WPAC: NORU - Low

[wxmann_91]

 https://twitter.com/wxmann/status/891896357757214720

[1900hurricane]

Not quite sure what to make of Noru at the moment. Cloud tops have warmed dramatically, more than would be expected with diurnal cycles alone. Recent microwave imagery doesn't appear to indicate that there are any system flaws. Recent IR images actually look a little bit like subtle eyewall replacement is taking place, boring the eye out to an even larger diameter. Confusing mixed signals for sure.

[1900hurricane]

JMA's track forecast is interesting. It is very much in line with the most recent 00Z ECMWF run.

[1900hurricane]

The 00Z runs of the UKMET and CMC are even more dramatic with the left turn after day 3. Very interesting.

[Digital-TC-Chaser]

Appears to be starting the recurving now to the NW.

If the GFS is correct Norru has alot of expanding still to come.

[euro6208]

WDPN31 PGTW 310900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 07W (NORU) WARNING NR
43//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUPER TYPHOON 07W (NORU), LOCATED APPROXIMATELY 141 NM SOUTHWEST
OF IWO TO, HAS TRACKED WESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A SYMMETRIC ANNULAR
SYSTEM WITH A RING OF DEEP CONVECTION SURROUNDING A WELL-DEFINED 15-
NM EYE. THE INITIAL INTENSITY IS ASSESSED AT 130 KNOTS BASED ON
MULTI-AGENCY CURRENT INTENSITY DVORAK ESTIMATES RANGING FROM T6.5 TO
T7.0 (127 TO 140 KNOTS). ENVIRONMENTAL CONDITIONS ARE CURRENTLY VERY
FAVORABLE WITH A POINT SOURCE OVER THE SYSTEM AND A STRONG EASTWARD
OUTFLOW CHANNEL INTO THE SUBTROPICAL WESTERLY JET AND TUTT CELL TO
THE EAST. SSTS ARE ALSO VERY FAVORABLE AROUND 29 TO 30C. STY 07W IS
DRIFTING WESTWARD WITHIN A COMPETING STEERING ENVIRONMENT FROM
RIDGES TO THE NORTH, WEST AND SOUTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST TRACK PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE, HOWEVER, THE FORECAST TRACK IS SHIFTED
MORE WESTWARD.
B. STY 07W IS FORECAST TO TRACK NORTHWESTWARD OVER THE NEXT 36
HOURS AS THE SOUTHEASTERN RIDGE STRENGTHENS AND THE NORTHERN RIDGE
RETREATS TO THE NORTHWEST. THE EASTWARD OUTFLOW CHANNEL WILL PERSIST
AND SSTS WILL REMAIN BETWEEN 29 AND 30 CELSIUS. TY IS FORECAST TO
WEAKEN SLIGHTLY OVER THE NEXT 36 HOURS AS IT EXHAUSTS MOST OF THE
ENERGY AVAILABLE FROM THE WARM WATER. BEYOND TAU 36 A MID-LATITUDE
TROUGH WILL ERODE THE NORTHERN RIDGE AND INTRODUCE A DEGREE VERTICAL
WIND SHEAR CAUSING THE SYSTEM TO ACCELERATE NORTHWARD AND WEAKEN TO
100 KNOTS. MODEL GUIDANCE IS SHOWING FAIRLY GOOD AGREEMENT THROUGH
TAU 36 WITH THE EXCEPTION OF COAMPS BEING THE EASTERN OUTLIER.
BEYOND TAU 36 MODELS BEGIN TO DIVERGE AS THE TROUGH INTERACTS WITH
THE NORTHERN RIDGE.
C. AROUND TAU 72, THE TROUGH WILL HAVE PASSED AND THE NORTHERN
RIDGE IS EXPECTED TO BUILD BACK HALTING THE NORTHWARD ADVANCE OF STY
07W AND THE TRACK WILL SHIFT SLIGHTLY WESTWARD DURING THIS TIME. THE
EXACT POSITION AND TIMING OF THE TURN DEPENDS LARGELY ON THE SPEED
AND STRENGTH OF THE PASSING TROUGH WHICH WILL DETERMINE THE STRENGTH
AND ORIENTATION OF THE NORTHERN STEERING RIDGE. STY 07W WILL BECOME
QUASI-STATIONARY AGAIN AROUND TAU 96 TO 120 AS THE SOUTHEASTERN
RIDGE COMPETES WITH THE NORTHERN RIDGE. DYNAMIC MODEL GUIDANCE IS
IMPROVING BUT STILL SHOWS A SIGNIFICANT SPREAD IN POSSIBLE TRACK
SCENARIOS. OVERALL, THE MODELS ARE IN AGREEMENT WITH THE FORECAST
SCENARIO BUT THE SEPARATION BETWEEN TRACK POSITIONS AT TAU 120 IS
ABOUT 575 NM. THE EXCEPTIONS ARE UKMET AND THE JAPANESE ENSEMBLE
WHICH SHOW A MORE WESTWARD TRACK IN THE LATER TAUS DUE TO THE
NORTHERN RIDGE ORIENTING ITSELF ON AN EAST-WEST AXIS. THE EXTENDED
MODEL GUIDANCE IS IN GENERAL AGREEMENT WITH THE EXCEPTIONS NOTED
ABOVE THAT STY 07W WILL NOT KEEP TRACKING WESTWARD, BUT RATHER TURN
TO THE NORTH OR NORTHEAST BEYOND TAU 120 AS ANOTHER TROUGH ENTERS
THE REGION, AGAIN ERODING THE NORTHERN RIDGE, AND ALLOWING THE
SOUTHEASTERN RIDGE TO ASSUME STEERING. DUE TO THE LARGE DEGREE OF
COMPLEXITY IN THE STEERING ENVIRONMENT THERE IS LOW CONFIDENCE IN
THE FORECAST TRACK.//
NNNN

