AVIATION FORECAST DISCUSSION FOR 00Z TAF CYCLE
AFDCHI CWFA BETWEEN CONVECTIVE SPOKES NOW...WITH AFTERNOON TSRA NOW OUT
OVER THE LAKE...WITH THE NEXT WAVE OVER CENTRAL ILLINOIS HEADING
NORTHEASTWARD. WINDS GENERALLY LIGHT AND VARIABLE EXCEPT IN AND
AROUND THUNDERSTORMS. EXPECT GENERALLY VFR CIGS WITH THE THUNDER.
LATER TONIGHT...VSBYS AND CIGS DROP AS FOG DEVELOPS AND FILLING
UPPER LOW APPROACHES...PRODUCING MORE STRATIFORM RA/DZ. EXPECT IFR
CONDITIONS FROM A BIT AFTER MIDNIGHT UNTIL NEAR DAYBREAK WHEN
INCREASING NW FLOW INDUCES MIXING THAT RAISES CIGS TO MVFR...THEN
VFR IN THE AFTERNOON AS WINDS BACK TO WEST.
JHV
DISCUSSION FOR 330 PM GRIDS/ZFP
MAIN FORECAST CONCERNS INVOLVE CONVECTION/PRECIP TRENDS TONIGHT WITH
UPPER LOW WOBBLING THROUGH MIDWEST...THEN PRECIP TRENDS NEXT SEVERAL
DAYS WITH PROGRESSIVE UPPER PATTERN.
SATELLITE LOOP SHOWS THE LOW AS SWIRL IN CLOUDS OVER SOUTHWEST
MISSOURI THIS AFTERNOON...WITH CONVECTIVE DEVELOPMENT NOTED IN
SAT/RADAR IMAGERY IN MOIST FLOW FEEDING FROM KY-IND-ERN IL. 18Z
SOUNDING OUT OF ILX INDICATES STEEP LAPSE RATES WITH FREEZING LEVEL
AROUND 7500 FT...THOUGH SOMEWHAT DRY LOW LEVELS YIELDING A CAPE OF
930 J/KG. SURFACE DEWPOINTS ARE HIGHER ACROSS MUCH OF WFO CHICAGO FA
HOWEVER...WITH MODIFIED ACARS SOUNDING RESULTING IN ABOUT 1200 J/KG.
SOUNDINGS SHOW SOME BACKING WITH HEIGHT THROUGH LOWEST 3.5 KM...SO
MAIN SEVERE THREAT INTO EARLY EVENING TO BE HAIL WITH RELATIVELY
VERTICAL PULSING UPDRAFTS AND LOW WBZ/FREEZING LEVEL. HIGHEST THREAT
FOR THUNDER OVER EASTERN PORTIONS OF FA...WITH BETTER LOW LEVEL
MOISTURE...HEATING WITH BREAKS IN CLOUD COVER...AND CLOSER PROXIMITY
TO SYNOPTIC SCALE DYNAMICS NORTHEAST OF WEAKENING UPPER SYSTEM. WILL
GO WITH SCATTERED/OCCASIONAL MENTION ESPECIALLY EARLY TONIGHT FOR
SHOWERS/THUNDER WITH HIGHEST POPS EAST. LIGHT WIND FIELD AS SURFACE
TROF MOVES THROUGH TONIGHT...WITH AREAS OF LIGHT FOG LATE.
WILL KEEP CHANCE POPS FOR SHOWERS INTO FRIDAY MORNING AS UPPER LOW
FILLS AND TROF AXIS PASSES TO EAST. SECOND CLOSED UPPER SYSTEM DROPS
INTO PLACE OVER WISCONSIN...WITH DRY AIR WRAPPING INTO IL AROUND
SOUTHERN PERIPHERY...THOUGH COLD POOL ALOFT MAY RESULT IN SOME
AFTERNOON AND EVENING INSTABILITY SHOWERS IN NORTHERN COUNTIES PER
GOING FORECAST. LOW PULLS OFF TO EAST OVER WEEKEND WITH NCEP
ENSEMBLES IN REASONABLE AGREEMENT WITH OPERATIONAL GFS RUNS. NEXT
CHANCE FOR PRECIP TO BE MONDAY...AS LOW PRESSURE MOVES ACROSS
SOUTHERN CANADA AND DRAGS COLD FRONT INTO AREA. CHANCE LINGERS INTO
WED AS FRONT PUSHES SOUTH...THEN WEAK HIGH PRESSURE THURSDAY.
