY OR ABOVE IN SOME
CASES. BEGINNING IN THE EASTERN THIRD OF THE COUNTRY...STRONG
SURFACE RIDGING WILL ALLOW FOR ADEQUATE RADIATIONAL COOLING ON
SATURDAY MORNING. THIS WILL BRING THE FIRST FREEZE TO MANY
LOCATIONS AS SUCH TEMPERATURES PUSH AS FAR SOUTH AS NASHVILLE TN
INTO THE INTERIOR CAROLINAS. WHILE NO DAILY TEMPERATURE RECORDS
ARE EXPECTED TO BE BROKEN...SOME RECORD LOWS ARE POSSIBLE OVER THE
UPPER GREAT LAKES INTO THE UPPER MID-ATLANTIC/LOWER NEW ENGLAND.
LOOKING TO AN AREA WHERE ABOVE NORMAL TEMPERATURES WILL BE THE
NORM...GENERAL WESTERLY FLOW SHOULD KEEP CONDITIONS MILD FROM THE
ROCKIES EASTWARD TO THE GREAT PLAINS. AT TIMES READINGS 5 TO 10
DEGREES ABOVE CLIMATOLOGY WILL BE WIDESPREAD BY EARLY NEXT WEEK.
ACROSS THE PACIFIC NORTHWEST AND INTO NORTHERN CA...AN ACTIVE
STORM TRACK SHOULD KEEP CONDITIONS COOL GIVEN THE EXPECTATIONS OF
ABUNDANT CLOUDS AND BANDS OF PRECIPITATION.

WARM ADVECTION PRECIPITATION ALONG THE ADVANCING FRONT IS IN THE
FORECAST FROM THE ARKLATEX UP TO THE GREAT LAKES. GIVEN STRONGER
FORCING TO THE NORTH...LOCALLY HEAVIER PRECIPITATION IS POSSIBLE
OVER THE GREAT LAKES THIS WEEKEND WITH A THREAT FOR SNOW GIVEN
SOME REMNANT ARCTIC AIR REMAINING IN PLACE. THE CHANCES FOR SNOW
WILL MOVE TOWARD INTERIOR NEW ENGLAND BY LATE IN THE WEEKEND INTO
EARLY NEXT WEEK. AS THE COASTAL LOW DEVELOPS...ANY CLOSER TO
TRAJECTORY TO THE COAST WOULD BRING HIGHER AMOUNTS NEAR FAR
EASTERN SECTIONS OF THE MID-ATLANTIC/NEW ENGLAND
. THE MOST
CONSISTENT AREA OF UNSETTLED WEATHER WILL BE ACROSS NORTHERN
CA/PACIFIC NORTHWEST INTO THE UPPER INTERMOUNTAIN WEST WITH
COASTAL RAIN AND HIGHER ELEVATION SNOWS. THIS MULTI-DAY EVENT
SHOULD PERSIST INTO THE MIDDLE OF NEXT WEEK WHICH MAINTAINS THE
FAIRLY WET PATTERN. EVENTUALLY A RETURN OF ADDITIONAL SHOWERS ARE
POSSIBLE OVER THE MIDDLE MS VALLEY/UPPER MIDWEST/GREAT LAKES BY
MID-WEEK AS THE LEAD PACIFIC TROUGH TRACKS EASTWARD.


RUBIN-OSTER

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CTP starting to mention

QUOTE
Return flow of milder air arrives on Sunday ahead of another sfc
low and frontal system, and today`s solutions are colder than
previous in bringing a chance of mixed rain and snow showers
central and north and chc rain showers south Sunday into Sunday
evening, followed by another shot of cold air behind it
with a
weak lake effect regime keeping post frontal lake clouds and
flurries/light snow showers over the northwest mountains Monday
into early Tuesday.


http://forecast.weather.gov/product.php?si...&glossary=1
21 Oct 2017
Time to start another thread for the second of the two storms next week, in our region. As many already know, I have high confidence in outcome when the signal from the Typhoon Rule is such that it is. Here is the GFS depiction of Lan just before it recurves and heads toward the Bering Sea region.

Attached Image


To recap, for those who may not know, the Typhoon Rule (TR) holds that when a typhoon recurves prior to or just at landfall with Japan, the most typical result is for this storm to use the outflow process, to buckle the jet stream. This, in turn, pumps the heights downstream of the system and can/usually does raise the PNA across the continent, allowing for colder air to dislodge into a (usually) long wave trough across the east.

Additionally, the storm from mid week next week (covered in MaineJay's thread) sets the table for the resultant trough to have an easier time "carving" (digging) deep enough to reinforce the cooler/cold air.

WPC, in the extended disco, has this to say.