[euro6208]

Here are the latest from the global models. The whole of Japan might be hit with CMC showing a rather bizarre track and first takes it to Okinawa. EURO and GFS has a monster.

JMA



NAVGEM



CMC




EURO



GFS

[euro6208]

I have a feeling this might be underestimated due to it's small size and with dvorak having a hard time with these type of systems (Add in a well defined eye that has persisted so long). If Emily managed to develop into a TD with no dvorak and a TS with 1.0, How much stronger can this be?

[tolakram]

SLIDER visible archive from yesterday.

http://rammb-slider.cira.colostate.edu/?sat=himawari&sec=full_disk&x=10643&y=6287&z=4&im=6&ts=1&st=20170731000000&et=20170731065000&speed=130&motion=loop&map=1&lat=0&p%5B0%5D=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider

[doomhaMwx]

NOAA-19 RGB Imagery
07-31-17 6:28am UTC

[euro6208]

Just found out Noru is the strongest TC so far this year in all basins. Incredible.

[NotoSans]

I personally think that Ernie is stronger than Noru but JTWC went with 130kt for that one (ironically due to constraints).

[dexterlabio]

This reminds me a bit of STY Atsani in 2015 with the huge, clear eye. Also once a Cat5, though just like Noru, one could debate one of the high-end Cat4's we've had were more impressive.

[galaxy401]

Very impressive looking Typhoon. Looks like it's almost annular too. Potential serious situation for Japan to monitor.

[shah83]

12z GFS has 892mb landfall roughly at Nagoya.

Good thing the HWRF hasn't nearly been so enthusiastic with landfall predictions, huh?

[Kingarabian]

Serious situation for Japan. Thanks to the warming off of the east coast of Japan, waters can support a deep TC this far north.