.CHI...NONE
RATZER
AREA FORECAST DISCUSSION
NWS CHICAGO IL
AFDCHI 246 PM CST THU MAR 20 2003
DISCUSSION FOR 330 PM GRIDS/ZFP
MAIN FORECAST CONCERNS INVOLVE CONVECTION/PRECIP TRENDS TONIGHT WITH
UPPER LOW WOBBLING THROUGH MIDWEST...THEN PRECIP TRENDS NEXT SEVERAL
DAYS WITH PROGRESSIVE UPPER PATTERN.
SATELLITE LOOP SHOWS THE LOW AS SWIRL IN CLOUDS OVER SOUTHWEST
MISSOURI THIS AFTERNOON...WITH CONVECTIVE DEVELOPMENT NOTED IN
SAT/RADAR IMAGERY IN MOIST FLOW FEEDING FROM KY-IND-ERN IL. 18Z
SOUNDING OUT OF ILX INDICATES STEEP LAPSE RATES WITH FREEZING LEVEL
AROUND 7500 FT...THOUGH SOMEWHAT DRY LOW LEVELS YIELDING A CAPE OF
930 J/KG. SURFACE DEWPOINTS ARE HIGHER ACROSS MUCH OF WFO CHICAGO FA
HOWEVER...WITH MODIFIED ACARS SOUNDING RESULTING IN ABOUT 1200 J/KG.
SOUNDINGS SHOW SOME BACKING WITH HEIGHT THROUGH LOWEST 3.5 KM...SO
MAIN SEVERE THREAT INTO EARLY EVENING TO BE HAIL WITH RELATIVELY
VERTICAL PULSING UPDRAFTS AND LOW WBZ/FREEZING LEVEL. HIGHEST THREAT
FOR THUNDER OVER EASTERN PORTIONS OF FA...WITH BETTER LOW LEVEL
MOISTURE...HEATING WITH BREAKS IN CLOUD COVER...AND CLOSER PROXIMITY
TO SYNOPTIC SCALE DYNAMICS NORTHEAST OF WEAKENING UPPER SYSTEM. WILL
GO WITH SCATTERED/OCCASIONAL MENTION ESPECIALLY EARLY TONIGHT FOR
SHOWERS/THUNDER WITH HIGHEST POPS EAST. LIGHT WIND FIELD AS SURFACE
TROF MOVES THROUGH TONIGHT...WITH AREAS OF LIGHT FOG LATE.
WILL KEEP CHANCE POPS FOR SHOWERS INTO FRIDAY MORNING AS UPPER LOW
FILLS AND TROF AXIS PASSES TO EAST. SECOND CLOSED UPPER SYSTEM DROPS
INTO PLACE OVER WISCONSIN...WITH DRY AIR WRAPPING INTO IL AROUND
SOUTHERN PERIPHERY...THOUGH COLD POOL ALOFT MAY RESULT IN SOME
AFTERNOON AND EVENING INSTABILITY SHOWERS IN NORTHERN COUNTIES PER
GOING FORECAST. LOW PULLS OFF TO EAST OVER WEEKEND WITH NCEP
ENSEMBLES IN REASONABLE AGREEMENT WITH OPERATIONAL GFS RUNS. NEXT
CHANCE FOR PRECIP TO BE MONDAY...AS LOW PRESSURE MOVES ACROSS
SOUTHERN CANADA AND DRAGS COLD FRONT INTO AREA. CHANCE LINGERS INTO
WED AS FRONT PUSHES SOUTH...THEN WEAK HIGH PRESSURE THURSDAY.
