WPAC: NORU - Low

[1900hurricane]

For the near term at least, it does appear that Noru is beginning to organize again. Dry air is still hanging around, but it does appear to modifying.

[1900hurricane]

Here are JMA's obs for Chichijima, since it appears that Noru may pass very close to the island.

[Kingarabian]

For the near term at least, it does appear that Noru is beginning to organize again. Dry air is still hanging around, but it does appear to modifying.

[mg]https://www.nrlmry.navy.mil/tcdat/tc17/WPAC/07W.NORU/amsr2/color36/20170728.1528.gcomw1.x.color36.07WNORU.65kts-976mb-276N-1431E.58pc.jpg[/img]

[mg]https://www.nrlmry.navy.mil/tcdat/tc17/WPAC/07W.NORU/tc_ssmis/91h/1degreeticks/20170728.1819.f16.x.91h_1deg.07WNORU.65kts-976mb-276N-1431E.76pc.jpg[/img]

Thus far, one step forward two steps back with these Pacific systems.

[mrbagyo]

[euro6208]

WDPN31 PGTW 282100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (NORU) WARNING NR 33//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 07W (NORU), LOCATED APPROXIMATELY 194 NM NORTH-NORTHEAST OF
IWO TO, HAS TRACKED SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS THE
SYSTEM IS STRUGGLING TO MAINTAIN ITSELF, WITH WEAK AND FLARING
CONVECTION. THE EYE THAT HAS BEEN VISIBLE HAS DISSIPATED FOR THE
TIME BEING, THOUGH THERE ARE SIGNS THAT IT IS STARTING TO FORM
AGAIN. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
MULTI-AGENCY SATELLITE FIXES AND A MICROWAVE EYE FEATURE OBSERVED IN
A 281546Z 37GHZ GPM IMAGE. THE INITIAL INTENSITY REMAINS AT 65 KNOTS
AND IS BASED ON SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES OF
T4.0 (65 TO 77 KNOTS) FROM ALL REPORTING AGENCIES. ENVIRONMENTAL
ANALYSIS INDICATES THE SYSTEM RESIDES IN A MARGINALLY FAVORABLE
AREA. A SMALL POINT SOURCE HAS BEEN ANALYZED NEAR THE CENTER,
PROVIDING ENOUGH OUTFLOW TO MAINTAIN THE SYSTEM AT ITS CURRENT
INTENSITY. VERTICAL WIND SHEAR (VWS) IS LOW (10-15 KNOTS) AND THE
SYSTEM IS MOVING SOUTH OVER PROGRESSIVELY WARMER WATERS, WITH SEA
SURFACE TEMPERATURES NOW NEAR 28 TO 29 CELSIUS. TY NORU IS CURRENTLY
TRACKING SOUTHWESTWARD ALONG THE EASTERN BOUNDARY OF A SUBTROPICAL