[Alyono]

tim to rain on the parade of a massive typhoon hitting Japan

Every year the models show this. Every time, we these come in as unraveling, large cat 1s. Occassionally, we get a cat 2

I wouldn't be surprised if we see a 950mb ish typhoon. However, that may only support 75-80 kt winds at landfall

[euro6208]

WDPN31 PGTW 312100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (NORU) WARNING NR
45//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 07W (NORU), LOCATED APPROXIMATELY 164 NM WEST-SOUTHWEST
OF IWO TO, HAS TRACKED NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A
WEAKENING SYSTEM STILL LACKING IN SIGNIFICANT BANDING, BUT WITH A
WELL-DEFINED 15 NM WIDE EYE. THE CONVECTIVE STRUCTURE HAS WEAKENED
SOMEWHAT OVER THE PAST SIX HOURS, WITH DEEP CONVECTION NOW CONFINED
TO THE SOUTHEASTERN HALF OF THE EYEWALL AND A BREAK IN THE EYEWALL
BEGINNING TO DEVELOP ON THE NORTHWEST SIDE. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE LARGE EYE FEATURE.
UNFORTUNATELY, THERE HAS BEEN NO MICROWAVE PASS SINCE A 311346Z PASS
WHICH SHOWED A SOLID RING OF CONVECTION IN THE 91GHZ BAND, WITH SOME
WEAKENING OF THE EYEWALL EVIDENT EVEN AT THAT TIME. THE INITIAL
INTENSITY HAS BEEN LOWERED TO 110 KNOTS, BASED ON MULTI-AGENCY
SUBJECTIVE INTENSITY ESTIMATES OF T5.0 TO T6.0 (90 TO 115 KNOTS).
ENVIRONMENTAL ANALYSIS INDICATES THE SYSTEM REMAINS IN A FAVORABLE
ENVIRONMENT. A WEAK EASTWARD OUTFLOW CHANNEL INTO A TUTT CELL TO THE
EAST ALONG WITH AN UPPER-LEVEL POINT SOURCE ARE PROVIDING THE SYSTEM
WITH DECENT OUTFLOW. VERTICAL WIND SHEAR (VWS) IS LOW (5-10 KNOTS)
AND SEA SURFACE TEMPERATURES (SSTS) OF 30 DEG CELSIUS ARE ALSO
FAVORABLE. TY 07W IS HOWEVER TRAVERSING AN AREA OF LOWER OCEAN HEAT
CONTENT (OHC) WHICH IS HELPING TO WEAKEN IT. 07W IS TRACKING SLOWLY
NORTHWESTWARD WITHIN A COMPETING STEERING ENVIRONMENT WITH RIDGES TO
THE NORTH, WEST AND SOUTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST TRACK PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. STY 07W IS FORECAST TO TRACK NORTHWESTWARD OVER THE NEXT 72
HOURS AS THE SOUTHEASTERN RIDGE STRENGTHENS AND MOVES WESTWARD,
WHILE THE NORTHERN RIDGE RETREATS TO THE NORTHWEST. AN UPPER-LEVEL
TROUGH WILL MOVE BY TO THE NORTH AROUND TAU 36, BUT IS NOT
FORECASTED TO DIG FAR ENOUGH SOUTH TO WEAKEN THE RIDGE SUFFICIENTLY
TO ALLOW THE SYSTEM TO TURN NORTHWARDS. BY TAU 72, THE SYSTEM BEGINS
TO TURN MORE WESTWARD AS THE NORTHERN RIDGE BUILDS IN BEHIND THE
TROUGH ACROSS THE NORTH OF THE SYSTEM. TY 07W IS FORECAST TO SLOWLY
WEAKEN THROUGH TAU 24 AS THE EASTWARD OUTFLOW CHANNEL WEAKENS
FURTHER AND EVENTUALLY CUTS OFF, RESULTING IN DECREASED OUTFLOW.
