Transcript A Comparison of Tropical Cyclones Hanna vs. Ike with
2008 “PRE-Season” In Review: A Comparison of Tropical Cyclones Fay, Hanna, and Ike with Regards to Predecessor Rainfall Event (PRE) Development
Michael L. Jurewicz, Sr.
NOAA/NWS, Binghamton, NY Northeast Regional Operational Workshop November 5-6, 2008
Fay
Fay Overview Fay came ashore as a Tropical Storm over the FL Keys on Aug. 19, then slowly meandered across the FL Peninsula the next several days Synoptic Back-drop: Cutoff low over the southern plains Large, building anticyclone over the eastern U.S., to the north and northeast of Fay
700 mb Analysis, 1200 UTC, 19 Aug.
Ridge Axis
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Fay
925 mb Analysis, 1200 UTC, 19 Aug.
Ridge Axis
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Fay
300 mb Analysis, 1200 UTC, 19 Aug.
SR Null-Case Composites
700 mb heights (dam) and upward vertical motion (shaded, μb s-1) 925 mb heights (dam), θe (K), and 200 mb winds (shaded, m s-1) Center of composite TC
24-Hour QPE Through 1200 UTC, 20 Aug.
Fay’s Direct Rainfall
Radar Mosaic, 2100 UTC, 20 Aug.
Parcel Trajectories Red – About 925 mb Blue – About 700 mb Green – About 500 mb
700 mb Analysis, 1200 UTC, 21 Aug.
Ridge Axes
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Fay
24-Hour QPE Through 1200 UTC, 21 Aug.
Disorganized Convection Fay’s Direct Rainfall
Radar Mosaic, 1800 UTC, 21 Aug.
Parcel Trajectories Red – About 925 mb Blue – About 700 mb Green – About 500 mb
700 mb Analysis, 1200 UTC, 22 Aug.
Ridge Axes
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Fay
24-Hour QPE Through 1200 UTC, 22 Aug.
Still Disorganized Convection Fay’s Rainfall
Radar Loop – 20 Aug. to 24 Aug.
A Classic Null-Case Fay produced tremendous rainfall across parts of the Southeastern U.S. Several day totals of 20”+ in parts of FL Due to the direct impacts of Fay’s rainfall shield and her slow movement PRE development not observed Expansive mid-level ridge was in place; nearly enveloped Fay Precipitation maxima stayed tightly clustered around the circulation center
Hanna
Hanna Overview Hanna came ashore as a Category 1 Hurricane near the NC/SC border around 0600 UTC, 6 Sept.
Synoptic Back-drop: Large western Atlantic ridge and central U.S. troughiness Deep southerly flow regime over the eastern states
700 mb Heights/Winds, 0000 UTC, 6 Sept.
925 mb Heights/Theta-E and 200 mb Winds, 0000 UTC, 6 Sept.
Theta-E Ridge Line
Hanna Falls Within the SR Category; SR TC Tracks and PRE Locations
All SR TC Tracks All SR PPTC Tracks; with PRE centroids (colored dots)
SR PPTC Composites (PRE - 12)
Trough axis Ridge axis θ e -Ridge axis 700 mb heights (dam) and upward vertical motion (shaded, μb s -1 ) 925 mb heights (dam), θ e (K), and 200 mb winds (shaded, m s -1 ) Center of composite TC
Conceptual Model: LOT PRE Ahead Of SR Or AR TC
UL Jet LL θ e -Ridge Axis PREs Mid-level Streamlines Revised and updated from Fig. 13 of Bosart and Carr (1978) See inset TC Rainfall Representative TC Tracks
PRE Outlook Synoptic setting seemed somewhat favorable for potential PRE development poleward of Hanna TC embedded within southerly 700 mb flow, with short wave upstream However, trough was less amplified than the composites Strengthening upper-level jet streak to the north Developing 925 mb theta-e ridge, although a little broader and farther east than the composites Proximity of low-level boundary
850 mb Moisture Transport, 0000 UTC, 6 Sept.
850 mb Moisture Transport, 1200 UTC, 6 Sept.
Precipitable Water and Low-Level Winds, 0000 UTC, 6 Sept.
Precipitable Water and Low-Level Winds, 1200 UTC, 6 Sept.
Radar Loop, 0000 – 1500 UTC, 6 Sept.
