277
FXCA20 KWBC 102020
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
319 PM EST FRI JAN 10 2025
FORECAST BULLETIN 09 JANUARY 2025 AT 19 UTC
A WEAKENING POSITIVELY TILTED UPPER TROUGH WITH AN AXIS ACROSS THE
CENTRAL PLAINS USA/ WESTERN CHIHUAHUA/ BAJA CALIFORNIA SUR
ASSOCIATES TO A UPPER JET STREAK THAT EXTENDS FROM THE
SINALOA/CHIHUAHUA INTO THE OHIO VALLEY. THIS WILL HAVE AN
IMPORTANT ROLE IN ASCENT OVER NORTHERN MEXICO TODAY THROUGH
SATURDAY... PRIMARILY IMPACTING COAHUILA AND NUEVO LEON... WHERE A
SUBTLE INCREASE IN MOISTURE WILL YIELD TO A RAINFALL MAXIMA OF 15
- 20MM THROUGH SATURDAY MORNING. AS THE UPPER TROUGH EXITS INTO
THE INTERIOR USA... UPPER LEVELS WILL BECOME LESS FAVORABLE FOR
ASCENT.
IN THE PACIFIC TO THE SOUTHWEST OF MEXICO... A NEGATIVELY TITLED
UPPER TROUGH IS ASSISTING WITH THE DIFFLUENT PATTERN OVER
WEST-CENTRAL MEXICO TODAY THROUGH SUNDAY EVENING. ALTHOUGH THE
TROUGH IS EXPECTED TO GRADUALLY LOSE ITS NEGATIVE TILT... THE
INDUCED DYNAMIC ASCENT WILL LOWER PRESSURES AND DRAW A MOIST PLUME
FROM THE TROPICAL PACIFIC... WHICH WILL ENHANCE PRECIPITATION IN
SOUTHWESTERN STATES OF MEXICO. THROUGH SATURDAY MORNING... THE
HIGHEST RAINFALL AMOUNTS ARE EXPECTED IN COLIMA/ MICHOACAN/
GUERRERO WITH FORECAST MAXIMUM TOTALS OF 15 - 30MM/DAY. BY
SATURDAY MORNING THROUGH SUNDAY MORNING... EXPECT AN INCREASE IN
MOISTURE IN THE LOW LEVELS IN MICHOACAN AND GUERRERO... WHICH WILL
YIELD TO A RAINFALL MAXIMA OF 20 - 35MM IN MICHOACAN AND RAINFALL
MAXIMA OF 15 - 25MM TO THE EJE VOLCANICO CENTRAL AND GUERRERO IN
MEXICO. BY SUNDAY MORNING THROUGH MONDAY MORNING... LOW LEVEL
MOISTURE WILL BEGIN TO DECREASE... HOWEVER... ASCENT WILL STILL BE
FAVORABLE IN THE AREA AND THUS YIELD TO RAINFALL MAXIMA OF 15MM IN
MICHOACAN AND 15 - 20MM IN SOUTHERN GUERRERO.
IN THE GULF OF MEXICO... UPPER LEVEL SPEED DIVERGENCE IS PRESENT
OVER SOUTHERN VERACRUZ/ TABASCO/ OAXACA/ CHIAPAS. AT THE
SURFACE... A POTENT COLD FRONT IS RAPIDLY PROPAGATING ACROSS THE
SOUTHEAST US... GULF OF MEXICO INTO SOUTHERN VERACRUZ...
ACCOMPANIED BY A 30-40 KT NORTES EVENT. BY FRIDAY EVENING THE
FRONT IS EXPECTED TO EXTEND FROM THE SOUTHEAST USA INTO
TABASCO...TEHUANTEPEC GAP... WITH A STATIONARY BOUNDARY DRAPING
ACROSS THE SIERRA MADRE ORIENTAL. BY SATURDAY EVENING... THE FRONT
IS FORECAST AS A STATIONARY BOUNDARY ACROSS THE FAR NORTHWEST
BAHAMAS... FLORIDA KEYS... INTO A DISSIPATING BOUNDARY ACROSS THE
NORTH-CENTRAL YUCATAN PENINSULA... NORTHERN GUATEMALA. AHEAD OF
THE FRONT... THE CHANGE IN WIND DIRECTION IS ASSISTING IN AN
ENHANCEMENT IN MOISTURE CONVERGENCE. EXPECT THE GREATEST
PRECIPITATION IMPACTS IN SOUTH VERACRUZ AND WEST TABASCO.