WHILE THE SYSTEM WILL CONTINUE TRACKING ALONG THE 30 DEG SST
ISOTHERM, IT WILL TRACK OVER DECREASING OHC VALUES, LEADING TO
FURTHER SLOW WEAKENING. BETWEEN TAUS 24 AND 36, TY 07W IS EXPECTED
TO MAINTAIN INTENSITY AS THE LIMITED OUTFLOW IS OFFSET BY INCREASING
OHC AS THE SYSTEM CROSSES A HIGH OHC POOL. ANOTHER ROUND OF
INTENSIFICATION IS FORECAST BETWEEN TAUS 48 AND 72 AS THE SYSTEM
TAPS INTO A POLEWARD OUTFLOW CHANNEL AHEAD OF A MID-LATITUDE TROUGH
DIGGING IN FROM THE NORTH. MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 36, BUT SHOWS SIGNIFICANT AND INCREASING UNCERTAINTY
THEREAFTER, WITH NAVGEM, UKMET AND JMA SHOWING A TURN NEARLY DUE
WEST AFTER TAU 48, WHILE GFS, HWRF AND COAMPS-TC ARE THE NORTH AND
EAST OUTLIERS. INTENSITY GUIDANCE IS EQUALLY SPREAD, WITH HWRF
BRINGING THE SYSTEM DOWN TO MINIMAL TYPHOON STRENGTH BY TAU 48 AND
COAMPS-TC KEEPING INTENSITY ABOVE 100 KNOTS THROUGH THE SAME TIME.
WITH THE HIGH UNCERTAINTY IN THE TRACK AND INTENSITY GUIDANCE AND
THE UNCERTAINTY WITH REGARDS TO THE INTERACTION WITH THE MID-
LATITUDE TROUGH, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE
FORECAST.
C. BY AROUND TAU 72, THE MID-LATITUDE TROUGH WILL HAVE PASSED
AND THE NORTHERN RIDGE IS FORECAST TO BUILD BACK IN, PUSHING TY 07W
TO A MORE NORTHWESTWARD TRACK THROUGH THE END OF THE FORECAST
PERIOD. THE EXACT POSITION AND TIMING OF THE TURN DEPENDS ON THE
SPEED, STRENGTH AND ORIENTATION OF THE NORTHERN STEERING RIDGE. TY
07W IS EXPECTED TO SLOWLY WEAKEN AFTER TAU 72, DUE TO INCREASING
NORTHERLY PRESSURE AND VWS ALONG THE EASTERN EDGE OF THE UPPER LEVEL
RIDGE TO THE NORTH, AND TRAVERSAL OVER AN AREA OF LOWER OHC. THE
SYSTEM WILL REACH A MINIMUM OF 85 KNOTS BY TAU 96 BUT MAINTAIN THAT
INTENSITY THROUGH TAU 120 AS RADIAL OUTFLOW IS AGAIN REESTABLISHED
BY THIS TIME. DYNAMIC MODEL GUIDANCE IS COMING INTO BETTER AGREEMENT
WITH THE OVERALL TRACK TOWARD THE WEST-NORTHWEST AFTER TAU 72 BUT
STILL SHOW A SIGNIFICANT SPREAD IN POSSIBLE TRACK SCENARIOS, WITH
SEPARATION BETWEEN OUTLIERS AT TAU 120 APPROACHING 500 NM. UKMET AND
JAPANESE MODELS REMAIN THE WESTWARD OUTLIERS, TAKING THE TRACK OVER
THE NORTHERN RYUKUS, WHILE COAMPS-TC IS THE NORTHERN OUTLIER MOVING
THE SYSTEM NEARLY DUE NORTH BY TAU 120. DUE TO THE LARGE DEGREE OF
COMPLEXITY IN THE STEERING ENVIRONMENT AND LARGE UNCERTAINTY IN THE
MODEL GUIDANCE, THERE IS LOW CONFIDENCE IN THE FORECAST TRACK.//
NNNN

[mrbagyo]

Not sure if it's dry air or Noru just wants to become a trucktire donut. Huge developing eye.

[Digital-TC-Chaser]

I will be interesting to see if the Typhoon will begin being steered by the upper-levels latter in the week. If so the typhoon would likely turn W and landfall in China not Japan .