AREA FORECAST DISCUSSION
NWS CHICAGO IL
AFDCHI 250 AM CST WED JAN 9 2002
FORECAST CONCERNS INCLUDE TEMPS TODAY WITH EARLY PASSAGE OF THERMAL
TROUGH...AND MINOR CHANCES OF PRECIP WITH APPROACHING FRONT AND
UPPER TROUGH.
UNSEASONABLY WARM TEMPS BLANKETED THE CENTRAL PLAINS TUESDAY...WITH
READINGS REACHING INTO THE 60S AS NEARBY AS CENTRAL IOWA. 06Z ACARS
SOUNDING OUT OF ORD SHOWS WARM ADVECTION HAS PUSHED H8 TEMPS TO +10
C. MODELS CONTINUE TO INDICATE THAT AXIS OF THERMAL RIDGE TO BE OVER
OUR AREA EARLY TODAY...WITH WEAK COLD ADVECTION TAKING OVER
THEREAFTER. AFTERNOON MAXES A BIT TRICKY...ESPECIALLY NORTHWEST
WHERE CAA HAS BETTER CHANCE OF HOLDING TEMPS DOWN A BIT. WILL TACK
ON A FEW DEGREES TO MOS NUMBERS NORTHWEST...AND GO WITH WARMER MAVS
REST OF FORECAST AREA. RECORD TODAY AT ROCKFORD IS 55...AND COULD
COME NEAR THAT. RECORD FOR CHI IS 60 AND SHOULD BE OUT OF REACH.
AFTER TODAY MOS NUMBERS VERY CLOSE AND A BIT MILDER THAN GOING
FORECAST. WITH THE MAIN BULK OF COLDER AIR FORECAST TO REMAIN ACROSS
EASTERN CANADA...WILL RAISE BOTH MIN AND MAX TEMPS JUST A SMIDGE
THROUGH FRIDAY IN LINE WITH 00Z MAV/FWC NUMBERS.
CONTINUE TO BE UNIMPRESSED WITH CHANCES FOR ANY PRECIP NEXT 48
HOURS. MODELS SIMILAR IN DEVELOPING POSITIVE TILT UPPER TROF ACROSS
THE AREA BY 48 HOURS OR SO...AS ENERGY CUTTING ACROSS WESTERN US
RIDGE AND DROPPING SOUTHEAST OUT OF CANADA COMBINE. AIRMASS REMAINS
VERY DRY HOWEVER...WITH CURRENT SURFACE AND SATELLITE OBS SHOWING
NOTHING BUT CIRRUS AND VERY PATCHY AC OVER THE CENTRAL AND NORTHERN
PLAINS. MODELS CONTINUE TO INCREASE LAYER RH VALUES ALONG THE
BAROCLINIC ZONE AS IT DROPS SOUTHWARD OVER CENTRAL IL TONIGHT BUT
OTHER THAN SOME VERY WEAK FRONTOGENETIC FORCING...SEE NO REAL SOURCE
OF ORGANIZED LIFT FOR PRECIP. WITH THIS IN MIND WILL PULL FLURRIES
OUT OF NORTHERN GROUPS...AND JUST LEAVE A MENTION OF CHANCE
SPRINKLES TONIGHT AND FLURRIES THURSDAY ACROSS SOUTHERN COUNTIES
CLOSER TO FRONT. NEXT SHORT WAVE MOVES SOUTHEAST INTO THE AREA FOR
SATURDAY...WITH CHANCE SNOW SHOWERS ALREADY IN THE FORECAST. QUICK
GLANCE AT NEW MRF SHOWS EXTENDED IN GOOD SHAPE.
THANKS MKE...IWX AND DVN FOR COORDINATION.
.CHI...NONE
RATZER
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
AFDDDC 300 AM CST WED JAN 9 2002
...CHALLENGES THIS CYCLE WILL BE TEMPERATURES AND CHANCES FOR
PRECIPITATION IN THE WEST TOMORROW...
THE 00Z DIAGNOSTICS SHOW THE BROAD EASTERN CONUS UPPER TROUGH
GRADUALLY DAMPENING AND MOVING INTO THE ATLANTIC. THE WESTERN CONUS
UPPER RIDGE WAS MOVING INTO THE PLAINS AND CONTINUES TO FLATTEN OUT
AS SHORT WAVE ENERGY FROM THE PACIFIC ERODES IT. THE VERY BROAD
SURFACE WARM TROUGH FROM MINNESOTA TO TEXAS REFLECTS THE STRONG
DOWNSLOPE WARMING EXPERIENCED DURING THE DAY YESTERDAY WHICH
RESULTED IN RECORD HIGH TEMPERATURES ACROSS THE FORECAST AREA.