QUOTE
FARTHER UPSTREAM THERE IS STEADILY IMPROVING CONSENSUS IN
PRINCIPLE FOR NORTHEAST PACIFIC ENERGY AMPLIFYING INTO THE LOWER
48 AFTER MIDWEEK BUT WITH A LOT OF DETAIL DIFFERENCES REGARDING
THE LEADING SURFACE REFLECTION
. BY THU-SAT THE MOST PRONOUNCED
TREND IN THE GUIDANCE OVER THE PAST DAY OR SO IS TOWARD
SHARPER/WESTWARD TROUGH AMPLIFICATION IN RESPONSE TO A MUCH
SHARPER/NORTHWARD EXTENDING EASTERN PACIFIC RIDGE. THIS TREND IS
EVIDENT IN BOTH OPERATIONAL MODELS AND THE ENSEMBLE MEANS, AND
SEEMS PLAUSIBLE GIVEN THE STRONG UPSTREAM BERING SEA SYSTEM THAT
REPRESENTS THE EXTRATROPICAL EVOLUTION OF TYPHOON LAN
. THE
AMPLIFYING PATTERN SEEMS TO FAVOR THE CLUSTER OF 12Z
GFS-GEFS/ECMWF-ECMWF MEAN VERSUS THE 18Z GFS THAT BECOMES MORE
PROGRESSIVE WITH THE CONUS TROUGH. NOTE THAT WHILE THERE IS
DECENT MODEL/ENSEMBLE MEAN AGREEMENT AT THE MOMENT, ENSEMBLE
SPAGHETTI PLOTS SHOW SOME VERY DIFFERENT SOLUTIONS FROM SOME
MEMBERS SO THERE IS POTENTIAL FOR EVOLUTION TO STRAY SIGNIFICANTLY
FROM CURRENT CONSENSUS.

http://www.wpc.ncep.noaa.gov/discussions/h...php?disc=pmdepd

Given that discussion, it's easy to understand how the two camps come to differing solutions. The GFS allowing for the EC trough, while the Euro emphasizes Western trough - allowing heights to rise in the E.

Euro

Attached Image


GFS - the 6z ups the bid to the Euro and goes even deeper

Attached Image


And, it's not only upstream that we have to watch. Looking to the south, we see a parcel of tropical energy bringing deeper PWAT values towards the S US. While this influence does not, directly, affect the storm in our region - I believe it does make the higher PWAT and moisture "more available" to the long wave trough and whatever shortwave it may spawn at the base of the digging trough.
Attached Image


And, finally, looking downstream where we have, what I believe is, a Rex Block in the Atlantic (how strong this is - subject to interpretation). So we have at least some "slow down" in the "now buckled" flow.


Attached Image


Attached Image

Amazingly, that block has been consistently signaled in most GFS runs over the past 5 days, and a few Euro Op runs, TBH.

All that being said, and all things considered, I am going GFS with this system. After looping the Euro v. GFS, as the frame times relate to the eventuality of Lan's course, I believe the GFS has the correct idea due to that model better respecting the overall tenants of the TR.

That would lead to this, or something like this...
Attached Image


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Attached Image


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Total Accum does include some from Round One, but 24 hour view does not do the whole region justice. But you get the idea, wet begets wet.

To alter an ongoing pattern, it takes a potent system (Lan) and supporting players (blocking, tropical tap). I believe we just might have that with this potential.

Closing this opening post as it's one of the longest I've probably ever done and my at-thur-it-is is flaring up. laugh.gif
Attached Image
2 Oct 2017
Models have a cold front, of decent strength, pushing through for end of the weekend/early next week.

Time to discuss, I suppose. Here's the H5 vort map from 18z, just so we have a "generalized" idea of what we're up against.

Attached Image


12z Euro for today, shows a southern bred coastal reflection - seems to get kicked by the inland wave


Attached Image



Attached Image


http://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
1 Sep 2017
I'll change the topic description of mods want me to. Figured I'd keep this discussion separate from the "never ending" cool down thread laugh.gif

I guess there's a big storm happening elsewhere - that there's not already a thread for this. Or, maybe we've just had enough of Ol' Harv

Rain sandwich

Attached Image


Disco from CTP

Virga and CAD all in a summer time discussion? ohmy.gif tongue.gif

QUOTE
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
High pressure is keeping most of the region dry, while clouds
from what was once Harvey continue to stream into and thicken
over the region.

My far SWRN zones are seeing the first chance of some light rain
as has been hinted at by the HRRR since yesterday. The near
term CAMs keep this light rain confined to the border counties
for much if not all of the overnight
so I only went for a slow
increase in the chances for some light rain or drizzle spreading
NE later tonight.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Saturday looks cloudy cool (chilly?) and damp. Still a big
question of how much it will rain with an initially very dry
airmass in place.
I am thinking that the first part of the day
will favor cloudy and cool conditions with perhaps some periods
of light rain or a misty drizzle. The deeper we get into the day
the better will be the chances for rain.

