Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 281114
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
614 AM CDT TUE APR 28 2015

.SYNOPSIS...
ISSUED AT 401 AM CDT TUE APR 28 2015

HIGH PRESSURE SPRAWLING FROM THE GREAT LAKES ACROSS THE UPPER MS
VALLEY AND NORTHERN PLAINS WAS PROVIDING ANOTHER NIGHT OF CLEAR
SKIES AND SEASONABLY COOL TEMPERATURES. IN THE UPPER LEVELS...A
BLOCKING PATTERN PERSISTED WITH A LOW OVER TX TOPPED BY A RIDGE AXIS
REACHING FROM NEB NORTHEAST ACROSS THE GREAT LAKES.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 401 AM CDT TUE APR 28 2015

HIGH PRESSURE WILL AGAIN BE THE PRIMARY FEATURE TODAY THROUGH
TONIGHT...KEEPING SKIES MOSTLY CLEAR WHILE A WEAK SURFACE PRESSURE
GRADIENT AND WEAK FLOW ALOFT KEEP WINDS RELATIVELY LIGHT.

THE FORECAST WILL THUS FOLLOW THE TREND OF THE PAST SEVERAL
DAYS...GOING WITH PERSISTENCE PLUS A FEW DEGREES WARMING AS DEEP
MIXING TAPS INTO WARMER AIR ALOFT. THE DRY AIRMASS WILL QUICKLY
RECOVER AFTER ANOTHER COOL START IN THE MID 30S TO LOWER 40S THIS
MORNING. MOS GUIDANCE LOOKS TO HAVE  REASONABLY CAPTURED THIS TREND
AND HAVE GONE CLOSE TO A BLEND WITH A RANGE FROM THE UPPER 60S
NORTHEAST TO THE LOWER 70S ELSEWHERE.

TONIGHT...A WEAKENING UPPER LEVEL TROUGH MIGRATES SOUTHEAST THROUGH
THE AREA. HOWEVER...WITH DRY AIR AND ONLY WEAK FORCING...SENSIBLE
WEATHER WILL BE LIMITED TO A VERY MINOR WIND SHIFT TO THE NORTH AND
PERHAPS A FEW HIGH CLOUDS. THESE FEATURES...ALONG WITH CONTINUED
WARMING OF THE AIRMASS...WILL LEAD TO WARMER MINS THAN PREVIOUS
NIGHTS. BASED ON RECENT VERIFICATION...WILL CONTINUE TO TREND CLOSER
TO THE COOLEST GUIDANCE WITH MINS FROM AROUND 40 TO THE MID 40S.

.LONG TERM...(WEDNESDAY THROUGH NEXT MONDAY)
ISSUED AT 401 AM CDT TUE APR 28 2015

WEDNESDAY AND THURSDAY...AS OPPOSED TO YESTERDAY/S MODEL RUN AT THIS
TIME...SOME MORE MODEL AGREEMENT IN HANDLING COLD CORE CLOSED UPPER
LOW DROPPING SOUTH DOWN ACRS THE WESTERN GRT LKS IN A TEMPORARY
BLOCKED MID CONUS PATTERN ON WED. LLVL EAST-NORTHEAST PUSH ALSO TO
FOCUS A LAKE MI BOUNDARY SOMEWHERE ACRS NORTH CENTRAL IL INTO NW IL
AS WED PROGRESSES. THE LATEST MODEL RUNS ARE SUGGESTING THAT THE
UPPER LEVEL LOW AND ASSOCIATED VORT SPOKE ROTATING DOWN OVER STEEP
LLVL LAPSE RATES AND THE CONVERGENT FOCAL POINT OF THE LK
BOUNDARY... TO PRODUCE SCTRD AFTERNOON SHOWERS AND EVEN A FEW
THUNDERSTORMS... WHICH MAY THEN LAST WELL INTO WED EVENING BEFORE
STARTING TO DECAY DIURNALLY. THE QUESTION IS HOW FAR WEST SOME OF
THIS ACTIVITY MAY MAKE IT AND HOW MUCH INTO THE LOCAL FCST AREA.
INTERESTING THAT THE NEW 00C ECMWF IS THE FARTHEST WEST MAKING IT TO
DBQ AND THE QUAD CITES WED AFTERNOON AND EVENING...WHILE THE NAM AND
GFS ARE TARGETING AREAS FURTHER TO THE EAST IN NW IL. WILL GO WITH
SLIGHT CHC POPS ALONG AND EAST OF THE MS RVR TO JUST SOUTHEAST OF
THE QUAD CITIES...AND CHC POPS IN THE FAR EAST FOR NOW. WONDER IF
THERE COULD BE SOME LAND SPOUT POTENTIAL RIGHT IN THE VCNTY OF THE
SFC FRONT DURING PRIME DIURNAL HEATING. HIGHS WED IN THE UPPER 60S
TO LOW 70S. WILL BANK ON THE UPPER LOW GYRATING FAR ENOUGH OFF TO
THE SOUTHEAST FOR A DRY DAY THU ALLOWING UPPER RIDGE AXIS TO SLIDE
EAST-SOUTHEAST ACRS THE UPPER MS RVR VALLEY. ENHANCED NORTH TO
NORTHEAST BOUNDARY LAYER AND DEEPER FETCH THAT DAY NOT THE WARMEST
OF FLOWS... HIGHS MAY BE HELD IN THE UPPER 50S TO LOW TO MID 60S.
UPPER RIDGE OVERHEAD AND COOL/DRIER SFC DPT INFLUX MAY ALLOW FOR
SOME LOWS IN THE 30S TO LOW 40S THU NIGHT.

