097
FXCA20 KWBC 151902
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
301 PM EDT THU OCT 15 2026
FORECAST BULLETIN 15 OCTOBER 2026 AT 1902 UTC:
AN UPPER-LEVEL TROUGH MOVING ACROSS THE U.S. TODAY WILL BE CUT OFF
ON ITS SOUTHWESTERN FLANK, REMAINING AS CYCLONIC CIRCULATION
CENTERED OVER SOUTHERN CALIFORNIA WHILE THE REMAINDER CONTINUES
EASTWARD FRIDAY INTO THE WEEKEND. THIS SPLITTING WILL ENHANCE
UPPER-LEVEL DIVERGENCE OVER NORTHWESTERN MEXICO SUPPORTING STRONG
UPWARD MOTION LATER TODAY INTO FRIDAY. THE MID-LEVEL MOISTURE FLOW
EXTENDING FROM TROPICAL STORM SIMON INTO NORTH AMERICA WILL BE
CONSTRAINED AND EVENTUALLY CUT OFF AS STRONG NORTHERLY WINDS
DEVELOP, SATURATING THE AIR MASS OVER THIS REGION WHILE INCREASING
CYCLONIC POTENTIAL VORTICITY (PV). STRONG LOW-LEVEL MOISTURE
CONVERGENCE WILL BE SUPPORTED BY THE ASSOCIATED COLD FRONT MOVING
BENEATH. HEAVY RAINFALL IS LIKELY OVER CHIHUAHUA LATER TODAY INTO
FRIDAY WITH MAXIMUM DAILY RAINFALL ACCUMULATIONS OF 30-60 MM. ON
SATURDAY, MID-LEVEL FLOW WILL DRIVE A MOISTURE PLUME FURTHER WEST
TO INTERACT WITH THE EXISTING DYNAMICS, TRIGGERING SHOWERS OVER
THE BAJA CALIFORNIA PENINSULA AND SONORA.
OFF SOUTHWESTERN MEXICO, HURRICANE TRUDY WILL APPROACH THE
SOUTHWESTERN COAST OF MEXICO SUPPLYING THE REGION WITH ABUNDANT
MOISTURE ACROSS THE PACIFIC COAST INTO THE GULF COAST BY THE
WEEKEND. A TROPICAL WAVE CROSSING THE WESTERN CARIBBEAN WILL
SUPPORT THE LOW-LEVEL MOISTURE CONVERGENCE. A SERIES OF MID-LEVEL
SHORTWAVES WILL INCREASE PV OVER THE NORTHWESTERN CARIBBEAN TO
TRIGGER ISOLATED HEAVY SHOWERS IN CUBA AND FROM NORTHEASTERN
NICARAGUA TO QUINTANA ROO TODAY. THE INTERACTION BETWEEN HURRICANE
TRUDY APPROACHING FROM THE SOUTH, THE TROPICAL WAVE FROM THE EAST
AND THE COLD FRONT FROM THE NORTHWEST WILL CREATE A POOL OF
ABUNDANT MOISTURE AND DYNAMIC INSTABILITY, LEADING TO WIDESPREAD
THUNDERSTORMS EXTENDING FROM THE MEXICAN GULF COAST TO WESTERN
HONDURAS AND ALONG THE SIERRA MADRE DEL SUR COAST ON FRIDAY AND
SATURDAY. AS THE COLD FRONT MOVES FURTHER SOUTHEAST ON SATURDAY,
MODERATE TO LOCALLY HEAVY STORMS WILL DEVELOP FROM WESTERN CUBA TO
THE NORTHERN BAHAMAS, WHERE MARGINAL RISK OF SEVERE WEATHER IS
FORECAST.
A PERTURBED LOW-LEVEL FLUX MOVING ACROSS NORTHERN SOUTH AMERICA
WILL CREATE A SERIES OF LOW-LEVEL TROUGHS FROM THE EASTERN TO THE
WESTERN AMAZON BASIN TODAY, PROVIDING SIGNIFICANT LOW-LEVEL
MOISTURE CONVERGENCE. SCATTERED AREAS OF MID-LEVEL PV WILL SUPPORT
UPWARD MOTION DEVELOPMENT WHILE A DENSE PLUME OF SATURATED AIR
DEVELOPS FROM ORINOQUIA TO THE SOUTHWEST, OVER WESTERN AMAZON
BASIN, AND SOUTHEAST INTO THE CENTRAL AMAZON BASIN. THESE
MID-TO-LOWER LEVEL DYNAMICS WILL CONTINUE OVER THE NEXT FEW DAYS,
WHILE UPPER-LEVEL DIVERGENCE WILL DEVELOP LATER FRIDAY INTO
SATURDAY ACROSS ORINOQUIA INTO THE WESTERN AND CENTRAL AMAZON
BASIN, SUPPORTING DEEP CONVECTION DEVELOPMENT. MAXIMUM DAILY
RAINFALL ACCUMULATIONS OF 20-35 MM ARE FORECAST ON FRIDAY AND UP
TO 40 MM ON SATURDAY.
MID-LEVEL FLOW ACROSS NORTHERN SOUTH AMERICA WILL ADVECT SOME
MOISTURE AND PV FROM THE AMAZON BASINS OVER THE ANDES INTO THE
PACIFIC REGION LATER TODAY, WHILE A MEANDERING WEST-COMPONENT
LOW-LEVEL INLAND FLOW DEVELOPS ALONG THE NORTHWESTERN SOUTH
AMERICAN COAST. HEAVY STORMS WILL DEVELOP LATER TODAY ALONG THE
COLOMBIAN PACIFIC COAST AND THE ANDES FROM COLOMBIA TO NORTHERN
ECUADOR, CONTINUING ON FRIDAY AND SATURDAY, WHEN THE HIGHEST
ACCUMULATION TOTALS WILL REMAIN OVER COLOMBIAN.
TROPICAL WAVES INITIALIZED AT 12 UTC:
TYP SOF INIT 16/00 16/12 17/00 17/12 18/00 18/12 19/00 19/12
TW 13N 32W 34W 37W 41W 43W 46W 49W 51W 54W
TW 17N 59W 63W 65W 67W 70W 73W 75W 77W 79W
TW 17N 82W 85W 87W 88W 88W 89W 90W 92W 93W
SANCHEZ-PEREZ...(WPC)
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