HOWEVER... A POTENT MID LEVEL RIDGE IN THE NORTHERN CARIBBEAN SEA
WILL DRIVE STABILIZATION OF THE MID LEVELS IN THE SOUTH GULF OF
MEXICO. THUS... THE HIGHEST RAINFALL MAXIMA EXPECTED THROUGH
SATURDAY MORNING AND DECREASING DAILY AS THE MID LEVEL RIDGE
STRENGTHENS THROUGH THE WEEKEND AND EVENTUALLY PROJECTING INTO THE
LOWER LEVELS BY SATURDAY EVENING. EXPECT AMOUNTS GENERALLY IN THE
15-25MM MAXIMA RANGE...ALTHOUGH VERY ISOLATED HIGHER MAXIMA IS
POSSIBLE IN INTERACTIONS WITH TERRAIN.
IN CENTRAL AMERICA... A DECAYING COLD FRONT IS BEING ANALYZED AS A
FRONTAL SHEAR LINE EXTENDING ALONG 15N AND INTO NORTHEAST COSTA
RICA ON FRIDAY. THIS WILL FAVOR A RAINFALL MAXIMA OF 15 - 25MM
THROUGH SATURDAY MORNING... WHILE AMOUNTS ARE EXPECTED TO DECREASE
DAILY THEREAFTER UPON DISSIPATION OF THE SHEAR LINE AND A
STRENGTHENING OF THE MID-LEVEL RIDGE OVER THE REGION.
IN THE CARIBBEAN... A COLD FRONT IS EXPECTED TO BE JUST TO THE
NORTH OF PUERTO RICO AND ACROSS NORTHERN HISPANIOLA TONIGHT. BY
SATURDAY EVENING... IT WILL DECAY INTO A STATIONARY BOUNDARY
ACROSS GUADELOUPE AND A FRONTAL SHEAR LINE ALONG 15N INTO THE
CENTRAL CARIBBEAN SEA BASIN. BY SUNDAY EVENING... THE FRONTAL
SHEAR LINE WILL REMAIN ACROSS DOMINICA AND GUADELOUPE. TO THE
SOUTH OF THESE BOUNDARIES... ENHANCED EASTERLY FLOW IS ANTICIPATED
DUE TO THE MID AND UPPER LEVEL RIDGES DOMINATING THE REGION. ON
SATURDAY MORNING THROUGH SUNDAY MORNING... THE MOISTURE
CONVERGENCE ASSOCIATED WITH THE DECAYING STATIONARY BOUNDARY WILL
SUPPORT A RAINFALL MAXIMA OF 15MM IN MONTSERRAT AND GUADELOUPE. IN
THE WINDWARD ISLANDS... EXPECT A MAXIMA OF 10MM DUE TO ENHANCED
EASTERLIES AS WELL. BY SUNDAY MORNING INTO MONDAY MORNING... THE
REMAINING FRONTAL SHEAR LINE AND EASTERLY LOW LEVEL WIND FLOW WILL
FAVOR A RAINFALL MAXIMA OF 10MM IN THE SOUTHERN LEEWARD ISLANDS.
IN SOUTH AMERICA... REGIONS OF GREATEST PRECIPITATION IMPACT WILL
REMAIN ALONG THE CONVERGENCE ZONES IN THE PACIFIC AND ATLANTIC AND
THE NEAR EQUATORIAL TROUGH. IN ECUADOR... THE COMBINATION OF UPPER
LEVEL DIVERGENCE... WEAK ONSHORE FLOW IN THE BASE OF THE
PANAMANIAN TROUGH... AND SEA SURFACE TEMPERATURES ABOVE 26 CELSIUS
WILL FAVOR AN ACTIVATION OF DIURNAL CONVECTION IN COASTAL AREAS.
EXPECT A RAINFALL MAXIMA OF 20 - 35MM THROUGH SATURDAY MORNING.
AFTER THIS PERIOD EXPECT MAXIMA GENERALLY IN THE 15 - 25MM RANGE.
IN THE GUIANAS... A LOW LEVEL TROUGH WILL PROPAGATE THROUGH THE
REGION THROUGH SUNDAY MORNING. THE GREATEST PRECIPITATION IMPACT
FROM THIS TROUGH WILL OCCUR TODAY THROUGH SATURDAY MORNING. AS IT
MOVES WEST... EXPECT A DRYING TREND IN THIS REGION.
GALVEZ...(WPC)
TINOCO...(WPC)
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