FRIDAY...FLATTENING MEAN STEERING FLOW TO SPILL BROAD/LOW AMPLITUDE
NORTHWESTERLIES ACRS THE REGION BY LATE FRI...WITH THE LATEST MEDIUM
RANGE SOLUTIONS STILL SUGGESTING AN UPPER LEVEL WAVE AND ASSOCIATED
SFC FRONT TO TRY AND PUSH INTO THE AREA FROM THE NW LATE FRI OR FRI
NIGHT. LATEST SOLUTIONS REALLY DAMPEN THIS FEATURE AS IT MAKES IN-
ROADS...AS WELL AS MARGINAL LOOKING LLVL MOISTURE CONVERGENCE ALONG
IT SUPPORTING THIS FRONT JUST KICKING UP WEAKER SHOWERS OR A FEW
STORMS IN THE LOCAL AREA LATER FRI AFTERNOON AND EVENING. ENOUGH PRE-
FRONTAL RETURN FLOW TO HELP PULL FRI HIGHS BACK UP INTO THE UPPER
60S TO AROUND 70.

SATURDAY THROUGH NEXT MONDAY...THE LATEST 00Z RUN MREF AND ENSEMBLES
CONTINUE TO ADVERTISE ORGANIZING WESTERLIES ACRS MUCH OF THE WESTERN
2/3S OF THE CONUS TO START THE WEEKEND OFF WITH. IN SUCH A PATTERN
LLVL WARM AND MORE MOIST CONVEYOR WILL ALSO LOOK TO DEVELOP UP OFF
THE WESTERN GULF AN MAKE STRIDES NORTHWARD. AGAIN AT THIS POINT...
DIFFICULT TO DETERMINE WHERE WEST-TO-EAST WARM FRONT WILL TIGHTEN
AND THEN TRY TO RETREAT...ACTING AS A FOCAL POINT FOR THIS WARM
MOIST CONVEYOR TO STREAM UP AND OVER/CONVERGE TO HELP FUEL
CONVECTION. TIMING EMBEDDED SHORT WAVES IN THE SYNOPTIC PATTERN FOR
PRECIP WINDOWS ALSO A CHORE AT THIS JUNCTURE IN THE FCST GAME ALONG
WITH VARIOUS MODEL DISCREPANCIES. EXAMPLE THE 00Z GFS IS NOW DRY
FRO SAT NIGHT...WHILE THE NEW EURO BLOSSOMS A NOCTURNAL WARM AIR
ADVECTION WING OF SHOWERS AND THUNDERSTORMS SAT NIGHT INTO SUNDAY
MORNING. BUT THEY ARE PICKING UP ON A LARGER TROF COMBINING WITH
ADEQUATE LLVL MOISTURE/THTA-E FEED FOR A CONVECTIVE WINDOW LATE
SUNDAY AND SUNDAY NIGHT. DEPENDING ON WHEN THE MAIN FRONT WHICH
THE MODELS DEPICT ORIENTED FROM NE-TO-SW PUSHES EAST AND
SOUTH...PRECIP CHANCES TO CONTINUE ALONG IT WELL INTO MON. THE 00Z
GFS DOES PUSH IT THRU IN TIME FOR A DRY MON AFTERNOON...WHILE THE
NEW ECMWF IS STRONGER WITH APPALACHIAN LLVL RIDGING HINDERING
EASTWARD FRONTAL PROGRESSION. FRONTAL PLACEMENT AND CONVECTIVE
DEBRIS ALL TO BE BIG PLAYERS IN TEMPERATURE WARM UP POTENTIAL OVER
THE WEEKEND...WITH LARGE VARIANCES POSSIBLE FROM DAY TO DAY. IF
SAT IS MAINLY DRY...SOME MID 70S POSSIBLE. ..12..

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 613 AM CDT TUE APR 28 2015

VFR CONDITIONS CONTINUE AS BROAD HIGH PRESSURE OVER THE REGION
PROVIDES MOSTLY CLEAR SKIES AND LIGHT WINDS. INITIAL LIGHT AND
VARIABLE WINDS THIS MORNING SHOULD BECOME MAINLY NORTH AROUND 5 TO
10 KTS LATER THIS MORNING AND REMAIN NORTHERLY THROUGH TONIGHT.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...12
AVIATION...SHEETS


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