.CHI...NONE
RATZER
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
AFDDDC 245 PM CST THU MAR 20 2003
DAYS 1-2...
MAIN CONCERN FOR THIS FORECAST CYCLE IS TEMPERATURES AND CHANCES FOR
PRECIPITATION LATE FRIDAY INTO EARLY SATURDAY.
THE 12Z DIAGNOSTICS WERE AGAIN LIMITED MISSING SOUNDINGS. DNR AND
ABQ WERE 10142 AGAIN TODAY AS WERE MAF AND OAX WHILE THE LBF RUN WAS
SHORT. HARD TO VALIDATE SHORT TERM MODEL SOLUTIONS UNDER THESE
CONDITIONS, BUT FORTUNATELY, THE MODELS APPEAR TO BE DOING WELL OVER
MOST OF THE CONUS. ACARS AND AIREP DATA INDICATE THAT THE STRONG
WINDS ALOFT AT OAK ARE IN ERROR WHILE ONLY THE AVN SEEMS TO HAVE
DONE A REASONABLE JOB WITH THE JET DIVING INTO THE PACIFIC COAST.
THE OTHER MODELS ARE EITHER TOO WEAK WITH THIS JETLET OR HAVE IT
COMPLETELY OUT OF POSITION. ELSEWHERE, THE MAJOR MIDLATITUDE CYCLONE
OVER THE CONUS IS NOW CROSSING THE MID MISSISSIPPI VALLEY REGION AS
AN UPSTREAM SHORT WAVE TROUGH ALOFT DIGS INTO THE PACIFIC COAST IN A
RELATIVELY PROGRESSIVE PATTERN. A SOMEWHAT DAMPENED DIRTY RIDGE
ALOFT IS POISED TO CROSS THE HIGH PLAINS REGION LATE TODAY INTO
TONIGHT IN ADVANCE OF THE UPSTREAM SHORT WAVE TROUGH ALOFT. FARTHER
WEST ACROSS THE PACIFIC THE UPPER LEVEL WESTERLIES CONTINUE TO SHOW
A STRENGTHENING AND EXPANDING ZONAL WIND BELT FROM THE ASIAN PLATEAU
EASTWARD BUT THAT WILL MAINLY INFLUENCE THE LATER PERIODS OF THIS
FORECAST AS A MORE ZONAL FLOW PATTERN ESTABLISHES ITSELF ACROSS THE
CONUS. IN THE BOUNDARY LAYER NORTHERLY GRADIENT WINDS SHOULD
GRADUALLY SLACKEN TODAY AS THE CYCLONE TO THE EAST MOVES AWAY
ALLOWING A COOL HIGH TO BUILD OVER THE REGION TONIGHT INTO FRIDAY.
AS MENTIONED ABOVE, THE AVN WILL BE THE MODEL OF CHOICE DUE TO ITS
BETTER RESOLUTION OF EAST PACIFIC FEATURES. ADDITIONALLY, THE ETA
CONTINUES TO LOOK TOO DRY COMPARED TO THE AVN AS HAS BEEN THE CASE
FOR A LONG TIME NOW. GIVEN THAT, WILL LOOK FOR ISENTROPIC UPGLIDE TO
DEVELOP OVER THE COOL SURFACE HIGH ON FRIDAY DEVELOPING CLOUDS AND
SOME WIDESPREAD LIGHT RAIN LASTING THROUGH FRIDAY NIGHT AND INTO
SATURDAY MORNING. AMOUNTS WILL LIKELY NOT BE GREAT DUE TO SOMEWHAT
LIMITED MOISTURE, BUT MANY AREAS SHOULD MEASURE AND WILL THIS GO
ABOVE THE MOS POPS FOR THE EVENT. WITH CLEARING SKIES TONIGHT
MORNING LOWS WILL LIKELY BE A LITTLE BELOW THE MOS WHILE THE CLOUDS
AND RAIN FOR FRIDAY SHOULD KEEP HIGH TEMPERATURES CLOSER TO THE
COOLER MAV. UNLESS THE RAIN AND CLOUDS EXIT EARLIER THAN EXPECTED
ON SATURDAY THE MOS LOOKS FAR TO WARM AND WILL AGAIN STICK WITH THE
COOLER MAV FOR HIGHS ON SATURDAY AND STAY CLOSE TO THE NEARLY
IDENTICAL FWC AND MAV FOR LOWS SATURDAY MORNING.