RIDGE ANCHORED OVER THE EAST CHINA SEA AND SOUTHERN JAPAN.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. THE STEERING RIDGE WILL CONTINUE TO STEER TY 07W SOUTHWESTWARD
OVER THE NEXT 48 HOURS. THEREAFTER, TY NORU SLOWS SIGNIFICANTLY AND
BECOMES QUASI-STATIONARY AS THE STEERING ENVIRONMENT WEAKENS. BY TAU
48, UPPER LEVEL RIDGES DEVELOP AND STRENGTHEN TO THE WEST, NORTH,
AND SOUTH, COMPLETELY COCOONING THE SYSTEM IN A RIDGE PATTERN,
RESULTING IN THE QUASI-STATIONARY MOVEMENT. BY TAU 72, TY NORU IS
EXPECTED TO DRIFT SLOWLY WEST, AS THE ENTIRE RIDGE POCKET MOVES
SLOWLY TO THE WEST, DRAGGING TY NORU WITHIN IT. THE INTENSITY
FORECAST IS GENERALLY FLAT, THOUGH DEVIATIONS BOTH HIGHER AND LOWER
CAN BE EXPECTED AS THE SYSTEM UNDERGOES CYCLICAL INTENSIFICATION AND
WEAKENING. THE UPPER LEVEL OUTFLOW PATTERN IS FORECAST TO REMAIN
ESSENTIALLY UNCHANGED, WITH BRIEF SPURTS OF INTENSIFICATION AS THE
POINT SOURCE EXPANDS, AND THE SYSTEM TRAVERSES OVER WARMER WATERS.
THE SYSTEM IS FORECAST TO PEAK AT 75 KNOTS BY TAU 48 AND THEREAFTER
WEAKEN SLIGHTLY AS UPWELLING REDUCES THE AVAILABLE ENERGY. DYNAMIC
MODEL GUIDANCE IS IN GENERAL AGREEMENT THROUGH TAU 24, BUT SO
CONSIDERABLE UNCERTAINTY BEYOND THAT, THOUGH ALL MODELS AGREE ON THE
SHIFT TO A WESTWARD TRACK BY TAU 72, THE UNCERTAINTY BEING IN THE
DEGREE AND SPEED OF THE TURN. DUE TO THE HIGH MODEL UNCERTAINTY,
THERE IS LOW CONFIDENCE IN THIS PORTION OF THE FORECAST TRACK.
C. BEYOND TAU 72, THERE IS LARGE DEGREE OF AMBIGUITY IN THE STEERING
ENVIRONMENT, WITH THE AFOREMENTIONED RIDGE PATTERN REMAINING IN
PLACE THROUGH THE END OF THE FORECAST PERIOD. MODEL GUIDANCE SHOWS
SIGNIFICANT SPREAD BEYOND TAU 72, WITH ECMWF, HWRF, EGRR AND JGSM
INDICATING THE SYSTEM TRACKING WEST, THEN NORTHEAST AFTER TAU 96 IN
RESPONSE TO A DEVELOPING WEAKNESS IN THE NORTHERN RIDGE. GFS,
NAVGEM, COAMPS-TC ON THE OTHER HAND SHOW A TURN TO THE SOUTH AND
EAST THEN NORTH BY TAU 120. THE JTWC TRACK LIES NEAR THE MULTI-MODEL
CONSENSUS. BEYOND TAU 72, INTENSITY IS FORECAST TO REMAIN FLAT, WITH
A SLIGHT UPTICK BY TAU 120, AS THE SYSTEM BEGINS TO TAP INTO A
ROBUST EQUATORWARD OUTFLOW CHANNEL. DUE TO THE HIGHLY UNCERTAIN
TRACK GUIDANCE, THERE IS LOW CONFIDENCE IN THE FORECAST TRACK.//
NNNN