I did undercut model blended high temps by several degrees. This
looks like a classic warm season cold air damming scenario.
With a strong high off to our north and east and an approaching
low from the SW, the guidance shows a strong low level northerly
component to the ageostrophic flow which will help keep us
anomalously cool for the early days of September.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
*Wet start to holiday weekend followed by improving/rain-free
conditions Sunday into Monday (Labor Day)
*No significant flooding impacts expected from the remnants of
Harvey


http://forecast.weather.gov/product.php?si...&glossary=1
16 Aug 2017
While most of the tropics attention is currently in the Atlantic basin (with good cause for many, I admit), a look at the Trop Pac region shows the recurve of Typhoon Banyan. As we know from our TR observations, such recurve leads to an E US trough in the day 7-10 time pd

Attached Image


As acknowledged in the Extended Disco from WPC

QUOTE
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
241 AM EDT WED AUG 16 2017

VALID 12Z SAT AUG 19 2017 - 12Z WED AUG 23 2017

...PATTERN OVERVIEW/GUIDANCE EVALUATION/PREFERENCES...

GUIDANCE SHOWS A MODERATELY PROGRESSIVE PATTERN ACROSS NORTHERN
U.S. AND SOUTHERN CANADA. A TROUGH CROSSING THE EAST WILL LIFT
AWAY AFTER THE WEEKEND WHILE AN UPSTREAM TROUGH WITH EMBEDDED
CLOSED LOW WILL CONTINUE STEADILY EASTWARD FROM WESTERN CANADA.
THIS TROUGH SHOULD AMPLIFY SOME AS IT REACHES EASTERN NORTH
AMERICA, LIKELY COVERING THE NORTHEASTERN QUADRANT OF THE LOWER 48
BY DAY 7 WED. BEYOND THE RIDGE BUILDING INTO WESTERN-CENTRAL
CANADA AND NORTHERN ROCKIES/HIGH PLAINS, ANOTHER TROUGH WILL
APPROACH THE PACIFIC NORTHWEST AND WESTERN CANADA DURING THE
LATTER HALF OF THE PERIOD. OVER MORE SOUTHERN LATITUDES ENERGY
ROUNDING THE EASTERN PACIFIC RIDGE WILL SETTLE INTO A TROUGH/UPPER
LOW NEAR THE CALIFORNIA COAST AND A RETROGRADING ATLANTIC RIDGE
WILL RAISE HEIGHTS FROM THE SOUTHEAST INTO SOUTHERN PLAINS.

BASED ON MODELS/ENSEMBLES THROUGH THE 12Z/18Z CYCLES THE MOST
CONTENTIOUS PART OF THE FORECAST INVOLVES THE NORTHEASTERN PACIFIC
TROUGH DURING THE LATTER HALF OF THE PERIOD. THE PORTION OF THE
FEATURE REACHING THE GULF OF ALASKA REGION SHOULD INCLUDE A
CONTRIBUTION FROM RECURVING TYPHOON BANYAN
PLUS INPUT FROM
UPSTREAM NORTHERN PACIFIC FLOW AND HIGHER LATITUDE ALASKA FLOW.
AMONG THE AVAILABLE SOLUTIONS THE FASTER 12Z ECMWF SEEMS TO BECOME
ONE OF THE LESS LIKELY BY DAY 7 WED AS THE GENERAL EVOLUTION
TOWARD MORE AMPLIFIED FLOW SHOULD HOLD BACK TROUGH TIMING
SOMEWHAT. AT THE SAME TIME THE SLOWER GFS HAD BEEN SOMEWHAT
FASTER IN EARLIER RUNS. THE 12Z CMC (PERHAPS WITH EXCESSIVE
AMPLITUDE) OFFERS A COMPROMISE. THERE IS ENOUGH COMPLEXITY IN THE
OVERALL TROUGH EVOLUTION AND LACK OF CLEAR TRENDING IN THE ECMWF
MEAN AND SLOWER GEFS MEAN THUS FAR TO FAVOR A COMPROMISE AMONG THE
NON-12Z ECMWF SOLUTIONS. WITH THE NEW 00Z GFS/GEFS MEAN/CMC IN,
THE LATTER TWO NUDGED TOWARD THE 12Z ECMWF MEAN WITH THE GFS
REMAINING SLOWER/MORE CLOSED.


So, it's no shock that the global models are reflecting that in their medium to long range time period. 6z GFS Operational run, for example.

Attached Image


Even for the warm time period, a 12-16 anom in surface temps will be noticeable to most.

I don't have Euro surface temp maps but the 850mb view reflects a similar outcome.

Attached Image


I would imagine the cool down would be preceded by a front passage and even though the air mass out in front is not overly hot, the contrast in temperature should help aide other dynamic aspects and lead to a decent outbreak of storms near or at severe level
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