WINTER 2014-15
FORECAST
REVIEW
HYPE… IS GOING TO BE A
BIG ISSUE FOR THIS WINTER
**It started back in JULY with a few HYPSTER
meteorologists issuing forecasts in JULY !! **
Once those forecasts/ hype were issued… Social
Media was flooded with “weenies” issuing similar
such forecasts.
Everyone of these “ forecasts” all features severe
cold and huge amount of snow for Midwest/ East
coast
WEENIE… term used to describe high school
students and adults who think they are the next
Jim Cantore – (but actually work 3rd shift at
WalMart)
THIS is the
Twitter Page I
post updates on
during winter
season– and
all seasons tyat
are about
“operational “
(Regular)
weather
forecasts
BRIEF REVIEW
OF LAST WINTER
• VAST MAJORITY OF FORECASTS (govt & private)
CALLED FOR A MILD or very MILD WINTER
• OCT & NOV 2013 WERE NOT COLD AT ALL
• MANY INDICATORS WERE UNFAVORABLE FOR
COLD/ SNOWY PATTERN IN CENTRAL/ EAST US
BRIEF REVIEW
OF LAST WINTER part 2
• SO WHAT HAPPENED?
• In NOV 2013 A LARGE POOL OF VERY WARM
SSTA (Sea surface temperature Anomalies )
DEVELOPED IN NE PACIFIC / GULF OF ALASKA
• THAT POOL OF WARM SSTAs SIGNIFICANTLY
ALTERED THE OVERALL PATTERN.
• As as long as the Pool of warm SSTAs existed
then the pattern would NOT change …
This shows the
“ surprise” pool of
warm SSTAs that
developed in mid
NOVEMBER 2013.
Most forecasts were
already issued by Mid
NOV so they missed
this
POLAR VORTEX DEVELOPS IN OCT/NOV and
LASTS UNTIL JUNE. IT’S SIZE … INTENSITY
….POSITION IS ** CRITICAL ** IN DETERMING
THE WINTER PATTERNS OVER ALL OF THE
NORTH HEMISPHERE
-AO
+AO
As you can see the large pool of very
warm SSTAs did NOT weaken or move.
In fact it increased during the winter
ACTUAL JAN 2014
500 MB PATTERN
RIDGE
RIDGE
PV
PV
This is what the
actual 500 mb
pattern looked like
in FEB 2014
RIDGE
RIDGE
PV
PV
This shows mean temps of the USA from
12/1/13 to 3/1/14 and impact of the 6
Arctic air mass out breaks
1
1
2
3
4 5
6
This shows AO phases and Intensity from
12/12/13 to 4/1/14. EVERY TIME the AP
dropped into “ negative” territory there was an
Arctic air mass out break
2
34
5
6
WXRISK WINTER 2014-15
FORECAST SUMMARY
• NOV looks to be a MILD month and 1st half of
DEC east of the Mississippi river generally mild
• NOT AS COLD AS LAST YEAR… (this is obvious)
• NOT as many snow events (many places on
East coast had 15-20 ”middle size “ events)
BUT bigger winter storms
• Increased Risk of ICE STORMS over Ohio valley
Middle Atlantic New England
WXRISK FORECAST MAPS
DEC 2014
WXRISK FORECAST MAPS
JAN 2015
WXRISK FORECAST MAPS
FEB 2015
THE DETAILS
UNDERSTANDING THE FORECAST
30 DAY & SEASONAL FORECASTING IS HALF
SCIENCE / HALF ART. You have to do it all the
time to be good at it. PROBLEMS:
• Media plays up USELESS Farmers Almanac.
Then e when they bust folks think its a ‘real’
forecast
• Issuing Winter forecast in July. 100% CHAOS
theory/ rules says its BS.
• TV Mets who are pressured by news manager
but have no clue what they are doing
SEASONAL FORECASTING
is based on:
• The CURRENT atmosphere
• Current and future Seas Surface temp
anomalies/ pattern
• Figuring out which factors are going to the
DRIVERS or dominating force
• SOIL MOISTURE
• “WHAT COULD GO WRONG ?”
EL NINO FOR THE WINTER ?