MODEL MASS FIELD INITIALIZATIONS WERE AGAIN GOOD ACROSS THE DATA
RICH CONUS. OVER THE EASTERN AND NORTHERN PACIFIC AIREP AND ACARS
DATA APPEARS TO HAVE ADEQUATELY SAMPLED THE FLOW OF BOTH THE PACIFIC
COAST SYSTEM AND THE UPSTREAM KICKER APPROACHING 140W. GIVEN THIS,
SYNOPTIC SCALE FEATURES ARE EXPECTED TO BE WELL HANDLED BY THE
MODELS WITH THE MAIN DIFFERENCES BETWEEN THEM RESULTING FROM
OROGRAPHIC EFFECTS AND THEIR MOISTURE SCHEMES. THE ETA WILL BE
PREFERRED FOR THIS FORECAST CYCLE AS THE POLAR BAROCLINIC ZONE
STRENGTHENS FORCING AN AREA OF FRONTOGENESIS SOUTH THROUGH THE
REGION DURING THE DAY TODAY AND LEADING TO A NORTHEASTERLY UPSLOPE
ENVIRONMENT FOR TONIGHT AND THURSDAY.
MOISTURE ALONG THE UPPER BAROCLINIC ZONE SHOULD WORK INTO THE REGION
OUT OF THE ROCKIES ALONG THE KANSAS NEBRASKA BORDER AREA BY LATE
AFTERNOON AND THEN SINK SOUTH ACROSS KANSAS TONIGHT AND TOMORROW
WITH UPSLOPE PRECIPITATION DEVELOPING OVER THE HIGH TERRAIN OF EAST
COLORADO. THE MAIN QUESTION WILL BE HOW FAR EAST THE PRECIPITATION
AND UPSLOPE LOW CLOUD EXTENDS ON THURSDAY. ALL MODELS DEVELOP AT
LEAST SOME LOW LEVEL SATURATION AND A LITTLE PRECIPITATION FOR THE
FAR WEST ON THURSDAY AS THE ELEVATED BAROCLINIC ZONE SLIDES SOUTH
ACROSS THE REGION. WITHOUT ABUNDANT MOISTURE ANY PRECIPITATION WOULD
LIKELY BE VERY LIGHT BUT AM LOATH TO LEAVE IT OUT ENTIRELY AND WILL
INTRODUCE SOME SMALL CHANCE POPS IN THE WEST FOR THURSDAY. CLOUD
COVER TONIGHT INTO THURSDAY SHOULD MODERATE TEMPERATURES ENOUGH THAT
THE PRECIPITATION SHOULD BE LIMITED TO SPOTTY LIGHT RAIN IF IT
OCCURS AT ALL. FWC MOS APPEARS TO BE ON TRACK AND WILL GENERALLY USE
IT.
DAY 3-10...
COLD AIR SETTLING INTO CNTL KS AND OK THURSDAY NIGHT WILL BEGIN TO
ERODE DURING THE DAY ON FRIDAY. 85H/7H WINDS DO BEGIN TO BACK TO THE
WEST THROUGH THE DAY, HOWEVER DOWNSLOPE FLOW DOES NOT APPEAR TO BE
THAT STRONG. THEREFORE AM LEANING TOWARDS A SLOWER EROSION OF THE
COLD AIR, ESPECIALLY IN THE EAST ON FRIDAY SO WILL TRIM A FEW
DEGREES OF GUIDANCE FOR AFTERNOON READINGS.
THE REMAINDER OF THE FORECAST LOOKS ON TRACK THEREFORE NO ADDITIONAL
CHANGES PLANNED.
PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE
CONTAINED WITHIN THE DODGE CITY ZONE FORECAST.
DDC 060/032 043/023 046 000
GCK 058/032 043/021 047 002
EHA 061/033 044/022 050 002
LBL 061/034 044/024 050 002
HYS 058/035 043/024 045 000
P28 062/037 046/025 047 000
.DDC...NONE.
JOHNSON/BURGERT