Archive for October 12th, 2008|Daily archive page

Tropical Storm Nana, the 14th Named Storm of the Atlantic Season – Not Likely To Survive

LEFT CLICK IMAGE TO ENLARGE

LEFT CLICK IMAGE TO ENLARGE

THE IMAGE ABOVE AND THE STATEMENT BELOW ARE BOTH TIME SENSITIVE – RELEASED AT 5 PM EDT 10-12-2008  IMAGE AND STATEMENT SOURCE = NATIONAL HURRICANE CENTER.

000

WTNT44 KNHC 122047

TCDAT4

TROPICAL STORM NANA DISCUSSION NUMBER   1

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL142008

500 PM EDT SUN OCT 12 2008

ALTHOUGH THE CONVECTIVE ORGANIZATION OF THE AREA OF LOW PRESSURE

LOCATED OVER THE EASTERN ATLANTIC HAS DEGRADED SOME THIS

AFTERNOON…THE SYSTEM HAS MAINTAINED SUFFICIENT CONVECTION FOR A

LONG ENOUGH PERIOD TO CONSIDER IT A TROPICAL CYCLONE.  DURING THE

AFTERNOON…THE CENTER OF THE CYCLONE HAS BECOME EXPOSED WELL TO

THE WEST OF THE LARGE AREA OF DEEP CONVECTION DUE TO WESTERLY

SHEAR.  AN ASCAT OVERPASS FROM 12Z INDICATED MAXIMUM WINDS OF 30-35

KT.  GIVEN THE TYPICAL LOW BIAS OF THIS INSTRUMENT…THE CYCLONE IS

DECLARED A TROPICAL STORM…THE FOURTEENTH OF THE 2008 SEASON.  THE

LONG-TERM SURVIVAL OF NANA SEEMS BLEAK AS STRONG UPPER-LEVEL

WESTERLIES ARE FORECAST TO CONTINUE.  ALL THE INTENSITY GUIDANCE

SHOWS WEAKENING AND SO DOES THE OFFICIAL FORECAST.  THE OFFICIAL

FORECAST SHOWS NANA DEGENERATING INTO A REMNANT LOW IN ABOUT 48

HOURS…BUT IT WOULD NOT BE SURPRISING IF IT OCCURRED SOONER.

NANA HAS BEEN MOVING SLOWLY WEST-NORTHWESTWARD OR 290/6 KT.  THE

TRACK GUIDANCE PREDICTS A SLOW WEST-NORTHWESTWARD MOTION AROUND THE

SOUTH SIDE OF A LOW- TO MID-LEVEL RIDGE OVER THE EASTERN ATLANTIC.

THE CYCLONE IS FORECAST TO BE NEAR THE SOUTHWESTERN PERIPHERY OF

THE RIDGE IN A COUPLE OF DAYS AND SHOULD TURN TOWARD THE NORTHWEST

AHEAD OF A DEEP-LAYER TROUGH THAT DEVELOPS OVER THE CENTRAL

ATLANTIC.  THE TRACK FORECAST IS CLOSE TO THE MIDDLE OF THE

GUIDANCE ENVELOPE…BUT IS SLOWER THAN THE MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      12/2100Z 16.4N  37.9W    35 KT

12HR VT     13/0600Z 16.7N  39.0W    30 KT

24HR VT     13/1800Z 17.0N  40.4W    25 KT

36HR VT     14/0600Z 17.4N  41.7W    25 KT

48HR VT     14/1800Z 17.9N  43.0W    25 KT…REMNANT LOW

72HR VT     15/1800Z 19.0N  46.0W    20 KT…REMNANT LOW

96HR VT     16/1800Z…DISSIPATED

$$

FORECASTER BROWN

NORBERT IS MOVING TOWARD THE NORTHEAST, 10-12-08

LEFT CLICK IMAGE TO ENLARGE

LEFT CLICK IMAGE TO ENLARGE

LEFT CLICK IMAGE TO ENLARGE

LEFT CLICK IMAGE TO ENLARGE

IMAGES ARE TIME SENSITIVE!

Norbert has reached the mainland of Mexico after recently ripping though the Baja peninsula.  It’s strength is likely to diminish quickly but it will maintain tropical storm intensity for quite some distance into Mexico and could easily effect weather in west Texas and New Mexico early this week.  Notice that the storm is now elongated (oval, rather than circular).  The elongation is along the axis of wind shear which is depicted in the second image which was completed about two hours earlier than the first image.  So, the two images are not a perfect match-up but they are close.  It looks as though the storm is likely to continue traveling 40 to 45 degrees east of due north along the direction of winds aloft.