There is some “ skepticism” about a El
NINO is REALLY coming this time. Back in
March & April it LOOKED like a Moderate
El Nino was developing but by JULY the El
Nino collapsed
Actual DATA – NOT Models/ forecast clearly shows el Nino round 2 IS coming
and it will be a WEAK El Nino
this easy to read
SUMMARY of El
NINO Forecasts
clearly show a “
WEAK” event for this
Winter
All WEAK El Nino temperature anomalies
DJF ( DEC- JAN – FEB) since 1900
based on 1951-2010
climate record
Based on 1981-2010
climate record
NOT ALL EL NINO EVENTS ARE
THE SAME as shown by Recent
discovery by Japan’s wx folks
Modoki El Nino
events have a
HIGH Probability
of bringing Colder
& Snowier then
Normal Winters
for central /
eastern US
The severely
snowy winter of
2009-10 was a
MODOKI El Ninonotice how the
warm El Nino
waters shifted
WEST from late
OCT to DEC
CURRENT SSTAs in the
PACIFIC BASIN
BLOCKING JET STREAM
PATTERNS IN WINTER
TYPICALLY WEATHER PATTERNS MOVE FROM
WEST TO EAST .. Some times slow sometimes fast
• Occasionally a ‘ CONVOLUTED’ Jet stream
pattern will form ..in the wx biz these unusual
Jet stream patterns are called BLOCKING
PATTERN
• There are many different types of BLOCKING
PATTERNS
• They bring about PROLONGED or REPEATING
patterns periods of same kind of weather… can
last for several weeks
LARGE AREAS OF COLDER THAN NORMAL and
WARMER THAN NORMAL OCEAN WATER TEMPS
HAVE A CAUSE and /or REINFORCE BLOCKING
PATTERNS
PDO
Pacific Decadal Oscillation
-PDO
+PDO
-PDO … both SEASONAL AND LONG
TERM Tend to Favor the Negative PNA
pattern (-PNA)
+PDO … both SEASONAL AND LONG
TERM Tend to Favor the Positive PNA
pattern (+PNA)
CURRENT SSTAs in the
PACIFIC BASIN
+PDO
THERE HAS BEEN SOME
RECENT COOLING IN NE
PACIFIC
AUG 2014 PDO = +0.67
SEPT 2014 PDO= +1.08
All DEC +PDO = THESE SORT
OF TEMPS ANOMALIES
All FEB +PDO = THESE
SORT OF TEMPS
ANOMALIES
All JAN +PDO = THESE SORT
OF TEMPS ANOMALIES
THE ARCTIC OSCILLATION
-AO/ +AO
Yes it can get “ cold” in the Winter months over
central & eastern CONUS with a Neutral/
Positive AO… but not a sustained cold pattern.
It is IMPOSSIBLE to get a Significant and/ or
Major East coast Snowstorm without –AO and/
or -AO that moves to Neutral/ Positive AO
The AO during the WINTER OF 2009-10 ..
With its non stop big snowstorms-- Historic /
severe all winter long
The AO during the Super warm snowless
WINTER of 2011-12.. Historic / positive all
winter long
SIBERIAN SNOW COVER IN
OCTOBER ….and NORTH
AMERICAN / US WINTERS
2 WAYS TO MEASURE SNOW IN
SIBERIA IN OCTOBER
SAI - Snow Advanced Index
SCE – snow cover extent
SAI … closely matches AO
Taking the SAI into forecast Models
DRAMATICALLY improves forecast accuracy
SO WHAT ABOUT OCT 2014?
Snow cover expansion in weeks
39…40…31…42… 43 are the KEY
As of 10/17 the SCE is at a
RECORD setting pace
This shows the snow cover rate of
expansion / Advance (SAI)
On left side this shows actual snow cover extent
(SCE) while Right Side shows the expansion
relative to “ normal” (SAI)
NAO
aka “THE GREENLAND BLOCK” IS A CRITICALLY
IMPORTANT JET STREAM PATTERN THAT
AFFECTS WEATHER PATTERNS OVER
Central and Eastern US…. eastern CANADA …Much
of EUROPE
-NAO
+NAO
MODERATE or STRONG –NAO increases
chances of Big east coast Winter storms
and this Probability goes way up if pattern
features -NAO and –AO
SUPER MEGA SNOWSTORM
WINTER OF 2009-10 FEATURE
**RECORD** -NAO VALUES
and LASTED ALL WINTER
LONG
THE RECORD WARM/
SNOWLESS WINTER OF 201112… FEATURED NEAR
RECORD ** HIGH +NAO **
THAT ALOS LASTED ALL
WINTER LONG
This ‘ schematic’ of what Sea surface
temperature Anomalies look like in
OCTOBER when the NAO was mostly
Negative in Winter
ACTUAL SSTAs IN MID OCTOBER
RE ALMOST A TEXT BOOK MATCH
SUMMARY FOR
WINTER 2014-15
• M.E.I.
• WESTERN EL NINO ?
(modoki)
• +PDO / PNA
• -NAO/ ssta in North Atlantic
• SIBERIAN SNOW COVER
/AO PHASE ??
WHAT COULD GO WRONG?
• M.E.I./ WEAK EL NINO fails to show
RESULT- weaker southern Jet stream
colder overall pattern
• NO MODOKI ( western) EL NINO …
RESULT even split of Midwest/ east coast storms
• +PDO / +PNA BREAKS DOWN…
RESULT ..wild swing in overall pattern & more precip
for western third of Conus
• -NAO goes Positive for most of Winter
Ice storm threat Increase
• -AO turns Positive for most of the winter .
Given the HUGE near record Siberian Snow cover in
OCT…I don’t see how this is possible
FINAL
UPDATE
NOV 18-19