DAYS 3-7...
FORECAST REASONING HAS NOT CHANGED MUCH FROM YESTERDAY. GLOBAL
DIAGNOSTICS CONTINUE TO POINT TOWARD MORE OF A ZONAL, PROGRESSIVE
PATTERN OVER THE CONUS FOR THE UPCOMING WEEK. EMBEDDED WITHIN THIS
PATTERN, WE WILL SEE A SERIES OF SHORTWAVES MOVE THROUGH THE CENTRAL
US. THE MODELS ARE IN GENERAL AGREEMENT ON THIS.
THE FIRST WAVE, CURRENTLY OVER THE FAR WESTERN US, WILL MOVE THROUGH
THE SOUTHERN PLAINS LATE TOMORROW AND EARLY SATURDAY. ANOTHER PIECE
OF ENERGY IS EXPECTED TO MOVE ACROSS THE NORTHERN PLAINS AND
SOUTHERN CANADA LATE SUNDAY. THIS SYSTEM IS EXPECTED TO BRING A COLD
FRONT THROUGH THE AREA SOMETIME ON MONDAY. THE ECMWF AND GFS DIFFER
ON THE TIMING AND THE STRENGTH OF THE COLD AIR, WITH THE EURO BEING
FASTER AND A BIT WARMER. WILL SIDE WITH THE EURO BASED ON THE FACT
THAT THE GFS IS LIKELY TOO SLOW WITH THE FRONTAL MOVEMENT. BY LATE
MONDAY, ANOTHER SOUTHERN BRANCH WAVE IS EXPECTED TO MOVE INTO THE
PLAINS WITH GOOD ISENTROPIC LIFT OVER THE FRONTAL BOUNDARY TO THE
SOUTH. AT THIS TIME, WILL CONTINUE TO GO WITH AN ALL RAIN SOLUTION,
BECAUSE IT DOESN'T LOOK COLD ENOUGH TO SUPPORT SNOW. ALSO SHIFTED
THE TIMING OF THE CHC POPS TO MONDAY EVENING THROUGH TUESDAY
AFTERNOON AND INCREASED THEM TO 50%. INSERTED ANOTHER CHANCE FOR
SHOWERS ON THURSDAY AS ANOTHER WAVE APPROACHES THE PLAINS.
AS FOR TEMPS, BUMPED HIGHS UP INTO THE 70S ACROSS THE AREA ON SUNDAY
WITH GOOD DOWNSLOPE FLOW, WARM H85 TEMPS, AND FULL INSOLATION. ALSO
TWEAKED HIGHS DOWN ON MONDAY WITH THE EXPECTED FRONTAL PASSAGE
DURING THE DAY. OTHERWISE, MADE NO OTHER BIG CHANGES TO THE GOING
TEMP FORECAST.
PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE
CONTAINED WITHIN THE DODGE CITY ZONE FORECAST.
DDC 33 50 36 55 / 0 30 30 60
GCK 32 50 36 57 / 0 60 60 60
EHA 35 52 37 57 / 30 60 60 60
LBL 35 51 37 55 / 0 60 60 60
HYS 31 50 34 56 / 0 0 30 30
P28 36 50 36 53 / 0 0 30 60
.DDC...NONE.
JOHNSON/LACY