[euro6208]

[euro6208]

Stronger on the latest EURO...919 mb and GFS still crazy calling for 889 mb but misses Japan...If the models are right, Noru will be around for more than 7 more days.

[euro6208]

NAVGEM down to 949 mb peak.

[1900hurricane]

Here's the 00Z RJAO sounding. It's basically completely saturated, which is to be expected near the center of a tropical cyclone.

[euro6208]

WDPN31 PGTW 290900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 07W (NORU) WARNING NR 35//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 07W (NORU), LOCATED APPROXIMATELY 60 NM SOUTH OF CHICHI
JIMA, HAS TRACKED SOUTH-SOUTHWESTWARD AT 09 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTI-SPECTRAL SATELLITE IMAGERY SHOWS DEEP
CONVECTION WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC).
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON BOTH
MULTI-AGENCY SATELLITE FIXES AND A 290406Z 37GHZ GMI IMAGE DEPICTING
A WELL DEFINED MICROWAVE EYE FEATURE. THE INITIAL INTENSITY REMAINS
AT 65 KNOTS AND IS HEDGED ON THE HIGHER END OF DVORAK CURRENT
INTENSITY ESTIMATES RANGEING FROM T3.5 (55 TO 65 KNOTS) TO T4.0 (65
TO 77 KNOTS). ENVIRONMENTAL ANALYSIS INDICATES THAT THE SYSTEM IS
LOCATED IN AN AREA OF LOW VERTICAL WIND SHEAR (10-15 KNOTS) AND IS
TRACKING THORUGH AND AREA OF HIGH SEA SURFACE TEMPERATURES (29 C).
TYPHOON NORU CURRENTLY LACKS WELL DEFINED OUTFLOW CHANNELS HOWEVER;
ENOUGH RADIAL OUTFLOW IS OCCURING TO MAINTAIN THE SYSTEM. TYPHOON
NORU CONTINUES TO TRACK SOUTHWESTWARD ALONG THE EASTERN PERIPHERY OF
A SUBTROPICAL STEERING RIDGE (STR) LOCATED TO THE WEST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. THE SUBTROPICAL RIDGE TO THE WEST WILL REMAIN THE PRIMARY
STEERING FEATURE THROUGH TAU 24 CAUSING THE SYSTEM TO CONTINUES ITS
CURRENT SOUTHWEST TRACK. BEYOND TAU 24 THE SYSTEM WILL BEGIN TO SLOW
DUE TO A WEAKENING IN THE STEERING RIDGE. AFTER TAU 36 A SUBTROPCIAL
RIDGE LOCATED OVER SOUTHERN JAPAN BUILDS IN TO THE NORTHWEST OF
TYPHOON NORU AND THE NEAR EQUITORIAL RIDGE BUILDS IN THE SOUTHEAST
OF THE SYSTEM. THE PRESCENCE OF THESE RIDGES PLACES TYPHOON 07W IN
THE CENTER OF THREE RIDGE STEERING FEATURES FURTHER REDUCING THE
SYSTEMS SPEED. FROM TAU 36 TO 72 THE SYSTEM WILL BECOME QUASI
STATIONARY TRACKING SLOWLY TO THE WEST. THE INTENSITY FORECAST
REMAINS SIMILAR TO PREVIOUS FORECASTS WITH ONLY SMALL VARIATIONS AS
THE RESULT OF CYCLICAL INTENSIFICATION AND WEAKENING. THE UPPER
LEVEL OUTFLOW PATTERN IS FORECAST TO REMAIN MARGINALLY FAVORABLE
WITH CONSISTENT RADIAL OUTFLOW THROUGH TAU 48, WITH SOME MINIMAL
INTENSIFCATION AROUND TAU 36, AS THE SYSTEM TRACKS OVER WARMER
WATERS. THE SYSTEM IS FORECAST TO PEAK AT 75 KNOTS BY TAU 36 AND
THEREAFTER WEAKEN SLIGHTLY AS THE SYSTEM TRACKS INTO AN AREA OF
LOWER OCEAN HEAT POTENTIAL. DYNAMIC MODEL GUIDANCE IS IN GENERAL
AGREEMENT THROUGH TAU 48, BUT BEGIN TO DIVERGE ONCE THE SYSTEM
BEGINS TO TURN WESTWARD. WITH THE IMPROVING MODEL AGREEMENT IN
THE STORMS TURN TOWARD THE WEST, THERE IS HIGH CONFIDENCE IN THIS
PORTION OF THE JTWC FORECAST TRACK.
C. IN THE LATER TAUS 07W IS FORECAST TO TURN NORTHWESTWARD
THROUGH THE END OF THE FORECAST. IN GENERAL ALL OF THE MODELS HAVE
THE SYSTEM BEGINNING TO ROUND THE NORTHWEST PERIOPHERY OF THE NEAR
EQUITORIAL RIDGE LOCATED TO THE SOUTHEST AS IT BEGINS TO RECURVE.
MODEL GUIDANCE IS POOR AGREEMENT AS TO HOW QUICKLY THE SYSTEM WILL
TURN TO THE NORTHWEST AND HOW QUICKLY IT WILL ACHIEVE A NORTHELY
TRACK. THE GREATEST OUTLYER OF THE MODEL GUIDANCE IS NAVGEM WHICH
HAS THE SYSTEM TRACKING THE FARTHEST WEST BEFORE IT RECURVES.
INTENSITY IS FORECAST TO SLIGHTLY WEAKEN AFTER TAU 96 AS TYPHOON
NORU TRACKS THROUGH COOLER SEA SURFACE TEMPERATURES AND VERTICAL
WIND SHEAR INCREASES. DUE TO THE UNCERTAIN TRACK GUIDANCE, THERE IS
LOW CONFIDENCE IN THIS PORION OF THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

[euro6208]

[mrbagyo]

Convection has started to cool again. This might be the second bout of intensification the guidance has been showing.

[galaxy401]

It's not often we see a long lived storm in the WPAC. Noru is just hanging around.

[1900hurricane]

Looks like Noru is almost free of the dry air.

