It's dry air that is hurting development right now...

[hurricanetrack]

TROPICAL ATLC...MID/UPPER LEVEL RIDGE HAS SHIFTED N OF THE AREA OVER THE E ATLC NOW EMERGING FROM AFRICA NEAR JUST S OF THE CANARY ISLANDS NEAR 26N13W EXTENDING SW TROUGH 20N40W TO 12N60W. THE NWD MIGRATION OF THE UPPER RIDGE IS ALLOWING DEEP ELY FLOW AND LOW SHEAR VALUES TO DEVELOP OVER MUCH OF THE TROPICAL ATLC. HOWEVER...VERY DRY AIR APPEARS TO BE LIMITING TROPICAL WAVE CONVECTION.

Well- this seems to be the reason why nothing is developing from our strong wave train at the moment. That SAL phenomenon has got to give. Any word on forecasting the upturns and downswings of the SAL? It would be nice to know when the SAL is not going to be a major factor.

[Derek Ortt]

Nearly impossible to forecast SAL outbreaks. However, for more info, I suggest reading Dunion's article in the March BAMS issue which discusses the SAL

[HURRICANELONNY]

It's not really the Sal that is the direct cause of the waves dissapating but the Subtropical Ridge strength is:W/CNTRL ATLC...
ALTHOUGH THE SUBTROPICAL RIDGE IS LOCATED ALONG ITS
CLIMATOLOGICAL POSITION FROM 32N52W TO 29N70W TO CNTRL FL...
PRESSURES REMAIN ABOUT 2-4 MB HIGHER THAN AVERAGE ESPECIALLY E
OF 60W. THIS STRONG HIGH PRES CONTINUES TO FEED WAVES OF SAHARAN
DUST ACROSS THE ATLC...WITH THE LATEST SURGE APPROACHING THE
LESSER ANTILLES AND NE COAST OF S AMERICA IN THE WAKE OF THE
STRONG CARIBBEAN WAVE. A MID/UPPER LOW IS CENTERED NE OF THE
LEEWARD ISLANDS NEAR 25N5W DRIFTING N AND...WITH THE HELP OF AN
UPPER LEVEL ANTICYCLONE NEAR 13N58W...IS HELPING TO PROVIDE
STRONG SWLY SHEAR TO THE WAVE WITH ALMOST ALL ASSOCIATED
CONVECTION STILL E OF THE ISLANDS. ELSEWHERE...NE/E UPPER LEVEL
FLOW OVER THE SW ATLC IS PUSHING A FEW TSTMS SWWD OVER THE GULF
STREAM TOWARDS FL. SCATTERED MODERATE CONVECTION FROM 29N-32N
BETWEEN 75W-78W AND AN ISOLATED TSTM BETWEEN GRAND BAHAMA ISLAND
AND THE COAST OF FL.

[Derek Ortt]

The SAL inhibits convection by prociding a temp inversion, very strong vertical shear, and allows very dry air to be advected into the systems. All 3 of those factors result in the dissipation of convection

[hurricanemike]

Use this site for SAL Monitoring http://cimss.ssec.wisc.edu/tropic/real-time/wavetrak/sal-atl.html

[Aquawind]

SAL is no pal of mine..

...STRONG SUBTROPICAL RIDGE EXTENDS FROM
THE AZORES SW THROUGH 31N55W THEN W TO FLORIDA NEAR 29N80W.
ALTHOUGH THE RIDGE IS LOCATED NEAR ITS MEAN CLIMATOLOGICAL JULY
POSITION SURFACE PRESSURES REMAIN HIGH. THIS PATTEN CONTINUES TO
SUPPORT WAVES OF DRY SAHARAN AIR AND DUST TO PROPAGATE ACROSS
THE ATLC.

TROPICAL ATLANTIC...
UPPER LEVEL RIDGE REMAINS ACROSS E TROPICAL ATLC FROM SENEGAL
NEAR 14N16W-12N45W. THE NWD MIGRATION OF THE RIDGE IS PRODUCING
DEEP ELY FLOW AND LOW SHEAR ACROSS MUCH OF THE TROPICAL ATLC.
HOWEVER...A STRONG SAHARAN AIRMASS WITH LEADING EDGE APPROACHING
60W...IS CAPPING SIGNIFICANT CONVECTIVE DEVELOPMENT WITH THE
TROPICAL WAVES. MID LEVEL LOW IS DEVELOPING NEAR 9N20W AND COULD
BE ASSOCIATED WITH A DEVELOPING TROPICAL WAVE.

$$
WALLACE


http://www.nhc.noaa.gov/text/MIATWDAT.shtml?