QPE, 0600-1200 UTC, 6 Sept. “PRE-like” Rainfall
A Quick PRE A band of heavy rainfall did develop north of Hanna from late Friday, 9/6 into Sat., 9/7 However, it was transient in nature; almost like a progressive warm front feature Limited rainfall in most areas to 1” or less Parts of RI/southeast MA did get heavier amounts (2 3” and locally higher, in just a 3-6 hour period) • Best combination of moisture inflow and jet dynamics
Hanna’s Direct Rainfall Shield A narrow band of heavy rain accompanied Hanna up the Eastern Seaboard Maximum rainfall shifted increasingly just to the left of track with poleward extent Typical of transitioning TC Generally, 3 6” of rain fell within a 6-10 hour period Dry antecedent conditions and the lack of a significant “Along-Track” PRE mitigated any serious flood problems
Radar Loop from 1200 UTC, 6 Sept. to 0600 UTC, 7 Sept.
QPE, 1200 UTC, 6 Sept. to 1200 UTC, 7 Sept.
Where heavier rains fell earlier
Ike
Ike Overview Ike came ashore as a Category 2 Hurricane along the TX coast around 0600 UTC, 13 Sept.
Synoptic Back-drop: Large southeastern U.S. ridge and western states troughiness Deep southerly flow regime over the southern Plains and up the Mississippi Valley
700 mb Heights/Winds, 0600 UTC, 12 Sept.
925 mb Heights/Theta-E and 200 mb Winds, 0600 UTC, 12 Sept.
Theta-E Ridge Line
Ike Falls Within the CG Category; CG TC Tracks and PRE Locations
All CG Tracks All CG PPTC Tracks; with PRE centroids (colored dots)
PRE Outlook Synoptic setting seemed favorable for potential PRE development poleward of Ike TC embedded within southerly 700 mb flow, with trough upstream Strengthening upper-level jet streak to the north/northeast Sharpening 925 mb theta-e ridge axis Nearly stationary low-level boundary
Derived Total Precipitable Water, 0600 UTC, 12 Sept.
Channel of Moisture Inflow
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Ike
Precipitable Water, 0600 UTC, 12 Sept.
850 mb Moisture Transport, 0600 UTC, 12 Sept.
Radar Loop, 0000 – 1800 UTC, 12 Sept.
Parcel Trajectories Red – About 850 mb Blue – About 700 mb Green – About 500 mb
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Ike
Total Rainfall for PRE in Southern KS
Flood Pictures (West Wichita, KS)
700 mb Analysis, 1200 UTC, 13 Sept.
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Ike
300 mb Analysis, 1200 UTC, 13 Sept.
925 mb Analysis, 1200 UTC, 13 Sept.
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Ike
850 mb Moisture Transport, 1200 UTC, 13 Sept.
Precipitable Water, 1200 UTC, 13 Sept.
Radar Loop, 0600-1800 UTC, 13 Sept.
Total Rainfall for PRE in Northern IL
Ike’s Significant PRE Two well defined PRE First from central OK to southern KS late on Thu., 9/11 and early Fri., 9/12 Widespread 6”+ rainfall, with an embedded band of 10 15” (Wichita, KS set all-time 24 hour precipitation record (nearly 11”)) Second from northern MO/southeastern IA to northern IL/IN Several bands of 5 10” rainfall (locally higher amounts)
Ike’s Direct Rainfall Shield TC Ike picked up speed as it gained latitude A band of 3 6” rainfall spread from the southern Plains, to the Mississippi Valley, to the Lower Great Lakes region Fortunately for KS, most of this rainfall occurred east of the Wichita area Parts of MO and IL not so lucky Exacerbated existing flood problems from the PRE
Radar Loop from 1800 UTC, 13 Sept. to 1200 UTC, 14 Sept.
QPE, from 0600-1200 UTC, 14 Sept. Hardest hit areas from Ike’s first PRE
QPE, from 1200-1800 UTC, 14 Sept.
Hardest hit areas from Ike’s second PRE
Flood Pictures (Chicago area)
Summary Fay produced very heavy rainfall; but no PRE Strong ridge to the north/northeast prevented significant moisture advection outward from the TC’s circulation center Hanna produced a transient PRE-like feature to its north Fast PRE movement kept rainfall amounts down Not much overlap between PRE and direct TC rainfall Ike produced two substantial PRE Stationary forcing features (frontal boundary and back building upper-level jet) were better able to anchor/lift deep tropical moisture plume PRE had considerably more impact than direct TC rainfall in KS PRE + TC rainfall created major runoff problems in MO and IL