[euro6208]

WDPN31 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (NORU) WARNING NR
37//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 07W (NORU), LOCATED APPROXIMATELY 28 NM
SOUTHEAST OF IWO TO, HAS TRACKED SOUTH-SOUTHWESTWARD AT 08 KNOTS
OVER THE PAST SIX HOURS. THE SYSTEM IS CURRENTLY TRACKING EAST OF
IWO TO, WHICH IS REPORTING 10-MIN MEAN NORTHERLY SUSTAINED WINDS AT
35 TO 37 KNOTS WITH GUSTS AS HIGH AS 55 KNOTS AND MINIMUM SLP NEAR
985MB. THESE OBSERVATIONS, ALONG WITH DVORAK CURRENT INTENSITY
ESTIMATES OF 3.5 (55 KNOTS) FROM ALL AGENCIES, SUPPORT THE INITIAL
INTENSITY ASSESSMENT OF 60 KNOTS AND DOWNGRADE FROM TYPHOON
STRENGTH. ADDITIONALLY, A 291747Z SSMI 85GHZ IMAGE SHOWS A WELL-
ORGANIZED SYSTEM WITH TIGHTLY-CURVED DEEP CONVECTIVE BANDING
WRAPPING INTO A WELL-DEFINED CENTER. OVERALL, THERE IS GOOD
CONFIDENCE IN THE INITIAL POSITION BASED ON RECENT SATELLITE IMAGERY
AND SURFACE OBSERVATIONS. TS 07W IS TRACKING EQUATORWARD ALONG THE
EASTERN PERIPHERY OF AN EXTENSION OF THE SUBTROPICAL RIDGE (STR)
POSITIONED TO THE WEST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. THIS FORECAST REMAINS HIGHLY
CONSISTENT WITH THE PREVIOUS JTWC FORECAST.
B. IN AN EFFORT TO SIMPLIFY THE FORECAST REASONING, TS 07W WILL
REMAIN WITHIN A COMPETING STEERING ENVIRONMENT THROUGH TAU 72, WITH
A SLOW, SOMEWHAT ERRATIC, SLOW SOUTHWARD TO WESTWARD FORECAST TRACK.
THE EXACT TRACK IS DIFFICULT TO ASCERTAIN WITH AVAILABLE DYNAMIC
MODEL TRACKERS INDICATING A WIDE SPREAD IN SOLUTIONS. IN GENERAL THE
SYSTEM WILL BE STUCK BETWEEN A STR TO THE NORTHWEST, ENTRENCHED OVER
WESTERN JAPAN, AND A BROAD STR TO THE SOUTHEAST. ADDITIONALLY, THERE
ARE NO DYNAMIC SHORTWAVE MIDLATITUDE TROUGHS PRESENT TO SUFFICIENTLY
ERODE THE STR UNTIL AFTER TAU 72. TS 07W SHOULD CONTINUE TO GO
THROUGH SIGNIFICANT CHANGES IN INTENSITY AS IT TRACKS OVER WARM SST
WHILE MAINTAINING FAVORABLE OUTFLOW. THEREFORE, THE INTENSITY
FORECAST REMAINS UNCHANGED WITH GRADUAL RE-INTENSIFICATION STILL
EXPECTED.
C. AFTER TAU 72, A MIDLATITUDE SHORTWAVE TROUGH IS FORECAST TO
DEEPEN OVER EASTERN JAPAN, WHICH WILL ERODE THE WESTERN STR OVER
JAPAN AND AMPLIFY THE STR TO THE EAST OF TS 07W. THIS WILL RESULT IN
A POLEWARD TURN IN THE FORECAST TRACK AS THE EASTERN STR BECOMES THE
DOMINANT STEERING RIDGE. HOWEVER, HIGH UNCERTAINTY REMAINS DUE TO
THE WIDE SPREAD IN DYNAMIC MODEL GUIDANCE DUE TO WIDELY DIFFERING
DEPICTIONS OF THE STRENGTH AND ORIENTATION OF THE STR AND
MIDLATITUDE TROUGH. DUE TO THE COMPLEXITY OF THE STEERING PATTERN
AND LARGE MODEL SPREAD, THERE IS LOW CONFIDENCE IN THE EXTENDED
RANGE (AND BEYOND) FORECAST TRACK.//
NNNN

[1900hurricane]

I think chances are good that Noru is back to being a typhoon once more.

[talkon]

It's not often we see a long lived storm in the WPAC. Noru is just hanging around.

The 12Z GFS even shows Noru hanging around for the full 16 days after having another Fujiwhara (which I find quite funny and implausible.) The 18Z doesn't, though.

[1900hurricane]

Intense convection is firing back up on the south side of Noru, and the eye is trying to clear out. Noru is both moving over warmer and more heat-laden waters and away from dry air. Considering a well conserved structure and light upper level winds, it wouldn't surprise me to see Noru go back up fairly quickly. It's moving slow, so upwelling could eventually become a problem, but for now at least, this is definitely a system back on the upswing.

[1900hurricane]

872 mb peak.

Verification time has come (just about), and this didn't exactly pan out...